Psechrus nathanael, Sudhin & Sarma & Sen, 2025

Sudhin, Puthoor Pattammal, Sarma, Shouvik Mali Pratyush Das & Sen, Souvik, 2025, Two new species of the spider genus Psechrus Thorell, 1878 (Araneae: Psechridae) from northeastern India, Zootaxa 5609 (3), pp. 419-429 : 422-428

publication ID	https://doi.org/10.11646/zootaxa.5609.3.7
publication LSID	lsid:zoobank.org:pub:BE0EE77D-C71A-4EA4-B986-6F330D230505
DOI	https://doi.org/10.5281/zenodo.15215524
persistent identifier	https://treatment.plazi.org/id/73560112-CE3B-A920-C6F2-5E66B72CFEBA
treatment provided by	Plazi
scientific name	Psechrus nathanael
status	sp. nov.

Treatment

Psechrus nathanael sp. nov.

Figs 4–8 View FIGURE 4 View FIGURE 5 View FIGURE 6 View FIGURE 7 View FIGURE 8

Type material. Holotype ♂ ( NZC-ZSI-9429/18 ) from INDIA: Nagaland: Peren District, Ngwalwa (25°39’38”N 93°47’06”E), 547 m a.s.l., 28.II.2024, leg. P. P. Sudhin. GoogleMaps Paratypes: 2♀♀ ( NZC-ZSI-9430/18 ), same data as for holotype. GoogleMaps 2♂ ♂ & 1♀ ( NZC-ZSI-9431/18 ) GoogleMaps , Meghalaya: Ri Bhoi District, Anderson Tea Estate (25°47’42”N, 91°53’03”E), 810 m a.s.l., 13.VI.2024, leg. P. P. Sudhin. GoogleMaps

Etymology. The specific epithet is a noun in apposition, dedicated to our friend Mr. Nathanael P. A. Newmai, in recognition of his unwavering support during our surveys in Nagaland and Meghalaya, as well as his passion for spiders and their conservation in northeastern India.

Diagnosis. The male copulatory organ of P. nathanael sp. nov. is most similar to that of P. himalayanus Simon, 1906 in having a similar shape of conductor and U-shaped sperm duct, but it can be distinguished by the following combination of characters: embolus in ventral view broader than in P. himalayanus , slightly curved medially with distal third directed anteroretrolaterally (embolus narrower and almost straight in P. himalayanus ); conductor in retrolateral view at its proximal section broader than in P. himalayanus ; sperm duct covers two-thirds of the area of tegulum (half of the tegulum in P. himalayanus ) (cf. Figs 5A View FIGURE 5 , 6A View FIGURE 6 vs Bayer 2012: figs 31b, 85g). The female genitalia of P. nathanael sp. nov. is most similar to that of P. marsyandi Levi, 1982 in general shape of epigyne and vulva, from which it can be distinguished by the following combination of characters: median septum anterolaterally with prominent lobe at each side (less prominent in P. marsyandi ); copulatory openings relatively large and located medially on epigyne (small, and located mediolaterally in P. marsyandi ); copulatory ducts longer than in P. marsyandi ; spermathecal heads with long stalk (with very short or without any stalk in P. marsyandi ) (cf. Figs 5C–E View FIGURE 5 , 7A–B View FIGURE 7 vs Bayer 2012: figs 34A–D, 88i, 91i). The vulva of P. nathanael sp. nov. can also be differentiated from those of P. demiror Bayer, 2012 and P. pakawini Bayer, 2012 by the spermathecal heads with (at least slightly) longer stalk (cf. Figs 5E View FIGURE 5 , 7B View FIGURE 7 vs Bayer 2012: figs 91j, l).

