Type material: IZB; male holotype; western Serbia, Hadži-Prodanova pećina Cave, near the village of Raščići, Ivanjica, 650 m asl.; 28th June 2018; leg. D. Antić. – Coll. AS; one male and one juvenile paratypes; collected together with the holotype. – Coll. AS; one female paratype; same cave and collector; 17th October 2018. All specimens mounted in Marc André II solution.

Other material studied: Coll. AS; one specimen of unknown sex collected together with the holotype; mounted on an aluminium stub and coated with palladium-gold.

Etymology: This species is named after Prof. Dr Jovan Cvijić (1865-1927), a widely known Serbian geomorphologist, former president of the Serbian Royal Academy of Sciences, and one of the first explorers of the Hadži-Prodan Cave in 1914. The epithet is a name in the genitive case.

Description:

Body: Body lengths 3.9 mm (female paratype), 3.3 mm (holotype), 3.4 mm (male paratype) and 2.6 mm (juvenile paratype) (Fig. 1). Epicuticle smooth when examined under an optical microscope. Body clothed with few medium-sized, thin, smooth (or with one thin distal barb) setae.

Head: Antennae of same length as body in juvenile and slightly shorter in adults (Table 1), with 27 (female paratype), 29 (juvenile paratype), and 30 (male holotype) antennomeres. Bacilliform sensillum of third antennomere in ventral position, between macrosetae d and e, 20 µm long. Medial antennomeres slightly elongated: 1.5-1.6 times longer than wide; apical antennomere 1.5 longer than wide. Each medial and distal antennomere with 18-20 thin gouge sensilla (30 µm) in a single distal whorl, as well as with two conical sensilla (7 µm) in same whorl. Cupuliform organ occupying 1/3 of total length of last antennomere; with 12-16 spheroidal olfactory chemoreceptors with an eccentric or centric column surrounded by concentric, incompleted expansions covered by a visible polygonal net with porous surface (Figs 2–3). Protruding frontal process carrying numerous tubercular setae. Length ratios of three macrosetae along each side of line of insertion of antennomere and x setae being 30/37/30/42, a/i/p/x in holotype. Three pairs of longer macrosetae on dorsal side of head in asl, psm, psl position. Labial palps suboval, each with conical latero-external sensillum near two gard setae, seven normal setae in anterior portion, and up to 60-80 neuroglandular setae in medial and posterior position.

Thorax: Pronotum with 1+1 ma, 3+3 la, 2+2 lp_2,3 macrosetae; mesonotum with 1+1 ma, 3+3 (3+2) la_1-3, 2+2 lp_2,3; metanotum with 1+1 ma, 1+1 la, 2+2 lp_2,3; long, thin notal macrosetae with barbs in distal half; few smooth (or with a thin distal barb) clothing setae (holotype: 5+3, 14+13, 15+14 on pronotum, mesonotum, and metanotum) (Fig. 4). Metathoracic legs reaching eighth abdominal segment, with two dorsal femoral macroseta of 0.25-0.20 mm length, with thin barbs in distal three-fourths, as well as two ventral macrosetae similar in shape and length as dorsal macrosetae (Fig. 5); two tibial metathoracic macrosetae with 1-5 thin distal barbs; calcars with long, thin barbs in several rows on one side; tarsus with two ventral rows of larger setae with distal barbs and with two dorsal and two ventral subapical smooth macrosetae; slightly unequal claws (posterior claw 1.2 longer than anterior claw) with large lateral crests; posterior claw with a small backward overhang. Abdomen: Urotergites I-III with 1+1 post₁ macrosetae; urotergite IV with 1+1 la, 2+2 post_1,2 macrosetae; urotergite V with 1+1 la, 5+5 post_1-5; urotergite VI with 2+2 (1+1) la, 5+5 post_1-5; urotergite VII with 2+2 la, 5+5 post_1-5; urotergite VIII with 6+6 post; abdominal segment IX with 8+8 (8+7) post macrosetae; all urotergal macrosetae long and barbed in distal three-fourths; urosternite I with 7+7 macrosetae, urosternites II-VII with 5+5, and urosternite VIII with 2+2 macrosetae. Stylar setae with a few barbs: apical seta with basal tooth and two thin barbs, subapical seta with two or three thin barbs, and medio-sternal seta with a long distal barb and a thin short one. Complete cercus of holotype 1.3 times longer than body, with base divided into three secondary articles followed by nine primary articles (Table 1); each primary cercus bearing 2-10 irregularly arranged whorls of long barbed macrosetae, 1-2 distal whorls of smooth long setae, and one apical whorl of short thin setae with tiny distal barbs.

Secondary sex characters: First urosternite of males with two rows of up to 43 glandular g₁ setae, subcylindrical appendages slightly enlarged in distal area, with up to 25 glandular a₁ setae (Fig. 6). Females with subcylindrical appendages carrying up to nine glandular a₁ setae.

