The present study is based on oribatid mite material collected during October and November 2012 in the course of a Russian-Ethiopian expedition to southern Ethiopia. An annotated checklist of identified taxa is provided, with 22 species, 19 genera and 15 families recorded. A new species, Perscheloribates paratranslamellatus sp. n., from xerophytic forest litter is described. It is most similar morphologically to Perscheloribates translamellatus (Pérez-Iñigo & Baggio, 1991), but differs from the latter by larger body size, presence of a rudimentary translamellar line, absence of prolamellar lines, longer setae p1 and elongate openings of sacculi Sa, S1. A supplementary description of Paroppia breviseta (Balogh, 1962) based on Ethiopian specimens is presented.
Currently, oribatid mite (Acari: Oribatida) fauna of Ethiopia includes little more than 150 species (Ermilov et al. 2012a, b; Ermilov & Rybalov 2013a, b). This work forms part of our ongoing study of the Ethiopian oribatids. The present investigation is based on new material collected in the course of a two-month Russian-Ethiopian expedition during October and November 2012. An annotated checklist of identified oribatid mite taxa is provided (Table 1).
The genus Perscheloribates (Scheloribatidae) was proposed by Hammer (1973) with Perscheloribates clavatus Hammer, 1973 as type species. The genus comprises 44 species that collectively have pan- and subtropical distributions (Subías 2004; online version 2013). Up to now, eight species have been recorded from the Ethiopian region (Ermilov et al. 2011): P. crassisetosus Ermilov, Rybalov & Franke, 2011, P. ethiopicus (Mahunka, 1986), P. luminosus (Hammer, 1961), P. minimus (Mahunka, 1992), P. minutus (Pletzen, 1965), P. rustenburgensis (Pletzen, 1963), P. shiraensis (Evans, 1953) and P. tzitzikamaensis (Pletzen, 1963). The identification key to aforementioned species and generic diagnostic characters were presented by Ermilov et al. (2011). The new species is described as Perscheloribates paratranslamellatus sp. n.
The collected material further included Paroppia breviseta (Balogh, 1962) (Oppiidae), a species described from Tanzania (Balogh 1962). The original description of this species is, however, incomplete and brief (lacking information about the measurements of morphological structures, leg setation, and solenidia together with the morphology of the gnathosoma). P. breviseta is redescribed based on newly sampled Tanzanian specimens.
MATERIAL AND METHODS
Mosses on trees were collected by hand (total volume = 0.03 m3). Litter was collected by taking 10 samples using a stainless steel frame (50 × 50 cm) and passed through a sifter (mesh size 2 × 2 cm). Oribatid mites were extracted into 75 % ethanol using Berlese funnels with ambient light for the first three days and 160 W electric lamps (at a distance of 25–30 cm) from the fourth until the seventh day.
Specimens were mounted in lactic acid on temporary cavity slides for measurement and illustration. All body measurements are presented in micrometres. The body length was measured in lateral view, from the tip of the rostrum to the posterior edge of the ventral plate. Notogastral width refers to the maximum width in dorsal view. The lengths of body setae were measured in lateral view. Formulae for leg setation are given in parentheses according to the sequence: trochanter-femur-genu-tibia-tarsus (famulus included). Formulae for leg solenidia are given in square brackets according to the sequence: genu-tibia-tarsus. General terminology used in this paper follows that summarised by Coetzer (1967–1968), and Norton and Behan-Pelletier (2009).
The holotype material is deposited at the Zoological Institute of the Russian Academy of Sciences, St Petersburg, Russia (ZISP). The paratype material is deposited at the Siberian Zoological Museum, Novosibirsk, Russia (SZMN) and in the personal collection of the first author (PC).
List of collecting sites:
Et-12–10: 09°04′N 38°08′E, 10 km north of Ginchi city, Chilimo forest (Hagenia abyssinica and Juniperus sp. forming the canopy), 2900 m, mosses on trees, 25.x.2012 (collected by L.B. Rybalov and A.I. Bastrakov).