Description. Male. (Holotype, NZC-ZSI-9429/18) ( Figs 4A–B View FIGURE 4 , 5A–B View FIGURE 5 , 6 View FIGURE 6 ) Measurements: body length 20.36; carapace length 8.55, width 6.13, anterior width of carapace 3.34; opisthosoma length 11.81, width 4.61. Eye diameters:AME 0.34, ALE 0.38, PME 0.49, PLE 0.49. Eye interdistances:AME–AME 0.18, AME–ALE 0.04, ALE– ALE 1.02, PLE–PLE 1.72, PME–PME 0.17, PME–PLE 0.19, AME–PME 0.54, ALE–PLE 0.30. Clypeus height at AME 0.87, clypeus height at ALE 0.71. Chelicerae 2.62 long, with three promarginal and four retromarginal teeth. Measurement of palp and legs: Palp 11.39 [4.11, 1.40, 2.19, 3.69], leg I 52.89 [14.01, 4.08, 15.48, 14.18, 5.14], II 41.42 [11.46, 3.73, 12.36, 10.01, 3.86], III 29.38 [8.46, 2.90, 7.77, 6.85, 3.40], IV 42.14 [12.48, 3.41, 11.39, 10.22, 4.84]. Leg formula: 1423. Spination. Palp: femur pl 1 rl 1 do 3. Legs: femur I–II pl 6 rl 6 do 4, III–IV pl 5 rl 5 do 4; tibia I pl 3 rl 3 plv 3 rlv 3, II pl 3 rl 3 plv 4 rlv 4, III pl 2 rl 3 plv 2 rlv 1, IV pl 3 rl 3 plv 3 rlv 3; metatarsus I pl 5 rl 5, II pl 4 rl 4 v 2, III–IV pl 3 rl 3 plv 2 rlv 2 v 1; tarsus I–IV spineless. Carapace pale yellow, covered with dark brown setae, with a broad, light brown median band, and narrow light brown lateral bands; the median band with a broad pale-yellow marking anteriorly, and a triangle-shaped pale-yellow marking posteriorly, the sides of median band undulating; the lateral bands extending from behind PLE ( Fig. 4A View FIGURE 4 ). Eye field light greyish-brown, covered with setae ( Fig. 4A View FIGURE 4 ). Clypeus pale yellow. Chelicerae pale yellow to reddish-yellow, covered with setae. Endites pale yellow, scopulate, outer margins with black lines, sparsely covered with long black setae ( Fig. 4B View FIGURE 4 ). Labium pale yellow, covered with black setae ( Fig. 4B View FIGURE 4 ). Sternum light brown, covered with long erect black setae and short black setae; sides yellowish, covered with short white setae ( Fig. 4B View FIGURE 4 ). Legs pale yellow, reddish-brown towards the distal segments; coxae of leg I ventrally with macrosetae. Opisthosoma dorsally greyish-brown, suffused with grey patches, anteriorly with a median spindle-shaped pale-yellow marking ( Fig. 4A View FIGURE 4 ); laterally with several longitudinal grey dotted lines on brown background. Venter light greyish-brown, medially with a pale-yellow longitudinal stripe extending the entire length of opisthosoma, more prominent in anterior region ( Fig. 4B View FIGURE 4 ). Spinnerets grey to greyish-brown. Palp as shown in Figs 5A–B View FIGURE 5 , 6 View FIGURE 6 : tegulum (T) and cymbium light reddish-yellow, rest of segments pale yellow ( Fig. 5A–B View FIGURE 5 ); tibia provided with three fields of long, strong, and densely arranged black setae ( Figs 5A–B View FIGURE 5 , 6 View FIGURE 6 ); cymbium dorsally covered with dense scopula, covering approximately two-thirds of its surface ( Figs 5B View FIGURE 5 , 6B View FIGURE 6 ); tegulum nearly oval, with a U-shaped sperm duct (SD) reaching posterior third of the tegulum in ventral view ( Figs 5A View FIGURE 5 , 6A View FIGURE 6 ); subtegulum clearly visible in ventral view; conductor (C) relatively broad and long, with anteroretrolateral orientation, arising in 10 o’clock position on tegulum ( Figs 5A View FIGURE 5 , 6A View FIGURE 6 ); embolus (E) medium-sized, distally third slightly curved retrolaterally, narrowing towards the distal region, arising retrolaterally at distal half of tegulum ( Figs 5A View FIGURE 5 , 6A View FIGURE 6 ).