Taxonomic affinities: Plusiocampa (Didymocampa) cvijici sp. nov. shares some taxonomical features with two species of the presumably paraphyletic subgenus Didymocampa: Plusiocampa (Didymocampa) evallonychia Silvestri, 1949 from Crimenan caves and Plusiocampa (Didymocampa) euxina Condé, 1996 from Movile Cave in Romania. Among other taxonomical features we point out the following: the absence of medial posterior macrosetae on mesonotum and metanotum; 1+1 posterior macrosetae on first to third urotergites; 5+5-6+6 macrosetae on second to seventh urosternites; stylar setae with a few thin barbs (Condé, 1996; Sendra et al., 2020a; Silvestri, 1949). Plusiocampa (D.) cvijici sp. nov. differs from both species by some taxonomical features: 3+3 and 1+1 lateral anterior macrosetae on mesonotum and metanotum [vs. 2+2 la, 1+2 la in P. (D.) euxina and 1+1 la, 0+0 la in P. (D.) evallonychia], 8+8 post macrosetae on abdominal segment IX [vs. 9+9 in P. (D.) euxina and P. (D.) evallonychia]. Plusiocampa (D.) euxina is geographically and taxonomically closest to P. (D.) cvijici sp. nov. due to similarities in the macrosetae distribution pattern, their slightly subequal claws, and few smooth notal clothing setae. The new species differs from P. (D.) euxina not only in the aforementioned number of lateral anterior notal macrosetae and the number of macrosetae on the eighth abdominal segment, but P. (D.) euxina also has few tubercular setae on the frontal process, three ventral tibial macrosetae, short lateral processes with a few barbs on the pretarsus, and barbed subapical tarsal setae. Plusiocampa (D.) cvijici sp. nov. is distinguished from P. (D.) euxina by more tubercular setae, two ventral tibial macrosetae, longer smooth lateral processes protruding beyond the tips of the claws, and smooth subapical tarsal setae.

Type locality: The Hadži-Prodanova pećina Cave, located in western Serbia (the Dinarides), is a national natural monument and a well-known Palaeolithic site rich in late Pleistocene mammal fossils (Mihailović & Mihailović, 2003; Bogićević et al., 2017) (Fig. 7). The entrance of this multilevel cave with a length of 420 m is situated at 630 m a.s.l. The cave is mainly dry, without a cave stream, and it consists of three main chambers: the lower, middle and upper one. It is a residence for six Chiroptera species (Paunović, 2016). Besides, the cave is rich in arthropods, of which the most important are Balkan troglophiles, viz., the harvestman Mitostoma cancellatum (Roewer, 1917), the millipedes Apfelbeckia insculpta (L. Koch, 1867) and Brachydesmus herzogowinensis Verhoeff, 1897, as well as Serbian troglobionts such as the springtail Pseudosinella ivanjicae Ćurčić, Lučić & Boškova, 1999 and the ground beetle Duvalius starivlahi Guéorguiev, Ćurčić & Ćurčić, 2000, both only known from the Hadži-Prodanova pećina Cave. The new species was found under stones in the main (middle) chamber of the cave.

Type material: MHNG; female holotype; Bosnia & Herzegovina, Lukina pećina Cave, Srednja stijena, Tajan, Zavidovići; 11th July 2018; leg. D. Antić. – MHNG; one male a one female paratypes (labelled ♂2 paratype and ♀7 paratype) collected from the same cave on 17th November 2019; leg. A. Bajraktarević, E. Balić, D. Zgonjanin, A. Sinković. – NHMB; two female paratypes (labelled ♀2 paratype and ♀6 paratype) collected together with the holotype. – Coll. AS.; one male, three female and one juvenile paratypes (labelled ♂1 paratype, ♀2, ♀3, ♀7 paratypes and J1 paratype) collected together with the holotype.

Other material studied: Coll. AS; one female collected together with the holotype. – Coll. AS; three females and one juvenile; same cave and collectors, sampled on 17th November 2019; mounted in Marc André II solution. – Coll. AS; one specimen of unknown sex collected together with the holotype; mounted on an aluminium stub and coated with palladium-gold.

Etymology: This species is named in honor of the members of the “Atom” Sport and Science-Research Club, Zavidovići, Bosnia and Herzegovina, for their determination and hard work at protecting speleological objects in Bosnia and Herzegovina, for collecting cave animals, as well as for saving human lives in the mountains of Bosnia and Herzegovina whilst risking their own lives. Additionally, D.A. is grateful to them for their long-lasting friendship. Noun in apposition.

Description:

Body: Body length 4.4 mm (males), 4.5-6.5 mm (females) and 3.6 mm in one juvenile (Fig. 8) (Table 2). Epicuticle smooth when seen under optical microscope; body with numerous medium-sized, smooth (or with a distal thin barb) clothing seta.

Head: Antennae length 0.73-0.84, shorter than body (Table 2), with 32-38 antennomeres (perhaps regenerated distal antennomers). Bacilliform sensillum of third antennomere in a ventral position, between macrosetae d and e, 15 µm long. Medial antennomeres slightly elongated, 1.7 times longer than wide; apical antennomere 2.3 times longer than wide. Eight to ten thin gouge sensilla (28 µm) in a single distal whorl on each medial and distal antennomere; two conical sensilla (9 µm) in same whorl. Cupuliform organ occupying less than 1/3 of total length of last antennomere, with 7-9 spheroidal olfactory chemoreceptors with an eccentric or centric column surrounded by a concentric fold. Non-protruding frontal process with three smooths anterior macrosetae and no tubercular setae. In holotype these macrosetae along each side of line of insertion of antennomere and smooth x setae with length ratios of a/i/p/x, 36/34/29/39, respectively. Three pairs of slightly longer smooth macrosetae on dorsal side of head in ma, la, lp position. Labial palps suboval, each with a conical latero-external sensillum near two gard setae, six normal setae in anterior portion, and up to 60 neuroglandular setae in medial and posterior position.

