Pseudochactidae Gromov, 1998, type genus: Pseudochactas Gromov, 1998.

Diagnosis: Pseudochactinae may be separated from the other two subfamilies of Pseudochactidae as follows. The anteromedian margin of the carapace is recessed (posterior to the anterolateral margins) and sublinear in Pseudochactinae (fig. 10) but protruding (anterior to the anterolateral margins) in the other subfamilies, convex (procurved) in Troglokhammouaninae (fig. 11) and shallowly concave (recurved) in Vietbocapinae (fig. 12). The posterolateral margins of the carapace are angular and slanting in Pseudochactinae (fig. 10) but gently curved in the other subfamilies (figs. 11, 12). The circumocular sutures of the carapace are complete and connected posteriorly in Pseudochactinae (fig. 10), complete but disconnected posteriorly in Troglokhammouaninae (fig. 11), and partial (disconnected) in Vietbocapinae (fig. 12). The dorsoventral projection (“anterior process”) on the prolateral surface of the pedipalp patella is pronounced in Pseudochactinae (fig. 23E, G) but moderately developed in the other subfamilies (figs. 28, 34, 38, 42). The secondary accessory and retroventral carinae of the pedipalp chela manus are entirely fused in Pseudochactinae (figs. 24C, 25C) but incompletely fused, with a slight disjunction evident in the proximal third, in the other subfamilies (figs. 29, 30, 35, 36, 39, 43). The ventral surface of the sternum is flat/planar in Pseudochactinae (fig. 13A, C) but shallowly concave in the other subfamilies (figs. 13B, D, 14). The spinules of the basitarsi and telotarsi of legs I–IV are short in Pseudochactinae (fig. 15A) but long in the other subfamilies (fig. 15B–D). The peg sensillae of the pectinal teeth are relatively short, stout, flattened and truncate distally, with laterodistal processes in Pseudochactinae but long, cylindrical, tubular or bottle shaped, and rounded distally, without laterodistal processes in the other subfamilies. The telson vesicle is globose in Pseudochactinae (fig. 20A, B) but elongate in the other subfamilies (figs. 20C, D, 21).

Pseudochactinae may be further separated from Troglokhammouaninae as follows. The base coloration of the tegument is yellow in Pseudochactinae but brown in Troglokhammouaninae. The dorsomedian, dorsal secondary, subdigital, and retromedian carinae of the pedipalp chela manus are absent, and the ventromedian carina vestigial, in Pseudochactinae (figs. 24, 25), whereas the dorsomedian, dorsal secondary and subdigital carinae are vestigial, and the retromedian and ventromedian carinae partial in Troglokhammouaninae (figs. 29, 30). The lateral margins of the sternum are sublinear in Pseudochactinae (fig. 13A, C) but recurved medially in Troglokhammouaninae (fig. 13B, D). The pectines possess 8–12 median lamellae and 9–13 teeth in Pseudochactinae (tables 3, 5, 6) but 12–16 median lamellae and 13–17 teeth in Troglokhammouaninae (tables 3, 5, 7, 8). The posterior granules of the dorsosubmedian and dorsolateral carinae of metasomal segments I–IV are similar in size and shape to the preceding granules in Pseudochactinae (fig. 16A, B) but markedly larger than the preceding granules and spiniform in Troglokhammouaninae (fig. 16C, D). The median lateral carinae are partial, becoming obsolete anteriorly on metasomal segment III, and vestigial or absent on IV in Pseudochactinae (fig. 18A, B) but complete on III and IV in Troglokhammouaninae (fig. 18C, D).

Pseudochactinae may be further separated from Vietbocapinae as follows. The tegument is infuscate (e.g., on the carapace, tergites, and legs) in Pseudochactinae but immaculate in Vietbocapinae. The median and lateral ocelli are present in Pseudochactinae (fig. 10) but absent in Vietbocapinae (fig. 12). The pedipalps are relatively robust, with the chela fingers of the adult male sinuous and sexually dimorphic in Pseudochactinae (figs. 24, 25), whereas the pedipalps are gracile, with the fingers of the adult male sublinear, and similar to the adult female in Vietbocapinae (figs. 35, 36). The prolateral ventral carina of the pedipalp chela manus is complete in Pseudochactinae (figs. 24D, 25D) but absent or obsolete in Vietbocapinae (figs. 35D, 36D, 39D, 43D). Tibial spurs are present on legs III and IV in Pseudochactinae (fig. 15A) but absent in Vietbocapinae (fig. 15C, D). The lateral and ventral surfaces of the telson vesicle possess granular carinae in Pseudochactinae (figs. 18A, B, 20A, B) whereas the lateral surfaces are smooth, and the ventral surfaces smooth or with sparsely granular (obsolete) carinae in Vietbocapinae (figs. 19, 21). The subaculear tubercle is obsolete (evident as a very small bump) in Pseudochactinae but absent in Vietbocapinae.

Included Taxa: One genus comprising two species (table 1): Pseudochactas Gromov, 1998.

Distribution: Endemic to Central Asia and presently recorded from the countries of Afghanistan, Tajikistan, and Uzbekistan (fig. 6).

Ecology: Both species of Pseudochactinae are epigean, occurring above ground (fig. 2).

Pseudochactas Gromov, 1998: 1003, type species by monotypy: Pseudochactas ovchinnikovi Gromov, 1998; Fet, 2000: 426; Lourenço, 2000a: 24, 32, fig. 6; 2001: 5; Soleglad and Fet, 2001: 1–4, 8, 12, 13, 19, 21, 22, 24, 28, 34, appendix B; 2003a: i, 8, 11–13, 18–20, 29, 30, 32–35, 53, 54, 60, 65–69, 72, 75–79, 88, 89, 121, 122, 135, 139, 143–146, 148, 150–155, 174, figs. 1, 4, 10–12, 41, 49, 57, 64, 92, 108, 115, B-1, B-2, B-3, tables 3, 4, 9, appendices A–C; 2003b: 5, 8, 9, 12, 18–20, 22, 24, 26, figs. 2, 3, 14; Fet et al., 2003: 2, 3, 5, 10, fig. 1, table 1, appendix; 2005: 4, 5, 9, 19–25, 27, figs. 1, 2, 23–25, table 2; Fet and Soleglad, 2005: 27, table 2; Prendini and Wheeler, 2005: 451, 454, 459–462, 470, 474, 482, tables 3, 5, 10; Fet et al., 2006: 272; Graham and Fet, 2006: 2, 11; Prendini et al., 2006: 211, 213, 216, 217, 219, 220, 222, 224–227, 229, 234, 235, 237–243, tables 1, 3, 4, 6, 7, figs. 8–10; Kovařík, et al., 2007: 207; Lourenço, 2007a: 771, 774; Volschenk et al., 2008: 651, 661, 663; Lourenço and Pham, 2010: 2; Loria and Prendini, 2014: 5, 19, 21, tables 2, 4; Lourenço, 2014: 37; Beron, 2018: 834; Francke, 2019: 14, 32, 38.

Preudochactas: Gromov, 1998: 1003.

Diagnosis: As for subfamily.

Included Taxa: Two species: Pseudochactas mischi Soleglad et al., 2012; Pseudochactas ovchinnikovi Gromov, 1998.

Distribution: As for subfamily.

Ecology: As for subfamily.

Pseudochactas mischi Soleglad et al., 2012: 89–97, tables I, II, figs. 1–13, 14–18 (part), 19a, 19b, 20, 21 (part); Howard et al., 2019: 74, fig. 3G.

Type Material: Holotype: 1 subad. ♀(FKPC), AFGHANISTAN: Uruzgan [Orozgan] Prov.: Tarin Kowt Distr.: Bolakh [Balagh] village, 1380 m (4300 ft), 32°32′N 65°40′E, xi.2011, M. Misch.

Diagnosis: Pseudochactas mischi may be separated from the morphologically similar P. ovchinnikovi, by means of differences in coloration and carination. The coloration is paler and yellowish, the carapace, tergites, and legs immaculate, in P. mischi but darker and brownish, the carapace, tergites and legs infuscate, in P. ovchinnikovi. The lyriform anterosubmedial carinae of the carapace are absent in P. mischi but obsolete, granular in P. ovchinnikovi (fig. 10). The retrodorsal carina of the pedipalp patella is costate in P. mischi but costate granular in P. ovchinnikovi (fig. 23E, F). The pedipalp chela, metasoma, and telson vesicle are more robust (proportionally shorter and broader) in P. mischi than P. ovchinnikovi (tables 3, 6). The pectines possess 8 or 9 median lamellae and 9 or 10 teeth in P. mischi (tables 3, 5) but 9–12 median lamellae and 10–13 teeth in P. ovchinnikovi (tables 3, 5, 6). The median lateral carinae are complete on metasomal segment II, and partial on V in P. mischi but partial, becoming obsolete anteriorly, on II, and absent or obsolete on V in P. ovchinnikovi (fig. 18A, B). The telson vesicle lateral and ventral surfaces are more coarsely and densely granular in P. mischi than P. ovchinnikovi (figs. 18A, B, 20A, B).

Description: The following description supplements the original description of the holotype. As Soleglad et al. (2012) suggested, the holotype and only known specimen is indeed a subadult female. The adults of both sexes are unknown.

Total length: Small, 18 mm (table 3).

Color: Tegument base coloration pale yellowish orange, immaculate. Chelicerae, pedipalps (except chela fingers), legs, posterior third of tergites and sternites, metasoma, and telson slightly paler than carapace, pedipalp chela fingers, and anterior two-thirds of tergites and sternites. Pedipalp chela fingers light reddish. Sternum, genital operculum, pectines, and sternites pale yellow. Aculeus black.

Chelicerae: Fixed finger, dorsal margin with four teeth (basal, median, subdistal, distal); basal and median teeth fused into bicuspid (“conjoined on trunk”); space between median and subdistal teeth U-shaped; ventral margin with four small denticles (ventral accessory denticles). Movable finger, dorsal margin with three teeth (median, subdistal, retrolateral distal), without basal teeth; ventral margin with four small denticles (ventral accessory denticles) and serrula in distal third; retrolateral (dorsal) distal and prolateral (ventral) distal teeth subequal, retrolateral (dorsal) distal tooth smaller than prolateral (ventral) distal tooth and opposable. Ventral surface of fingers and manus with numerous long, dense macrosetae.

Carapace: Carapace slightly wider than long. Anterior margin sublinear, shallowly recessed medially; anterolateral margins entire; posteromedian margin shallowly concave (recurved); posterolateral margins angular, slanting. One pair of very small anterolateral major (ALMa) ocelli situated close to anterolateral margins of carapace, other lateral ocelli absent. Anterosubmedial depressions, medial to lateral ocelli, well developed. Median ocular tubercle situated anteromedially on carapace, distance from anterior margin 33% of carapace length (table 3); pair of median ocelli considerably larger than lateral ocelli; superciliary carinae obsolete, not protruding above ocelli; interocular sulcus shallow, obsolete. Circumocular sutures complete, connected posteriorly (postocular); circumocular triangle subtriangular (broad V-shape); median ocular curvatures present. Anteromedian depression narrow, shallow; posteromedian sulcus very shallow anteriorly, becoming slightly deeper posteriorly; posterolateral sulci very shallow, wide, weakly curved; posteromarginal sulcus narrow, shallow. Carapacial surfaces smooth, except for sparse granulation anteromedially, and acarinate.

Pedipalps: Pedipalps relatively robust; segments almost apilose, sparsely covered in short microsetae and few macrosetae. Pedipalp femur length 67% greater than width (table 3). Femur with seven carinae evident; promedian carina obsolete, reduced to few spiniform granules in proximal two-thirds of segment; prodorsal, proventral and retrodorsal carinae well developed, granular to costate granular (serrate to crenulate); dorsomedian and retromedian carinae weak, granular rows; retroventral carina vestigial, comprising short granular row; dorsal intercarinal surface sparsely granular proximally; other intercarinal surfaces smooth. Pedipalp patella length 57% greater than width (table 3). Patella with six carinae evident; prodorsal carina well developed, granular; retrodorsal carina well developed, costate; proventral and retroventral carinae well developed, costate granular (crenulate); prolateral surface, dorsoventral “vaulted” projection (“anterior process”) well developed, with prominent pair of dorsal and ventral spiniform granules (“patellar spurs”) proximally, demarcating pair of vestigial, prolateral carinae (“dorsal and ventral patellar spur carinae”), reduced to two granules; dorsomedian, retromedian, and ventromedian carinae absent; intercarinal surfaces smooth. Pedipalp chela relatively short and broad; manus globose, height 4% greater than width and length 33% greater than width (table 3); length of movable finger 4% greater than length of manus. Chela with six carinae evident; dorsomedian carina reduced to few granules at base of fixed finger, becoming obsolete proximally on manus; digital carina well developed, granular in proximal sixth, remainder costate; secondary accessory and retroventral carinae entirely fused; retroventral carina well developed, granular proximally, becoming costate distally, aligned parallel to longitudinal axis of chela, with distal margin connected to retrolateral movable finger condyle; prodorsal, promedian, and proventral carinae weakly developed, each comprising few isolated granules; dorsal secondary, subdigital, retromedian (retrolateral secondary) and ventromedian carinae absent or obsolete; intercarinal surfaces smooth. Fixed and movable fingers, dentate margins sublinear (♀), no proximal “gap” evident when closed; median denticle rows comprising seven (n = 2) oblique and slightly imbricated subrows (tables 3, 4), decreasing in length distally; each subrow comprising large retrolateral denticle proximally (absent from proximal subrow, for total of six retrolateral denticles on fixed and movable fingers), several small median denticles, and large prolateral denticle distally, slightly offset (total of six and seven prolateral denticles on fixed and movable fingers, respectively); terminal (prolateral) denticle of first subrow enlarged; accessory denticles absent.

Trichobothria: Orthobothriotaxic, Type D, β configuration, trichobothrium d₂ situated on femur dorsal surface, d₃ and d₄ in same axis, parallel and closer to retrodorsal carina than d₁, angle formed by d₁, d₃ and d₄ opening toward prolateral surface, with the following segment totals: femur, 12 (6 dorsal, 3 prolateral, 3 retrolateral); patella, 10 (3 dorsal, 1 prolateral, 6 retrolateral); chela, 13 (5 manus, 8 fixed finger). Total number of trichobothria per pedipalp, 35. Five trichobothria on femur, i₄, d₁, d₂, d₄, and d₆, one on patella, est₁, and one on chela fixed finger, ib₂, noticeably smaller than others (“petite”). Trichobothrium Et₁ situated distally on manus, aligned with or proximal to movable finger condyle; eb situated on fixed finger, slightly distal to movable finger condyle; esb₂ situated in proximal third of fixed finger, approximately aligned with proximal retrolateral denticle of median denticle row.

Legs: Leg I maxillary lobes (coxapophyses), distal margins rounded, unmodified (not spatulate or dilate) anteriorly, terminating flush with lobes of leg II. Legs I and II tibiae, retrolateral margins each with scattered macrosetae, without spurs; III and IV with spurs, smooth, without spinelets. Basitarsi with few scattered macrosetae, pro- and retrolateral rows of short spinules, and pair of pro- and retrolateral pedal spurs. Telotarsi with pair of ventrosubmedian rows of short spinules; proventral and retroventral rows of macrosetae absent, only few scattered macrosetae laterally; laterodistal lobes reduced and truncated; median dorsal lobe very short; ungues short, distinctly curved, equal in length; unguicular spur (dactyl) pronounced, pointed.

Sternum: Sternum, Type 1, pentagonal, length 5% greater than posterior width (table 3), lateral margins sublinear, parallel, ventral surface flat, without concave region or median furrow, posteromedian depression wide, shallow.

Pectines: Three marginal (anterior) lamellae, proximal sclerite considerably longer, distal sclerite short; eight or nine median lamellae (tables 3, 5); fulcra present, very small. Proximal median lamella and basal pectinal tooth unmodified. Pectinal teeth present along entire posterior margin of each pecten (♀); tooth count: nine or 10 (♀). Pectinal peg sensillae unknown.

Genital operculum: Opercular sclerites completely separated, genital papillae absent (♀).

Male and female reproductive organs: Unknown.

Mesosoma: Pre- and posttergites I–VI surfaces smooth, acarinate, each with pair of shallow submedian depressions; VII surface smooth, with pair of costate granular (crenulate) dorsosubmedian and dorsolateral carinae almost reaching posterior margin of segment. Sternites III–VII surfaces smooth, acarinate; III–VI, respiratory spiracles (stigmata) small, subcircular.

Metasoma: Metasoma relatively short, total length 31% greater than combined length of prosoma and mesosoma (table 3); segments I–V progressively increasing in length, I–III wider than long, width of length for segment I, 156%; II, 124%; III, 113%; IV, 89%; and V, 46%. Metasoma almost apilose, sparsely covered in short microsetae. Eight carinae on segments I, IV, and V, 10 on II and III. Dorsosubmedian carinae well developed, costate granular (crenulate) throughout length of segments I–IV, absent on V; converging posteriorly. Dorsolateral carinae well developed, costate granular (crenulate) throughout length of segments I–V; converging posteriorly on I and V, subparallel on II–IV. Dorsosubmedian and dorsolateral carinae of segments I–IV each terminating posteriorly with slightly enlarged granule. Median lateral carinae complete, costate granular (crenulate) throughout length of segments I and II, partial, reduced to posterior half on III, obsolete on IV, partial, granular, reduced to anterior half on V. Ventrolateral carinae well developed, costate granular (crenulate) on I–V; converging posteriorly on I and V, subparallel on II–IV. Ventrosubmedian carinae absent or obsolete on segment I, obsolete, granular to costate granular (crenulate) on II, well developed, costate granular (crenulate) throughout length of III–V; subparallel on II and III, converging posteriorly on IV and V. Ventromedian carina obsolete on segment V. Intercarinal surfaces smooth.

Telson: Telson large, suboval. Vesicle globose, 4% wider than metasomal segment V (table 3), with flattened dorsal surface and rounded ventral surface, height 54% of length; dorsal surface smooth, lateral surfaces with three pairs of granular carinae, ventral surfaces with two pairs of granular carinae; anterodorsal lateral lobes (“vesicular tabs”) distinct, each with two spiniform granules; subaculear tubercle very small, obsolete. Aculeus short, shallowly curved, 35% of telson length. Venom glands unknown.

Variation and sexual dimorphism: Unknown.

Distribution: Known only from the type locality, near Bolakh [Balagh] village, in the Tarin Kowt District of the Uruzgan [Orozgan] Province of Afghanistan (fig. 6). At 1380 m, the type locality is the highest elevation recorded for the family (Soleglad et al., 2012).

Ecology: The habitat and habitus of this species are consistent with the lapidicolous ecomorphotype (Prendini, 2001b). The holotype and only known specimen was collected in an arid, semidesert area, from under a stone in semiwet soil on the eastern bank of a dry riverbed (wadi) named Sarab Kariz, running from north to south (Soleglad et al., 2012). The remains of an exuvium, likely belonging to the same species, were found less than 50 m away, in the same wadi. According to Soleglad et al. (2012), the humid conditions of this microhabitat are noteworthy because P. ovchinnikovi also exhibits affinity to wet microhabitats (Fet et al., 2004; Prendini et al., 2006), which is unusual for Central Asian scorpions.

Soleglad et al. (2012) mention at least three species of Buthidae found in sympatry with P. mischi at the type locality: Hottentotta saulcyi (Simon, 1880), Mesobuthus haarlovi Vachon, 1958 and Orthochirus afghanus Kovařík, 2004.