Female. (paratype) ( Figs 4C–D View FIGURE 4 , 5C–E View FIGURE 5 , 7 View FIGURE 7 ): body length 20.36; carapace length 10.83, width 7.32, anterior width of carapace 3.94; opisthosoma length 16.21, width 8.58. Eye diameters:AME 0.49, ALE 0.60, PME 0.52, PLE 0.63. Eye interdistances: AME–AME 0.20, AME–ALE 0.12, ALE–ALE 1.02, PLE–PLE 2.06, PME–PME 0.31, PME– PLE 0.22, AME–PME 0.39, ALE–PLE 0.29. Clypeus height at AME 1.23, clypeus height at ALE 1.10. Chelicerae 3.32 long. Measurement of palp and legs: Palp: 11.39 [4.11, 1.40, 2.19, 3.69], leg I 52.88 [14.00, 4.08, 15.48, 14.18, 5.14], II 41.41 [11.46, 3.73, 12.36, 10.00, 3.86], III 29.38 [8.46, 2.90, 7.77, 6.85, 3.40], IV 42.34 [12.48, 3.41, 11.39, 10.22, 4.84]. Leg formula: 1423. Spination. Palp: femur pl 1 rl 1 do 3. Legs: femur I–II pl 5 rl 6 do 5, III–IV pl 5 rl 5 do 5; tibia I pl 2 rl 3 plv 4 rlv 4, II pl 4 rl 4 plv 4 rlv 4, III pl 3 rl 3 plv 2 rlv 2, IV pl 3 rl 3 plv 2 rlv 1; metatarsus I–II pl 3 rl 3 plv 2 rlv 2 v 1, III pl 4 rl 3 plv 3 rlv 3 v 1, IV pl 3 rl 3 plv 2 rlv 1; tarsus I–IV spineless. In all details as male, except the following: female longer and more robust than male; opisthosoma slightly lighter, with separated lateral longitudinal grey dotted lines; chelicerae, endites, and labium darker. coxae of leg I ventrally without macrosetae. Genitalia as shown in Figs 5C–E View FIGURE 5 , 7 View FIGURE 7 . Epigynal field wider than long; slit sense organs (SO) and epigynal muscle sigilla anteriorly beyond epigynal field ( Figs 5C View FIGURE 5 , 7A View FIGURE 7 ); median septum (MS) large, broader than long, anterolaterally with lateral humps on each sides ( Figs 5C–D View FIGURE 5 , 7A View FIGURE 7 ); copulatory openings large, nearly oval, separated from each other, positioned medially beyond the lateral humps mentioned above ( Figs 5C–D View FIGURE 5 , 7A View FIGURE 7 ); copulatory ducts relatively short, broad, and transparent ( Figs 5E View FIGURE 5 , 7B View FIGURE 7 ); spermathecal heads (SH) with relatively long stalk ( Figs 5E View FIGURE 5 , 7B View FIGURE 7 ); fertilization ducts curved, oriented posteriorly, positioned at the posterior region of spermathecal base (SBA) ( Figs 5E View FIGURE 5 , 7B View FIGURE 7 ).

Note. The himalayanus group currently comprises 11 species distributed across northern India, Nepal, Bhutan, China, Myanmar, Thailand, Laos, Cambodia, and Vietnam ( Bayer, 2014). This group is characterized by the presence of a distinct field of macrosetae on the ventral side of the male coxae of legs I ( Bayer 2012). The presence of these macrosetae, along with the general morphology of the male and female copulatory organs, strongly supports the placement of this new species within the himalayanus group.

Distribution. India (Nagaland and Meghalaya) ( Fig. 8 View FIGURE 8 ).