Thorax: Pronotum with 1+1 ma, 4+4-3+3 la, 2+2 lp_2,3 macrosetae; mesonotum with 1+1 ma, 3+3 la_1-3, 2+2 lp_2,3; and metanotum with 1+1 ma, 1+1 la, 2+2 lp_2,3; long barbed notal macrosetae with barbs in distal two-thirds; smooth clothing setae or clothing setae with a thin distal barb, and longer marginal setae with thin distal barbs in their distal half (Fig. 9). Metathoracic legs reaching the ninth abdominal segment, with similar lengths of femur, tibia and tarsus, including pretarsus (Fig. 9) (Table 2). One dorsal femoral macroseta in distal half with thin 0.20-0.30 mm long barbs; three barbed ventral macrosetae slightly shorter than dorsal macrosetae; three short tibial metathoracic macrosetae barbed in distal half; calcars with thin barbs in several rows on one side; tarsus with two ventral rows of slightly larger setae with distal barbs; two smooth dorsal subapical setae and two barbed ventral setae on tarsus; claws slightly unequal (posterior claw 1.2-1.3 times longer than anterior claw), with large lateral crests and smooth setiform lateral processes; posterior claw with large backward overhang (Fig. 10).

Abdomen: Urotergites I-III with 1+1 post₁ macrosetae; urotergite IV with 1+1 la, 3+3 (4+3) post_1-3 macrosetae; urotergite V-VII with 1+1 la, 5+5 post_1-5; urotergite VIII with 6+6 post; abdominal segment IX with 8+8 post macrosetae; all urotergal macrosetae long and barbed in distal three-fourths; urosternite I with 7+7 macrosetae; urosternites II-VII with 5+5; urosternite VIII with 2+2 macrosetae; urosternal macrosetae with a few long distal barbs. Stylus with smooth apical seta carrying a basal tooth, subapical and medio-sternal setae with four or five long thin barbs. No intact cercus in any specimen; the most complete cercus 4.5 mm long (♀6-paratype), with basal article divided into three secondary articles followed by eight primary articles; each primary cercal article bearing 2-8 irregulary shaped whorls of long macrosetae with thin distal barbs, one distal whorl of smooth long setae, and one apical whorl of short thin setae with tiny distal barbs.

Secondary sex characters: First urosternite of males bearing a narrow field with one or two rows of up to 29 glandular g₁ setae; subcylindrical appendages with a small field of up to 15 glandular a₁ setae; females possessing subcylindrical appendages with up to 13 glandular a₁ setae.

Taxonomic affinities: Plusiocampa (P.) atom sp. nov. shows similarities with P. (P.) latens Condé, 1948, a species with several known localities in the Dinaric karst (Sendra et al., 2020a). Both species have equal macrosetae patterns on thorax and abdomen (Condé, 1948). Plusiocampa (P.) atom sp. nov. differs from P. (P.) latens in two characters: it has three ventral macrosetae and up to 38 antennomeres, whereas P. (P.) latens has only two ventral macrosetae and 24-27 antennomeres.

Type locality: The Lukina pećina Cave is located in the “Tajan” Nature Monument, in central Bosnia and Herzegovina (Fig. 11). This is a cave system with two entrances close to each other and a total length of 247 m. It is well-known for its remains of an autochthonous Upper Pleistocene fauna and for traces of the cave bear (Lukić-Bilela et al., 2009). As far as arthropods are concerned, two other troglobites were found in the cave, viz., the millipede Brachydesmus mulaomerovici Makarov, Ćurčić & Antić in Antić et al., 2013 and the woodlouse Cyphonethes tajanus Karaman & Horvatović, 2018, both recently discovered and described, and endemic to subterranean habitats in the “Tajan” Nature Monument.

Material studied: Coll. AS; three males and five females; Serbia, Pričevska pećina Cave, Pričevac, Papratna, Stara Planina; 17th June 2019; leg. D. Antić & D. Stojanović.

Type material: MHMZOO; male holotype; Croatia, Grabovčića jama Cave, Radošić; 4th November 2014; leg T. Rađa. – MHMZOO; one male and five female paratypes (labelled ♂2 paratype, and ♀5 to ♀9 paratypes); same cave and collector as holotype sampled 27th October 2014. – MHNG; two female paratypes (labelled ♀1 paratype and ♀4 paratype); same cave, data and collecter as holotype. – NHMB; one female paratype (labelled ♀11 paratype); same cave and collector as holotype; sampled 27th October 2014. – Coll. AS; two female paratypes (labelled ♀2 paratype and ♀3 paratype); same cave, data, and collector as holotype. – Coll. AS; one male and three female paratypes (labelled ♀10 paratype, ♀12 paratype, ♀13 paratype and ♂3 paratype); same cave and collector as holotype sampled 27th October 2014.

Other material studied: Coll. AS; two males and two females from the same cave and collector; sampled on 27th October 2014; mounted on an aluminium stage and coated with palladium-gold.

Etymology: This species is dedicated to the French zoologist Camille Bareth, who has been working with diplurans throughout her prolific career and described 27 new species and 3 subspecies of troglobitic campodeids. She also worked intensely on the morphology and physiology of the group, to which she devoted more time and effort than any other researcher. In addition, she is the co-author of an article where she and her colleague Dr Bruno Condé suggested the possibility that the specimens identified by them as Plusiocampa (Stygiocampa) cf. remyi, could belong to a new taxon. This is confirmed and the new species is described below. The specific epithet is a name in the genitive case.