Conservation Status: Pseudochactas mischi is presently known from only a single locality. Although the true extent of its distribution is unknown, its apparent ecological requirement for humidity suggests a restricted area of occupancy in the predominantly arid environment of south-central Afghanistan. Therefore, this species is characterized by an acute restriction in both its area of occupancy and number of known localities: it is only known to exist at a single location, the extent of occurrence is less than 5000 km², and the area of occupancy less than 500 km². Additionally, a continuing decline in the quality of its habitat is observed, inferred, and projected. According to Soleglad et al. (2012), the wadi where P. mischi was collected, was largely undisturbed until around the year 2000, when roads were constructed and the local population was able to collect firewood and livestock feed. The impact of this habitat degradation on P. mischi is unknown but presumed to be negative. The threat of habitat degradation, taken together with the restricted distributional range, which is completely unprotected, warrants its assignment to the Endangered category of the IUCN Red List. This species is expected to be prone to the effects of human activities (or stochastic events, the impact of which is increased by human activities, e.g., climate change) within a very short period of time in an unforeseeable future and is therefore considered to be facing a very high risk of extinction in the wild.

Pseudochactas ovchinnikovi Gromov, 1998: 1003–1008, figs. 1, 2 (1–12), and 3 (1–8); Fet, 2000: 426; Lourenço, 2000a: 32, fig. 6; Soleglad and Fet, 2001: 1, 22; 2003a: i, 8, 11, 12, 18, 20, 29, 30, 32, 33, 54, 60, 65, 67, 150–153, 155, figs. 1, 4, 10–12, 41, 49, 57, 92, 108, B-1, B-2, B-3, appendices B, C; 2003b: 5, 8, 18, 20, figs. 2, 3, 14; Fet et al., 2003: 2, 3, 5, fig. 1, table 1; 2004: 61, 62, 66, fig. 1; 2005: 4, 6, fig. 3; Prendini and Wheeler, 2005: 454, table 5; Fet et al., 2006: 269, 271, table 1; Graham and Fet, 2006: 1, 4, fig. 1; Prendini et al., 2006: 211, 212, 214, 215, 217, 220–224, 228–239, tables 1, 6, 7, figs. 1–7, 11–47; Lourenço, 2007a: 771; 2007b: 5, 6; Kamenz and Prendini, 2008: 8, 21, 22, table 2, pl. 1, appendix 1; Soleglad and Fet, 2008: 29; Volschenk et al., 2008: 652, 655, 661, 663, 665, 670, 675, tables 1, 2, fig. 3C, appendix; Lourenço and Pham, 2010: 1, 2, 12; Botero-Trujillo and Noriega, 2011: 41; Lourenço, 2012a: 237, appendix A; Lourenço and Pham, 2012: 80, 84; Soleglad et al., 2012: 89, 90, 92–97, tables I, II, figs. 14–18 (part), 21 (part); Klußmann-Fricke et al., 2012: 546, table 1; Loria and Prendini, 2014: 12, fig. 3F, appendix S1: 10, appendix S2: 7; Lourenço, 2014: 36; Borges and Graham, 2016: 89; Lourenço, 2017a: 19; Lourenço et al., 2018: 265; Teruel et al., 2020: 10.

Type Material: UZBEKISTAN: Surkhandarya Region: Uzun Distr.: Holotype: 1 subad. ♂(ZMMSU), Okmachit [Ak-Mechet], ca. 7 km W–4 km WSW, E slope of Babatag Mt. Range, 38°02′50″N 68°14′22″E–38°01′45″N 68°15′30″E, 760–1010 m, 29.iv–9.v.1994, A.V. Gromov. Para-types: 2 ♀, 3 subad. ♂ (AGPC) [examined], 3 [subad.?] ♂ (VFPC), Okmachit [Ak-Mechet], ca. 7 km W–4 km WSW, E slope of Babatag Mt. Range, 38°02′50″N 68°14′22″E–38°01′45″N 68°15′30″E, 760–1010 m, 29.iv–9.v.1994, A.V. Gromov and S.V. Ovchinnikov. TAJIKISTAN: Leninskii Distr.: Paratype ♀ (AGPC), Aruktau Mt. Range, near Gandzhina village [37°58′N 68°34′E], 10.iv.1988, S.L. Zonstein and A.S. Zorkin [examined].

Diagnosis: Pseudochactas ovchinnikovi may be separated from the morphologically similar P. mischi, by means of differences in coloration and carination. The coloration is darker and brownish, the carapace, tergites, and legs infuscate, in P. ovchinnikovi but paler and yellowish, the carapace, tergites, and legs immaculate, in P. mischi. The lyriform anterosubmedial carinae of the carapace are obsolete, granular in P. ovchinnikovi (fig. 10) but absent in P. mischi. The retrodorsal carina of the pedipalp patella is costate granular in P. ovchinnikovi (fig. 23E, F) but costate in P. mischi. The pedipalp chela, metasoma, and telson vesicle are more gracile (proportionally longer and narrower) in P. ovchinnikovi than P. mischi (tables 3, 6). The pectines possess 9–12 median lamellae and 10–13 teeth in P. ovchinnikovi (tables 3, 5, 6) but 8 or 9 median lamellae and 9 or 10 teeth in P. mischi (tables 3, 5). The median lateral carinae are partial, becoming obsolete anteriorly, on metasomal segment II, and absent or obsolete on V in P. ovchinnikovi (fig. 18A, B) but complete on segment II, and partial on V in P. mischi. The telson vesicle lateral and ventral surfaces are more finely and sparsely granular in P. ovchinnikovi (figs. 18A, B, 20A, B) than P. mischi.

Description: The following description, based on the material examined, including the only known adult male and 20 adult females, updates the description of Prendini et al. (2006), augmenting Gromov's (1998) original description, Soleglad and Fet's (2001) interpretation of the Type D trichobothrial pattern, Soleglad and Fet's (2003b) definition of the Type 1 sternum of P. ovchinnikovi, and supplemental data by Soleglad and Fet (2003a), Fet et al. (2004), and Soleglad et al. (2012).

Total length: Small, 19.4 mm (♂) or 27.6 mm (22.6–30 mm, n = 11) (♀) (tables 3, 6).

Color: Tegument base coloration yellow to light brown. Carapace diffusely infuscate, with brownish marbled pattern; tergites entirely infuscate or infuscate in anterior two-thirds, brownish; pedipalp chela fingers darker, lightly infuscate, reddish brown; prolateral surfaces of leg femora and patellae infuscate, brownish; other surfaces immaculate, yellowish. Chelicerae, pedipalps (except chela fingers), legs, posterior third of tergites, metasoma, and telson slightly paler than carapace (fig. 1A). Leg tibiae and tarsi, and retrolateral surfaces of femora and patellae, sternum, genital operculum, pectines and sternites pale yellow. Aculeus black.

Chelicerae: Fixed finger, dorsal margin with four teeth (basal, median, subdistal, distal); basal and median teeth fused into bicuspid (“conjoined on trunk”); space between median and subdistal teeth U-shaped; ventral margin with four or five small denticles (ventral accessory denticles). Movable finger, dorsal margin with three teeth (median, subdistal, retrolateral distal), without basal teeth; ventral margin with four or five small denticles (ventral accessory teeth) and serrula in distal third; retrolateral (dorsal) distal and prolateral (ventral) distal teeth subequal, retrolateral (dorsal) distal tooth only slightly smaller than prolateral (ventral) distal tooth, and opposable. Ventral surface of fingers and manus with numerous long, dense macrosetae.

Carapace: Carapace slightly longer than wide, anterior width 61% (♂) or 57% (55%–60%, n = 9) (♀) of length, posterior width 100% (♂) or 97% (92%–103%, n = 9) (♀) of length (table 6). Anterior margin sublinear, shallowly recessed medially; anterolateral margins entire; posteromedian margin shallowly concave (recurved); posterolateral margins angular, slanting (fig. 10). One pair of very small anterolateral major (ALMa) ocelli situated close to anterolateral margins of carapace, other lateral ocelli absent. Anterosubmedial depressions, medial to lateral ocelli, well developed. Median ocular tubercle situated anteromedially on carapace, distance from anterior margin 23% (♂) or 29% (27%–34%, n = 9) (♀) of carapace length (table 6); pair of median ocelli considerably larger than lateral ocelli; pair of weakly developed, smooth superciliary carinae, not protruding above ocelli; interocular sulcus shallow, obsolete. Circumocular sutures complete, connected posteriorly (postocular); circumocular triangle subtriangular (broad V-shape); median ocular curvatures present. Anteromedian depression narrow, shallow; posteromedian sulcus very shallow anteriorly, becoming slightly deeper posteriorly; posterolateral sulci very shallow, wide, weakly curved; posteromarginal sulcus narrow, shallow. Carapacial surfaces almost entirely smooth, except for scattered, fine granulation on interocular surface and along anterior margin; acarinate, except for pair of obsolete, granular anterosubmedial carinae, arranged in lyriform configuration, anterior to median ocular tubercle and prolateral to circumocular sutures.

Pedipalps: Pedipalps relatively robust; segments almost apilose, sparsely covered in short microsetae and occasional macrosetae. Pedipalp femur length 67% (♂) or 67% (64%–69%, n = 11) (♀) greater than width (tables 3, 6). Femur with eight carinae evident (fig. 23A–D); promedian carina obsolete, reduced to few spiniform granules in proximal two-thirds of segment; prodorsal, proventral, and retrodorsal carinae well developed, costate granular; dorsomedian carina weak, granular; retromedian carina weak, comprising short row of granules medially; retroventral and ventromedian carinae vestigial, reduced to few granules proximally; intercarinal surfaces smooth. Pedipalp patella length 56% (♂) or 54% (50%–59%, n = 11) (♀) greater than width (tables 3, 6). Patella with six carinae evident (fig. 23E–H); retrodorsal, retroventral, and proventral carinae well developed, costate granular to costate; prodorsal carina well developed, granular to costate granular; prolateral surface, dorsoventral “vaulted” projection (“anterior process”) well developed, with prominent pair of dorsal and ventral spiniform granules (“patellar spurs”) proximally, the dorsal more strongly developed, demarcating pair of obsolete, granular prolateral carinae (“dorsal and ventral patellar spur carinae”); dorsomedian, retromedian, and ventromedian carinae absent; intercarinal surfaces smooth. Pedipalp chela relatively short and broad; manus globose, width 17% (♂) or 26% (13%–37%, n = 9) (♀) greater than height and length 30% (♂) or 28% (21%–38%, n = 11) greater than width (tables 3, 6); length of movable finger 25% (♂) or 16% (12%–21%, n = 11) (♀) greater than length of manus. Chela with seven carinae evident (figs. 24, 25); dorsomedian carina reduced to weak row of granules at base of fixed finger, becoming obsolete proximally on manus; digital carina well developed, granular to costate granular; dorsal secondary, subdigital and retromedian (retrolateral secondary) carinae absent; secondary accessory and retroventral carinae entirely fused; retroventral carina well developed, granular, aligned parallel to longitudinal axis of chela, with distal margin connected to retrolateral movable finger condyle; ventromedian carina vestigial, reduced to proximal granules; proventral carina obsolete, reduced to few isolated granules near prolateral condyle of movable finger; prodorsal and promedian carinae weakly developed, each comprising series of isolated granules; intercarinal surfaces smooth except for coarse, scattered granules on prolateral surface of manus, near base of fixed and movable fingers, granulation becoming very fine and even on fingers. Fixed and movable fingers, dentate margins sublinear (♀) or slightly sinuous, movable finger with very shallow lobe, proximally and fixed finger with correspondingly shallow notch, proximally (♂), no proximal “gap” evident when closed; median denticle rows comprising seven (n = 107) oblique and slightly imbricated subrows (tables 4, 6), decreasing in length distally; each subrow comprising large retrolateral denticle proximally (absent from proximal subrow, for total of six retrolateral denticles on fixed and movable fingers), several small median denticles, and large prolateral denticle distally, slightly offset (total of seven prolateral denticles on fixed and movable fingers); terminal (prolateral) denticle of first subrow enlarged; accessory denticles absent.

Trichobothria: Orthobothriotaxic, Type D, β configuration, trichobothrium d₂ situated on femur dorsal surface, d₃ and d₄ in same axis, parallel and closer to retrodorsal carina than d₁, angle formed by d₁, d₃ and d₄ opening toward prolateral surface, with the following segment totals (figs. 23–25): femur, 12 (6 dorsal, 3 prolateral, 3 retrolateral); patella, 10 (3 dorsal, 1 prolateral, 6 retrolateral); chela, 13 (5 manus, 8 fixed finger). Total number of trichobothria per pedipalp, 35. Five trichobothria on femur, i₄, d₁, d₂, d₄, and d₆, one on patella, est₁, and one on chela fixed finger, ib₂, noticeably smaller than others (“petite”). Trichobothrium Et₁ situated distally on manus, aligned with or proximal to movable finger condyle; eb situated on fixed finger, slightly distal to movable finger condyle; esb₂ situated in proximal third of fixed finger, approximately aligned with proximal retrolateral denticle of median denticle row.

Legs: Leg I maxillary lobes (coxapophyses), distal margins rounded, unmodified (not spatulate or dilate) anteriorly, terminating flush with lobes of leg II (fig. 22B, D). Legs I and II tibiae, retrolateral margins each with scattered macrosetae, without spurs (fig. 15A); III and IV with spurs, smooth, without spinelets. Basitarsi with few scattered macrosetae, pro- and retrolateral rows of short spinules, and pair of pro- and retrolateral pedal spurs. Telotarsi with pair of ventrosubmedian rows of short spinules; proventral and retroventral rows of macrosetae absent, only few scattered macrosetae laterally; laterodistal lobes reduced and truncated; median dorsal lobe very short; ungues short, distinctly curved, equal in length; unguicular spur (dactyl) pronounced, pointed.

Sternum: Sternum, Type 1, pentagonal, posterior width 100% (♂) or 89% (80%–103%, n = 11) (♀) of length (tables 3, 6), lateral margins sublinear, parallel, ventral surface flat, without concave region or median furrow, posteromedian depression round, moderately developed, defined posteriorly by slight outer ridge (fig. 13A, C).

Pectines: Three marginal (anterior) lamellae, proximal sclerite considerably longer, distal sclerite short (fig. 13A, C); 10/11 (9–12, n = 54) (♂) or 10/10 (9 or 10, n = 50) (♀) median lamellae (tables 5, 6); fulcra present, very small. Proximal median lamella and basal pectinal tooth unmodified. Pectinal teeth present along entire posterior margin of each pecten (♂, ♀); 11/12 (10–13, n = 54) (♂) or 11/11 (10 or 11, n = 53) (♀) teeth. Pectinal peg sensillae short, stout, flattened and truncate distally, with pair of laterodistal processes; sensillar sockets smooth.

Genital operculum: Opercular sclerites completely separated, prominent genital papillae visible along entire length (♂) or absent (♀) (fig. 13A, C). Genital plugs observed in some females.

Male reproductive organs: Paraxial organ without accessory glands. Hemispermatophore lamelliform, pars recta absent; basal lobe present.

Female reproductive organs: Ovariuterus comprising reticulate mesh of six cells. Oocytes contained in sessile follicles directly contacting ovaruterine tubes.

Mesosoma: Pretergites surfaces smooth and shiny. Posttergites I–VI surfaces very finely and uniformly granular, granulation becoming slightly coarser near posterior margins, acarinate, each with pair of shallow submedian depressions (fig. 22A, C); VII surface smooth, with pair of costate granular dorsosubmedian and dorsolateral carinae almost reaching posterior margin of segment. Sternites III–VII surfaces entirely smooth, acarinate (fig. 22B, D), with scattered macrosetae, posterior margins with sparse row of macrosetae; III–VI, respiratory spiracles (stigmata) small, oval (fig. 13A, C); V posteroventral margin with pale, raised, triangular surface; VII width 38% (♂) or 41% (37%–45%, n = 9) (♀) greater than length (table 6).

Metasoma: Metasoma relatively short, total length 30% (♂) or 19% (12%–25%, n = 8) (♀) greater than combined length of prosoma and mesosoma (table 6); segments I–V progressively increasing in length, I and II wider than long, width of length for segment I, 124% (♂) or 148% (129%–169%, n = 11) (♀); II, 100% (♂) or 107% (97%–121%) (♀); III, 92% (♂) or 91% (86%–100%) (♀); IV, 65% (♂) or 71% (65%–76%) (♀); and V, 37% (♂) or 38% (35%–43%) (♀). Metasoma almost apilose, sparsely covered in short microsetae. Eight carinae on segments I and IV, 10 on II and III, and nine on V (figs. 16A, B, 18A, B, 20A, B). Dorsosubmedian carinae well developed, costate granular throughout length of segments I–IV, absent on V; converging posteriorly. Dorsolateral carinae well developed, costate granular throughout length of segments I–V; converging posteriorly on I and V, subparallel on II–IV. Dorsosubmedian and dorsolateral carinae of segments I–III each terminating posteriorly with slightly enlarged granule. Median lateral carinae complete, costate granular throughout length of segment I, partial, granular, becoming obsolete anteriorly on II and III, vestigial or absent on IV, reduced to few granules medially or absent on V. Ventrolateral carinae well developed, costate granular, but becoming obsolete anteriorly on segment I, continuous throughout length of II–V; converging posteriorly on I and V, subparallel on II–IV. Ventrosubmedian carinae absent or obsolete on segment I, obsolete, costate on II, well developed, costate granular throughout length of III–V; subparallel on II and III, converging posteriorly on IV and V. Ventromedian carina absent or obsolete, comprising weak row of granules, on segment V. Intercarinal surfaces smooth.

Telson: Telson large, suboval (figs. 16A, B, 18A, B, 20A, B). Vesicle globose, 9% (♂) or 19% (11%–29%, n = 11) (♀) wider than metasomal segment V (tables 3, 6), with flattened dorsal surface and rounded ventral surface, height 52% (♂) or 50% (47%–54%, n = 11) of length; dorsal surface smooth, lateral surfaces with three pairs of obsolete, granular carinae, ventral surfaces with two pairs of obsolete, granular carinae; anterodorsal lateral lobes (“vesicular tabs”) distinct, each with two spiniform granules; subaculear tubercle very small, obsolete. Aculeus short, shallowly curved, 22% (♂) or 29% (27%–30%, n = 10) (♀) of telson length. Venom glands thin walled, simple, and unfolded.

Intraspecific variation: No significant variation.

Ontogenetic variation: Immature stages of P. ovchinnikovi are paler in color and less sclerotized than adults, and the posteroventral margin of mesosomal sternite V does not exhibit a pale, raised, triangular surface as in the adults of both sexes. Males and females closely resemble one another externally until the final instar. However, immature stages are easily sexed by examination of the genital aperture. Most of the specimens identified as adult males by Gromov (1998) are subadult. These include the largest male specimens examined by Prendini et al. (2006). Upon dissection, none of these specimens possessed gonads or hemispermatophores, and are probably penultimate instars. The sole confirmed adult male specimen lacks a distended mesosoma and is slightly secondarily sexually dimorphic, but also significantly smaller (carapace length, 2.3 mm; table 6) than most of the other males examined. More adult male specimens need to be collected to determine whether penultimate instars are larger than sexually mature males or this male specimen is simply a small adult.

