Psechrus zygon, Bayer, 2012

Bayer, Steffen, 2012, The lace-sheet-weavers — a long story (Araneae: Psechridae: Psechrus), Zootaxa 3379 (1), pp. 1-170 : 132-135

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 ).

Figures

FIGURES 73a–e. Psechrus zygon sp. nov., from Sri Lanka, Central Prov., ♀ copulatory organ. a–c ♀ holotype SB 846, d–e ♀ SB 631. a, e Epigyne, ventral view. b, d Vulva, dorsal view. c Schematic course of internal duct system.

FIGURES 74a–d. Psechrus zygon sp. nov. (doubtful identification), ♂ SB 848 from Sri Lanka, Central Prov. a–c ♂ palp (a prolateral, b ventral, c retrolateral view). d ♂ left palpal femur, retrolateral view.

FIGURES 89a–p. Psechrus spp., photos of epigyne, ventral view. a P. sinensis. b P. triangulus. c P. tingpingensis. d P. obtectus sp. nov. e P.fuscaisp. nov. f P. kunmingensis. g P. senoculatus. h P.clavis sp. nov. i P. kenting. j P. taiwanensis. k P. crepido sp. nov. l P. cebu. m P. torvus. n P. hartmanni sp. nov. o P. zygon sp. nov. p P. tauricornis sp. nov. a ♀ paratype SB 524 from China, Guizhou Prov. b ♀ holotype SB 881 from China, Yunnan Prov. c ♀ paratype SB 194 from China, Hunan Prov. d ♀ paratype SB 1153 from Vietnam, Bac Thai Prov. e ♀ holotype SB 954 from China, Yunnan Prov. f ♀ SB 953 from China, Yunnan Prov. g ♀ SB 886 from China, Sichuan Prov. h ♀ paratype SB 614 from Taiwan, Taoyuan County. i ♀ paratype SB 618 from Taiwan, Taitung County. j ♀ holotype SB 238 from Taiwan. k ♀ paratype SB 984 from India, Tamil Nadu Prov. l ♀ paratype SB 151 from Philippines, Cebu Prov. m ♀ SB 941 from Sri Lanka, Central Prov. n ♀ paratype SB 845 from Sri Lanka, Central Prov. o ♀ holotype SB 846 from Sri Lanka, Central Prov. p ♀ paratype SB 849 from Sri Lanka, Central Prov.

FIGURES 92a–p. Psechrus spp., photos of vulva, dorsal view. a P. sinensis. b P. triangulus. c P. tingpingensis. d P. obtectus sp. nov. e P.fuscaisp. nov. f P. kunmingensis. g P. senoculatus. h P.clavis sp. nov. i P. kenting. j P. taiwanensis. k P. crepido sp. nov. l P. cebu. m P. torvus. n P. hartmanni sp. nov. o P. zygon sp. nov. p P. tauricornis sp. nov. a ♀ paratype SB 524 from China, Guizhou Prov. b ♀ holotype SB 881 from China, Yunnan Prov. c ♀ paratype SB 194 from China, Hunan Prov. d ♀ paratype SB 1155 from Vietnam, Bac Thai Prov. e ♀ holotype SB 954 from China, Yunnan Prov. f ♀ SB 953 from China, Yunnan Prov. g ♀ SB 886 from China, Sichuan Prov. h ♀ paratype SB 831 from Taiwan, Chiayi County. i ♀ paratype SB 618 from Taiwan, Taitung County. j ♀ holotype SB 238 from Taiwan. k ♀ paratype SB 984 from India, Tamil Nadu Prov. l ♀ paratype SB 151 from Philippines, Cebu Prov. m ♀ SB 941 from Sri Lanka, Central Prov. n ♀ paratype SB 845 from Sri Lanka, Central Prov. o ♀ holotype SB 846 from Sri Lanka, Central Prov. p ♀ paratype SB 849 from Sri Lanka, Central Prov.

FIGURE 94. Distribution of Psechrus in southern India and Sri Lanka. Symbols: species belonging to the torvus-group. Arrow: Distribution of P. crepido sp. nov.