Description:

Body: Body length 3.4-5.9 mm (males, n= 3), 5.5-8.7 mm (females, n= 11) (Table 3). Epicuticle smooth under optical microscope, when seen at high magnification, weakly reticulated, showing irregular polygonal structures of various sizes (Fig. 20); body set with numerous moderately long clothing setae with thin barbs almost all over over surface.

Head: Eleven apparently complete and intact antennae with 40-50 antennomeres; antennae 1.07-1.25 times longer than body (Table 3); medial antennomeres 2-3 times longer than wide; apical antennomere 3 times longer than wide. Cupuliform organ with several uncountable, complex and apparently laminar olfactory chemoreceptors opening to the exterior through a very narrow hole (Fig. 12). Distal and central antennomeres with three whorls of macrosetae carrying distal barbs and scattered smooth setae, as well as a single distal whorl of 16-18 long gouge sensilla (26-38 µm long), and up to two conical 8 µm long sensilla (Figs 13–15). Proximal antennomeres with typical trichobothria, plus a small bacilliform sensillum (8 µm long) on third antennomere in a ventral position. Frontal process with a moderate conical protrusion covered with a few tuberculate setae carrying a few thin barbs (Fig. 17). The three macrosetae along each side of line of insertion of antennomere and x setae with thin distal barbs; length ratios of a/i/p/x being 23/27/26/29. Labial palps large and suboval, with a conical latero-external sensillum, two guard setae, up to thirteen setae on anterior border, and up to 250 neuroglandular setae (Fig. 16).

Thorax: Thoracic macrosetae: pronotum with 1+1 ma, 3+3 la_1-3, 2+2 lp_2,4 macrosetae; mesonotum with 1+1 ma, 2+2 lp_2,4 macrosetae; metanotum with 2+2 (2+1; 1+1) lp_2,3 macrosetae (Figs 18–21). All thoracic macrosetae long and with thin barbs almost all over; thin marginal setae slightly longer than clothing setae, both with thin distal barbs almost all over their surface (Figs 19–21). Legs elongated, metathoracic legs reaching beyond end of abdomen; femur, tibia and tarsus with pretarsus similar in length (Table 3). Femora carrying well-differentiated long subapical ventral macrosetae. Calcars completely covered with thin barbs (Fig. 23). Tarsus with two rows of ventral setae, these similarly barbed but larger than clothing setae, plus several thin long setiform sensilla all over tarsus. Tarsus with three dorsal and two ventral subapical setae with thin barbs all over. Claws unequal in size, posterior claw longer than anterior claw (posterior claw: anterior claw ratio = 1.5-1.6: 1), both claws with large lateral crests. Ventral side of claws noticeably ridged and covered with a micro-granular surface; posterior claw large, with a backward overhang. Lateral processes of pretarsus setiform, with a few thin proximal barbs (Figs 22, 24–25).

Abdomen: Distribution of abdominal macrosetae on tergites: 1+1 la on IV; 1+1 la, 1+1 post₅ on IV; 1+1 la, 3+3 post_3,4,5 on VI-VII; 5+5 post_1-5 on VIII; 8+8 post on IX. All tergal abdominal macrosetae long and well-differentiated, with thin barbs in distal four-fifths. Urosternite I with 24+24-21+21 (18+18 in smaller specimen: ♂2 paratype) well-barbed macrosetae (Figs 26–31); urosternites II-VII with 15+15-13+13 (11+11 in smaller specimen = ♂2 paratype) macrosetae (Figs 32–33); urosternite VIII with 3+3-4+4 macrosetae (Fig. 36); urosternal macrosetae of medium length or longer and with long barbs, some divided into micro-barbs all over distal two-thirds (Figs 28–29, 33). Stylar apical setae including a long basal tooth, subapical setae completely covered with barbs all around; medial setae thinner than others, with short barbs in distal two-thirds (Figs 34, 37). Eversible vesicles large, with two different surface textures (Figs 34–35). No intact cerci available in studied material; the most complete cercus present on ♀6 paratype: basal article with 12 secondary articles followed by 18 primary articles, total length 12 mm. Length of cercal articles increasing from proximal to distal articles. Each article with a variable number of irregular whorls of almost completely barbed macrosetae, from three on proximal articles to 18 on distal articles, mixed with few irregular whorls of long smooth setae. All primary articles with a short, thin, distally barbed whorl of seta (Figs 38–39).

Secondary sex characters: Female urosternite I with subcylindrical appendages, each one bearing up to 17 glandular a₁ setae in a distal field (Figs 30–31). Male urosternite I with enlarged appendages, each one bearing up to 80 glandular a₁ setae in a distal field; posterior edge of urosternite I with a field of up to 240 glandular g₁ setae arranged in four rows; additionally about eighty short setae in an anterior position, these clearly differentiated from clothing setae by their barbed middle portion (Figs 26–27).