Sexual dimorphism: The genital papillae, visible the entire length and thus completely separating the two sclerites of the genital operculum (fig. 13A), are the characters of primary external sexual dimorphism in the male. The opercular sclerites are also separated for most of their length in the female, although genital papillae are absent (fig. 13C). Few secondary sexual characters are observed in the only confirmed adult male, compared with adult females and immature stages of both sexes. The most obvious are the slightly more developed pectines, the teeth of which are somewhat larger, although similar in number (fig. 13A, C; tables 5, 6). In addition, the adult male is proportionally more slender (fig. 22), with a slightly longer metasoma and telson (table 6), slightly longer and more sinuous fingers on the pedipalp chela (figs. 24, 25), and slightly more pronounced granulation on the carapace, pedipalps, and tergites, than the adult female.

Distribution: Pseudochactas ovchinnikovi is known from only a few localities in the Babatag mountain range of southeastern Uzbekistan and a single locality in the Aruktau mountain range (southern foothills of Gardaniushti range) of southwestern Tajikistan (fig. 6). The localities in Uzbekistan are separated from the locality in Tajikistan by the Kofirnixon River. Most of the specimens originate from Dikhana (Dukhana or Dukhone) Canyon, on the eastern slopes of the Babatag range. All the known locality records occur at elevations ranging from 720–1010 m, in a semiarid savanna dominated by sparse grasses, xerophile perennials and Pistachio trees (Gromov, 1998; Prendini et al., 2006; Soleglad et al., 2012).

Ecology: Pseudochactas ovchinnikovi is a lapidicolous species (Prendini, 2001b) that inhabits the cracks and crevices of near vertical mud walls on steep, eroded riverbanks and gullies (fig. 2). Compared with the pseudochactid species inhabiting the caves of Southeast Asia, P. ovchinnikovi is rather compressed dorsoventrally, presumably an adaptation to its relatively arid habitat. A few specimens have been found under stones. Most of the specimens were collected during the spring months of April–May, when much of the annual rainfall is received in the region (Gromov, 1998; Soleglad and Fet, 2003a; Fet et al., 2004). Specimens collected by the first author were found to be more abundant on humid nights, especially following convectional thunderstorms that occurred during the late afternoon. Several were found very close to the edge of a small stream, sitting on moist mud banks, suggesting a requirement for high humidity. Fet et al. (2004) and Soleglad et al. (2012) likewise reported finding P. ovchinnikovi actively foraging at night on wet mud along the small temporary stream at the bottom of Dikhana Canyon. It is not known whether P. ovchinnikovi spends most of the dry season in aestivation, as suggested by Soleglad and Fet (2003a) and Fet et al. (2004). Specimens were observed to be actively moving on the mud faces, suggesting the species is an errant forager (Bradley, 1988; Polis, 1990; Prendini, 2001b), and were very sensitive to light, retreating rapidly into cracks in the mud walls even when exposed to the UV.

At the Dikhana Canyon, P. ovchinnikovi was collected in sympatry with three other scorpion species, all buthids: Mesobuthus eupeus (C.L. Koch, 1839), Mesobuthus kreuzbergi Fet et al., 2018, and Orthochirus scrobiculosus (Grube, 1873). The much larger M. kreuzbergi was common in the cracks and crevices of the mud walls inhabited by P. ovchinnikovi, but preferred drier situations, further from the stream; O. scrobiculosus was also found there but was far less common. Mesobuthus eupeus was not syntopic with these species; it was found under stones and in burrows on flat ground between the riverbanks.

Conservation Status: Despite the low agricultural potential of the semiarid savanna in which P. ovchinnikovi occurs, the habitat is heavily utilized for livestock grazing by the local subsistence farming community. Much of the herbaceous layer has been heavily overgrazed, especially by goats, and widespread soil erosion is evident (fig. 2). The impact of this habitat degradation on P. ovchinnikovi is unknown but presumed to be negative. The threat of habitat degradation, taken together with the fairly restricted distributional range, which is completely unprotected, warrants its assignment to the Endangered category of the IUCN Red List. This species is characterized by an acute restriction in both its area of occupancy and number of known localities: it is known to exist at fewer than five fragmented locations, the extent of occurrence is estimated to be less than 5000 km², and the area of occupancy is estimated to be less than 500 km². A continuing decline in the quality of its habitat is observed, inferred, and projected. This species is expected to be prone to the effects of human activities (or stochastic events, the impact of which is increased by human activities, e.g., climate change) within a very short period of time in an unforeseeable future, and is therefore considered to be facing a very high risk of extinction in the wild.

Material Examined: UZBEKISTAN: Surkhandarya Region: Uzun Distr.: Okmachit [Ak-Mechet], ca. 7 km W–4 km WSW, E slope of Babatag Mt. Range, 38°02′50″N 68°14′22″E–38°01′45″N 68°15′30″E, 760–1010 m, 29.iv–9.v.1994, A.V. Gromov, 1 ♀, 6 juv. (AGPC); Okmachit, ca. 7 km W, E slope of Babatag Mt. Range, 38°02′50″N 68°14′22″E, ca. 1010 m, 13.v.1995, O.V. Lyakhov, 2 juv. (AGPC); Okmachit, ca. 6.5–7 km W, E slope of Babatag Mt. Range, 38°02′50″N 68°14′22″E–38°02′04″N 68°14′51″E, 905–1010 m, 30.iv–2.v.2002, A.V. Gromov, 6 ♀, 7 subad. ♂, 1 subad. ♀, 26 juv. (AGPC); Okmachit, ca. 5 km WSW, E slope of Babatag Mt. Range, 38°02′26″N 68°14′59″E–38°02′01″N 68°15′08″E, 760–830 m, 3.v.2002, A.V. Gromov, 1 ♀, 10 juv. (AGPC); Okmachit, ca. 5–6 km WSW, E slope of Babatag Mt. Range, 38°02′01″N 68°14′03″E–38°01′36″N 68°15′00″E, 730–870 m, 4.v.2002, A.V. Gromov, 1 ♂, 1 subad. ♂ (AMNH), 3 ♀, 16 subad. ♂, 1 subad. ♀, 67 juv. (AGPC); Dikhana [Dukhana] Canyon, foothills of E slopes of Babatag Mountain Range, ca. 5 km WSW of Akmechet village, 38°01′38.3″N 68°15′11.9″E, 722 m, 20–24.v.2003, L. Prendini and A.V. Gromov, UV detection on earthen walls and rocky slopes along riverbanks and canyon walls through mountains, hard clayey soil, short grass cover with small trees and shrubs, 9 ♀, 9 subad. ♂, 3 subad. ♀, 18 juv. ♂, 10 juv. ♀ (AMNH), 3 juv. ♀ (AMCC 159928 [LP 2303A–C]); Dikhana Canyon, ca. 5.5 km WSW of Okmachit, E slope of Babatag Mt. Range, 38°01′33″N 68°14′26″E, ca. 774 m, 22.v.2003, A.V. Gromov and L. Prendini, 1 juv. (AGPC).

Type genus, here designated: Troglokhammouanus Lourenço, 2007.

Diagnosis: Troglokhammouaninae may be separated from the other two subfamilies of Pseudochactidae as follows. The base coloration of the tegument is brown in Troglokhammouaninae but yellow in the other subfamilies. The anteromedian margin of the carapace is convex (procurved) in Troglokhammouaninae (fig. 11) but sublinear in Pseudochactinae (fig. 10) and shallowly concave (recurved) in Vietbocapinae (fig. 12). The circumocular sutures of the carapace are complete but disconnected posteriorly in Troglokhammouaninae (fig. 11), complete and connected posteriorly in Pseudochactinae (fig. 10), and partial (disconnected) in Vietbocapinae (fig. 12). The dorsomedian, dorsal secondary, and subdigital carinae of the pedipalp chela manus are vestigial, and the retromedian and ventromedian carinae partial in Troglokhammouaninae (figs. 29, 30), whereas the dorsomedian, dorsal secondary, subdigital, and retromedian carinae are absent, and the ventromedian carina vestigial, in the other subfamilies (figs. 24, 25, 35, 36, 39, 43). The lateral margins of the sternum are recurved medially in Troglokhammouaninae (fig. 13B, D) but sublinear in the other subfamilies (figs. 13A, C, 14). The posterior granules of the dorsosubmedian and dorsolateral carinae of metasomal segments I–IV are markedly larger than the preceding granules and spiniform in Troglokhammouaninae (fig. 16C, D) but similar in size and shape to the preceding granules, in the other subfamilies (figs. 16A, B, 17). The median lateral carinae of metasomal segments III and IV are complete in Troglokhammouaninae (fig. 18C, D) but partial, becoming obsolete anteriorly on III, and vestigial or absent on IV in the other subfamilies (figs. 18A, B, 19).

Troglokhammouaninae may be further separated from Pseudochactinae as follows. The anteromedian margin of the carapace is protruding (anterior to the anterolateral margins) in Troglokhammouaninae (fig. 11) but recessed (posterior to the anterolateral margins) in Pseudochactinae (fig. 10). The posterolateral margins of the carapace are gently curved in Troglokhammouaninae (fig. 11) but angular and slanting in Pseudochactinae (fig. 10). The dorsoventral projection (“anterior process”) on the prolateral surface of the pedipalp patella is moderately developed in Troglokhammouaninae (fig. 28E, G) but pronounced in Pseudochactinae (fig. 23E, G). The secondary accessory and retroventral carinae of the chela manus are incompletely fused, with a slight disjunction evident in the proximal third, in Troglokhammouaninae (figs. 29C, 30C) but entirely fused in Pseudochactinae (figs. 24C, 25C). The ventral surface of the sternum is shallowly concave in Troglokhammouaninae (fig. 13B, D) but flat/planar in Pseudochactinae (fig. 13A, C). The spinules of the basitarsi and telotarsi of legs I–IV are long in Troglokhammouaninae (fig. 15B) but short in Pseudochactinae (fig. 15A). The pectines possess 12–16 lamellae and 13–17 teeth in Troglokhammouaninae (tables 3, 5, 7, 8) but 8–12 median lamellae and 9–13 teeth in Pseudochactinae (tables 3, 5, 6). The peg sensillae of the pectinal teeth are long, cylindrical, tubular or bottle shaped, and rounded distally, without laterodistal processes in Troglokhammouaninae but relatively short, stout, flattened, and truncate distally, with laterodistal processes in Pseudochactinae. The telson vesicle is elongate in Troglokhammouaninae (fig. 18C, D) but globose in Pseudochactinae (fig. 18A, B).

Troglokhammouaninae may be further separated from Vietbocapinae as follows. The tegument is infuscate (e.g., on the carapace, tergites, and legs) in Troglokhammouaninae but immaculate in Vietbocapinae. The median and lateral ocelli are present in Troglokhammouaninae (fig. 11) but absent in Vietbocapinae (fig. 12). The pedipalps are relatively robust, with the chela fingers of the adult male sinuous and sexually dimorphic in Troglokhammouaninae (figs. 29, 30), whereas the pedipalps are gracile, with the chela fingers of the adult male sublinear and similar to the adult female in Vietbocapinae (figs. 35, 36). The prolateral ventral carina of the pedipalp chela manus is complete in Troglokhammouaninae (figs. 29D, 30D) but absent or obsolete in Vietbocapinae (figs. 35D, 36D, 39D, 43D). Tibial spurs are present on legs III and IV in Troglokhammouaninae (fig. 15B) but absent in Vietbocapinae (fig. 15C, D). The lateral and ventral surfaces of the telson vesicle possess granular carinae in Troglokhammouaninae (figs. 18C, D, 20C, D), whereas the lateral surfaces are smooth and the ventral surfaces smooth or with sparsely granular (obsolete) carinae in Vietbocapinae (figs. 19, 21). The subaculear tubercle is obsolete (evident as a very small bump) in Troglokhammouaninae (fig. 18C, D) but absent in Vietbocapinae (fig. 19).

Included Taxa: As defined in the present contribution, Troglokhammouaninae accommodates one genus and species (table 1): Troglokhammouanus Lourenço, 2007.

Distribution: Endemic to the Southeast Asian country of Laos, where it has been recorded only in Khammouane Province (fig. 7).

Ecology: The sole species of Troglokhammouaninae is hypogean, having been collected below ground, in caves (fig. 3).

Remarks: The morphological similarities between Troglokhammouanus and Pseudochactas are mostly symplesiomorphic. Phylogenetic analyses, whether based on morphology, DNA sequences or a combination thereof, place Troglokhammouanus as the sister group of Vietbocapinae, rendering the nominotypical subfamily, Pseudochactinae, paraphyletic. A new, monotypic subfamily, Troglokhammouaninae, is hereby created to restore the monophyly of Pseudochactinae.

Troglokhammouanus Lourenço, 2007a: 774, type species by monotypy: Troglokhammouanus steineri Lourenço, 2007a; 2007b: 1–6, figs. 1–24; Vignoli and Prendini, 2009: 3, table 1; Prendini, 2011: 117; Lourenço and Leguin, 2012: 71; Soleglad et al., 2012: 95, 96; Loria and Prendini, 2014: 5, 20, 21, tables 2, 4; Lourenço, 2014: 31, 36; Beron, 2015: 172; Sharma et al., 2015b: 4, fig. 2d; Lourenço, 2017a: 19; Loria and Prendini, 2018: 186, table 2; Lourenço et al., 2018: 265; Francke, 2019: 16, 32, 39; Sendi et al., 2020: 288.

Diagnosis: As for subfamily.

Included Taxa: As redefined in the present contribution, Troglokhammouanus accommodates a single species: Troglokhammouanus steineri Lourenço, 2007.

Distribution: As for subfamily.

Ecology: The sole species of Troglokhammouanus is hypogean, inhabiting the dark zone of a deep cave (fig. 3).

Troglokhammouanus steineri Lourenço, 2007a: 771, 775, 776, figs. 1, 3 (4–15), 4 (16–24); 2007b: 1–6, figs. 1–24; Lourenço and Pham, 2010: 2, 12; Botero-Trujillo and Noriega, 2011: 42; Jäger, 2012: 37; Lourenço, 2012a: 233, 236, 237, appendix A; Lourenço and Leguin, 2012: 71; Lourenço and Pham, 2012: 80, 84; Soleglad et al., 2012: 89; Steiner, 2013: 416; Loria and Prendini, 2014: appendix S1: 10, appendix S2: 7; Lourenço, 2014: 31; Beron, 2015: 184; Sharma et al., 2015a: 354; 2015b: 4, 7, figs. 1e, 2c, 3b; Lourenço, 2017a: 19–21, 23, fig. 1; Beron, 2018: 834; Lourenço et al., 2018: 265; Ballesteros et al., 2019: table S1; Francke, 2019: 32; Howard et al., 2019: 76, table 1; Santibáñez-López et al., 2019b: 26, table 3.

Troglokhammouanus louisanneorum Lourenço, 2017a: 20–23, figs. 1, 4–16; syn. nov.

Type Material: LAOS: Khammouane Prov.: Boualapha Distr.: Hin Namno National Biodiversity Conservation Area: Holotype ♀ (MNHN RS 9098) [examined], juv. ♂ paratype (MNHN RS 9099) Boualapha, Tham Xe Bangfai (cave), Ban Nong Ping [17°22′23.6″N 105°50′11.8″E], 14.ii.2007, H. Steiner, midsection of cave [2–3 km from entrance], on sand [alluvial soil and sand bank next to river edge]. Gnommalath Distr.: Troglokhammouanus louisanneorum: Holotype ♀ (MNHN), Ban Naden, Tham Nam Lot cave (17°30′17.9″N 105°23′08.2″E), 176 m, 8.xi.2011, L. Deharveng and A. Bedos, 350–450 m from main cave entrance.

Diagnosis: As for subfamily.

Description: The following description, based on the holotype female of T. steineri, and material examined, including 10 adult males and 61 adult females, supplements the original descriptions of Lourenço (2007a, 2017a) and supplemental data in Lourenço (2007b).

Total length: Small, 32.2 mm (28.4–36.4 mm, n = 9) (♂) or 38.5 mm (35.8–41.3 mm, n = 13) (♀) (tables 3, 7, 8).

Color: Tegument base coloration reddish yellow to reddish brown. Carapace diffusely infuscate, with brownish marbled pattern; tergites with paired submedial and sublateral stripes of brownish infuscation longitudinally, or immaculate; other surfaces immaculate. Carapace, pedipalps, tergites, and metasoma reddish yellow to reddish brown. Chela fingers, pedipalpal and metasomal carinae dark reddish brown. Chelicerae, legs, sternum, genital operculum, and sternites pale yellow. Pectines pale, yellowish white. Telson paler than metasomal segment V. Aculeus black.

Chelicerae: Fixed finger, dorsal margin with four teeth (basal, median, subdistal, distal); basal and median teeth fused into bicuspid (“conjoined on trunk”); space between median and subdistal teeth U-shaped; ventral margin with five or six small denticles (ventral accessory denticles). Movable finger, dorsal margin with three teeth (median, subdistal, retrolateral distal), without basal teeth; ventral margin with five or six small denticles (ventral accessory denticles) and serrula in distal third; retrolateral (dorsal) distal and prolateral (ventral) distal teeth subequal, retrolateral (dorsal) distal tooth smaller than prolateral (ventral) distal tooth, and opposable. Ventral surface of fingers and manus with numerous long, dense macrosetae.

Carapace: Carapace slightly longer than wide, anterior width 51% (43%–55%, n = 9) (♂) or 50% (45%–57%, n = 13) (♀) of length, posterior width 90% (85%–94%, n = 9) (♂) or 95% (79%–102%, n = 13) (♀) of length (tables 3, 7, 8). Anterior margin convex (procurved), protruding medially; anterolateral margins entire; posteromedian margin shallowly concave (recurved); posterolateral margins gently curved (fig. 11). One pair of very small anterolateral major (ALMa) ocelli situated close to anterolateral margins of carapace, other lateral ocelli absent. Anterosubmedial depressions, medial to lateral ocelli, well developed. Median ocular tubercle situated anteromedially on carapace, distance from anterior margin 32% (26%–37%, n = 9) (♂) or 33% (30%–35%, n = 11) (♀) of carapace length (tables 7, 8); pair of median ocelli considerably larger than lateral ocelli; pair of weakly developed, smooth superciliary carinae, not protruding above ocelli; interocular sulcus shallow, obsolete. Circumocular sutures complete but disconnected posteriorly; circumocular triangle subtriangular (broad V-shape); median ocular curvatures present. Anteromedian depression narrow, shallow; posteromedian sulcus very shallow anteriorly, becoming slightly deeper posteriorly; posterolateral sulci very shallow, wide, weakly curved; posteromarginal sulcus narrow, shallow. Carapace acarinate; surfaces finely to moderately granular, except on anteromedian depression and along lateral and posterior margins.