Et-12–11: 08°58′N 37°51′E, Ambo Plant Protection Research Center, xerophytic forest on vertisols, 2077 m, litter (sifter), 20.xi.2012 (collected by L.B. Rybalov and A.I. Bastrakov).
Samples from the collecting sites yielded 22 species, 19 genera and 15 families. Pedrocortesella africana Pletzen, 1963, Liacarus shipitsyni Ermilov, Rybalov & Kemal, 2011, Zetorchella pedestris Berlese, 1916 and Scheloribates discifer Balogh, 1959 were the only species recorded from mosses on trees; all other species were recorded only from forest litter (Table 1).
Family Scheloribatidae Grandjean, 1933
Genus Perscheloribates Hammer, 1973
Perscheloribates paratranslamellatus sp. n. Figs 1–2
Etymology: From the Latin prefix para (near) referring to the the similarity between the new species and the species Perscheloribates translamellatus (Pérez-Iñigo & Baggio, 1991).
Diagnosis: body size 481-531 × 298-348; rostrum rounded; rudimentary translamellar line; prolamellar lines absent; prodorsal setae setiform, barbed; sensilli spindle-form, ciliate; exobothridial setae short; one pair of notogastral setae p 1 present; sacculi Sa, S1 with elongate openings, S2, S3 with rounded openings; ventral setae setiform, slightly barbed, and with little difference in length; leg claws serrate on dorsal side.
Measurements. Body (length × width): 481 × 298 (holotype ♂); 481-531 × 298-348 (paratypes: l♂ 4♀).
Integument. Body brown and light brown. Dorsal and ventral surfaces of body smooth, lateral surfaces weakly microgranulate.
Prodorsum (Figs 1A, 1B, 1D; 2A, 2B). Rostrum slightly protruding, rounded. Lamellae located dorsolaterally, as long as half of prodorsum (in lateral view), without cusps. Translamellar line (tr) rudimental, at tips of lamellae. Prolamellar lines absent. Sublamellar lines distinct, long. Sublamellar porose areas (Al) very small, rounded (2–4). Keel-shaped chitinised ridges (kf) distinct. Rostral (ro, 61–69), lamellar (le, 90–102) and interlamellar (in, 114–127) setae setiform, barbed. Sensilli (ss, 110–118) spindle-form (with long stalk, elongated lanceolate head and well developed thin apex), with numerous cilia. Exobothridial setae (ex, 4–6) short, thin, smooth.
Notogaster (Figs 1A, 1C). Anterior notogastral margin convex medially. Dorsophragmata (D) of medium size, widely rounded. Nine pairs of notogastral setae represented by alveoli; only one pair of thin, smooth setae developed (p 1 8–10). Four pairs of sacculi present: Sa, S1 with elongate openings, S2, S3 with small, rounded openings. Circumgastric band of muscle sigillae distinct. Opisthonotal gland openings (gla) and lyrifissures developed in typical arrangement for genus.
Anogenital region (Figs 1B, 1C). Three pairs of adanal (ad 1—ad 3 16–20), one pair of aggenital (ag, 16–20), two pairs of anal (an 1 an 2 12–16) and four pairs of genital (g 1-g 4, 16–20) setae setiform, slightly barbed. Lyrifissures i ad in para-anal position, located nearly to anal aperture.
Epimeral and lateral podosomal regions (Figs 1B, 1D). Apodemes 1, 2, 3 and sejugal apodemes distinct. Epimeral setal formula: 3-1-3-3. Setae (16–24) setiform, thin, slightly barbed; medial setae little shorter than others. Pedotecta I (Pd I) large, concave; pedotecta II (Pd II) rounded anteriorly. Discidia (dis) triangular, rounded. Circumpedal carina (cp) distinct.