Taxonomic affinities: More than two decades ago, Condé & Bareth (1996) referred to one male and two females sampled in the Vranjača pećina Cave near Kotlenice (Split, Croatia) as Plusiocampa (Stygiocampa) cf. remyi because of differences in secondary sex characters of the male. These traits consist of enlarged appendages with a large apical field of glandular a₁ setae and a large field of glandular g₁ setae on the posterior border (Figs 26–31). The same structures are found in four males collected in the nearby Grabovčića jama Cave (Radošić, Croatia). This morphological distinction encouraged us to propose a new species from the Vranjača pećina and Grabovčića jama specimens, i.e. Plusiocampa (Stygiocampa) barethae Sendra & Rađa, sp. nov. In addition to the characters mentioned above, there are several other differences between P. (S.) barethae sp. nov. and P. (S.) remyi, such as shorter and thinner gouge sensilla in P. (S.) remyi; 1+1 lateral anterior macrosetae on third urotergite in P. (S.) remyi, which are absent in P. (S.) barethae sp. nov.; and 9+9 to 11+11 posterior macrosetae on the ninth abdominal segment in P. (S.) remyi instead of 8+8 posterior macrosetae as in P. (S.) barethae sp. nov.

Type locality: The Grabovčića jama Cave, with a narrow, approximately 1 × 0.6 m wide entrance, is situated at 230 m a.s.l (Fig. 40). The bottom, at 45 m depth, is reached through a series of small pits. The interior of the cave is humid, with an annual mean temperature of about 10°C. The specimens were collected on flowstone at a depth of approximately 30 m (Fig. 41), in complete darkness. More than ten individuals of different sizes were spotted on our third visit to the cave.

Material studied: Coll. AS; one male and thirteen females; Serbia, Izviđačka Cave, canyon of the river Suvaja, Mt Beljanica, near Despotovac; 14th July 2018; leg Đ. Marković. – Coll. AS; one male and five females; from the same cave; 6th June 2018; leg. S. Ćurčić. – Coll. AS; two females and one juvenile; Serbia, Vlaška Cave, Mt Beljanica; 11th April 2010; leg. I. Njunjić. – Coll. AS; three females; Serbia, Lazareva (Zlotska) Cave, village of Zlot, Kučaj Mts, near Bor; 15th November 2018; leg. D. Antić, D. Stojanović. – Coll. AS; three females; Serbia, Lazareva (Zlotska) Cave, village of Zlot, Kučaj Mts, near Bor; 16th June 1996; leg. S. Ognjenović. – Coll. AS; one female; Serbia, Jama u Vrtačelju Pit, Vrtačelje, Kučaj Mts; 17th October 2007; leg. S. Ognjenović. – Coll. AS; three females and six specimens; Serbia, Vernjikica Cave, village of Zlot, Kučaj Mts, near Bor; 15th November 2018; leg. D. Antić, D. Stojanović. – Coll. AS; three females; Serbia, Bogovinska Cave, village of Bogovina, Kučaj Mts, Boljevac; 16th November 2018; leg. D. Antić, D. Stojanović.

Taxonomic notes: SEM observations have revealed and supplemented some taxonomic features, such as a narrow hole of the cupuliform organ (Fig. 44); very long shafts of trichobothria (Fig. 45); a quadrangular protruding frontal process with non-tuberculated setae (Figs 46–47); thin and long neuroglandular setae on subspherical labial palps with enlarged asymmetrical openings (Figs 48–49); slightly elongated nota with macrosetae on pronotum (1+1 ma, 3+3 la, 1+1 lp₂), a lack of macrosetae on mesonotum and metanotum with a microreticulated surface visible under SEM (Figs 50–53); tibia with barbed calcars (Fig. 56); claws unequal (posterior claw: anterior claw ratio = 1.45: 1); tarsal setae with long barbs from base to tip; dorsal surface of claws almost smooth, longitudinal grooves on ventral side with a pattern of tiny transversal ridges between them (Figs 54–55, 57); first urosternite of females carrying subcylindrical appendages ending in a small field of glandular a₁ setae (Figs 58–59); long urosternal macrosetae with long, thin barbs in half to three-fourths of distal portion (Figs 58, 60); styli carrying short apical setae with a few long barbs, and longer subapical and medial setae with long barbs almost from base to tip (Fig. 61); large eversible vesicles with two well-differentiated areas (Fig. 61).

Biogeographical note: The new localities of the material studied slightly enlarge the previously known geographical range.

Material studied: Coll. AS; one juvenile; Montenegro, Začirska Cave, village of Začir, near Rijeka Crnojevića, Cetinje; 25th June 2018; leg. D. Antić, Đ. Marković. – Coll. AS; one female; Bosnia & Herzegovina, Jazvina Cave, Kamešnica; 1st July 2018; leg. T. Rađa.

Taxonomic note: The female from Jazvina Cave is without medial anterior macrosetae on its metanotum.

Biogeographical note: The new localities of the material studied slightly enlarge the previously known geographical range.

Type material: MHMZOO; female holotype; Croatia, Golubinka pod Kraljevcom Cave, Radošić; 10th September 2014; leg. T. Rađa. – MHNG; one male paratype (labelled ♂1 paratype); same cave and collector; 15th November 2014. – Coll. AS; one male paratype (labelled ♂2 paratype); same cave and collector; 18th April 2014. All material mounted in Marc André II solution.

Other studied material: Coll. AS; two specimens of unknown sex; collected together with holotype; mounted on an aluminium stub and coated with palladium-gold.

Etymology: This species is named after Vicko Dulčić (1923-1985), a Croatian caver and founder of the Speleological Society “Špiljar”, Split, Croatia. Name in the genitive case.

Description:

Body: Body length 4.7 mm (♀ holotype), 3.2 and 4.5 mm (♂1 and ♂2 paratypes). Epicuticle smooth when examined under optical microscope, thin reticular under high magnification (SEM, up to 1000x) (Fig. 70); body with thin, medium-sized, barbed clothing setae.