Pedipalps: Pedipalps relatively robust; segments almost apilose, sparsely covered in short microsetae and occasional macrosetae. Pedipalp femur length 68% (65%–71%, n = 9) (♂) or 64% (59%–68%, n = 13) (♀) greater than width (tables 3, 7, 8). Femur with seven carinae evident (fig. 28A–D); promedian carina obsolete, reduced to few spiniform granules in proximal two-thirds of segment; prodorsal, proventral and retrodorsal carinae well developed, costate granular; dorsomedian carina moderately developed, granular; retromedian and retroventral carinae vestigial, reduced to few granules proximally; ventromedian carina absent; intercarinal surfaces smooth. Pedipalp patella length 62% (59%–70%, n = 9) (♂) or 61% (58%–62%, n = 13) (♀) greater than width (tables 3, 7, 8). Patella with six carinae evident (fig. 28E–G); retrodorsal, retroventral, and proventral carinae well developed, costate granular to costate; prodorsal carina well developed, granular to costate granular; prolateral surface, dorsoventral “vaulted” projection (“anterior process”) moderately developed, with prominent pair of dorsal and ventral spiniform granules (“patellar spurs”) proximally, the dorsal more strongly developed, demarcating pair of obsolete, granular prolateral dorsal and ventral carinae (“patellar spur carinae”); ventromedian carina vestigial, reduced to proximal granules; dorsomedian and retromedian carinae absent; intercarinal surfaces smooth. Pedipalp chela relatively short and broad; manus globose, width 28% (21%–32%, n = 9) (♂) or 25% (18%–33%, n = 13) (♀) greater than height and length 14% (8%–19%, n = 9) (♂) or 21% (17%–26%, n = 11) (♀) greater than width (tables 3, 7, 8); length of movable finger 16% (8%–24%, n = 9) (♂) or 24% (16%–35%, n = 11) (♀) greater than length of manus. Chela with 10 carinae evident (figs. 29, 30); dorsomedian carina complete, granular; dorsal secondary and subdigital carinae vestigial, reduced to granules proximally on manus; digital carina well developed, costate granular; retromedian (retrolateral secondary) carina partial, comprising granular row medially; secondary accessory and retroventral carinae incompletely fused, slight disjunction evident in proximal third; retroventral carina well developed, granular, aligned parallel to longitudinal axis of chela, with distal margin connected to retrolateral movable finger condyle; ventromedian carina partial, comprising granular row in proximal quarter; prodorsal, promedian, and proventral carinae obsolete, each reduced to series of isolated granules; intercarinal surfaces smooth except for coarse, scattered granules on prolateral surface of manus, near base of fixed and movable fingers. Fixed and movable fingers, dentate margins sublinear (♀) or markedly sinuous, movable finger with shallow lobe, proximally and fixed finger with correspondingly shallow notch, proximally (♂), no proximal “gap” evident when closed; median denticle rows comprising seven (6 or 7, n = 143) (fixed finger) or eight (6–8, n = 141) (movable finger) oblique and slightly imbricated subrows (tables 3, 4, 7, 8), decreasing in length distally; each subrow comprising large retrolateral denticle proximally (absent from proximal subrow, for total of seven retrolateral denticles on fixed and movable fingers), several small median denticles, and large prolateral denticle distally, slightly offset (total of seven and eight prolateral denticles on fixed and movable fingers, respectively); terminal (prolateral) denticle of first subrow enlarged; accessory denticles absent.

Trichobothria: Orthobothriotaxic, Type D, β configuration, trichobothrium d₂ situated on femur dorsal surface, d₃ and d₄ in same axis, parallel and closer to retrodorsal carina than d₁, angle formed by d₁, d₃ and d₄ opening toward prolateral surface, with the following segment totals (figs. 28–30): femur, 12 (6 dorsal, 3 prolateral, 3 retrolateral); patella, 10 (3 dorsal, 1 prolateral, 6 retrolateral); chela, 13 (5 manus, 8 fixed finger). Total number of trichobothria per pedipalp, 35. Five trichobothria on femur, i₄, d₁, d₂, d₄, and d₆, one on patella, est₁, and one on chela fixed finger, ib₂, noticeably smaller than others (“petite”). Trichobothrium Et₁ situated distally on manus, aligned with or proximal to movable finger condyle; eb situated on fixed finger, slightly distal to movable finger condyle; esb₂ situated in proximal third of fixed finger, approximately aligned with proximal retrolateral denticle of median denticle row.

Legs: Leg I maxillary lobes (coxapophyses), distal margins rounded, unmodified (not spatulate or dilate) anteriorly, terminating flush with lobes of leg II (figs. 26B, 27B, D). Legs I and II tibiae, retrolateral margins each with scattered macrosetae, without spurs (fig. 15B); III and IV with spurs, smooth, without spinelets. Basitarsi with few scattered macrosetae, pro- and retrolateral rows of long spinules, and pair of pro- and retrolateral pedal spurs. Telotarsi with pair of ventrosubmedian rows of long spinules; proventral and retroventral rows of macrosetae absent, only few scattered macrosetae laterally; laterodistal lobes reduced and truncated; median dorsal lobe very short; ungues short, distinctly curved, equal in length; unguicular spur (dactyl) pronounced, pointed.

Sternum: Sternum, Type 1, pentagonal, posterior width 89% (80%–104%, n = 9) (♂) or 86% (79%–97%, n = 11) (♀) of length (tables 7, 8), lateral margins recurved medially, ventral surface shallowly concave, posteromedian depression round (fig. 13B, D).

Pectines: Three marginal (anterior) lamellae, proximal sclerite considerably longer, distal sclerite short (fig. 13B, D); 15/14 (13–16, n = 92) (♂) or 13/13 (12–14/12–15, n = 190) (♀) median lamellae (tables 3, 5, 7, 8); fulcra present, small. Proximal median lamella and basal pectinal tooth unmodified. Pectinal teeth present along entire posterior margin of each pecten (♂, ♀); 16/15 (14–17, n = 94) (♂) or 14/14 (13–15/13–16, n = 190) (♀) teeth. Pectinal peg sensillae long, cylindrical, tubular or bottle shaped, and rounded distally, without pair of laterodistal processes; sensillar sockets smooth.

Genital operculum: Opercular sclerites completely separated, prominent genital papillae visible along entire length (♂) or absent (♀) (fig. 13B, D). Genital plugs observed in some females.

Male reproductive organs: Paraxial organ without accessory glands. Hemispermatophore lamelliform, pars recta absent (fig. 31); basal lobe present.

Female reproductive organs: Ovariuterus comprising reticulate mesh of six cells. Oocytes contained in sessile follicles directly contacting ovaruterine tubes.

Mesosoma: Pretergites surfaces smooth and shiny. Posttergites I–VI surfaces moderately to coarsely granular, granulation becoming slightly coarser near posterior margins, acarinate, each with pair of shallow submedian depressions (figs. 26A, 27A, C); VII surface sparsely granular, with pair of costate granular dorsosubmedian and dorsolateral carinae reaching posterior margin of segment. Sternites III–VII surfaces entirely smooth, acarinate (figs. 26B, 27B, D), with scattered macrosetae, posterior margins with sparse row of macrosetae; III–VI, respiratory spiracles (stigmata) small, oval (fig. 13B, D); V posteroventral margin with pale, raised, triangular surface; VII width 41% (34%–47%, n = 9) (♂) or 41% (36%–46%, n = 11) (♀) greater than length (tables 7, 8).

Metasoma: Metasoma relatively short, total length 24% (16%–28%, n = 9) (♂) or 18% (13%–32%, n = 11) (♀) greater than combined length of prosoma and mesosoma (tables 7, 8); segments I–V progressively increasing in length, I and II wider than long, width of length for segment I, 126% (118%–136%, n = 9) (♂) or 138% (124%–156%, n = 13) (♀); II, 101% (92%–109%) (♂) or 107% (96%–118%) (♀); III, 88% (76%–97%) (♂) or 93% (88%–100%) (♀); IV, 65% (59%–68%) (♂) or 68% (64%–74%) (♀); and V, 35% (32%–37%) (♂) or 36% (34%–39%) (♀). Metasoma almost apilose, sparsely covered in short microsetae. Eight carinae on segment I, 10 on II–IV, and nine on V (figs. 16C, D, 18C, D, 20C, D). Dorsosubmedian carinae well developed, costate granular throughout length of segments I–IV, absent on V; converging posteriorly. Dorsolateral carinae well developed, costate granular throughout length of segments I–V; converging posteriorly on I and V, subparallel on II–IV. Dorsosubmedian and dorsolateral carinae of segments I–IV each terminating posteriorly with enlarged, spiniform granule. Median lateral carinae complete, costate granular throughout length of segments I–V. Ventrolateral carinae well developed, costate granular, but becoming obsolete anteriorly on segments I and II, continuous throughout length of III–V; converging posteriorly on I and V, subparallel on II–IV. Ventrosubmedian carinae absent on segment I, obsolete, costate on II, well developed, costate granular throughout length of III–V; subparallel on II and III, converging posteriorly on IV and V. Ventromedian carina moderately developed, granular, on segment V. Intercarinal surfaces smooth.

Telson: Telson large, suboval (figs. 16C, D, 18C, D, 20C, D). Vesicle elongate, width 105% (101%–112%, n = 9) (♂) or 106% (97%–117%, n = 13) (♀) of metasomal segment V width (tables 3, 7, 8), with flattened dorsal surface and rounded ventral surface, height 37% (32%–44%, n = 9) (♂) or 39% (34%–47%, n = 13) (♀) of length; dorsal surface smooth, lateral surfaces with three pairs of obsolete, granular carinae, ventral surfaces with two pairs of obsolete, granular carinae; anterodorsal lateral lobes (“vesicular tabs”) distinct, each with two spiniform granules; subaculear tubercle absent. Aculeus short, shallowly curved, 23% (21%–27%, n = 9) (♂) or 24% (21%–32%, n = 13) (♀) of telson length. Venom glands thin walled, simple and unfolded.

Intraspecific variation: One juvenile was completely depigmented and one adult female partially depigmented, including the ocelli (figs. 11E, 27A, B). No other significant variation was noted.

Ontogenetic variation: Immature stages of T. steineri are paler in color and less sclerotized than adults, and the posteroventral margin of mesosomal sternite V does not exhibit a pale, raised, triangular surface as in the adults of both sexes. Males and females closely resemble one another externally until the final instar. However, immature stages are easily sexed by examination of the genital aperture.

Sexual dimorphism: The genital papillae, visible the entire length and thus completely separating the two sclerites of the genital operculum (fig. 13B), are the characters of primary external sexual dimorphism in the male. The opercular sclerites are also completely separated in the female, although genital papillae are absent (fig. 13D). Adult males may be further separated from adult females and immature stages based on several secondary sexual characters. The most obvious are the sexually dimorphic pedipalp chelae, the fixed and movable fingers of which are markedly sinuous in the adult male (figs. 29, 30), as well as the more developed pectines, the median lamellae of which are more numerous and the teeth somewhat larger, and more numerous (fig. 13B, D; tables 3, 5, 7, 8). In addition, the adult male is proportionally more slender (fig. 26), with a slightly longer metasoma and telson (tables 7, 8), and slightly more pronounced granulation on the carapace, pedipalps, and tergites than the adult female (fig. 27). The pale, raised, triangular surface on the posteroventral margin of sternite V is more pronounced in the adult male (fig. 26B) than the adult female.

Distribution: Endemic to the Boualpha District of Khammouane Province, Laos, where it has been recorded from a single cave, Tham Xe Bangfai (also known as Xe Bangfai River Cave or Tham Khoun Xe), in the Hin Namno National Biodiversity Conservation Area, near Nong Ping (fig. 7). Two expeditions to the putative type locality of T. louisanneorum, Tham Nam Lot (Lod), near Ban Naden, in the Gnommalath District, failed to confirm the presence of this species.

Ecology: Specimens collected by the first author at Tham Xe Bangfai were found with UV light detection, from the twilight zone to approximately 3 km from the downstream entrance (resurgence) (fig. 3B–D). Whereas specimens were observed in the dark zone during daytime, specimens were only observed in the twilight zone at night. It is not known how far the species extends into the river cave, which is approximately 11 km long, but the greatest abundance of individuals was observed between 300–500 m from the entrance, and their abundance appeared to decrease with increasing distance (more than 500 m upstream). Although a few specimens were collected on flowstone rock faces, the vast majority were collected close to the water, on moist muddy riverbanks at several “beaches” within the cave (fig. 3E). Most were collected in cracks between the drying mud slabs or among sticks and other vegetative debris trapped between rocks, almost always on moist soil (fig. 3F–H). None were taken on the dry sand banks or dry rock faces higher upslope. Although these moist areas presumably harbor a greater abundance of prey, the apparent preference of T. steineri for moist substrates, also observed in the epigean P. mischi and P. ovchinnikovi (Fet et al., 2004; Prendini et al., 2006; Soleglad et al., 2012), strongly suggests an ecological requirement for moisture.

Although no specimens of T. steineri have thus far been collected outside the cave, the morphology of this species suggests it is troglophilous rather than troglobitic (Prendini, 2001b; Volschenk and Prendini, 2008). The ocelli, especially the median pair, are well developed, as in some epigean scorpions from low light environments, e.g., rainforests (Loria and Prendini, 2021), the tegument of most individuals does not lack pigmentation (indeed, the base coloration is darker than in the two epigean species of Pseudochactas), and there is no obvious attenuation of the pedipalps or legs, as in Vietbocapinae. It is conceivable that T. steineri is restricted to the cave interior due to its requirement for high humidity rather than for darkness per se.

Two buthids, Lychas aberlenci Lourenço, 2013, and Lychas mucronatus (Fabricius, 1798) were collected in the deciduous forest surrounding the cave entrance. The remains of a scorpionid, Heterometrus laoticus Couzijn, 1981, presumably washed in by the Xe Bang Fai River, were collected inside.

Conservation Status: Troglokhammouanus steineri is very abundant in Tham Xe Bang Fai, which is very large (ca. 11 km long), relatively undisturbed, and situated within a protected area, the Hin Namno National Biodiversity Conservation Area. Due to difficult access, the surrounding forest is relatively intact, except for seasonal subsistence cultivation. Aside from an increase in disturbance associated with recreational ecotourism (e.g., caving and kayaking) in the cave, which could become a threat if unchecked, there appear to be few immediate threats to the survival of this species. Nevertheless, it is characterized by an acute restriction in both its area of occupancy and number of known localities: it is known to exist at one or perhaps two locations, the extent of occurrence is less than 5000 km², and the area of occupancy less than 500 km². Therefore, while presently of Least Concern, this species is prone to the effects of human activities (or stochastic events, the impact of which may be increased by human activities, e.g., climate change) within a very short period of time in an unforeseeable future, and potentially faces a high risk of extinction in the wild, warranting its assignment to the Endangered category of the IUCN Red List in the future.

Remarks: In the description of T. louisanneorum, Lourenço (2017a: 23) noted the following:

The new species is very similar to the only other known species of the genus, Troglokhammouanus steineri … Nevertheless, a few differences can be observed: (i) a generally paler coloration in the new species, which is yellow to reddish-yellow, with pale yellow legs, (ii) the granulation on pedipalps and tergites is stronger in the new species, (iii) dorsal and ventral spinoid tubercles of pedipalp patella weaker than on T. steineri, (iv) some morphometric values differ between the two species, although their overall size is almost identical. Furthermore, the two species were found in separate caves that are not connected.

No other morphological differences between T. louisanneorum and T. steineri can be discerned from the diagnosis or description, in the absence of which the minor differences noted by Lourenço (2017a) cannot be considered diagnostic for the following reasons. Coloration is known to vary considerably within and between conspecific populations of scorpions and the variation described falls well within the variation among the material examined from the type locality, a single cave, during the present study (e.g., although immatures of T. steineri are generally more infuscate than adults, a few are depigmented; figs. 11E, 27A, B). Similarly, the unspecified differences in granulation of the pedipalps and tergites between the two species, which includes the “weaker” tubercles on the pedipalp patella of T. louisanneorum, fall within the range of variation among the material examined from the type locality. Any possible morphometric differences offered by Lourenço (2017a) may be discounted on the grounds that two individuals (i.e., the holotypes of T. louisanneorum and T. steineri) do not comprise a statistical sample. Moreover, multivariate statistical analysis of the morphometric data presented by Lourenço (2007a, 2017a), together with new data (tables 3–5, 7, 8; appendices 4, 5, 7), was unable to separate the holotype of T. louisanneorum from the holotype of T. steineri or other individuals from the type locality, all of which clustered together across a morphospace comparable to that of other pseudochactid species (fig. 8).

It would therefore appear that the distinction between T. louisanneorum and T. steineri rests solely on their occurrence in two caves “that are not connected,” also known as the “caves as islands” paradigm (Mammola, 2019). The assumption that species occurring in different caves must be heterospecific, promulgated by others (e.g., Francke, 2009a), is problematic for three reasons. Firstly, geography is not heritable and cannot comprise part of a taxon diagnosis, regardless of the presence or absence of morphological (or genomic) differences. Secondly, no evidence has been presented that the caves are disconnected or, if true, that the scorpion (which appears to be troglophilous) might not occur in other caves, rock shelters or deep crevices in the 50 km between them. The type locality of T. steineri, Tham Xe Bang Fai, is 11 km long, but many other caves and cave networks are more than 50 km in length, e.g., the Clearwater Cave System, Malaysia (over 48 km long), Lechuguilla Cave, New Mexico (over 221 km long), the Shuanghedong Cave Network, China (over 240 km long), Optymistychna Cave, Ukraine (over 258 km long), the Sistema Ox Bel Ha (over 268 km long) and Sistema Dos Ojos (over 320 km long), both in Mexico, and the Mammoth Cave Network, Kentucky (over 652 km long). In attributing islandlike properties to caves, researchers must consider the presence of subterranean connections, as well as the vagility of the species of interest (Mammola, 2019). A network of fissures connecting two caves would make it difficult to consider the scorpion populations inhabiting them, to be isolated from one another. Lastly, there is doubt about the accuracy of the original collection data for T. louisanneorum. Two expeditions to Tham Nam Lot (Lod), in different years (June 2012, May 2018), failed to confirm the presence of this species, which is extremely abundant at the type locality, Tham Xe Bang Fai, although numerous other scorpions of several taxa (including the pseudochactid, A. lao), were collected. Not a single specimen of this species was found during either visit to Tham Nam Lot (Lod), whereas ca. 140 specimens were collected during a single visit to Tham Xe Bang Fai, conducted during the same season.

In view of the evidence that the holotypes are conspecific, and absent any evidence to the contrary, the following new synonym is proposed: Troglokhammouanus louisanneorum Lourenço, 2017 = Troglokhammouanus steineri Lourenço, 2007, syn. nov.

