Psechrus arcuatus, Bayer, 2012

Bayer, Steffen, 2012, The lace-sheet-weavers — a long story (Araneae: Psechridae: Psechrus), Zootaxa 3379 (1), pp. 1-170 : 45-46

publication ID	https://doi.org/ 10.11646/zootaxa.3379.1.1
DOI	https://doi.org/10.5281/zenodo.6303246
persistent identifier	https://treatment.plazi.org/id/D0272654-FFAC-586E-FF20-2D25FD6041B7
treatment provided by	Felipe
scientific name	Psechrus arcuatus
status	sp. nov.

Treatment

Psechrus arcuatus View in CoL sp. nov.

Figs 20a–c View FIGURES 20 , 87k View FIGURES 87 , 90k View FIGURES 90

Psechrus singaporensis View in CoL — Simon 1899: 79, misidentified.

Type material: Holotype ♀ ( SB 333 ), INDONESIA: Sumatra, Sumatera Barat Province: Baso ; E. Jacobson leg.; Coll. E. Reimoser; E. Reimoser det. P. singaporensis ; NHMW 12˙386 .

Etymology. The specific name refers to the anteriorly arcuated copulatory ducts in the holotype female (Latin “arcuatus” means “arcuated, curved”); adjective.

Diagnosis (see also diagnosis for singaporensis -group above). Females with rather complex median septum (MS) with anteriorly diverging margins ( Fig. 20a View FIGURES 20 ). Vulva similar to that of P. norops sp. nov. in having spermathecal heads (SH) located upon receptacula. Distinguished by the very large copulatory ducts (CD) (ca. 4–5x longer than diameter of receptaculum, Fig. 20b View FIGURES 20 ).

Description. Male: unknown.

Female (Tarsi of both legs I, III and IV lost):

Body and eye measurements. Carapace length 5.6, carapace width 4.0, anterior width of carapace 2.3, opisthosoma length 9.2, opisthosoma width 5.3. Eyes: AME 0.32, ALE 0.42, PME 0.43, PLE 0.39, AME–AME 0.19, AME–ALE 0.09, PME–PME 0.30, PME–PLE 0.33, AME–PME 0.53, ALE–PLE 0.45, clypeus height at AME 0.88, clypeus height at ALE 0.62.

Cheliceral furrow with three promarginal and five (left)/ four (right) retromarginal teeth.

Measurements of palp and legs. Leg formula: 1423. Palp: 7.1 [2.4, 1.0, 1.3, 2.4]; Legs: I 35.0 (without tarsus) [11.0, 2.2, 11.3, 10.5, –], II 30.9 [8.7, 2.0, 8.0, 7.8, 4.4], III 18.7 (without tarsus) [6.4, 1.7, 5.1, 5.5, –], IV 28.0 (without tarsus) [9.3, 1.9, 8.3, 8.5, –].

Palpal claw with 14 teeth.

Spination. Palp: 161{141}, 110, 1101, 2007{1014}; legs: femur I 654, II 556, III 545, IV 555; patella I–IV 000; tibia I–II 3038, III 3136, IV 3134; metatarsus I–III 3035, IV 3034.

Copulatory organ (see also diagnosis and general description of singaporensis -group). MS with two flat bulges posteriorly ( Fig. 20a View FIGURES 20 ). Copulatory openings large, located underneath the diverging, anterior sections of MSmargins. Slit sense organs and epigynal muscle sigilla outside epigynal field ( Fig. 20a View FIGURES 20 ). CD with characteristic arcuated anterior margin and ca. 3/4 winding until reaching receptaculum ( Fig. 20b View FIGURES 20 ).

Colouration (see also description for singaporensis -group and Psechrus ). Median bands on carapace slightly serrated. Width of lateral bands ca. 1.4x diameter of PME and slightly serrated.

Remarks. Simon (1899) examined juveniles and subadult females of Psechrus from Fort-de-Kock (today: INDONESIA: Sumatra: Sumatera Barat Prov.: Bukittinggi), which is only 8 km west of Baso, the type locality of P. arcuatus sp. nov. He identified them as P. singaporensis and stated that his determination was dubious. Unfortunately, it was not clear in Simon (1899) where the respective material had been deposited, hence it was not examined in the present study. Nevertheless, regarding the geographic situation, Simon (1899) most likely dealt with P. arcuatus sp. nov., instead of P. singaporensis .

Distribution. Indonesia [Sumatra] ( Fig. 99 View FIGURE 99 ).