Head: Antennae length similar to body length (antennae length: body lenght ratio = 0.98: 1), with 38 antennomeres. Bacilliform sensillum of third antennomere in a ventral position, between macrosetae d and e, 18 µm in length. Medial antennomeres elongated and 1.7 times longer than wide; apical antennomere 1.5 times longer than wide. Twelve to fourteen thin gouge sensilla (28 µm) in a single distal whorl on each medial and distal antennomere, plus one long bacilliform sensillum (13 µm) in same whorl (Figs 63–65). Cupuliform organ occupying less than 1/3 of total length of last antennomere, with numerous complex olfactory chemoreceptors with a centric column surrounded by radial folds; entire surface covered with a polygonal net with pores (Fig. 62). Frontal process with double protrusion above several tubercular setae (Figs 67–68). The three macrosetae along each side of line of insertion of antennomere and x setae with 4-8 thin barbs; length ratios of a/i/p/x in holotype being 39/45/38/56 (Fig. 68). Head carrying three pairs of moderately long, smooth macrosetae in asl, psm, psl position on dorsal side. Suboval labial palps, each with a bacilliform latero-external sensillum near two gard setae, with twelve normal setae in anterior portion and with up to 125 neuroglandular setae in medial and posterior position. Thorax: Pronotum with 1+1 ma, 4+4-5+5 la, 2+2 lp_2,3 macrosetae; mesonotum with 1+1 ma, 1+1 la, 3+3 lp_1-3; metanotum with 1+1 ma, 3+3 lp_1-3; long barbed notal macrosetae with barbs in distal two-thirds; marginal setae longer than clothing setae, with thin distal barbs (Figs 66, 69–70). Metathoracic legs reaching tenth abdominal segment; without ventral macrosetae and tibial macroseta; calcars with numerous long thin barbs in a few rows; tarsus with two ventral rows of larger, longer and more densely barbed setae than clothing setae, with numerous setiform sensilla among clothing setae (Fig. 73) and with two dorsal and two ventral subapical barbed setae; claws unequal (posterior claw 1.3 times longer than anterior claw), with large lateral crests and smooth setiform lateral processes or with a couple of barbs; posterior claw with large backward overhang; claws almost smooth on dorsal side, ventral side noticeably ridged and covered with micro-granular surface (Figs 71–72).

Abdomen: Urotergite I with 1+0 (0+0) post₁ macrosetae; urotergite II with 1+1 (0+1) post₁; urotergite III with 1+1 post₁; urotergite IV with 2+2 (2+1) post_1-2; urotergites V-VII with 1+1 la, 4+4 post_1-4; urotergite VIII with 6+6 post; abdominal segment IX with 9+9 (8+9) post; all urotergal macrosetae long and barbed in distal three-fourths; urosternite I with 7+7 macrosetae; urosternites II-VII with 6+6; urosternite VIII with 2+2; urosternal macrosetae with long medial and distal barbs (Fig. 75). Apical seta with a basal double tooth and two or three long thin barbs; subapical seta completely covered by short barbs; medio-ventral setae with four or six long thin barbs (Fig. 74). Eversible vesicles large, with proximal and distal areas of different microtexture (Fig. 76). Best preserved cercus broken; each primary article bearing from two to eight irregular whorls of long barbed macrosetae, one distal whorl of long smooth setae, and one apical whorl of short thin setae with tiny distal barbs. Secondary sex characters: First urosternite of males with subcylindrical appendages, each bearing 10 and 8 glandular a₁ setae; posterior border of urosternite I with 90 and 4 glandular g₁ setae in two males studied: one adult male (♂1 paratype) and one young male (♂2 paratype); female holotype with subcylindrical appendages, each carrying up to 16 glandular a₁ setae.

Taxonomic affinities: Plusiocampa (Stygiocampa) dulcici Sendra & Rađa, sp. nov. is closely related to Pluciocampa (Stygiocampa) denisi Condé, 1947 due to similarities in the distribution pattern of urotergal and urosternal macrosetae, both with 1+1 lateral anterior and 4+4 posterior macrosetae on the sixth and seventh urotergites, and 7+7 and 2+2 urosternal macrosetae on the first and seventh urosternites (Condé, 1947). A remarkable distinction from P. (S.) denisi is the number of lateral posterior macrosetae on the mesonotum and metanotum: P. (S.) dulcici sp. nov. has 3+3 such macrosetae on the mesonotum and metanotum, whereas P. (S.) denisi has 1+1 lateral posterior macrosetae on the mesonotum but none the metanotum. Other taxonomical features that differ between P. (S.) dulcici sp. nov. and P. (S.) denisi are the presence of macrosetae on the first to the third urotergites in P. (S.) dulcici sp. nov. vs. their absence in P. (S.) denisi, and the 6+6 macrosetae on the second to the seventh urosternite in P. (S.) dulcici sp. nov. vs. 5+5 in P. (S.) denisi.