Material Examined: LAOS: Khammouane Prov.: Boualapha Distr.: Hin Namno National Biodiversity Conservation Area: Tham Xe Bang Fai (Xe Bang Fai River Cave), 17°22′23.6″N 105°50′11.8″E, 159 m, left bank of Xe Bang Fai River (coming from downstream entrance): 19.ii.2012, L. Prendini and P. Kanyavong, very steep muddy beach on riverbank, with few cracks and no debris, UV detection, specimen on mud bank, 1 ♂ (AMNH), muddy beach on riverbank, with moderate to steep mud bank with few rocks, UV detection, all specimens on moist mud bank, 2 ♀, 1 subad. ♂, 4 juv. ♂, 1 juv. ♀ (AMNH), rocky beach of riverbank at base of “Stairway to Heaven,” with little mud except at base of rocks close to river, UV detection, 1 ♀, several imm. on moist mud, 1 imm. among vegetative debris caught between rocks, none on dry sand or rocks, 1 ♀, 1 subad. ♀, 3 juv. ♂ [1 juv. ♂ totally depigmented], 3 juv. ♀, pair of pedipalp chelae (AMNH), 1 juv. ♀ (AMCC [LP 11275]), 19–21. ii.2012, L. Prendini, P. Kanyavong, and W. Phimmathong, rocky beach on riverbank, with extensive mud and sand banks in places, UV detection, specimens mostly on mud banks, almost all on moist soil, 5 ♂, 9 ♀, 4 subad. ♂, 9 juv. ♂, 4 juv. ♀, dextral pedipalp femur and patella (AMNH), 1 juv. ♂ (AMCC [LP 11273]), 20.ii.2012, L. Prendini and P. Kanyavong, in twilight zone at cave entrance, muddy beach on riverbank, UV detection at night, specimens sitting on muddy banks (none collected at this site during daylight), 2 ♀ (AMNH), 20–21.ii.2012, L. Prendini, P. Kanyavong, and W. Phimmathong, large sandy beach of riverbank, midway through cave [type locality], with muddy bank immediately along river and muddy patches in several depressions further from river edge, UV detection, all specimens collected on moist muddy soil, some among vegetative debris (sticks, etc.) trapped between stones, others sitting in open on mud, one in mud cracks, one below stone, 7 ♀, 1 juv. ♀ (AMNH), 1 juv. ♀ (AMCC [LP 11272]); right bank of Xe Bang Fai River (coming from downstream entrance): 19–20.ii.2012, L. Prendini and P. Kanyavong, muddy beach of riverbank at bottom of “Balcony Passage,” ca. 300–500 m from downstream entrance of cave, UV detection during day: specimens very common on moist mud banks, mostly in cracks between drying mud slabs or among sticks and other vegetative debris caught between rocks, all collected on moist soil, none on dry sand banks higher upslope; UV detection at night: several ♂♂ sitting on flowstone rock faces, several ♀♀ and juv. on mud banks and cracked clay, 2 ♂ (1 ♂ partly cannibalized by ♀), 22 ♀, 2 subad. ♂, 4 subad. ♀, 5 juv. ♂, 7 juv. ♀, carapace and sinistral pedipalp chela (AMNH), 1 juv. ♀ (AMCC [LP 11271]), 19–21.ii.2012, L. Prendini, P. Kanyavong, and W. Phimmathong, muddy beach of riverbank between “Balcony Passage” and “Stairway to Heaven,” steep and dry with little cracked mud, relatively few rocks with trapped vegetative debris, UV detection, specimens uncommon, mostly on mud close to river edge, few higher upslope against cave walls, near moist flowstone, all specimens collected on moist mud surfaces, none on dry sand, 1 ♂, 7 ♀ (AMNH), 20.ii.2012, L. Prendini and P. Kanyavong, rocky beach of riverbank before second rapids, UV detection, several adult ♀♀ and imm. on mud bank or in rock crevices close to river, none on dry soil higher upslope, 5 ♀, 1 subad. ♀, 1 juv. ♂(AMNH), 20–21.ii.2012, L. Prendini, P. Kanyavong, and W. Phimmathong, rocky/muddy beach of riverbank before “Stairway to Heaven,” UV detection, several ♀♀ and imm. on muddy banks or among trapped vegetative debris between rocks, none on dry sand, 1 ♂, 4 ♀ [1 ♀depigmented ocelli], 4 subad. ♂, 1 subad. ♀, 2 juv. ♂, 8 juv. ♀ (AMNH), 1 juv. (AMCC [LP 11274]), 21.ii.2012, L. Prendini and W. Phimmathong, Oxbow Lake, rocky beach on riverbank, UV detection, specimens on rocky shore, 2 ♀, 1 subad. ♂, dextral pedipalp chela (AMNH).

Vietbocapinae Lourenço, 2012a: 232–234, type genus, by original designation: Vietbocap Lourenço and Pham, 2010; Lourenço, 2017a: 19; Pham et al., 2017: 134.

Diagnosis: Vietbocapinae may be separated from the other two subfamilies of Pseudochactidae as follows. The tegument is immaculate in Vietbocapinae but usually partially infuscate (e.g., on the carapace, tergites and legs) in the other subfamilies. The anteromedian margin of the carapace is shallowly concave (recurved) in Vietbocapinae (fig. 12) but sublinear in Pseudochactinae (fig. 10) and convex (procurved) in Troglokhammouaninae (fig. 11). The median and lateral ocelli are absent in Vietbocapinae (fig. 12) but present in the other subfamilies (figs. 10, 11). The circumocular sutures of the carapace are partial (disconnected) in Vietbocapinae (fig. 12) but complete in the other subfamilies, connected posteriorly in Pseudochactinae (fig. 10) and disconnected posteriorly in Troglokhammouaninae (fig. 11). The pedipalps are gracile, with the chela fingers of the adult male sublinear, and similar to the adult female in Vietbocapinae (figs. 35, 36), whereas the pedipalps are relatively robust, with the chela fingers of the adult male sinuous and sexually dimorphic in the other subfamilies (figs. 24, 25, 29, 30). The prolateral ventral carina of the pedipalp chela manus is absent or obsolete in Vietbocapinae (figs. 35D, 36D, 39D, 43D) but complete in the other subfamilies (figs. 24D, 25D, 29D, 30D). Tibial spurs are absent on legs III and IV in Vietbocapinae (fig. 15C, D) but present in the other subfamilies (fig. 15A, B). The lateral surfaces of the telson vesicle are smooth, and the ventral surfaces smooth or with sparsely granular (obsolete) carinae in Vietbocapinae (figs. 19, 21), whereas the lateral and ventral surfaces of the vesicle possess granular carinae in the other subfamilies (figs. 18, 20). The subaculear tubercle is absent in Vietbocapinae (fig. 19) but obsolete (evident as a very small bump) in the other subfamilies (fig. 18).

Vietbocapinae may be further separated from Pseudochactinae as follows. The anteromedian margin of the carapace is protruding (anterior to the anterolateral margins) in Vietbocapinae (fig. 12) but recessed (posterior to the anterolateral margins) in Pseudochactinae (fig. 10). The posterolateral margins of the carapace are gently curved in Vietbocapinae (fig. 12) but angular and slanting in Pseudochactinae (fig. 10). The dorsoventral projection (“anterior process”) on the prolateral surface of the pedipalp patella is only moderately developed in Vietbocapinae (figs. 34E, G, 38E, G, 42E, G) but pronounced in Pseudochactinae (fig. 23E, G). The secondary accessory and retroventral carinae of the pedipalp chela manus are incompletely fused, with a slight disjunction evident in the proximal third, in Vietbocapinae (figs. 35C, 36C, 39C, 43C) but entirely fused in Pseudochactinae (figs. 24C, 25C). The ventral surface of the sternum is shallowly concave in Vietbocapinae (figs. 14) but flat/planar in Pseudochactinae (fig. 13A, C). The spinules of the basitarsi and telotarsi of legs I–IV are long in Vietbocapinae (fig. 15C, D) but short in Pseudochactinae (fig. 15A). The peg sensillae of the pectinal teeth are long, cylindrical, tubular, or bottle shaped, and rounded distally, without laterodistal processes in Vietbocapinae but relatively short, stout, flattened, and truncate distally, with laterodistal processes, in Pseudochactinae. The telson vesicle is elongate in Vietbocapinae (fig. 19) but globose in Pseudochactinae (fig. 18A, B).

Vietbocapinae may be further separated from Troglokhammouaninae as follows. The dorsomedian, dorsal secondary, subdigital, and retromedian carinae of the pedipalp chela manus are absent, and the ventromedian carina vestigial, in Vietbocapinae (figs. 35, 36, 39, 43), whereas the dorsomedian, dorsal secondary and subdigital carinae are vestigial, and the retromedian and ventromedian carinae partial in Troglokhammouaninae (figs. 29, 30). The lateral margins of the sternum are sublinear in Vietbocapinae (fig. 14) but recurved medially in Troglokhammouaninae (fig. 13B, D). The posterior granules of the dorsosubmedian and dorsolateral carinae of metasomal segments I–IV are similar in size and shape to the preceding granules in Vietbocapinae (fig. 17) but markedly larger than the preceding granules and spiniform in Troglokhammouaninae (fig. 16C, D). The median lateral carinae are partial, becoming obsolete anteriorly on metasomal segment III, and vestigial or absent on IV in Vietbocapinae (fig. 19) but complete on III and IV in Troglokhammouaninae (fig. 18C, D).

Included Taxa: As redefined in the present contribution, Vietbocapinae accommodates three species in two genera (table 1): Aemngvantom, gen. nov.; Vietbocap Lourenço and Pham, 2010.

Distribution: Endemic to the Southeast Asian countries of Laos and Vietnam (fig. 7).

Ecology: All three species of Vietbocapinae are hypogean, having been collected in the dark zone of deep caves, 200 m to 5 km from the surface (fig. 4).

Type species: Vietbocap lao Lourenço, 2012 [= Aemngvantom lao (Lourenço, 2012), comb. nov.], here designated.

Vietbocap: Lourenço, 2012a: 232, 233 (part); Loria and Prendini, 2014: 5, 20, 21, tables 2, 4 (part); Sharma et al., 2015b: 4, fig. 2d; Pham et al., 2017: 134 (part); Lourenço et al., 2018: 264, 265, 269, 272 (part); Deharveng and Bedos 2018: 121 (part); Loria and Prendini, 2018: 186, table 2 (part); Ballesteros et al., 2019: supplementary text 2: 13; Francke, 2019: 16, 32, 39 (part); Lozano-Fernandez et al., 2019: 4, fig. 2.

Vietbokap: Beron, 2015: 172 (part).

Etymology: The generic name is the Lao word for scorpion, “aemngvan tom.”

Diagnosis: In addition to the marked genetic divergence between the two genera (fig. 9; table 12), Aemngvantom may be separated morphologically from Vietbocap, as follows. The anteromedian depression of the carapace is shallow, the circumocular triangle subtriangular (broad V-shaped), and median ocular curvatures present in Aemngvantom (fig. 12A, C, E), whereas the anteromedian depression of the carapace is deep, the circumocular triangle parallel sided (U-shaped) and the median ocular curvatures absent in Vietbocap (fig. 12B, D, F). The median ocular tubercle (demarcated by the posterior margin of the circumocular sulci) is situated anteromedially in Aemngvantom (fig. 12A, C, E) but medially in Vietbocap (fig. 12B, D, F). The anterolateral surfaces of the carapace are mostly granular in Aemngvantom (fig. 12A, C, E), whereas the surfaces are mostly smooth, but sparsely granular near the anterior carapace margin, in Vietbocap (fig. 12B, D, F). The anterolateral margins of the carapace are entire in Aemngvantom (fig. 12A, C, E), whereas pronounced rostrolateral incisions, lateral to the lateral ocelli, are present in Vietbocap (fig. 12B, D, F). The posteromedian margin of the carapace is shallowly concave (recurved) in Aemngvantom (fig. 12A, C, E) but sublinear to shallowly convex (procurved) in Vietbocap (fig. 12B, D, F). The pedipalp chela manus is globose, with the prolateral dorsal carina of the male complete in Aemngvantom, whereas the chela manus is elongate, with the prolateral dorsal carina of the male absent or obsolete, in Vietbocap. The median denticle rows of the chela fixed and movable fingers usually comprise 10 denticle subrows in Aemngvantom (tables 3, 4, 9, 10) but seven or eight subrows in Vietbocap (tables 3, 4, 10). Trichobothrium Et₁ is situated on the fixed finger, slightly distal to the movable finger condyle, and esb₂ approximately midway on the fixed finger, between the second and third most proximal retrolateral denticles of the median denticle row, in Aemngvantom (figs. 35B, 36B, 39B) whereas Et₁ is situated distally on the manus, aligned with or proximal to the movable finger condyle, and esb₂ in the proximal third of the fixed finger, between the first and second most proximal retrolateral denticles of the median denticle row, in Vietbocap (fig. 43B). The pectines possess 11–14 lamellae and 12–15 teeth in Aemngvantom (tables 3, 5, 9, 10) but 5–8 median lamellae and 6–10 teeth in Vietbocap (tables 3, 5, 10). The median lateral carinae of metasomal segment II are complete in Aemngvantom (fig. 19A–C) but partial, becoming obsolete anteriorly in Vietbocap (fig. 19D, E).

Included Taxa: Two species: Aemngvantom lao (Lourenço, 2012), comb. nov.; Aemngvantom thamnongpaseuam, gen. et sp. nov.

Distribution: Aemngvantom is endemic to the Southeast Asian country of Laos, where it has been recorded from two caves in the Gnommalath and Thakhek districts of Khammouane Province (fig. 7).

Ecology: The two known species of Aemngvantom are obligate troglobites, inhabiting the dark zone of deep caves, up to 500 m from the surface (fig. 4B–D, F–H). Both are markedly troglomorphic.

Remarks: Aemngvantom lao was previously assigned to the genus Vietbocap. However, numerous differences are evident between this species and its sister species, A. thamnongpaseuam, and V. canhi, especially concerning the morphology of the carapace and pedipalps. The pronounced morphological differences between the taxa from Laos and Vietnam, supported by multivariate statistical analysis (fig. 8), and taken together with the high levels of genetic divergence between them (fig. 9; table 12), which are comparable to the levels of divergence among the other pseudochactid genera, justify the creation of a new genus to accommodate the two species from Laos.

Vietbocap lao Lourenço, 2012a: 232, 234–237, figs. 2, 3, appendix A; 2012b: 733, table 1; Jäger, 2012: 37; Lourenço and Leguin, 2012: 71; Steiner, 2013: 416; Loria and Prendini, 2014: 3, table 1, appendix S1: 10, appendix S2: 7; Lourenço, 2014: 31; Sharma et al., 2015b: 2, 4, 7, figs. 1e, 2c, 3b; Beron, 2018: 834; Lourenço et al., 2018: 265; Howard et al., 2019: 76, table 1; Lozano-Fernandez et al., 2019: supplementary information: 3, 8, 13, 14, tables 1, 3, fig. 1A, B; Santibáñez-López et al., 2019a: 5; 2019b: 26, table 3.

Type Material: LAOS: Khammouane Prov.: Gnommalath Distr.: Holotype: 1 [juv.] ♀(MNHN RS 9096), paratype: 1 [juv.] ♀ (MNHN RS 9097), Grotte Tham Nam Lot au NO de Ban Naden (village) [Tham Nam Lot (cave), NW of Ban Naden village], 17°30′18″N 105°23′08″E, 176 m, 8.xi.2011, L. Deharveng and A. Bedos, 350–450 m from main cave entrance, collected by hand, Lao11-46 [examined].

Diagnosis: In addition to the marked genetic divergence between the two species (fig. 9; table 12), A. lao may be separated morphologically from A. thamnongpaseuam by means of the granulation and carination of the carapace, tergites and metasoma, and the relative proportions of the pedipalps and metasoma. The mediolateral and posteromedian surfaces of the carapace and the surfaces of posttergites I–VI are granular in A. lao (fig. 12A, C) but smooth or nearly so in A. thamnongpaseuam (fig. 12E). The ventrosubmedian carinae of metasomal segments II–IV are distinct in A. lao (fig. 21A, B) but absent or obsolete in A. thamnongpaseuam (fig. 21C). The dorsolateral and ventromedian carinae are distinct, and the median lateral carinae complete on segment V in A. lao (figs. 17A, B, 19A, B, 21A, B), whereas the dorsolateral carinae are obsolete, and the median lateral and ventromedian carina absent or obsolete on segment V in A. thamnongpaseuam (figs. 17C, 19C, 21C). Additionally, the pedipalp segments are proportionally longer and narrower, and the metasomal segments proportionally longer and broader in A. lao than A. thamnongpaseuam (figs. 17A–C, 19A–C, 21A–C, 34–36, 38, 39; tables 9, 10).

Description: The following description, based on the type material and material examined, which includes three adult males and five adult females, supplements the original description of two juvenile females, by Lourenço (2012a). Ratios are presented for adults only (table 9), whereas counts include immatures of both sexes (tables 3–5, 9).

Total length: Small, 27.5 mm (24.5–29.5 mm, n = 3) (♂) or 30.4 mm (23.4–37.4 mm, n = 6) (♀) (tables 3, 9).

Color: Tegument base coloration pale yellowish to reddish yellow (whitish in immatures), immaculate. Chelicerae, pedipalps (except chela fingers), legs, posterior third of tergites and sternites, and telson slightly paler than carapace, pedipalp chela fingers, anterior two-thirds of tergites and sternites, and metasoma. Chela fingers dark reddish; pedipalpal and metasomal carinae reddish. Sternum, genital operculum, pectines, and sternites pale, whitish. Aculeus reddish black.

Chelicerae: Fixed finger, dorsal margin with four teeth (basal, median, subdistal, distal); basal and median teeth fused into bicuspid (“conjoined on trunk”); space between median and subdistal teeth U-shaped; ventral margin with four or five very small denticles (ventral accessory denticles). Movable finger, dorsal margin with three teeth (median, subdistal, retrolateral distal), without basal teeth; ventral margin with four or five very small denticles (ventral accessory denticles) and serrula in distal third; retrolateral (dorsal) distal and prolateral (ventral) distal teeth subequal, retrolateral (dorsal) distal tooth slightly smaller than prolateral (ventral) distal tooth, and opposable. Ventral surface of fingers and manus with numerous long, dense macrosetae.

Carapace: Carapace slightly longer than wide, anterior width 45% (43%–47%, n = 3) (♂) or 51% (44%–69%, n = 6) (♀) of length, posterior width 90% (85%–92%, n = 3) (♂) or 89% (85%–97%, n = 6) (♀) of length (tables 3, 9). Anterior margin protruding but shallowly concave (recurved) medially; anterolateral margins entire; posteromedian margin shallowly concave (recurved); posterolateral margins gently curved (fig. 12A, C). Median and lateral ocelli absent. Anterosubmedial depressions, medial to lateral ocelli, well developed. Median ocular tubercle represented by smooth, slightly depressed surface, situated anteromedially on carapace, distance from anterior margin 33% (32%–34%, n = 3) (♂) or 32% (30%–34%, n = 5) (♀) of carapace length (table 9); superciliary carinae absent; interocular sulcus shallow, obsolete. Circumocular sutures partial (disconnected); circumocular triangle subtriangular (broad V-shape); median ocular curvatures (regardless of absence of median ocelli) present. Anteromedian depression narrow, shallow; posteromedian sulcus shallow anteriorly, becoming deeper posteriorly; posterolateral sulci very shallow, wide, weakly curved; posteromarginal sulcus narrow, shallow. Carapace acarinate; entirely moderately and densely granular (♂) or finely and sparsely granular (♀), except on posterolateral surfaces.

