Psechrus zygon Bayer 2012, sp. nov.
Creators: name: Bayer, Steffen
Publisher: name: Zenodo
Year: 2012
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Araneae
Psechridae
Psechrus
Psechrus zygon

description: Psechrus zygon sp. nov.
Figs 73a–e, 89o, 92o
Psechrus torvus — Levi 1982: 122, figs 16–28, ad part, figs 23–28 misidentified (figs 27–28: illustration of ♀).
Type material. Holotype ♀ (SB 846), SRI LANKA (‘ Ceylon’): Central Province: Nawalapitiya, ca. N 07°02', E 80°32', 915 m, road-banks; W.R. Sherriffs leg. 1914–1918, collected between February and May; W.R. Sherriffs det. P. torvus 1919; Tilg. 20-11-1960, ZMUC 5719; Paratype ♀ (SB 847), with same data as for holotype; ZMUC 5719.
Note on type material: W.R. Sherriffs collected Psechrus in the highlands of central Ceylon (Sherriffs 1919). He observed the webs of what he thought to be P. torvus in the area of Nawalapitiya (Sherriffs 1919). It is not clear if he had collected more material than what is deposited in ZMUC. It is also not clear if all the specimens were collected in the area of Nawalapitiya, but at least he did not mention any other localities in his publication (Sherriffs 1919).
Additional material examined. SRI LANKA (‘Ceylan’); E. Simon leg. before 1892; Simon det. P. torvus; Simon-Coll. No. 499; 1 ♀ (SB 631), MNHN AR170/6.
Identification of the following, additional material examined not absolutely certain.
SRI LANKA (‘ Ceylon’): Central Province: Nawalapitiya, ca. N 07°02', E 80°32', 915 m, road-banks; W.R. Sherriffs leg. 1914–1918, collected between February and May; W.R. Sherriffs det. P. torvus 1919; Tilg. 20-11- 1960; 1 ♂ (SB 848, see also remark below), ZMUC 5716.
Etymology. The specific name refers to the shape of the epigynal median septum of the female type specimens resembling a beam balance (Ancient Greek “zygon” means “beam of a balance”); term (noun) in apposition.
Diagnosis (see also diagnosis for torvus -group above). Females with posterior part of median septum (MS) longer than broad and narrow branches of tegimentum (TM) pointing almost laterally (Figs 73a, e). Distal section of copulatory duct (CD) located medial to spermathecal heads (SH) (Fig. 73b). Male (not absolutely certain if conspecific with P. zygon sp. nov., see remarks below) with short, stout and complex harpago (H), whose tip is pointing ventrally (Figs 74a,c). Conductor (C) entirely located in retrolateral half of tegulum (T) and broadest in most distal fourth (Fig. 74b).
Description. Male (not absolutely certain if conspecific with P. zygon sp. nov.):
Body and eye measurements. Carapace length 5.4, carapace width 4.1, anterior width of carapace 2.2, opisthosoma length 6.4, opisthosoma width 1.9. Eyes: AME 0.26, ALE 0.34, PME 0.35, PLE 0.35, AME–AME 0.13, AME–ALE 0.07, PME–PME 0.19, PME–PLE 0.22, AME–PME 0.41, ALE–PLE 0.35, clypeus height at AME 0.69, clypeus height at ALE 0.51.
Cheliceral furrow with three promarginal and four retromarginal teeth.
Measurements of palp and legs. Leg formula: 1423. Palp: 7.0 [2.8, 1.1, 1.2, 1.9]; Legs: I 52.7 [14.1, 2.5, 14.4, 14.9, 6.8], II 38.7 [10.6, 2.2, 10.3, 10.6, 5.0], III 26.9 [7.9, 1.6, 6.0, 7.5, 3.9], IV 42.3 [11.7, 1.9, 9.6, 12.6, 6.5].
Spination. Palp: 132, 110, 1101 (all spines very small); legs: femur I–II 546, III 545, IV 554; patella I–IV 000; tibia I 3038, II 3138, III 3124, IV 3136; metatarsus I–II 3037, III 3035, IV 4047.
Palpal femur ventrally modified with flat bulge and clearly curved dorsally (Fig. 74d). MC-I present in form of two large apical ones, MT-I as one large apical one. MC-II absent.
