Psechrus nathanael Sudhin, Sarma & Sen, 2025, sp. nov.
Creators: name: Sudhin, Puthoor Pattammal
name: Sarma, Shouvik Mali Pratyush Das
name: Sen, Souvik
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Araneae
Psechridae
Psechrus
Psechrus nathanael

description: Psechrus nathanael sp. nov.
Figs 4–8
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. Paratypes: 2♀♀ (NZC-ZSI-9430/18), same data as for holotype. 2♂ ♂ & 1♀ (NZC-ZSI-9431/18), 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.
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, 6A 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, 7A–B 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, 7B vs Bayer 2012: figs 91j, l).
Description. Male. (Holotype, NZC-ZSI-9429/18) (Figs 4A–B, 5A–B, 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). Eye field light greyish-brown, covered with setae (Fig. 4A). 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). Labium pale yellow, covered with black setae (Fig. 4B). Sternum light brown, covered with long erect black setae and short black setae; sides yellowish, covered with short white setae (Fig. 4B). 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); 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). Spinnerets grey to greyish-brown. Palp as shown in Figs 5A–B, 6: tegulum (T) and cymbium light reddish-yellow, rest of segments pale yellow (Fig. 5A–B); tibia provided with three fields of long, strong, and densely arranged black setae (Figs 5A–B, 6); cymbium dorsally covered with dense scopula, covering approximately two-thirds of its surface (Figs 5B, 6B); tegulum nearly oval, with a U-shaped sperm duct (SD) reaching posterior third of the tegulum in ventral view (Figs 5A, 6A); 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, 6A); embolus (E) medium-sized, distally third slightly curved retrolaterally, narrowing towards the distal region, arising retrolaterally at distal half of tegulum (Figs 5A, 6A).
Female. (paratype) (Figs 4C–D, 5C–E, 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, 7. Epigynal field wider than long; slit sense organs (SO) and epigynal muscle sigilla anteriorly beyond epigynal field (Figs 5C, 7A); median septum (MS) large, broader than long, anterolaterally with lateral humps on each sides (Figs 5C–D, 7A); copulatory openings large, nearly oval, separated from each other, positioned medially beyond the lateral humps mentioned above (Figs 5C–D, 7A); copulatory ducts relatively short, broad, and transparent (Figs 5E, 7B); spermathecal heads (SH) with relatively long stalk (Figs 5E, 7B); fertilization ducts curved, oriented posteriorly, positioned at the posterior region of spermathecal base (SBA) (Figs 5E, 7B).
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).
description: Published as part of 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, pp. 419-429 in Zootaxa 5609 (3) on pages 422-428, DOI: 10.11646/zootaxa.5609.3.7, http://zenodo.org/record/15215296