Psechrus quasillus, sp. nov.
Creators: name: Bayer, Steffen
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Araneae
Psechridae
Psechrus
Psechrus quasillus

description: Psechrus quasillus sp. nov.
Figs 19–20, 27 B,E, 30A, 33C, 35
Type material. Holotype ♀ (SB 1224): MALAYSIA: Borneo: Sarawak Prov.: Bau, Cave ‘ Gua Puang’, escarpment at Gunung Jambusan, in cave, 30 m, ca. 01°24'N, 110°11'E, P. Strinati leg. 04.XII.1987, sample no. Sar-87/49, MHNG. – Paratypes (1 ♂, 3 ♀, all material with the same data as for holotype): ♂ (SB 1223), 3 ♀ (SB 1225–1227), MHNG.
Additional material (2 pre-subadult ♀, 1 juvenile): All material with the same data as for holotype: 2 p.s.a. ♀ (SB 1229–1230), 1 juv. (SB 1228), MHNG.
Etymology. The specific name refers to the shape of the female epigyne which is reminiscent of a small wicker basket (Latin “ quasillus ” means ‘small wicker basket’); term (noun) in apposition.
Diagnosis. Males distinguished from those of all other Psechrus species by the following characters in combination: (1) conductor sheath-like and arising in ca. 1–2 o’ clock position in retrolateral half of tegulum (Figs 19 B, 27B); (2) embolus long (as long as width of tegulum) and virtually filiform (Figs 19 B–C, 27B); (3) palpal tibia distally with very conspicuous hump ventrally directly in front of intersegmental membrane (Figs 19 A,C, 27E).
Females distinguished from those of all other Psechrus species by the following characters in combination: (1) characteristic shape of median septum: waisted centrally, with widest section in posterior third and second widest in anterior third (Figs 20 A,D, 30A); (2) nearly round receptacula (Figs 20 B,E, 33C); (3) long copulatory duct with multiply curved course (Figs 20 B–C,E, 33C).
Description. Male: Body and eye measurements: Carapace length 4.7, maximal carapace width 3.5, anterior width of carapace 1.7, opisthosoma length 7.2, opisthosoma width 2.3. Eyes: AME 0.30, ALE 0.35, PME 0.36, PLE 0.35, AME–AME 0.09, AME–ALE 0.03, PME–PME 0.13, PME–PLE 0.22, AME–PME 0.33, ALE–PLE 0.29, clypeus height at AME 0.69, clypeus height at ALE 0.44.
Cheliceral furrow with three promarginal and four retromarginal teeth.
Spination: Palp: 131, 110 (prolateral one with only one third of the length and width of dorsal one), 1101 (all spines less than half as long and broad as spines on palpal femur); legs: femur I–II 666, III 556, IV 644; patella I–IV 000; tibia I–II 3036, III 3134, IV 3136; metatarsus I–III 3035, IV 3037.
Measurements of palp and legs: Palp 6.1 [2.1, 0.9, 1.1, 2.0], I 68.1 [17.4, 2.1, 18.2, 19.6, 10.8], II 50.7 [13.5, 1.9, 12.9, 14.7, 7.7], III 33.8 [9.6, 1.5, 8.7, 9.2, 4.8], IV 52.8 [13.8, 1.7, 13.4, 15.5, 8.4]. Leg formula: 1423. FEMI+MTT-I/CL=7.87, thus legs very long in relation to other Psechrus species.
Palpal femur ventrally modified with quite pointed extension in proximal half (Fig. 19 D). Macrosetae ventrally on coxae of leg I present, but in form of an apical row (proximal to that row only a few small and inconspicuous setae), apical row also present on trochanter of leg I & II.
Copulatory organ (see also diagnosis above): Cymbium long and slim (Figs 19 A–C, 27B,E) and with dense dorsal scopula covering 1/3 of cymbium (Fig. 27 E); tegulum ca. 2 times longer than broad, proximal half clearly broader than distal half and prolatero-distally with distinct swelling (Figs 19 B, 27B); conductor relatively long (Fig. 19 B–C), with prolateral direction, arising in a 1–2 o’clock position on tegulum (Fig. 19 B); embolus with prolateral direction except for short basal part (distal direction) (Fig. 19 B, 27B); sperm duct in ventral view characterised by the equably semicircular loop centrally in tegulum; subtegulum in ventral view slightly protruding underneath tegulum and only in prolateral fourth of proximal section of tegulum (Fig. 19 B), visible in prolateral view, but only small part of it (Fig. 19 A); palpal tibia ventrally with large field of multitudinous, conspicuous, short hairs on a large, protuberant section (lateral view) (Fig. 27 E).
