Psechrus leshukovi, Omelko & Fomichev, 2023

Omelko, M. M. & Fomichev, A. A., 2023, Two species of the genus Psechrus Thorell, 1878 (Araneae: Psechridae) from North Sumatra, Indonesia, Far Eastern Entomologist 482, pp. 1-9 : 3-6

Psechrus leshukovi sp. n.

https://zoobank.org/NomenclaturalActs/ B055F3D3-8B2E-4371-8424-2D5FEDB32CAF

Figs 1–3, 6,7 , 9–16

TYPE MATERIAL. Holotype – ♂, Indonesia: Sumatra Island , North Sumatra Prov., env. of Bukit Lawang Vill. [03°33ʹ N, 98°07ʹ E], 250 m, hand picking from web in small grottos, 1988 (precise date unknown), unknown collector ( ZMMU) . Paratypes: 2♂, same place and data ( ISEA 001.8985 ) .

DIAGNOSIS. By palp structure (cymbium dorsally with dense scopula, shape of tegulum, embolus, conductor and sperm duct) males of P. leshukovi sp. n. are most similar to those of P. singaporensis Thorell, 1894 (cf. Figs 9–16 and 15a–d , 84h in Bayer (2012)). The new species can be easily distinguished from the latter by long, thin, noticeably curved embolus (E) (vs. short, thick, almost straight), extending to the anterior edge of conductor (C) (vs. not reaching), base of embolus ( EB) in ventral view 4 times broader than embolus itself (vs. 1.2 times), and conductor Ɔ-shaped (vs. C-shaped) in ventral view (left palp) and strongly curved in retrolateral view (vs. not curved).

DESCRIPTION. Male (holotype). Body and eye measurements. Total length 10.59, carapace length 4.66, carapace width 2.88, anterior width of carapace 1.49, opisthosoma length 5.88, opisthosoma width 2.05. Eyes: AME 0.37, ALE 0.36, PME 0.34, PLE 0.29, AME–AME 0.10, AME–ALE 0.03, PME – PME 0.18, PME – PLE 0.22, AME– PME 0.26, ALE–PLE 0.28, clypeus height at AME 0.39, clypeus height at ALE 0.33 .

Carapace yellow with narrow (ca. 1x diameter of PME), gray, slightly serrated lateral bands. Median band gray with yellow mark anteriorly, slightly serrated. Chelicerae

yellowish with 3 promarginal and 4 retromarginal teeth. Maxillae light brown. Sternum yellowish at lateral margins with dark brown, triangle patch centrally. Legs and palps yellow, with vague dark annulations. Opisthosoma dorsally yellowish (grayish posteriorly), laterally grayish, ventrally light brown with narrow, yellow and black longitudinal line.

Measurements of palp and legs. Palp: 5.49 [1.79, 1.03, 0.86, 1.81]; Legs: I 56.75 [15.34, 1.87, 15.85, 16.49, 7.20], II 41.04 [11.06, 1.58, 10.65, 11.76, 5.99], III 27.03 [7.62, 1.35, 6.71, 7.53, 3.82], IV 45.23 [12.52, 1.52, 11.22, 13.59, 6.38].

Spination. Palp: 1410, 0000, 0000 (all palpal tibia spines small, some of them are setae-like); legs: femur I 6560, II 7650, III 5430, IV 5730; patella I–IV 0000; tibia I 3049, II 2036, III 3235, IV 3035; metatarsus I 3036, II 3036, III 3036, IV 4035.

Macrosetae ventrally on coxae I and trochanter I-II present, well developed ( Fig. 6 ).

Palp as in Figs 9–16 . Femur modified with a flat ventral bulge (FB). Cymbium (length/width ratio ca. 3.9) dorsally with scopula ( CS), covering almost half of cymbium. Conductor (C) wide, hyaline, poorly visible when bulbus not cut off from cymbium. Conductor 1.5 times wider in middle part, than at its base, strongly curved in pro- and retrolateral view. Embolus (E) long (about 1/3 of tegulum length) with broad base ( EB) in ventral view.

Female unknown.

BIOLOGY. Psechrus leshukovi sp. n., similar to many of its congeners appears to be a hemitroglobionts, meaning it is found both in caves and similar habitats without specific morphological adaptations to cave conditions (Birshtein, 1985).

NOTES. Based on the structure of its male palp, coloration, and legs spination P. leshukovi sp. n. belongs to P. singaporensis -group. Thus, this group comprises five species: P. arcuatus Bayer, 2012 , P. elachys Bayer, 2012 , P. leshukovi sp. n., P. norops Bayer, 2012 and P. singaporensis . Two species of the group ( P. arcuatus and P. singaporensis ) are known from Sumatra, other from Malaysian Peninsula and Thailand. It is worth noting that Bayer (2012) reported P. singaporensis from Bohorok Town [03°31ʹ N, 98°09ʹ E], which is in close proximity to Bukit Lawang Village (the distance is ca. 5 km). Bayer mentioned this record based on several female and juvenile specimens as doubtful. There is a high probability that these females from Bohorok Town actually belong to P. leshukovi sp. n. Specimens from Bohorok Town are stored in Nationaal Natuurhistorisch Museum Naturalis in Leiden ( Netherlands) ( RMNH). We don’t have the opportunity to study them.

DISTRIBUTION. Type locality only ( Figs 20, 21 ).

ETYMOLOGY. The specific name is a patronym in honor of Ivan Leshukov (Jakarta, Indonesia), Russian biologist and tourist guide working in Indonesia.

Figures

Figs 1–8. Psechrus leshukovi sp. n. (1–3, 6–7) and P. libelti (4–5, 8). 1, 4 – whole habitus, dorsal; 3, 5 – ditto, ventral; 2 – carapace, dorsal; 6 – coxae and trochanteri I–II; 7, 8 – cephalic part, anterior. Abbreviations: MC-I, MC-II – macrosetae ventrally on coxa of leg I and II; MT-I, MT-II – macrosetae on trochanter of leg I and II. Scale bars = 5 mm (1, 3, 4, 5), 1 mm (2, 7, 8), 0.2 mm (6).

Figs 9–16. Palp (9–11, 16) and bulb (12–15) of Psechrus leshukovi sp. n. 9, 12 – prolateral; 10, 13 – ventral; 11, 14, 16 – retrolateral; 15 – anterior. Abbreviations: C – conductor, CS – cymbial scopula, E – embolus, EB – embolic base, FB – femur bulge, SD – sperm duct, ST – subtegulum, T – tegulum. Scale = 0.2 mm.

Figs 20–21. Localities of Psechrus singaporensis-group species. Circle – P. leshukovi sp. n., square – P. singaporensis, diamong – P. norops, triangle – P. arcuatus, inverted triangle – P. elachys. One symbol may refer to more than one closely located collecting locality. Question mark denote locality without accurate coordinates. The frame on Fig. 21 refers to the content of Fig. 20.