Psechrus libelti Kulczyński, 1908

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 : 6-8

Psechrus libelti Kulczyński, 1908

Figs 4, 5, 8 , 17–19

P. libeltii Kulczyński, 1908: 561 , pl. 23, fig 31 (♀).

P. libelti : Bayer, 2012: 21, figs 5a-e, 6a-e, 82a, 84b-c, 87b, 90b (♂ ♀).

For the complete list of references see WSC (2023).

MATERIAL EXAMINED. 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, 1♀ ( ISEA 001 . 8986) .

DIAGNOSIS. The female of P. libelti is most similar to those of P. argentatus (Doleschall, 1857) in having broad and flat copulatory ducts ( CD) and receptacle heads ( RH) on long stalks but can be distinguished from it by septum (S) approximately as long as wide (vs. twice wider than long) and converging lateral margins (LM) (vs. parallel) (cf. Figs 17–18 and fig. 2g in Bayer (2012)). Endogyne of both species are nearly indistinguishable.

REDESCRIPTION. Female. Body and eye measurements. Total length 19.7, carapace length 7.0, carapace width 5.3, anterior width of carapace 3.1, opisthosoma length 14.0, opisthosoma width 6.7. Eyes: AME 0.43, ALE 0.46, PME 0.49, PLE 0.44, AME–AME 0.29, AME–ALE 0.13, PME – PME 0.21, PME –PLE 0.4, AME– PME 0.49, ALE–PLE 0.57, clypeus height at AME 1.09, clypeus height at ALE 0.93.

Carapace and chelicerae light brown. Chelicerae with 3 promarginal and 3 retromarginal teeth. Maxillae brown, darker distally. Sternum brown, with light setae at the edges. Legs and palps light brown with vague dark annulations. Opisthosoma cream-colored dorsally, ventrally brown, with narrow, white and dark brown longitudinal line.

Measurements of palp and legs. Palp: 9.4 [3.0, 1.3, 1.7, 3.4]; Legs: I 57.6 [16.3, 3.5, 16.2, 15.3, 6.3], II 42.1 [12.5, 3.0, 11.0, 11.0, 4.6], III 28.9 [8.9, 2.3, 7.0, 7.3, 3.4], IV 43.2 [13.0, 2.6, 11.0, 11.4, 5.2].

Spination. Palp: 1310, 1400, 2100, 2210; Legs: femur I 7770, II 7670, III 6560, IV 6740; patella I–IV 0000; tibia I 3034, II 3036, III 3135, IV 3034; metatarsus I 3035, II 3035, III 3035, IV 3034.

Epigyne structure ( Figs 17–19 ). Epigynal plate ( EP) 3 times longer than septum (S). Septum trapezoidal, nearly as long, as wide. Lateral margins (LM) converging. Epigynal muscle sigilla (EM) adjoining to epigynal plate. Copulatory ducts ( CD) twice wider than receptacle base (RB). Spermathecal bases bent anteriad. Stalks of receptacle heads ( RH) approximately twice shorter than receptacle bases. Receptacle heads bear distinct glands.

BIOLOGY. The same is in P. leshukovi sp. n.

NOTES. At the beginning of this research we initially believed that the treated female belonged to P. leshukovi sp. n. Later, after studying vulva of this specimen we concluded that it belongs to another species, even from a different species group. We identified this female as P. libelti , species described from Palembang (Sumatra). This case highlights that different species of Psechrus are able to inhabit the same cave, leading to the potential mismatching of males and females during the description of new species. A similar example of such syntopy, where two different species of Psechrus belonging to different species groups is already known from Laos. Psechrus laos Bayer, 2012 and P. luangprabang Jäger, 2007 were recorded from the same cave in Lak Sao [18°13ʹ38.2ʹʹ N, 104°44ʹ47.3ʹʹ E] (Bolikhamsay Province) ( Bayer, 2012). Thereby, repeatedly discovered syntopy/cohabitation of Psechrus species, combined with high diversity of this genus, should make the taxonomists working on this group careful when describing new species or missing sexes. Currently, about a quarter of Psechrus species (15 species out of 57) are known based on only one sex ( WSC, 2023).

DISTRIBUTION. Distributed in Malay Peninsula and Sumatra and Kalimantan Islands ( Bayer, 2012) .

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 17–19. Epigyne of Psechrus libelti. 17 – ventral, intact; 18 – ditto, macerated; 19 – ditto, dorsal. Abbreviations: CD – copulatory duct, EP – epigynal plate, FD – fertilization duct, EM – epigynal muscle sigilla, LL – lateral lobe, LM – lateral margins, RB – receptacle base, S – septum, RH – receptacle head.