Gnathosoma (Figs 2C–2E). Subcapitulum longer than wide: 118-123 × 82. Subcapitular setae setiform, barbed; h (28–32) longer than a, m (both 20). Lateral lips with two pairs of setiform, barbed adorai setae (or 1, or 2, 10–12). Palps (length 69–73) with setation 0-2-1-3-9(+ω;). Solenidion coupled with eupathidium acm. All setae (except some on tarsi) weakly barbed. Chelicerae (length 118–123) with two setiform, barbed cheliceral setae; cha (36–41) longer than chb (24–28).
Legs (Fig. 2F). Claw of each leg with several minute barbs on dorsally side. Formulae of leg setation and solenidia: I (1-5-2-4-19) [1-2-2], II(1-5-2-4-15) [1-1-2], III (2-3-1-3-15) [1-1-0], IV (1-2-2-3-12) [0-1-0]; homology of setae and solenidia indicated in Table 2. Almost all setae (except p) barbed or with short cilia. Famulus (e) short, straight, indistinctly dilated apically, blunted. Solenidia ω;1 on tarsi I, ω;1 and ω;2 on tarsi II, σ on genua III short, thickened, blunt-ended; other solenidia longer, thinner, setiform.
Holotype: ♂ ETHIOPIA: Et-12–10. Preserved in ethanol (ZISP).
Paratypes: 1♂ 4♀ ETHIOPIA: Et-12–10. Preserved in ethanol (1♂ 2♀ SZMN; 2♀ PC).
Distribution: At present, this species is only known from the type locality.
Remarks: In having one pair of notogastral setae p 1 (other setae represented by alveoli), spindle-form and ciliate sensilli, and rounded rostrum, P. paratranslamellatus sp. n. is r similar to P. translamellatus from Peru (Pérez-Iñigo & Baggio 1991); however, it differs from the latter by larger body size (481-531 × 298-348 versus 324-360 × 196-216), a rudimental translamellar line running nearly to lamellae (translamella complete in P. translamellatus), absence of prolamellar lines (present, not reaching insertions of rostral setae in P. translamellatus), longer setae p 1 (minute in P. translamellatus) and elongate openings of sacculi Sa, S1 (rounded in P. translamellatus).
From the Ethiopian species, Perscheloribates minutus (Pletzen 1965; Corpuz-Raros 1980) is the closest morphologically to P. paratranslamellatus sp. n.; however, it differs from P. minutus in that it has a larger body size (481-531 × 298-348 versus 343-394 × 216-303 in P. minutus), absence of prolamellar lines (present in P. minutus), and development of a single pair of notogastral setae p l (versus p 1-p 3 developed in P. minutus).
Oribatid mites collected from tree mosses (Et-12–10) and xerophytic forest litter (Et-12–11) in Ethiopia.
Leg setation and solenidia of Perscheloribates paratranslamellatus sp. n. Roman letters refer to normal setae (e — famulus), Greek letters refer to solenidia. Single (′) and double (″) apostrophes mark anteriorly and posteriorly placed setae on the given leg segments respectively Parentheses refer to a pair of setae.
Family Oppiidae Sellnick, 1937
Genus Paroppia Hammer, 1968
Paroppia breviseta (Balogh, 1962)
Oppia breviseta: Balogh 1962: 100.
Paroppia breviseta: Subías & Balogh 1989: 385.
Diagnosis (based on Ethiopian specimens): body size 315-332 × 182-199; rostrum rounded; rostral setae ciliate, longer than smooth lamellar and interlamellar setae; sensilli long, with elongate lanceolate, indistinctly barbed head; interbothridial region with three pairs of muscle sigillae; notogastral setae c represented by alveoli, other setae of medium size, thin, slightly barbed; anogenital setae of medium size, similar in length, smooth.
Measurements. Body (length × width): 315-332 × 182-199 (2♂ 5♀).
Integument. Body light brown. Dorsal and ventral surfaces of body smooth, lateral surfaces microgranulate.
Prodorsum (Figs 3A, 3C; 4A, 4B). Rostrum rounded. Rostral setae (24–32) setiform, unilaterally with short cilia. Lamellar and interlamellar setae similar in length (12), setiform, smooth. Sensilli (65–73) with long stalk and elongate lanceolate head; sensillar heads with several poorly developed barbs in anterior part (visible only under high magnification). Exobothridial setae and their alveoli absent. Interbothridial region with three pairs of muscle sigillae removed from each other.
