Psechrus ulcus, Bayer, 2012

Bayer, Steffen, 2012, The lace-sheet-weavers — a long story (Araneae: Psechridae: Psechrus), Zootaxa 3379 (1), pp. 1-170 : 28-29

publication ID 10.11646/zootaxa.3379.1.1


persistent identifier

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scientific name

Psechrus ulcus

sp. nov.

Psechrus ulcus View in CoL sp. nov.

Figs 10a–e View FIGURES 10 , 84f View FIGURES 84

Type material: Holotype ♂ (SB 141), INDONESIA: Borneo, Kalimantan Selatan Province: ca. 25 km E of Banjarbaru, near Riamkanan Dam, S 3°30'59'', E 115°01'00'', 50 m, primary forest; P. Schwendinger leg. 29.–31.X.2008; MHNG. GoogleMaps

Etymology. The specific name refers to the striking retrolateral process on palpal tibia (Latin “ulcus” means “excrescense, branch”); term (noun) in apposition.

Diagnosis (see also diagnosis for mulu -group above). Male with impressive bulky embolus base (EB) and embolus (E) ( Figs 10a–c View FIGURES 10 ) apically on tegulum (T), both with several ridges. E directed retrolaterally.

Description. Male:

Body and eye measurements. Carapace length 4.9, carapace width 3.1, anterior width of carapace 1.6, opisthosoma length 7.5, opisthosoma width 2.3. Eyes: AME 0.29, ALE 0.34, PME 0.35, PLE 0.34, AME–AME 0.20, AME–ALE 0.06, PME–PME 0.21, PME–PLE 0.26, AME–PME 0.42, ALE–PLE 0.36, clypeus height at AME 0.71, clypeus height at ALE 0.50.

Cheliceral furrow with three promarginal and four retromarginal teeth.

Measurements of palp and legs. Leg formula: 1423. Palp: 5.8 [2.1, 1.0, 0.9, 1.8]; Legs: I 65.8 [17.0, 2.0, 17.7, 20.0, 9.1], II 47.5 [12.7, 1.8, 11.7, 14.2, 7.1], III 32.6 [9.0, 1.4, 8.0, 9.6, 4.6], IV 50.6 [13.7, 1.6, 11.8, 15.7, 7.8].

Spination. Palp: 131, 110{000}, 1101{0000}; legs: femur I 667, II 666, III 656, IV 556; patella I–IV 000; tibia I 4048, II 3038, III 3136, IV 4146; metatarsus I–IV 3035.

Palpal femur bulky —but less distinct than in P. mulu — and modified with a rather pointed ventral extension. Its tip slightly pointing distally ( Fig. 10d View FIGURES 10 ). Palpal trochanter distally with 10–15 macrosetae ( Fig. 10e View FIGURES 10 ). Palpal tibia short, distally broader than proximally and with retrolateral process. The latter with long bristles ( Fig. 10b View FIGURES 10 ).

Copulatory organ (see also diagnosis and general description for mulu -group). T shorter than in P. mulu , centrally with distinctly light area, which is surrounded by sperm duct ( Figs 10b View FIGURES 10 , 84f View FIGURES 84 ) and prolatero-distally with ‘corner’ ( Figs 10b View FIGURES 10 , 84f View FIGURES 84 ). Cymbium dorsally with very dense scopula, covering ca. 1/3 of cymbium.

Female: unknown.

Colouration (see also description for mulu -group and Psechrus ). Median bands on carapace serrated. Lateral bands medium-sized to broad (1.5x diameter of PME) and not serrated. Sternum yellowish brown posteriorly and at lateral margins and with light brown tapered patch centrally. These two sections are not easy to discriminate due to the small colour differences.

Distribution. Indonesia [Southern Borneo] ( Fig. 100 View FIGURE 100 ).

Remarks: For the following reasons it is unlikely that the male holotype represents the conspecific male of P. borneo : 1) The type localities are ca. 700 km away from each other; 2) The females of P. mulu and P. borneo are similar. Consequently, for P. borneo I would anticipate a male that is similar to P. mulu . However, this does not apply to P. ulcus sp. nov., as its bulb differs clearly from the one of P. mulu .


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