Type locality: The Golubinka pod Krajevcem Pit is about 25 m deep and about 30 m long, with two entrances (Fig. 43) at 233 m a.s.l. through which the daylight reaches the bottom of the pit, allowing a Mediterranean shrub and moss community to grow. The final chamber is large, 20 × 24 m, with a mean annual temperature of around 10°C. Several specimens of the new species were collected under small stones at 22 m depth (Fig. 42). During the wet season the cave is very humid. Golubinka pod Kraljevcem is renowned for being the habitat of several cave species, i.e., Troglaegopis mosorensis (Kuščer, 1933) (Mollusca: Gastropoda), Neotrechus dalmatinus (L. Miller, 1861) (Insecta: Coleoptera), Psychoda sp. (Insecta: Diptera), Solentanodesmus insularis Antić & Reip in Antić et al., 2014 (Myriapoda: Diplopoda).

Material studied: Coll. AS; one male; Montenegro, Cetinjska Cave, Cetinje; 24th June 2018; leg. D. Antić. – Coll. AS; one male; Montenegro, Velika (Njegoševa) Cave, Njeguši, Mt Lovćen, Cetinje; 24th June 2018; leg. D. Antić. – Coll. AS; one female; Montenegro, Vojvode Dakovića Cave, Grahovo, Nikšić; 28th July 2018; leg. S. Ćurčić, N. Vesović. – Coll. AS; one male and two females; Bosnia & Herzegovina, Golubinka, Dabarsko Polje, Berkovići/Bileća; 18th June 2003; leg. S. Ognjenović. – Coll. AS; one male; Montenegro, Arapova Cave, Gornja Grabovica, Mt Durmitor; 29th July1993; leg. D. Pavićević. – Coll. AS; three males and three females; Montenegro, Vojvode Dakovića Cave, Grahovo, Nikšić; 28th July to 27th October 2018; leg. S. Ćurčić, N. Vesović, M. Kuraica. – Coll. AS; one male; Montenegro, Izeta Cave, Knežlaz, Kameno more, Kotor; 28th July to 27th October 2018; leg. S. Ćurčić, N. Vesović, M. Kuraica. – Coll. AS; three females; Montenegro, Lipska Cave, Lipa, Cetinje; 29th July to 28th October 2018; leg. N. Vesović. – Coll. AS; one male; Montenegro, Bijela Cave, Gornji Kazanci, near Nikšić; 17th November 2019; leg. D. Antić.

Biogeographical note: These localities extend the known distribution range of the species.

Type material: PSML; male holotype; Slovenia, cave P4, Kanin, Bovec; 3rd August 2018; leg. Š. Borko. – PSML; one female paratype (labelled ♀1 paratype); same cave, data, and collector. – MHNG; one male and two female paratypes (labelled ♀2 paratype, ♀3 paratype, ♂5 paratype); same cave, data, and collector. – Coll. AS; four male, one female and one juvenile paratypes (labelled ♀4 paratype, ♂2 paratype, ♂3 paratype, ♂4 paratype, ♂6 paratype and J1 paratype); same cave, data, and collector.

Other material studied: Coll. AS; five males and thirteen females; same cave, data, and collector as for type material mounted in Marc André II solution. – Coll. AS; six specimens of unknown sex; same cave, data, and collector; mounted on an aluminium stub and coated with palladium-gold.

Etymology: The new species is named after Joško Pirnat, a caver who significantly contributed to the speleological exploration of the area and without whom these remote sites could not have been explored. Name in the genitive case.

Description:

Body: Body length 4.3-4.9 mm (males), 4.1-5.6 mm (females) and 2.9 mm in one juvenile (in type series) (Fig. 77). Epicuticle smooth under optical microscope, weakly reticulated under high magnification (SEM, up to 1000x) (Figs 84–85); body covered with numerous thin, medium-sized clothing setae bearing two to five thin distal barbs.

Head: Antennae lengths ranging from 109% of body length in small specimens to 86% of body length in larger specimens, with 34-36 antennomeres (Table 4). Bacilliform sensillum of third antennomere in a ventral position, between macrosetae d and e, 13 µm in length. Medial antennomeres slightly elongated and 1.4 times longer than wide; apical antennomere 2.5 times longer than wide. Ten to fifteen thin and long gouge sensilla (30-38 µm long) in a single distal whorl on each medial and distal antennomere (Fig. 83); two conical sensilla (8 µm) in the same whorl. Cupuliform organ occupying less than 1/4 of total length of last antennomere, with eight to ten spheroidal olfactory chemoreceptors with a centric column surrounded by a concentric fold; entire surface covered with a polygonal net with pores (Figs 80–82). Non-protruding frontal process with three smooth, slightly tubercular anterior macrosetae and without tubercular setae. The three macrosetae along each side of line of insertion of antennomere and x setae with 2-4 long thin barbs; length ratios of a/i/p/x in holotype being 32/39/33/38. A pair of slightly longer smooth macrosetae on dorsal side of head in a psl position. Labial palps suboval, each with a conical latero-external sensillum near two gard setae, with five normal setae in anterior portion, and with up to 62 neuroglandular setae in a medial and posterior position. Narrow submentum with two posterior macrosetae with 3-5 long, thin distal barbs and a smooth anterior row of setae (Fig. 78).