Notogaster (Figs 3A, 3C, 4C). Anterior notogastral margin convex medially. A pair of small tubercles (tb) located dorsolaterally to anterior margin. Nine pairs of notogastral setae of medium size (18–24), setiform, with poorly developed barbs (visible only under high magnification); one pair (c) represented by alveoli. Circumgastric band of muscle sigillae distinct. Opisthonotal gland openings and lyrifissures developed in typical arrangement for genus.
Anogenital region (Figs 3B, 3C, 4G). Three pairs of adanal, one pair of aggenital, two pairs of anal, four pairs of genital setae similar morphologically: 12–26, setiform, thin, smooth. Lyrifissures i ad in para-anal position, located near to anal aperture.
Epimeral and lateral podosomal regions (Figs 3B, 3C). Apodemes 1, 2, 4 and sejugal apodemes distinct. Epimeral setal formula: 3-1-3-3. Setae 3c longer (24–28), barbed; other setae shorter (12–26), indistinctly barbed. Pedotecta I concave. Discidia triangular.
Gnathosoma (Figs 4D–4F). Subcapitulum anarthric, longer than wide: 65-73 × 49-53. Subcapitular setae similar in length (16–18), setiform, with one to three small barbs. Lateral lips without setae and associated alveoli. Palps (length 49–53) with setation 0-2-1-2-7(+ω;). Solenidion thickened, blunt-ended, pressed to the palptarsus, not coupled with eupathidium. All setae (except some on tarsi) weakly barbed. Chelicerae (length 65–73) with one tooth on each movable and fixed digit; both cheliceral setae similar in length (10), setiform, slightly barbed.
Legs (Figs 4H–4J). Claw of each leg smooth. Apophysis on tibiae I well developed. Formulae of leg setation and solenidia: I (1-5-2-4-20) [1-2-2], II (1-5-2-4-16)
[1-1-2], III (2-3-1-3-15) [1-1-0], IV (1-2-2-3-12) [0-1-0]; homology of setae and solenidia indicated in Table 3. Almost all setae (except p, s) barbed or with short cilia. Famulus short, straight, indistinctly dilated apically, blunted. Setae p on tarsi II–IV represented by poorly developed thorn-like setae. Solenidia σ on genua I, II and φ;1 on tibia I long, setiform; other solenidia shorter, thickened, blunt-ended.
Material examined: 2 ♂ 5♀ ETHIOPIA: Et-12–10. Preserved in ethanol (PC).
Distribution: At present, this species is only known from Tanzania and Ethiopia.
Remarks: The present Ethiopian specimens of P. brevipes are morphologically and in general appearance comparable to the Tanzanian specimens (Balogh 1962), although with slight differences: lamellar and interlamellar setae similar in length (interlamellar setae shorter in Tanzanian specimens), anterior part of sensillar heads with several poorly visible barbs (sensillar heads smooth in Tanzanian specimens), interlamellar muscle sigillae removed from each other (sigillae dense in Tanzanian specimens). We regard these differences as intraspecific (perhaps geographical) variability within the species.
We gratefully acknowledge Prof. Dr Gerd Weigmann (Free University of Berlin, Institute of Zoology, Berlin, Germany) and an anonymous reviewer for their valuable comments. This work was performed within the framework of the Joint Russian-Ethiopian Biological Expedition, financially supported by the Russian Academy of Sciences. We are appreciative to our Project Coordinators Dr Andrey Darkov and Ato Girma Yosef for management of the Expedition. We thank Mr Tariku Hunduma, director of the Ambo Plant Protection Research Center, Ethiopian Institute of Agricultural Research (EIAR), for supporting field studies and organising laboratory operations. We are also grateful to A.I. Bastrakov of the Institute of Ecological and Evolutionary Problems, Russian Academy of Sciences (RAS) for sampling assistance.