Pedipalps: Pedipalps gracile; segments almost apilose, sparsely covered in short microsetae and occasional macrosetae. Pedipalp femur length 78% (77%–78%, n = 3) (♂) or 79% (76%–81%, n = 6) (♀) greater than width (tables 3, 9). Femur with five carinae evident (fig. 34A–D); promedian carina vestigial, reduced to few proximal spiniform granules; dorsomedian, prodorsal, and proventral carinae weakly developed, granular; retrodorsal carina obsolete, reduced to few granules; retromedian, retroventral, and ventromedian carinae absent; intercarinal surfaces smooth. Pedipalp patella length 76% (75%–78%, n = 3) (♂) or 77% (76%–79%, n = 6) (♀) greater than width (tables 3, 9). Patella with six carinae evident (fig. 34E–H); prodorsal, retrodorsal, proventral, and retroventral carinae weak, granular; prolateral surface, dorsoventral “vaulted” projection (“anterior process”) moderately developed, with prominent pair of dorsal and ventral spiniform granules (“patellar spurs”) proximally, demarcating pair of obsolete, granular prolateral carinae (“dorsal and ventral patellar spur carinae”); dorsomedian, retromedian, and ventromedian carinae absent; intercarinal surfaces smooth. Pedipalp chela relatively short and broad; manus globose, width 10% (1%–22%, n = 3) (♂) or 7% (1%–12%, n = 6) (♀) greater than height and length 51% (50%–52%, n = 3) (♂) or 55% (52%–58%, n = 5) (♀) greater than width (tables 3, 9); length of movable finger 65% (63%–68%, n = 3) (♂) or 89% (82%–97%, n = 5) (♀) greater than length of manus. Chela with four (♀) or five (♂) carinae evident (figs. 35, 36); dorsomedian carina weakly developed, granular (♂) or absent (♀); digital carina weakly developed, granular; secondary accessory and retroventral carinae incompletely fused, slight disjunction evident in proximal third; retroventral carina weakly developed, granular (♂) or obsolete (♀), aligned parallel to longitudinal axis of chela, with distal margin connected to retrolateral movable finger condyle; ventromedian carina reduced to vestigial granules proximally; other carinae absent; intercarinal surfaces smooth. Fixed and movable fingers, dentate margins sublinear (♂, ♀), no proximal “gap” evident when closed; median denticle rows comprising 10 (n = 65) oblique and slightly imbricated subrows (tables 3, 4, 9), decreasing in length distally; each subrow comprising large retrolateral denticle proximally (absent from proximal subrow, for total of nine retrolateral denticles on fixed and movable fingers), several small median denticles, and large prolateral denticle distally, slightly offset (total of 10 prolateral denticles on fixed and movable fingers); terminal (prolateral) denticle of first subrow enlarged; accessory denticles absent.

Trichobothria: Orthobothriotaxic, Type D, β configuration, trichobothrium d₂ situated on femur dorsal surface, d₃ and d₄ in same axis, parallel and closer to retrodorsal carina than d₁, angle formed by d₁, d₃ and d₄ opening toward prolateral surface, with the following segment totals (figs. 34–36): femur, 12 (6 dorsal, 3 prolateral, 3 retrolateral); patella, 10 (3 dorsal, 1 prolateral, 6 retrolateral); chela, 13 (5 manus, 8 fixed finger). Total number of trichobothria per pedipalp, 35. Five trichobothria on femur, i₄, d₁, d₂, d₄, and d₆, one on patella, est₁, and one on chela fixed finger, ib₂, noticeably smaller than others (“petite”). Trichobothrium Et₁ situated on fixed finger, slightly distal to movable finger condyle; eb situated in proximal third of fixed finger, distal to most proximal retrolateral denticle of median denticle row; esb₂ situated approximately midway on fixed finger, between second and third most proximal retrolateral denticles of median denticle row.

Legs: Leg I maxillary lobes (coxapophyses), distal margins rounded, unmodified (not spatulate or dilate) anteriorly, terminating flush with lobes of leg II (figs. 32B, 33B). Legs I and II tibiae, retrolateral margins each with scattered macrosetae, without spurs (fig. 15D); III and IV without spurs. Basitarsi with few scattered macrosetae, pro- and retrolateral rows of long spinules, and pair of pro- and retrolateral pedal spurs. Telotarsi with pair of slightly irregular ventrosubmedian rows of long spinules; proventral and retroventral rows of macrosetae absent, only few scattered macrosetae laterally; laterodistal lobes reduced and truncated; median dorsal lobe very short; ungues short, distinctly curved, equal in length; unguicular spur (dactyl) pronounced, pointed.

Sternum: Sternum, Type 1, pentagonal, length 18% (10%–23%, n = 3) (♂) or 19% (2%–28%, n = 5) (♀) greater than posterior width (table 9), lateral margins sublinear, ventral surface shallowly concave, posteromedian depression round (fig. 14A, C).

Pectines: Three marginal (anterior) lamellae, proximal sclerite considerably longer, distal sclerite short (fig. 14A, C); 13/13 (12–14/11–14, n = 34) (♂) or 12/12 (12 or 13/11–13, n = 29) (♀) median lamellae (tables 3, 5, 9); fulcra present, very small. Proximal median lamella and basal pectinal tooth unmodified. Pectinal teeth present along entire posterior margin of each pecten (♂, ♀); 14/14 (13–15/12–15, n = 34) (♂) or 13/13 (13 or 14/12–14, n = 30) (♀) teeth. Pectinal peg sensillae long, cylindrical, tubular or bottle shaped, and rounded distally, without pair of laterodistal processes; sensillar sockets smooth.

Genital operculum: Opercular sclerites completely separated, prominent genital papillae visible along entire length (♂) or absent (♀) (fig. 14A, C). Genital plugs observed in some females.

Male reproductive organs: Paraxial organ without accessory glands. Hemispermatophore lamelliform, pars recta absent; basal lobe present.

Female reproductive organs: Ovariuterus comprising reticulate mesh of six cells. Oocytes contained in sessile follicles directly contacting ovaruterine tubes.

Mesosoma: Pretergites surfaces smooth and shiny. Posttergites I–VI surfaces finely and sparsely granular, acarinate, each with pair of shallow submedian depressions (figs. 32A, 33A); VII surface sparsely granular, with pair of granular dorsosubmedian and dorsolateral carinae reaching posterior margin of segment. Sternites III–V surfaces entirely smooth, acarinate, and sparsely covered in microsetae (figs. 32B, 33B); VI and VII surfaces granular, VII with granular ventrosubmedian and ventrolateral carinae (♂) or smooth, acarinate (♀); III–VII surfaces with scattered macrosetae, posterior margins with sparse row of macrosetae (more densely setose in ♂); III–VI, respiratory spiracles (stigmata) small, oval to round (fig. 14A, C); V posteroventral margin with pale, raised, triangular surface; VII width 35% (33%–36%, n = 3) (♂) or 39% (35%–44%, n = 5) (♀) greater than length (table 9).

Metasoma: Metasoma relatively short, total length 29% (27%–32%, n = 3) (♂) or 27% (15%–47%, n = 6) (♀) greater than combined length of prosoma and mesosoma (tables 3, 9); segments I–V progressively increasing in length, I wider than long (♀), width of length for segment I, 92% (89%–95%, n = 3) (♂) or 106% (100%–115%, n = 6) (♀); II, 81% (78%–87%) (♂) or 77% (71%–87%) (♀); III, 75% (72%–81%) (♂) or 68% (58%–81%) (♀); IV, 55% (54%–56%) (♂) or 50% (44%–55%) (♀); and V, 27% (27%–28%) (♂) or 26% (23%–32%) (♀). Metasoma with few short macrosetae. Ten carinae on segments I–III, eight on IV, and nine on V (figs. 17A, B, 19A, B, 21A, B). Dorsosubmedian carinae moderately developed, granular throughout length of segments I–IV, absent on V; converging posteriorly. Dorsolateral carinae moderately developed, granular throughout length of segments I–V; converging posteriorly on I and V, subparallel on II–IV. Dorsosubmedian and dorsolateral carinae of segments I–IV not terminating posteriorly with enlarged, spiniform granules, granules similar to preceding granules. Median lateral carinae complete, granular throughout length of segments I, II, and V, partial, becoming obsolete anteriorly on III, vestigial or absent on IV. Ventrolateral carinae moderately developed, granular, becoming obsolete anteriorly on segments I and II, continuous throughout length of III–V; converging posteriorly on I and V, subparallel on II–IV. Ventrosubmedian carinae obsolete, granular (♂) or absent (♀) on segment I, obsolete, granular (♂) or costate (♀) on II, moderately developed, granular throughout length of III–V; subparallel on II and III, converging posteriorly on IV and V. Ventromedian carina moderately developed, granular, on segment V. Intercarinal surfaces smooth.

Telson: Telson large, suboval (figs. 17A, B, 19A, B, 21A, B). Vesicle elongate, 10% (8%–14%, n = 3) (♂) or 17% (8%–27%, n = 6) (♀) wider than metasomal segment V (tables 3, 9), with flattened dorsal surface and rounded ventral surface, height 38% (34%–41%, n = 3) (♂) or 36% (31%–39%, n = 6) (♀) of length; dorsal surface smooth, lateral surfaces with three pairs of obsolete, granular carinae, ventral surfaces with two pairs of obsolete, granular carinae (♂) or lateral and ventral surfaces smooth (♀); anterodorsal lateral lobes (“vesicular tabs”) weakly developed, granular (♂) or obsolete (♀); subaculear tubercle absent. Aculeus short, shallowly curved, 29% (27%–33%, n = 3) (♂) or 28% (24%–30%, n = 6) (♀) of telson length. Venom glands thin walled, simple and unfolded.

Intraspecific variation: No significant variation.

Ontogenetic variation: Immature stages of A. lao are paler in color and less sclerotized, and the posteroventral margin of mesosomal sternite V does not exhibit a pale, raised, triangular surface as in the adults of both sexes. Males and females closely resemble one another externally until the final instar. However, immature stages are easily sexed by examination of the genital aperture.

Sexual dimorphism: The genital papillae, visible the entire length and thus completely separating the two sclerites of the genital operculum (fig. 14A), are the characters of primary external sexual dimorphism in the male. The opercular sclerites are also completely separated in the female, although genital papillae are absent (fig. 14B). Several secondary sexual characters are observed in the adult male, compared with adult females and immature stages of both sexes. The most obvious are the slightly better developed pectines, the median lamellae of which are more numerous and the teeth somewhat larger, and more numerous (fig. 14A, B; tables 3, 5, 9). In addition, the adult male is smaller and proportionally more slender (fig. 32), with a slightly longer metasoma and telson (table 9), and noticeably more pronounced granulation on the carapace, pedipalps, tergites, sternites, and metasoma than the adult female (fig. 33). The pale, raised, triangular surface on the posteroventral margin of sternite V is more pronounced in the adult male (fig. 32B) than the adult female.

Distribution: Endemic to the Gnommalath District of Khammouane Province, Laos, and presently recorded from a single cave, Tham Nam Lot (Lod), near Ban Naden (fig. 7). The cave is situated at the base of a limestone mountain, in a tropical forest at an elevation between 175–260 m (fig. 4D).

Ecology: All known specimens of A. lao were collected from the dark zone of a moist cave with pools of water in places, ca. 300–450 m from the cave entrance. Most specimens were collected with UV light detection, under stones or in rock cracks, from crevices in mud walls below flowstone walls, or walking on the surface (fig. 4G, H).

Like other Vietbocapinae, A. lao is an obligate troglobite with a highly specialized morphology, characterized by the absence of ocelli and pigmentation, attenuation of the pedipalps and legs, and slight enlargement of the telson (Prendini, 2001b; Volschenk and Prendini, 2008).

Two buthids, Lychas aberlenci and Lychas mucronatus, and a scorpionid, Heterometrus laoticus, were collected in the forest surrounding the cave entrance.

Conservation Status: Aemngvantom lao inhabits a relatively small cave, the only locality at which it has been recorded. The cave is somewhat disturbed, having been used for shelter and storage of ordnance on the Ho Chi Minh Trail during the Vietnam War. The relative proximity of the cave to a major road renders it readily accessible, access is unregulated, and it does not fall within a protected area. Limestone mining is an additional threat in the area. The threat of continued habitat degradation, taken together with the highly restricted distributional range, which is completely unprotected, warrants its assignment to the Endangered category of the IUCN Red List. This highly stenotopic species is characterized by an acute restriction in both its area of occupancy and number of known localities: it is known to exist at a single location, the extent of occurrence is less than 5000 km², and the area of occupancy less than 500 km². A continuing decline in the quality of its habitat is observed, inferred, and projected. This species is expected to be prone to the effects of human activities (or stochastic events, the impact of which may be increased by human activities, e.g., climate change) within a very short period of time in an unforeseeable future, and potentially faces a very high risk of extinction in the wild.

Remarks: Aemngvantom lao was previously assigned to the genus Vietbocap. However, numerous differences between this species and V. canhi, especially concerning the morphology of the carapace and pedipalps, supported by multivariate statistical analysis (fig. 8), and taken together with the high levels of genetic divergence between them (fig. 9; table 12), which are comparable to the levels of divergence among the other pseudochactid genera, justify the creation of a new genus.

Material Examined: LAOS: Khammouane Prov.: Gnommalath Distr.: Tham Nam Lot (Lod) near Ban Naden village, 17°30′13.8″N 105°23′09.2″E, 260 m, 13–14.vi.2012, L. Prendini, S.F. Loria, and P. Kanyavong, limestone cave in primary rainforest at base of limestone mountain, fairly moist cave with pools of water in places, entrances on both sides of mountain, specimens collected with UV light detection ca. midday, uncommon, taken mostly 300–400 m (roughly halfway) from main entrance in dark zone, mostly in moist areas, sitting in crevices in mud walls below flowstone walls, 1 ♀ running on surface, several specimens (including 1 ♂) in mud walls of side room, 2 ♂, 3 ♀, 1 subad. ♂, 3 subad. ♀, 3 juv. ♂, 7 juv. ♀ (AMNH), 2 juv. ♀ (AMCC [LP 11349, 11350]); Tham Nam Lot (Lod), near Ban Naden Village, inside cave, 17°30′13.8″N 105°23′09.2″E, 260 m, 19.v.2018, S.F. Loria, L. Ngo, S.T. Kangnavong, and P.T. Thon Thondet, deep in cave, walking on ground, under stones or in rock cracks, 2 ♀, 1 subad. ♀, 1 juv. ♀ (AMNH), 1 juv. ♂ (AMCC [LP 15570]), [telson] (AMCC [LP 15591]), same data except 20.v.2018, 1 ♂, 1 subad. ♂, 1 subad. ♀, 3 juv. ♀ (AMNH).

Type Material: LAOS: Khammouane Prov.: Thakhek Distr.: Phou Hin Boun National Biodiversity Conservation Area: Holotype ♀(AMNH/AMCC [LP 11351]), Tham Paseum [Tham Nong Paseum, Tham Nong Pa Seuam, Tham Pa Seuam, or Tham Pa Suam], 8.5 km from turnoff to Tham Phanong Pafa [Tham Nong Pa Fa or Tham Pa Fa] or Buddha Cave on main road Thakhek to Gnommalath (4 km E of Thakhek), 17°28′18″N 104°51′23.9″E, 141 m, 15.vi.2012, L. Prendini, S.F. Loria, and P. Kanyavong, limestone cave in primary rainforest, very wet cave with river running through, specimen taken from dark zone, in large terminal room [pillar room], ca. 500 m from cave entrance, with extensive rubble breakdown, stalactites, stalagmites and flowstone formations, specimen collected with UV light detection, ca. midday, sitting still on side of small stone.

Etymology: The specific epithet is a noun in apposition, taken from the name of the type locality, Tham Nong Pa Seuam.

Diagnosis: In addition to the marked genetic divergence between the two species (fig. 9; table 12), A. thamnongpaseuam may be separated morphologically from A. lao by means of the granulation and carination of the carapace, tergites, and metasoma, and the relative proportions of the pedipalps and metasoma. The mediolateral and posteromedian surfaces of the carapace and the surfaces of posttergites I–VI are smooth or nearly so in A. thamnongpaseuam (fig. 12E) but granular in A. lao (fig. 12A, C). The ventrosubmedian carinae of metasomal segments II–IV are absent or obsolete in A. thamnongpaseuam (fig. 21C) but distinct in A. lao (fig. 21A, B). The dorsolateral carinae are obsolete, and the median lateral and ventromedian carina absent or obsolete on segment V in A. thamnongpaseuam (figs. 17C, 19C, 21C), whereas the dorsolateral and ventromedian carinae are distinct, and the median lateral carinae complete on segment V in A. lao (figs. 17A, B, 19A, B, 21A, B). Additionally, the pedipalp segments are proportionally shorter and broader, and the metasomal segments proportionally shorter and narrower in A. thamnongpaseuam than A. lao (figs. 17A–C, 19A–C, 21A–C, 34–36, 38, 39; tables 9, 10).

Description: The following description is based on the holotype female and only known specimen. The male is unknown.

Total length: Small, 30.0 mm (table 10).

Color: Tegument base coloration pale yellowish, immaculate. Chelicerae, pedipalps (except chela fingers), legs, posterior third of tergites and sternites, and telson slightly paler than carapace, pedipalp chela fingers, anterior two-thirds of tergites and sternites, and metasoma. Chela fingers dark reddish; pedipalpal and metasomal carinae reddish. Sternum, genital operculum, pectines, and sternites pale, whitish. Aculeus reddish black.

Chelicerae: Fixed finger, dorsal margin with four teeth (basal, median, subdistal, distal); basal and median teeth fused into bicuspid (“conjoined on trunk”); space between median and subdistal teeth U-shaped; ventral margin with four or five very small denticles (ventral accessory denticles). Movable finger, dorsal margin with three teeth (median, subdistal, retrolateral distal), without basal teeth; ventral margin with four or five very small denticles (ventral accessory denticles) and serrula in distal third; retrolateral (dorsal) distal and prolateral (ventral) distal teeth subequal, retrolateral (dorsal) distal tooth slightly smaller than prolateral (ventral) distal tooth, and opposable. Ventral surface of fingers and manus with numerous long, dense macrosetae.

Carapace: Carapace slightly longer than wide, anterior width 53% of length, posterior width 99% of length (table 10). Anterior margin protruding but shallowly concave (recurved) medially; anterolateral margins entire; posteromedian margin shallowly concave (recurved); posterolateral margins gently curved (fig. 12E). Median and lateral ocelli absent. Anterosubmedial depressions, medial to lateral ocelli, well developed. Median ocular tubercle represented by smooth, slightly depressed surface, situated anteromedially on carapace, distance from anterior margin 31% of carapace length (table 10); superciliary carinae absent; interocular sulcus shallow, obsolete. Circumocular sutures partial (disconnected); circumocular triangle subtriangular (broad V-shape); median ocular curvatures (regardless of absence of median ocelli) present. Anteromedian depression narrow, shallow; posteromedian sulcus shallow anteriorly, becoming deeper posteriorly; posterolateral sulci very shallow, wide, weakly curved; posteromarginal sulcus narrow, shallow. Carapace acarinate; anterolateral, interocular, circumocular, and posteromedian surfaces finely and sparsely granular, mediolateral, and posterolateral surfaces smooth.

Pedipalps: Pedipalps gracile; segments almost apilose, sparsely covered in short microsetae and occasional macrosetae. Pedipalp femur length 76% greater than width (table 10). Femur with five carinae evident (fig. 38A–D); promedian carina vestigial, reduced to few proximal spiniform granules; dorsomedian, prodorsal and proventral carinae weakly developed, granular; retrodorsal carina obsolete, reduced to few granules; retromedian, retroventral and ventromedian carinae absent; intercarinal surfaces smooth. Pedipalp patella length 71% greater than width (table 10). Patella with six carinae evident (fig. 38E–H); prodorsal, retrodorsal, proventral, and retroventral carinae weak, granular; prolateral surface, dorsoventral “vaulted” projection (“anterior process”) moderately developed, with prominent pair of dorsal and ventral spiniform granules (“patellar spurs”) proximally, demarcating pair of obsolete, granular prolateral carinae (“dorsal and ventral patellar spur carinae”); dorsomedian, retromedian, and ventromedian carinae absent; intercarinal surfaces smooth. Pedipalp chela relatively short and broad; manus globose, width 18% greater than height and length 47% greater than width (table 10); length of movable finger 56% greater than length of manus. Chela with three carinae evident (fig. 39); dorsomedian carina reduced to few granules at base of fixed finger, becoming obsolete on manus; digital carina weakly developed, granular; secondary accessory and retroventral carinae incompletely fused, slight disjunction evident in proximal third; retroventral carina obsolete, aligned parallel to longitudinal axis of chela, with distal margin connected to retrolateral movable finger condyle; ventromedian carina reduced to vestigial granules proximally; other carinae absent; intercarinal surfaces smooth. Fixed and movable fingers, dentate margins sublinear (♀), no proximal “gap” evident when closed; median denticle rows comprising 10 (n = 2) oblique and slightly imbricated subrows (tables 4, 10), decreasing in length distally; each subrow comprising large retrolateral denticle proximally (absent from proximal subrow, for total of nine retrolateral denticles on fixed finger and nine or 10 on movable finger), several small median denticles, and large prolateral denticle distally, slightly offset (total of 10 prolateral denticles on fixed and movable fingers); terminal (prolateral) denticle of first subrow enlarged; accessory denticles absent.