Copulatory organ (see also diagnosis and general description for torvus -group). Harpago arising at almost 2:00 o’ clock position on tegulum. Embolus base relatively small (Figs 74b–c). Tegulum quite broad and sperm duct diagonal U-shaped (Fig. 74b). Cymbium dorsally with very dense scopula, covering 4/5 of cymbium. Palpal tibia medium sized to long (Figs 74a–c), its distal retrolateral bulge extending further (Fig. 74b) than in P. hartmanni sp. nov.
Female (Measurements of holotype first, those of other females as range in parentheses):
Body and eye measurements. Carapace length 7.4 (6.7–8.6), carapace width 5.1 (4.5–5.8), anterior width of carapace 3.1 (2.8–3.7), opisthosoma length 11.8 (10.1–12.5), opisthosoma width 6.0 (3.8–6.1). Eyes: AME 0.32 (0.29–0.38), ALE 0.42 (0.40–0.46), PME 0.43 (0.40–0.46), PLE 0.43 (0.40–0.44), AME–AME 0.25 (0.21–0.28), AME–ALE 0.11 (0.09, both), PME–PME 0.28 (0.27–0.36), PME–PLE 0.36 (0.35–0.43), AME–PME 0.68 (0.60–0.76), ALE–PLE 0.56 (0.51–0.61), clypeus height at AME 1.12 (1.02–1.66), clypeus height at ALE 0.88 (0.85–1.26).
Cheliceral furrow with three promarginal and four retromarginal teeth.
Measurements of palp and legs. Leg formula: 1423. Palp: 9.0 (8.1–9.7) [3.1 (2.8–3.4), 1.3 (1.1–1.4), 1.7 (1.6–1.8), 2.9 (2.6–3.1)]; Legs: I 48.3 (46.4–53.5) [12.8 (12.5–14.5), 3.2 (3.0–3.8), 13.4 (13.1–14.7), 12.9 (12.2–14.2), 6.0 (5.6–6.3)], II 37.2 (35.2–41.2) [10.2 (9.8–11.7), 2.8 (2.6–3.2), 9.9 (9.7–11.0), 9.7 (9.3–10.5), 4.6 (4.1–4.8)], III 26.1 (24.8–29.2) [7.9 (7.5–9.0), 2.2 (2.0–2.5), 6.1 (6.0–6.9), 6.6 (6.2–7.2), 3.3 (3.1–3.6)], IV 39.1 (38.3–42.4) [10.8 (11.2–11.7), 2.5 (2.3–2.9), 9.6 (9.7–10.5), 10.6 (10.3–11.7), 5.6 (4.8–5.6)].
Palpal claw with 14 (14–15) teeth.
Spination. Palp: 131 (131), 110 (110), 1101 (1101), 1014 (1014); legs: femur I 656 (666), II 646 (656) III 545 (545), IV 554 (555,554); patella I–IV 000 (000); tibia I– II 3038 (3038), III 2124 (2124), IV 3136 (3136); metatarsus I– II 3037 (3037), III 3035 (3035), IV 3036 (3037).
Copulatory organ (see also diagnosis and general description of torvus -group). Epigyne with many wrinkles and ridges surrounding MS and without (distinct) epigynal field (EF) (Fig. 73a). Copulatory ducts (CD) larger than receptacula. First loop of CD directed laterally. Spermathecal heads arising anteriorly on receptacula, where there is a fluent transition between distal section of CD and receptaculum (Fig. 73b).
Colouration of male and female (see also description for torvus -group and Psechrus). Sternum unicoloured yellowish brown. Median bands on carapace serrated. Lateral bands broad to very broad (2–2.5x diameter of PME) and serrated. Light longitudinal line ventrally on opisthosoma continuous and narrow. If measured centrally on opisthosoma, its width is 0.4–0.5 times the width of one half of the cribellum.
Variation of copulatory organs. Females: Branches of tegimentum (TM) may even more transversally orientated (Fig. 73e), which means they are pointing laterally. Second loop of CD may be smaller and narrower (Fig. 73d).
Remark: The label within the vial of the male (SB 848) comprises the same dates as the one within the vial of the two females. As this male has its own collection number it is not absolutely certain if it had been collected at exactly the same site as the females. Consequently, it is not absolutely certain if it really belongs to P. zygon sp. nov.
Distribution. Sri Lanka (Fig. 94).
description: Published as part of Bayer, Steffen, 2012, The lace-sheet-weavers — a long story (Araneae: Psechridae: Psechrus), pp. 1-170 in Zootaxa 3379 (1) on pages 132-135, DOI: 10.11646/zootaxa.3379.1.1, http://zenodo.org/record/6039832