Female (measurements of holotype given first, those of paratypes as range in parentheses):
Body and eye measurements: Carapace length 4.4 (4.9–5.1), maximal carapace width 3.2 (3.4–3.8), anterior width of carapace 1.9 (2.1–2.2), opisthosoma length 6.7 (7.6–7.8), opisthosoma width 2.6 (3.0–3.2). Eyes: AME 0.26 (0.26–0.27), ALE 0.35 (0.37–0.39), PME 0.35 (0.37–0.39), PLE 0.35 (0.37–0.38), AME–AME 0.13 (0.15–0.16), AME–ALE 0.07 (0.08–0.09), PME–PME 0.21 (0.17–0.18), PME–PLE 0.27 (0.28–0.29), AME–PME 0.35 (0.38–0.39), ALE–PLE 0.29 (0.31–0.32), clypeus height at AME 0.79 (0.68–0.78), clypeus height at ALE 0.59 (0.51–0.54).
Cheliceral furrow with three promarginal and four retromarginal teeth. Palpal claw with 14 (holotype) or 14 to 15 teeth.
Spination: Palp: 121 (121,131), 110 (110), 1101 (1101), 1014 (1014). Legs (both legs II of holotype are missing): femur I 656 (646,656), II – (646), III 555 (555), IV 544{554} (555, 545); patella I–IV 0 0 0 (I–IV 000); tibia I 3034 (3036), II – (3036,4036), III 4134{3135} (3134), IV 3132 (3132); metatarsus I 3035 (3035), II – (3035), III 3035 (3035), IV 3034{3035} (3034).
Measurements of palp and legs: Palp 6.0 (6.3–6.6) [2.0 (2.1–2.3), 0.8 (0.8–0.9), 1.2 (1.3–1.4), 2.0 (2.0–2.2)], I 40.4 (41.2–45.3) [10.7 (10.9–12.3), 1.9 (2.0–2.2), 11.5 (11.9–12.6), 10.1 (10.9–11.3), 6.2 (6.5–6.9)], II – (31.4–34.8) [– (8.8–9.9), – (1.8–2.0), – (8.5–9.2), – (7.7–8.6), – (4.6–5.1)], III 21.3 (22.5–24.2) [6.2 (6.7–7.1), 1.3 (1.4–1.5), 5.4 (5.6–6.2), 5.3 (5.6–6.0), 3.1 (3.2–3.4)], IV 32.4 (33.0–36.1) [9.3 (9.5–10.3), 1.6 (1.6–1.8), 8.4 (8.6–9.6), 8.1 (8.2–8.9), 5.0 (5.1–5.5)]. Leg formula: – (1423). FEM-I+MTT-I/CL=4.63–4.73, thus legs very long, longer than in females of any other Psechrus species.
Copulatory organ (see also diagnosis above): Copulatory openings relatively large (Figs 20 A,D, 30A); muscle sigilla anterior to epigyne ca. 2x longer than broad, two to four slit sense organs in the area of epigynal field, slit sense organs mostly located close proximal to muscle sigilla and close to epigynal field; epigynal field well developed and generally longer than broad (Figs 20 A,D, 30A). Spermathecal bases remarkably round; spermathecal heads slightly longer than broad, located postero-medially between spermathecal bases and distal section of copulatory duct (Figs 20 B,E, 33C). Course of internal duct system with several curves, partly narrow, as schematically pointed out (Fig. 20 C).
Colouration of male and female (see also description for Psechrus in Bayer 2012). Median bands on carapace serrated (in both sexes to the same degree), lateral bands broad (ca. 2.5 diameter of PME). Sternum with tapered patch centrally, as in most Psechrus species, but distinctly broad and only slightly darker than lateral light reddishlight-brown-yellow areas. Light longitudinal line ventrally on opisthosoma continuous and very narrow. If measured centrally on opisthosoma, its width is only ca. 1/5 (females) or 1/4 (males) the width of one half of the cribellum.
Intraspecific variation of female copulatory organs. Intraspecific variation is relatively low. There are specimens with a slightly shorter epigynal field (Fig. 20 D) and the receptacula slightly larger (Fig. 20 E) than usual (Fig. 20 B). The medial, strongly curved section of copulatory duct may be slightly less prominent (Fig. 20 E) than usually (Fig. 20 B). In some specimens the proximal medial rim of the spermathecal heads in dorsal view is more clearly visible (Fig. 20 E) than in other females (Fig. 20 B).
Distribution. Malaysia (Borneo) (Fig. 35).
description: Published as part of Bayer, Steffen, 2014, Seven new species of Psechrus and additional taxonomic contributions to the knowledge of the spider family Psechridae (Araneae), pp. 1-54 in Zootaxa 3826 (1) on pages 33-36, DOI: 10.11646/zootaxa.3826.1.1, http://zenodo.org/record/286429