Trichobothria: Orthobothriotaxic, Type D, β configuration, trichobothrium d₂ situated on femur dorsal surface, d₃ and d₄ in same axis, parallel and closer to retrodorsal carina than d₁, angle formed by d₁, d₃ and d₄ opening toward prolateral surface, with the following segment totals (figs. 38, 39): femur, 12 (6 dorsal, 3 prolateral, 3 retrolateral); patella, 10 (3 dorsal, 1 prolateral, 6 retrolateral); chela, 13 (5 manus, 8 fixed finger). Total number of trichobothria per pedipalp, 35. Five trichobothria on femur, i₄, d₁, d₂, d₄, and d₆, one on patella, est₁, and one on chela fixed finger, ib₂, noticeably smaller than others (“petite”). Trichobothrium Et₁ situated on fixed finger, slightly distal to movable finger condyle; eb situated in proximal third of fixed finger, distal to most proximal retrolateral denticle of median denticle row; esb₂ situated approximately midway on fixed finger, between second and third most proximal retrolateral denticles of median denticle row.

Legs: Leg I maxillary lobes (coxapophyses), distal margins rounded, unmodified (not spatulate or dilate) anteriorly, terminating flush with lobes of leg II (fig. 37B). Legs I and II tibiae, retrolateral margins each with scattered macrosetae, without spurs; III and IV without spurs. Basitarsi with few scattered macrosetae, pro- and retrolateral rows of long spinules, and pair of pro- and retrolateral pedal spurs. Telotarsi with pair of slightly irregular ventrosubmedian rows of long spinules; proventral and retroventral rows of macrosetae absent, only few scattered macrosetae laterally; laterodistal lobes reduced and truncated; median dorsal lobe very short; ungues short, distinctly curved, equal in length; unguicular spur (dactyl) pronounced, pointed.

Sternum: Sternum, Type 1, pentagonal, length 17% greater than posterior width (table 10), lateral margins sublinear, ventral surface shallowly concave, posteromedian depression round (fig. 14E).

Pectines: Three marginal (anterior) lamellae, proximal sclerite considerably longer, distal sclerite short (fig. 14E); 12/11 (n = 2) (♀) median lamellae (tables 5, 10); fulcra present, very small. Proximal median lamella and basal pectinal tooth unmodified. Pectinal teeth present along entire posterior margin of each pecten (♀); 13/13 (n = 2) (♀) teeth. Pectinal peg sensillae unknown.

Genital operculum: Opercular sclerites completely separated, genital papillae absent (♀) (fig. 14E).

Male and female reproductive organs: Unknown.

Mesosoma: Pretergites surfaces smooth and shiny. Posttergites I–VI surfaces smooth, acarinate, each with pair of shallow submedian depressions (fig. 37A); VII surface sparsely granular, with pair of granular dorsosubmedian and dorsolateral carinae reaching posterior margin of segment. Sternites III–VII surfaces smooth, acarinate (fig. 37B), with scattered macrosetae, posterior margins with sparse row of macrosetae; III–VI, respiratory spiracles (stigmata) small, oval to round (fig. 14E); V posteroventral margin with pale, raised, triangular surface; VII width 39% greater than length (table 10).

Metasoma: Metasoma relatively short, total length 22% greater than combined length of prosoma and mesosoma (table 10); segments I–V progressively increasing in length, I wider than long, width of length for segment I, 115%; II, 89%; III, 77%; IV, 52%; and V, 29%. Metasoma with few short macrosetae. Ten carinae on segment I, eight on II and III, six on IV, and four on V (figs. 17C, 19C, 21C). Dorsosubmedian carinae moderately developed, granular throughout length of segments I–IV, absent on V; converging posteriorly. Dorsolateral carinae moderately developed, granular throughout length of segments I–IV, obsolete on V; converging posteriorly on I and V, subparallel on II–IV. Dorsosubmedian and dorsolateral carinae of segments I–IV not terminating posteriorly with enlarged, spiniform granules, granules similar to preceding granules. Median lateral carinae complete, granular throughout length of segments I and II, partial, becoming obsolete anteriorly on III, absent on IV and V. Ventrolateral carinae moderately developed, granular, becoming obsolete anteriorly on segments I and II, continuous throughout length of III–V; converging posteriorly on I and V, subparallel on II–IV. Ventrosubmedian carinae absent on segment I, obsolete on II–V; subparallel on II and III, converging posteriorly on IV and V. Ventromedian carina absent on segment V. Intercarinal surfaces smooth.

Telson: Telson large, suboval. Vesicle elongate, 21% wider than metasomal segment V (table 10), with flattened dorsal surface and rounded ventral surface (figs. 17C, 19C, 21C), height 38% of length; dorsal, lateral and ventral surfaces smooth (♀); anterodorsal lateral lobes (“vesicular tabs”) obsolete; subaculear tubercle absent. Aculeus short, shallowly curved, 28% of telson length. Venom glands not examined but presumed to be thin walled, simple and unfolded, as in A. lao.

Variation and sexual dimorphism: Unknown.

Distribution: Endemic to the Thakhek District of Khammouane Province, Laos, and presently recorded from a single cave, Tham Nong Pa Seuam (also known as Tham Nong Paseum, Tham Paseum, Tham Pa Seuam, or Tham Pa Suam), in the Phou Hin Boun National Biodiversity Conservation Area, near Thakhek (figs. 4B, 7).

Ecology: The holotype was collected from the dark zone of a very wet cave with a river running through, in a large terminal room (known as the “pillar room”), ca. 400–500 m from the cave entrance, containing extensive rubble breakdown, stalactites, stalagmites, and flowstone formations (fig. 4C, F). The specimen was collected with UV light detection, during daytime, sitting on the side of a small stone. Extensive searches, including a second expedition, failed to collect additional specimens, although numerous exuviae were observed.

Like other Vietbocapinae, A. thamnongpaseuam is an obligate troglobite with a highly specialized morphology, characterized by the absence of ocelli and pigmentation, attenuation of the pedipalps and legs, and slight enlargement of the telson (Prendini, 2001b; Volschenk and Prendini, 2008).

A buthid, Lychas mucronatus, a hormurid, Liocheles australasiae (Fabricius, 1775), and an unidentified euscorpiid, Euscorpiops sp., were collected in the forest surrounding the cave entrance.

Conservation Status: Aemngvantom thamnongpaseuam inhabits a relatively small cave, the only locality at which it has been recorded. The cave is relatively undisturbed and situated within a protected area, the Phou Hin Boun National Biodiversity Conservation Area. Aside from an increase in disturbance associated with recreational ecotourism (caving), which could become a threat if unchecked, there appear to be few immediate threats to the survival of this species. However, the relative proximity of the cave to a major road renders it readily accessible and access is unregulated, hence a continuing decline in the quality of its habitat is projected. Additionally, this highly stenotopic species is characterized by an acute restriction in both its area of occupancy and number of known localities: it is known to exist at a single location, the extent of occurrence is less than 5000 km², and the area of occupancy less than 500 km². Therefore, it is prone to the effects of human activities (or stochastic events, the impact of which may be increased by human activities, e.g., climate change) within a very short period of time in an unforeseeable future, and potentially faces a high risk of extinction in the wild, warranting its assignment to the Endangered category of the IUCN Red List.

Vietbocap Lourenço and Pham, 2010: 6, type species by monotypy: Vietbocap canhi Lourenço and Pham, 2010; Prendini, 2011: 117; Lourenço, 2012a: 232, 233, 236 (part); Lourenço and Leguin, 2012: 71 (part); Lourenço and Pham, 2012: 80, 81, 84; Soleglad et al., 2012: 89, 95, 96; Loria and Prendini, 2014: 5, 20, 21, tables 2, 4 (part); Lourenço, 2014: 31, 36; Lourenço, 2017a: 19; Pham et al., 2017: 134 (part); Deharveng and Bedos 2018: 121 (part); Loria and Prendini, 2018: 186, table 2 (part); Lourenço et al., 2018: 264, 265, 269, 272 (part); Francke, 2019: 16, 32, 39 (part); Sendi et al., 2020: 288 (part).

Vietbokap: Beron, 2015: 172 (part).

Diagnosis: In addition to the marked genetic divergence between the two genera (fig. 9; table 12), Vietbocap may be separated morphologically from Aemngvantom, as follows. The anteromedian depression of the carapace is deep, the circumocular triangle parallel sided (U-shaped), and the median ocular curvatures absent in Vietbocap (fig. 12B, D, F) whereas the anteromedian depression is shallow, the circumocular triangle subtriangular (broad V-shaped), and median ocular curvatures present in Aemngvantom (fig. 12A, C, E). The median ocular tubercle (demarcated by the posterior margin of the circumocular sulci) is situated medially in Vietbocap (fig. 12B, D, F) but anteromedially in Aemngvantom (fig. 12A, C, E). The anterolateral surfaces of the carapace are mostly smooth, but sparsely granular near the anterior carapace margin, in Vietbocap (fig. 12B, D, F), whereas the surfaces are mostly granular in Aemngvantom (fig. 12A, C, E). Pronounced rostrolateral incisions in the anterolateral margins of the carapace, lateral to the lateral ocelli, are present in Vietbocap (fig. 12B, D, F), whereas the anterolateral margins are entire in Aemngvantom (fig. 12A, C, E). The posteromedian margin of the carapace is sublinear to shallowly convex (procurved) in Vietbocap (fig. 12B, D, F) but shallowly concave (recurved) in Aemngvantom (fig. 12A, C, E). The pedipalp chela manus is elongate, with the prolateral dorsal carina of the male absent or obsolete in Vietbocap, whereas the chela manus is globose, with the prolateral dorsal carina of the male complete, in Aemngvantom. The median denticle rows of the chela fixed and movable fingers comprise seven or eight denticle subrows in Vietbocap (tables 3, 4, 10) but usually 10 subrows in Aemngvantom (tables 3, 4, 9, 10). Trichobothrium Et₁ is situated distally on the manus, aligned with or proximal to the movable finger condyle, and esb₂ in the proximal third of the fixed finger, between the first and second most proximal retrolateral denticles of the median denticle row, in Vietbocap (fig. 43B) whereas Et₁ is situated on the fixed finger, slightly distal to the movable finger condyle, and esb₂ approximately midway on the fixed finger, between the second and third most proximal retrolateral denticles of the median denticle row, in Aemngvantom (figs. 35B, 36B, 39B). The pectines possess 5–8 median lamellae and 6–10 teeth in Vietbocap (tables 3, 5, 10) but 11–14 lamellae and 12–15 teeth in Aemngvantom (tables 3, 5, 9, 10). The median lateral carinae of metasomal segment II are partial, becoming obsolete anteriorly in Vietbocap (fig. 19D, E) but complete in Aemngvantom (fig. 19A–C).

Included Taxa: As redefined in the present contribution, Vietbocap accommodates a single species: Vietbocap canhi Lourenço and Pham, 2010.

Distribution: Vietbocap is endemic to the Southeast Asian country of Vietnam, where it has been recorded from two caves, Tiên Sơn and Thiên Đường, in the Bố Trạch District of Quảng Bình Province (figs. 4A, 7).

Ecology: The sole species of Vietbocap is an obligate troglobite, inhabiting the dark zone of deep caves, 200 m to 5 km from the surface (fig. 4E). The species is markedly troglomorphic.

Scorpionida sp. nov.: Moulds et al., 2010: 4–6, 17, 18, 20, 34, fig. 3.3, table 1.

Vietbocap canhi Lourenço and Pham, 2010: 7–12, figs. 3–24; Fet et al., 2011a: 15; Lourenço, 2012a: 233, 235–237, fig. 3G, appendix A; 2012b: 733, table 1; Lourenço and Leguin, 2012: 71; Lourenço and Pham, 2012: 81–84, fig. 3B, E, H; Soleglad et al., 2012: 89; Moulds et al., 2013: 14; Loria and Prendini, 2014: 3, table 1; Lourenço, 2014: 31; Beron, 2015: 184; Pham et al., 2017: 134, 135, fig. 1; Beron, 2018: 834; Lourenço et al., 2018: 265; Francke, 2019: 32.

Vietbocap thienduongensis Lourenço and Pham, 2012: 82–85, fig. 3A, C, D, F, G; Lourenço, 2012a: 236, 237, appendix A; 2012b: 732, 733, table 1, fig. 2; Lourenço and Leguin, 2012: 71; Soleglad et al., 2012: 89; Moulds et al., 2013: 14; Loria and Prendini, 2014: 3, table 1; Lourenço, 2014: 31, 37, fig. 6; Pham et al., 2017: 134, 136, figs. 1, 4; Beron, 2018: 834; Lourenço, 2018: 2, fig. 2; Lourenço et al., 2018: 264–267, 269, 271; syn. nov.

Vietbocap aurantiacus Lourenço et al., 2018: 268, 269, 271, figs. 6, 7; syn. nov.

Vietbocap quinquemilia Lourenço et al., 2018: 269–271, figs. 8–11; syn. nov.

Type Material: VIETNAM: Quảng Bình Prov.: Bố Trạch Distr.: Phong Nha-Kẻ Bàng National Park: Holotype: 1 [juv.] ♂ (MNHN RS 8850), paratypes: 1 [juv.] ♀ (MNHN RS 8851), 2 [juv.] ♀ (IEBR), Tiên Sơn cave, 17°32′N 106°16′E, 16.v.2010, D.-S. Pham, mid section of the cave (200 m from cave entrance), No. VNS-01. Vietbocap thienduongensis: Holotype [subad.] ♂ (MNHH), paratype [juv.] ♂(IEBR), Thiên Đường cave, mid section of cave (1800 m from cave entrance), 9.viii.2011, N.K. Dang. Vietbocap aurantiacus: Holotype ♀, paratype [juv.] ♀ (MNHN), paratype [juv.] ♀ (IEBR), Thiên Đường cave (17°31′10.3″N 106°13′22.9″E), midsection of cave (3000 m from cave entrance), 23.v.2013, D.-S. Pham. Vietbocap quinquemilia: Holotype: [juv.] ♂, paratype: [juv.] ♀ (MNHN), paratype ♀(IEBR), Thiên Đường cave (17°31′10.3″N 106°13′22.9″E), midsection of cave (5000 m from cave entrance), 6.iv.2015, D.-S. Pham. It is apparent from the measurements and illustrations provided in the descriptions (Lourenço and Pham, 2010, 2012; Lourenço et al., 2018) that all except the holotype of V. aurantiacus are immature.

Diagnosis: As for genus.

Description: The following description, based on the material examined, which includes eight adult females, supplements the descriptions of Lourenço and Pham (2010, 2012) and Lourenço et al. (2018). It is unclear from the published photographs and measurements whether any of the males collected thus far are adult (no adult males were examined in the present study). Based on size and coloration, the holotypes of V. canhi and V. quinquemilia are immature, whereas the holotype of V. thienduongensis appears to be subadult. Ratios are presented for adult females only (tables 3, 10) whereas counts include immatures of both sexes (tables 3–5, 10).

Total length: Small, 31 mm (27.2–35.8 mm, n = 9) (tables 3, 10).

Color: Tegument base coloration pale yellowish to reddish yellow (whitish in immatures), immaculate. Chelicerae, pedipalps (except chela fingers), legs, posterior third of tergites and sternites, and telson slightly paler than carapace, pedipalp chela fingers, anterior two-thirds of tergites and sternites, and metasoma. Chela fingers dark reddish; pedipalpal and metasomal carinae reddish. Sternum, genital operculum, pectines, and sternites pale, whitish. Aculeus reddish black.

Chelicerae: Fixed finger, dorsal margin with four teeth (basal, median, subdistal, distal); basal and median teeth fused into bicuspid (“conjoined on trunk”); space between median and subdistal teeth U-shaped; ventral margin with three to five very small denticles (ventral accessory denticles). Movable finger, dorsal margin with three teeth (median, subdistal, retrolateral distal), without basal teeth; ventral margin with four or five very small denticles (ventral accessory denticles) and serrula in distal third; retrolateral (dorsal) distal and prolateral (ventral) distal teeth subequal, retrolateral (dorsal) distal tooth smaller than prolateral (ventral) distal tooth, and opposable. Ventral surface of fingers and manus with numerous long, dense macrosetae.

Carapace: Carapace slightly wider than long, anterior width 52% (47%–60%, n = 9) of length, length 101% (90%–107%, n = 9) of posterior width (tables 3, 10). Anterior margin protruding but shallowly concave (recurved) medially; anterolateral margins with pronounced rostrolateral incisions, lateral to lateral ocelli; posteromedian margin shallowly concave (recurved); posterolateral margins gently curved (fig. 12B, D, F). Median and lateral ocelli absent. Anterosubmedial depressions, medial to lateral ocelli, well developed. Median ocular tubercle represented by smooth, flat to slightly depressed surface, situated approximately medially on carapace, distance from anterior margin 46% (44%–47%, n = 8) of carapace length (table 10); superciliary carinae absent; interocular sulcus obsolete, shallow to deep. Circumocular sutures partial (disconnected); circumocular triangle parallel sided (U-shape), median ocular curvatures (regardless of absence of median ocelli) absent. Anteromedian depression narrow, deep; posteromedian sulcus shallow anteriorly, becoming deeper posteriorly; posterolateral sulci very shallow, wide, weakly curved; posteromarginal sulcus narrow, shallow. Carapace surfaces entirely smooth, except near anterior margin, and acarinate.

Pedipalps: Pedipalps gracile; segments apilose. Pedipalp femur width 80% (78%–82%, n = 9) greater than length (tables 3, 10). Femur with five carinae evident (fig. 42A–D); promedian carina vestigial, reduced to few proximal spiniform granules; dorsomedian, prodorsal and proventral carinae weakly developed, granular; retrodorsal carina obsolete, reduced to few granules; retromedian, retroventral, and ventromedian carinae absent; intercarinal surfaces smooth. Pedipalp patella length 71% (70%–72%, n = 9) greater than width (tables 3, 10). Patella with six carinae evident (fig. 42E–H); prodorsal, retrodorsal, proventral, and retroventral carinae weak, granular; prolateral surface, dorsoventral “vaulted” projection (“anterior process”) moderately developed, with prominent pair of dorsal and ventral spiniform granules (“patellar spurs”) proximally, demarcating pair of obsolete, granular prolateral carinae (“dorsal and ventral patellar spur carinae”); dorsomedian, retromedian, and ventromedian carinae absent; intercarinal surfaces smooth. Pedipalp chela relatively short and broad; manus elongate, width 97% (87%–106%, n = 9) of height and 34% (32%–37%, n = 8) of length (tables 3, 10); length of movable finger 37% (25%–45%, n = 8) greater than length of manus. Chela with three or four carinae evident (fig. 43); dorsomedian carina reduced to vestigial granules proximally or absent; digital carina weakly developed, granular; secondary accessory and retroventral carinae incompletely fused, slight disjunction evident in proximal third; retroventral carina weakly developed, granular, aligned parallel to longitudinal axis of chela, with distal margin connected to retrolateral movable finger condyle; ventromedian carina reduced to vestigial granules proximally; other carinae absent; intercarinal surfaces smooth. Fixed and movable fingers, dentate margins sublinear, no proximal “gap” evident when closed; median denticle rows comprising eight (7 or 8, n = 68) oblique and slightly imbricated subrows (tables 3, 4, 10), decreasing in length distally; each subrow comprising large retrolateral denticle proximally (absent from proximal subrow, for total of six or seven retrolateral denticles on fixed and movable fingers), several small median denticles, and large prolateral denticle distally, slightly offset (total of seven or eight prolateral denticles on fixed and movable fingers); terminal (prolateral) denticle of first subrow enlarged; accessory denticles absent.