Thorax: Pronotum with 1+1 ma, 2+2 la, 2+2 lp_2,3 macrosetae; mesonotum with 1+1 sma, 1+1 sla or 1+0 sla - 0+1 la, 2+2 lp_2,3; metanotum with 1+1 lp₂; long, thin, barbed notal macrosetae in distal two-thirds; marginal setae slightly longer than clothing setae, with a few thin distal barbs (Fig. 79). Metathoracic legs reaching beyond end of abdomen; femur and tibia being the longest articles with a similar length (Table 4). One dorsal femoral macroseta in distal half with thin barbs 0.20-0.25 mm in length, and with three slightly shorter barbed ventral macrosetae (Figs 86–87); two (rarely three) short metathoracic tibial macrosetae barbed in distal half (Fig. 88); calcars with long thin barbs in two rows on one side (Fig. 89); tarsus with two ventral rows of smooth setae slightly larger and longer than clothing setae; two dorsal and two ventral subapical smooth setae on tarsus; very unequal claws (posterior claw 1.5-1.6 longer than anterior claw), with large lateral crests and smooth setiform lateral processes; posterior claw with large backward overhang; claws almost smooth on dorsal side, ventral side with a micro-bacilliform to granular surface between noticeable crests; an intermediate small, thin irregular structure present between the claws (Figs 90–93).

Abdomen: Urotergites III with 0+0 (rarely 0+1 post₁) macrosetae; urotergite IV with 0+0, 0+1 or 1+1 la, 1+1-2+1 post_1-2 macrosetae or 1+1-0+1 spost₁ submacrosetae; urotergite V with 1+1 la, 3+3-2+3 post_1-2,4 macrosetae or 2+1 spost_1-2 submacrosetae; urotergites VI-VII with 1+1 la, 4+4 post_1-4 macrosetae; urotergite VIII with 6+6 post; abdominal segment IX with 8+8 post macrosetae; all urotergal macrosetae long and barbed in distal three-fourths; urosternite I with 7+7 macrosetae; urosternites II-VII with 5+5; urosternite VIII with 2+2; urosternal macrosetae with a few long distal barbs. Apical seta with a basal tooth and two or three long thin barbs, subapical and medio-sternal setae with four or six long thin barbs (Fig. 96). Four cerci from four different specimens apparently complete and of similar length as body, except in ♀1 paratype (the largest) with cercus being 1.22 times longer than body; basal article divided into three or four secondary articles, followed by eight to eleven primary articles (Table 4); each primary cercus bearing two to ten irregular whorls of long barbed macrosetae, one to two distal whorls of smooth long setae, and one apical whorl of short thin setae with tiny distal barbs (Fig. 97).

Secondary sex characters: First urosternite of males carrying very large spherical appendages with a large field of up to 200 glandular a₁ setae (Figs 94–95); females with subcylindrical to conical appendages with up to 18 glandular a₁ setae.

Taxonomic affinities: The noticeable taxonomic traits in Plusiocampa (Venetocampa) pirnati sp. nov., such as the macroseta distribution pattern on nota and abdomen and the very unequal claws (posterior claw more than 1.5 longer than anterior claw), show strong similarities with Plusiocampa (Plusiocampa) hoelzeli (Neuherz, 1984), described from a cave in Carinthia (Austria) and recently reported from Renejevo brezno, Kanin Mountain, in Slovenia (Sendra et al., 2020a) (uncertain affinity, see discussion below). The absence of glandular g₁ setae and the presence of huge spherical appendages with numerous glandular a₁ setae in males show close similarities with Plusiocampa (Venetocampa) paolettii Bareth & Condé, 1984, described from a (not too distant) cave in Belluno, in the Italian Alps. At present, P. (V.) paolettii is considered to be closely related to P. (V.) pirnati sp. nov. and to belong in the controversial subgenus Venetocampa (see discussion). Both species are distinguished by the following traits: urotergal macrosetae present on the fourth urotergite, and 4+4 posterior macrosetae present on the sixth and seventh urotergite in P. (V.) pirnati sp. nov.; in P. (V.) paolettii the urotergal macrosetae on the fourth urotergite are absent and only 2+2 and 1+1 posterior macrosetae on the sixth and seventh urotergite are present; P. (V.) pirnati sp. nov. has 6+6 and 8+8 posterior macrosetae on the eighth urotergite, and on the ninth abdominal segment 4+4 macrosetae vs. 7+7 in P. (V.) paolettii. Lastly, P. (V.) pirnati sp. nov. has two or three ventral tibial macrosetae, whereas in P. (V.) paolettii such macrosetae are absent.

Type locality: Cave P4 (n. 1529) lies in the Kanin mountains (Bovec, Slovenia), in the western part of the Julian Alps (Figs 98–100). The cave entrance is located on the Kanin plateau, 2121 m above sea level, in a rocky area with an alpine vegetation. Cave P4 is part of a cave system that is 1320 m deep and 12 km long. The cave temperature varies with depth, from 1°C in the upper parts to 3°C at 1 km below the surface. Species richness and abundance is highest in the deeper parts of the cave. Animals were mostly collected with baited pitfall traps and very rarely by manual collecting from the surfaces. Most specimens were collected in the deep horizontal parts of the cave: always in wet areas, near constant drip water, on walls or in traps placed in gravel, but never on clay or sand. They were found together with Anophthalmus sp. beetles, Acari and several species of Collembola.

Renejevo brezno Cave (cave catalogue number 7090), where Plusiocampa (Plusiocampa) hoelzeli was found (Sendra et al., 2020a), is part of the same cave system as P4. The entrances of both caves are 1 km apart. In both caves diplurans were found at similar depths (always in deep parts of the caves). It is possible that the diplurans from Renejevo brezno Cave belong to P. (V.) pirnati, but the available specimens are too strongly damaged for a reliable identification. More diplurans from Renejevo brezno are needed to confirm taxonomic affinity.