Trichobothria: Orthobothriotaxic, Type D, β configuration, trichobothrium d₂ situated on femur dorsal surface, d₃ and d₄ in same axis, parallel and closer to retrodorsal carina than d₁, angle formed by d₁, d₃ and d₄ opening toward prolateral surface, with the following segment totals (figs. 42, 43): femur, 12 (6 dorsal, 3 prolateral, 3 retrolateral); patella, 10 (3 dorsal, 1 prolateral, 6 retrolateral); chela, 13 (5 manus, 8 fixed finger). Total number of trichobothria per pedipalp, 35. Five trichobothria on femur, i₄, d₁, d₂, d₄, and d₆, one on patella, est₁, and one on chela fixed finger, ib₂, noticeably smaller than others (“petite”). Trichobothrium Et₁ situated distally on manus, aligned with or proximal to movable finger condyle; eb situated on fixed finger, slightly distal to movable finger condyle; esb₂ situated in proximal third of fixed finger, between first and second most proximal retrolateral denticles of median denticle row.

Legs: Leg I maxillary lobes (coxapophyses), distal margins rounded, unmodified (not spatulate or dilate) anteriorly, terminating flush with lobes of leg II (figs. 40B, 41B). Legs I and II tibiae, retrolateral margins each with scattered macrosetae, without spurs (fig. 15D); III and IV without spurs. Basitarsi with few scattered macrosetae, pro- and retrolateral rows of long spinules, and pair of pro- and retrolateral pedal spurs. Telotarsi with pair of slightly irregular ventrosubmedian rows of long spinules; proventral and retroventral rows of macrosetae absent, only few scattered macrosetae laterally; laterodistal lobes reduced and truncated; median dorsal lobe very short; ungues short, distinctly curved, equal in length; unguicular spur (dactyl) pronounced, pointed.

Sternum: Sternum, Type 1, pentagonal, length 15% (7%–21%, n = 9) greater than posterior width (tables 3, 10), lateral margins sublinear, ventral surface shallowly concave, posteromedian depression round (fig. 14B, D, F).

Pectines: Three marginal (anterior) lamellae, proximal sclerite considerably longer, distal sclerite short (fig. 14B, D, F); 8/8 (7 or 8, n = 15) (♂) or 7/7 (5–7/5–8, n = 34) (♀) median lamellae (tables 3, 10); fulcra present, very small. Proximal median lamella and basal pectinal tooth unmodified. Pectinal teeth present along entire posterior margin of each pecten; 9/9 (8–10/8 or 9, n = 18) (♂) or 7/8 (6–8/6–9, n = 46) (♀) teeth. Pectinal peg sensillae long, cylindrical, tubular, or bottle shaped, and rounded distally, without pair of laterodistal processes; sensillar sockets smooth.

Genital operculum: Opercular sclerites completely separated, prominent genital papillae visible along entire length (♂) or absent (♀) (fig. 14B, D, F). Genital plugs observed in some females.

Male reproductive organs: Unknown.

Female reproductive organs: Ovariuterus comprising reticulate mesh of six cells. Oocytes contained in sessile follicles directly contacting ovaruterine tubes.

Mesosoma: Pretergites surfaces smooth and shiny. Posttergites I–VI surfaces smooth or nearly so, acarinate, each with pair of shallow submedian depressions (figs. 40A, 41A); VII surface sparsely granular, with pair of granular dorsosubmedian and dorsolateral carinae reaching posterior margin of segment. Sternites III–VII surfaces entirely smooth, acarinate (figs. 40B, 41B), with scattered macrosetae, posterior margins with sparse row of macrosetae; III–VI, respiratory spiracles (stigmata) small, oval (fig. 14B, D, F); V posteroventral margin with pale, raised, triangular surface; VII width 34% (25%–45%, n = 8) greater than length (table 10).

Metasoma: Metasoma relatively short, total length 24% (18%–44%, n = 9) greater than combined length of prosoma and mesosoma (tables 3, 10); segments I–V progressively increasing in length, I wider than long, width of length for segment I, 101% (95%–116%, n = 9); II, 76% (68%–86%); III, 65% (59%–72%); IV, 48% (44%–53%); and V, 23% (20%–25%). Metasoma with few short macrosetae. Ten carinae on segments I–III, eight on IV, and four on V (figs. 17D, E, 19D, E, 21D, E). Dorsosubmedian carinae moderately developed, granular throughout length of segments I–IV, absent on V; converging posteriorly. Dorsolateral carinae moderately developed, granular throughout length of segments I–IV, obsolete on V; converging posteriorly on I and V, subparallel on II–IV. Dorsosubmedian and dorsolateral carinae of segments I–IV not terminating posteriorly with enlarged, spiniform granules, granules similar to preceding granules. Median lateral carinae complete, granular throughout length of segment I, partial, becoming obsolete anteriorly on II and III, absent on IV and V. Ventrolateral carinae moderately developed, granular, becoming obsolete anteriorly on segments I and II, continuous throughout length of III–V; converging posteriorly on I and V, subparallel on II–IV. Ventrosubmedian carinae absent on segment I, obsolete, costate on II, moderately developed, granular throughout length of III–V; subparallel on II and III, converging posteriorly on IV and V. Ventromedian carina absent on segment V. Intercarinal surfaces smooth.

Telson: Telson large, suboval (figs. 17D, E, 19D, E, 21D, E). Vesicle elongate, 32% (20%–45%, n = 9) wider than metasomal segment V (tables 3, 10), with flattened dorsal surface and rounded ventral surface, height 37% (35%–39%, n = 8) of length; dorsal, lateral, and ventral surfaces smooth or nearly so (♀); anterodorsal lateral lobes (“vesicular tabs”) obsolete; subaculear tubercle absent. Aculeus short, shallowly curved, 31% (29%–33%, n = 8) of telson length. Venom glands thin walled, simple, and unfolded.

Intraspecific variation: The only morphological difference between the material from the two caves, which does not constitute ontogenetic variation or sexual dimorphism, concerns the median denticle rows on the fixed and movable fingers of the pedipalp chela, which comprise eight subrows in material from Tiên Sơn, the type locality of V. canhi, and seven subrows in material from Động Thiên Đường (Paradise Cave), the type locality of V. aurantiacus, V. quinquemilia, and V. thienduongensis (tables 3, 4, 10). This single difference is not considered sufficient to merit recognition at the species level, in the face of morphological similarity (fig. 8) and low genetic divergence (fig. 9; table 12).

Ontogenetic variation: Immature stages, including the types of V. canhi, V. quinquemilia, and V. thienduongensis, are paler in color and less sclerotized, and the posteroventral margin of mesosomal sternite V does not exhibit a pale, raised, triangular surface as in the adult stage. However, immature stages are easily sexed by examination of the genital aperture.

Sexual dimorphism: The genital papillae, visible the entire length and thus completely separating the two sclerites of the genital operculum (fig. 14B), are the characters of primary external sexual dimorphism in the male. The opercular sclerites are also completely separated in the female, although genital papillae are absent (fig. 14D, F). The only apparent secondary sexual characters observed in the male are the slightly better developed pectines, the median lamellae of which are more usually numerous and the teeth somewhat larger, and usually more numerous (fig. 14B, D, F; tables 3, 5, 10).

Distribution: Endemic to the Bố Trạch District of Quảng Bình Province, Vietnam, where it has been recorded from two caves, Tiên Sơn and Động Thiên Đường (Paradise Cave), near Sơn Trạch, in the Phong Nha-Kẻ Bàng National Park (fig. 7). The caves are situated in a karstic landscape, in tropical forest at an elevation of 200–250 m (fig. 4A).

Ecology: Specimens from Tiên Sơn were collected with UV detection in the dark zone of the cave, ca. 200–500 m from the entrance, sitting in rock crevices or under small stones, in a moist area with abundant speleothems, including dripstone and flowstone formations, stalactites, and stalagmites (fig. 4E). None were found in dry areas of cave. Specimens from Động Thiên Đường were also collected with UV detection in the dark zone, but much deeper, at sites between 1–5 km from the cave entrance, under rocks, in limestone cracks, or walking on the surface. Động Thiên Đường is approximately 31 km in length.

Vietbocap canhi is an obligate troglobite, characterized by the absence of ocelli and pigmentation, attenuation of the pedipalps and legs, and slight enlargement of the telson (Prendini, 2001b; Volschenk and Prendini, 2008). It appears to be the most cave-adapted member of the family, displaying the most elongated pedipalp chela and distinct dorsoventral compression of the carapace.

Conservation Status: Vietbocap canhi is presently known from two caves, ca. 2.5 km apart, in the Phong Nha-Kẻ Bàng National Park. Whereas Tiên Sơn is a relatively small cave, Động Thiên Đường is very deep (ca. 31 km long), and V. canhi has been collected up to 5 km from the entrance of the latter. The anterior section of both caves is heavily disturbed: a concrete walkway and metal railings have been installed, and the cave brightly illuminated to display the speleothems. Few scorpions were observed in the illuminated parts of either cave. Access is restricted beyond the illuminated sections of both caves, however, where the habitat remains largely undisturbed. Despite the high level of protection afforded to its habitat, this highly stenotopic species is characterized by an acute restriction in both its area of occupancy and number of known localities: it is known to exist at only two locations, the extent of occurrence is less than 5000 km², and the area of occupancy less than 500 km². Therefore, it remains prone to the effects of human activities (or stochastic events, the impact of which may be increased by human activities, e.g., climate change) within a very short period of time in an unforeseeable future, and potentially faces a high risk of extinction in the wild, warranting its assignment to the Endangered category of the IUCN Red List.

Remarks: Lourenço and Pham (2012) described V. thienduongensis from Động Thiên Đường, a cave ca. 2.5 km from Tiên Sơn, the type locality of V. canhi. Lourenço and Pham (2012: 84) separated V. thienduongensis from V. canhi as follows:

(i) bigger size and distinct morphometric values; (ii) complete and more strongly marked circumocular sutures; (iii) chela fingers proportionally shorter (ratios of chela length/movable finger length 7.1/4.2 = 1.69 for V. canhi and 8.3/4.6 = 1.80 for V. thienduongensis sp. n. and with 8 subrows of granules vs. 7 sub-rows); (iv) sternum only slightly longer than wide (ratio 1.15 for V. canhi and 1.30 for V. thienduongensis sp. n.); (v) metasomal segments less carinated and granulated and with a weaker chaetotaxy; (vi) pedipalp carinae better marked; (vii) pectines shorter and more bulkier with 8 teeth. Moreover, the caves where the species have been found are totally isolated from one other and belong to distinct cave systems. Given that the two caves are only a few kilometres apart, it can be suggested that both Vietbocap species may have a common epigean ancestor that colonized the caves independently.

Lourenço et al. (2018) subsequently described the female of V. thienduongensis, and two new species from deeper in the same cave. Whereas the specimens of V. thienduongensis were collected 750–1800 m from the cave entrance, the holotype of V. aurantiacus was collected 3000 m from the entrance, and the types of V. quinquemilia, 5000 m from the entrance. According to Lourenço et al. (2018: 269, 271, 272):

Vietbocap thienduongensis and Vietbocap aurantiacus sp. n. are the two most geographically close species found in the cave, distant of 1.0 to 1.5 km. V. aurantiacus sp. n. can, however, be distinguished by a number of features: bigger size (35.8 vs 23.9 mm) and distinct morphometric values …; darker coloration, more to orange-yellow; anterior margin of carapace not depressed; sternum longer than wide …; metasomal segments and pedipalps better carinated and granulated; sternite V with a conspicuous white posterior inflated triangular zone; moderate serrula on chelicera movable finger.…

Vietbocap quinquemilia sp. n. is geographically separated of Vietbocap aurantiacus sp. n. by 2 km. Their general morphology although similar presents a number of differences and in fact V. quinquemilia seems more closely related to V. thienduongensis. This new species can however be characterized by a number of particular features: small size (only 20.2 mm for female) and distinct morphometric values (see measurements and ratios following the description); a very pale coloration almost whitish; this is the paler species known for the genus; median ocular tubercle on carapace only slightly depressed; cheliceral serrula moderately marked; tergites globally smooth; pedipalp carinae very weakly marked.…

It is difficult to estimate from the sole morphological study of these “populations” of Vietbocap living in the Thien Duong cave what is their precise degree of differentiation … Consequently, the question to be addressed is: are we faced with species, subspecies or only morphs of a large polymorphic species? For three of these populations, a specific status is here suggested in association with their possible allopatric distribution, though the number of available specimens is small to evaluate the robustness of the observed differences.… The presence of syntopic and closely related troglobitic species of a same genus in a same cave [sic] is quite exceptional. Molecular approaches will be necessary to evaluate the robustness of the observed differences between the species which have been recognized.

The hypothesis that three allopatric populations or species of Vietbocap inhabit Động Thiên Đường was tested and falsified in the present study by comparing DNA sequences of two nuclear (18S-ITS and 28S) and three mitochondrial (12S, 16S, and COI) gene loci from five samples collected at several sites along a transect 1–5 km from the entrance. The extremely low genetic divergence among the samples along this transect (fig. 9; table 12) are consistent with panmixis. In addition, the same loci were sequenced from three samples collected in Tiên Sơn, the type locality of V. canhi, only 2.5 km away. Similar levels of divergence among the samples from Tiên Sơn, and between those samples and the samples from Động Thiên Đường, falsified the hypothesis that the two caves harbor different species, refuting the unsubstantiated statement that the caves “are totally isolated from one other and belong to distinct cave systems.” The assumption that species occurring in different caves must be heterospecific, also known as the “caves as islands” paradigm (Mammola, 2019) suggested earlier by others (e.g., Francke, 2009a), is problematic for two reasons, noted earlier. Firstly, geography is not heritable and cannot comprise part of a taxon diagnosis, regardless of the presence or absence of morphological (or genomic) differences. Secondly, no conclusive evidence has been presented that the caves are disconnected or that these scorpions might not occur in other caves or passages in the 2.5 km between them. Several caves and cave networks in Southeast Asia are far longer than the distance between Tiên Sơn and Động Thiên Đường, e.g., Hang Sơn Đoòng (over 9 km long), Tham Xe Bang Fai (11 km long), and Phong Nha Cave (over 44 km long). Even Thiên Đường is more than 20 km long. As noted earlier, in attributing islandlike properties to caves, researchers should consider the presence of subterranean connections, as well as the vagility of the species of interest (Mammola, 2019). A network of fissures connecting two caves would make it difficult to consider the scorpion populations inhabiting them, to be isolated from one another.

Multivariate statistical analysis of the morphometric data presented by Lourenço and Pham (2010, 2012) and Lourenço et al. (2018), together with new data (tables 3–5, 10; appendices 4, 6, 7), was similarly unable to discriminate among the individuals from the two caves, which clustered together across a morphospace comparable to that of other pseudochactid species (fig. 8). It is apparent that ontogenetic differences were mistaken as diagnostic by Lourenço and Pham (2010, 2012) and Lourenço et al. (2018). Putatively diagnostic differences concerning size and morphometrics (table 3), coloration, granulation and/or carination, and the relative development of the circumocular sutures (affected by the sclerotization of the carapace tegument) reflect different stages of sexual maturity. Smaller size (and associated morphometric differences; tables 3, 10; appendices 4, 6, 7), paler coloration, weaker granulation and/or carination, and weakly developed circumocular sutures, as exemplified by the types of V. canhi and V. quinquemilia, are consistent with the immature stages, whereas larger size (and associated morphometric differences; tables 3, 10; appendices 4, 6, 7), darker coloration, stronger granulation and/or carination, and well developed sutures, as well as the presence of a pale, raised, triangular surface on the posteroventral margin of sternite V, exemplified by the holotype of V. aurantiacus, are consistent with the adult stage. The only characters that are ontogenetically invariant and offer any potential for species diagnosis are the counts of median denticle subrows on the fixed and movable fingers of the pedipalp chela, and the counts of pectinal teeth and lamellae. However, setting aside the absence of a statistical sample, the variation in these counts (e.g., a difference of one denticle subrow between individuals from the two caves, or of one pectinal lamella or tooth between individuals of the same sex in the same or different caves; tables 3–5) spans the normal levels of variation observed in other scorpion taxa, including pseudochactids.

In view of the overwhelming molecular and morphological evidence that the scorpions inhabiting both caves are conspecific, the following new synonyms are proposed: Vietbocap thienduongensis Lourenço and Pham, 2012 = Vietbocap canhi Lourenço and Pham, 2010, syn. nov.; Vietbocap aurantiacus Lourenço et al., 2018 = V. canhi, syn. nov.; Vietbocap quinquemilia Lourenço et al., 2018 = V. canhi, syn. nov.

Material Examined: VIETNAM: Quảng Bình Prov.: Bố Trạch Distr.: Phong Nha-Kẻ Bàng National Park: Tiên Sơn (Cave), 17°31′58.8″N 106°16′01.2″E, 200 m, 23.ii.2012, L. Prendini and V.A. Dang, dark zone of cave, ca. 200–500 m from entrance, UV detection in moist cave environment with abundant dripstone and flowstone formations, stalactites and stalagmites, specimens usually sitting in rock crevices or under small stones, mostly in moist situations (near areas where water collects from dripstone formations), none found in dry areas of cave, 7 ♀, 2 subad. ♂, 1 subad. ♀, 4 juv. ♂, 4 juv. ♀, pedipalp fragments (AMNH), 3 juv. ♀ (AMCC [LP 11270, 16750, 16751]); Thiên Đường (Cave), 200 m, 12.xi.2011, ex D.-S. Pham, cave, No. 1279, 1 juv. ♀ (AMCC [LP 11348]), Động Thiên Đường (Paradise Cave), 17°31′11.1″N 106°13′23″E, 248 m, 12–13.xi.2018, S.F. Loria, V.L. Ehrenthal, B.Đ. Trần, and H.V. Dương, blacklight in cave, specimens collected between 1 km and 5 km deep in cave, walking on ground, under rocks or in limestone cracks, ca. 1 km from cave entrance, 1 ♀(AMNH), 1 subad. ♀ (IEBR), [leg] (AMCC [LP 16533]), between 1 km and 5 km from cave entrance, 1 subad. ♂ (IEBR), [leg] (AMCC [LP 16535]), 1 subad. ♀ (AMCC [LP 16536]), ca. 5 km from cave entrance, 1 juv. ♂ (PNKB), [leg] (AMCC [LP 16534]), 1 juv. ♀ (PNKB), [leg] (AMCC [LP 16537]).