Trilacuna zayu Tong & Li, 2025

Shi, Songlu, Bian, Dongju, Tong, Yanfeng & Li, Shuqiang, 2025, First record of the genus Trilacuna Tong & Li, 2007 (Araneae, Oonopidae) from Xizang, China, with descriptions of three new species and one newly recorded species, ZooKeys 1229, pp. 213-232 : 213-232

Trilacuna zayu Tong & Li sp. nov.

Figs 5 K , 11 , 12 , 13 , 14 G, H

Material examined.

Holotype China • ♂ ( SYNU -908 ); Xizang, Nyingchi City, Zayu Co., Gaba Oil Field ; 28°38.849'N, 97°27.088'E, 2300 m elev.; 25. VII. 2013; Q. Cao leg. Paratypes. China • 1 ♂ ( SYNU -F-928 ); same data as holotype • 2 ♀ ( SYNU -909–910 ); Zayu Co., Dongriqugou ; 28°39.670'N, 97°28.657'E, 2470 m elev.; 23. VII. 2013; L. Lin leg.

Other material.

China • 1 ♂ ( SYNU -F-929 ); Zayu Co., Dongriqugou ; 28°39.670'N, 97°28.657'E, 2470 m elev.; 23. VII. 2013; Q. Cao leg. • 2 ♀ ( SYNU -F-931–932 ); same data as above • 1 ♀ ( SYNU -F-930 ); Zayu Co., Gaba Vill. ; 28°40.254'N, 97°27.780'E, 2460 m elev.; 24. VII. 2013; L. Lin leg.

Etymology.

The specific name is a noun in apposition taken from the type locality.

Diagnosis.

The new species is similar to T. longling Tong, Zhang & Li, 2019 in the ridges on posterior part of the male sternum, the small slit of the male epigastric region and the T-shaped sclerite of the endogyne, but can be distinguished by the elongated male palpal femur (Fig. 12 D ) vs. globular ( Tong et al. 2019: fig. 13 A), the cluster of bristle-like structures (cbs) on the median area of the bulb (Figs 12 A, J ) vs. lacking ( Tong et al. 2019: fig. 13 A), the long, belt-like structure (bls) of the psembolus (Fig. 12 I ) vs. many fiber-like lobes ( Tong et al. 2019: fig. 13 B), and the transversally elongated membranous structure (tms) of the endogyne (Fig. 14 H ) vs. lacking ( Tong et al. 2019: fig. 24 J).

Description.

Male. Body: yellowish-brown, legs lighter; habitus as in Fig. 11 A, C, E ; body length 1.64. Carapace (Fig. 11 B, F ): 0.72 long, 0.58 wide; sides granulate. Eyes (Fig. 11 B, F ): eyes well developed, nearly equal in size; ALE separated from edge of carapace by 1.4 diameters. Mouthparts (Figs 5 K , 11 D, H ): endites distally branched. Sternum (Fig. 11 D ): surface smooth; with several rows of ridges in posterior part. Abdomen (Fig. 11 A, C, E, G ): 0.84 long, 0.49 wide; surface smooth; sperm pore situated at level of anterior spiracles; with small slit anterior of groove connecting posterior spiracles. Palp (Fig. 12 A – K ): orange; 0.54 long (0.17, 0.10, 0.09, 0.16); femur elongated (width / length = 0.52); bulb triangle, with cluster of bristle-like structure (cbs) on median area; psembolus with long, belt-like structure (bls), a lateral curved branch (lb) and broad median branch (mb).

Female. Same as male except as noted. Body: length 1.89; habitus as in Fig. 13 A, C, E . Carapace: 0.77 long, 0.63 wide. Abdomen: 1.06 long, 0.67 wide. Epigastric area (Figs 13 A , 14 G ): with recurved, strongly sclerotized arches (sar). Endogyne (Fig. 14 H ): with narrow, transverse sclerite (tsc) and broad, transversally elongated membranous structure (tms); with anterior slender sclerite (as) and posterior small globular structure (glo); transverse bars (tba) with pair of short lateral apodemes (ap).

Distribution.

Known only from the type locality (Fig. 1 ).

Figures

Figure 1. Distribution records of Trilacuna species from the Himalaya region: green circles represent 22 known species, red circles indicate the three new species. 1. T. hazara; 2. T. bangla; 3. T. aenobarba; 4. T. besucheti; 5. T. loebli; 6. T. mahanadi; 7. T. meghalaya; 8. T. changzi; 9. T. hponkanrazi; 10. T. triseta; 11. T. zhigangi; 12. T. bawan; 13. T. cangshan; 14. T. cuneata; 15. T. datang; 16. T. fugong; 17. T. gongshan; 18. T. longling; 19. T. rastrum; 20. T. wuhe; 21. T. wumanshan; 22. T. xiaoheishan; 23. T. mainling sp. nov.; 24. T. metok sp. nov.; 25. T. zayu sp. nov.

Figure 5. Trilacuna mainling sp. nov., male holotype (A – H), Trilacuna metok sp. nov. (I), Trilacuna bangla (J), Trilacuna zayu sp. nov. (K) A, C, E, G prosoma, dorsal, ventral, lateral and anterior views B, D, F abdomen, dorsal, ventral and lateral views, arrow shows the small wedge-shaped process H – K endites, ventral view. Scale bars: 0.4 mm.

Figure 11. Trilacuna zayu sp. nov., male holotype A, C, E habitus, dorsal, ventral and lateral views B, D, F, H prosoma, dorsal, ventral, lateral and anterior views, arrow in D shows the small ridges G abdomen, ventral view, arrow shows the small slit. Scale bars: 0.4 mm.

Figure 12. Trilacuna zayu sp. nov., male left palp A – C (light) and D – K (SEM) A, D prolateral view B, E dorsal view C, F retrolateral view G bulb, prolateral view H, I, K distal part of bulb, dorsal, prolateral and retrolateral views J detail of bulb, prolateral view. Abbreviations: bls = belt-like structure; cbs = cluster of bristle-like structure; lb = lateral branch; mb = median branch. Scale bars: 0.1 mm (A – G); 0.05 mm (H – K).

Figure 13. Trilacuna zayu sp. nov., female paratype A, C, E habitus, dorsal, ventral and lateral views B, D, F, H prosoma, dorsal, ventral, lateral and anterior views G abdomen, ventral view. Scale bars: 0.4 mm.

Figure 14. Trilacuna spp., endogyne A, B Trilacuna mainling sp. nov. C, D Trilacuna metok sp. nov. E, F Trilacuna bangla Grismado & Ramírez, 2014 G, H Trilacuna zayu sp. nov. A, C, E, G ventral view B, D, F, H dorsal view. Abbreviations: ap = apodeme; as = anterior sclerite; glo = globular structure; psp = posterior spiracle; sar = sclerotized, recurved arches; tba = transverse bars; tms = transverse membranous structure; tsc = transverse sclerite. Scale bars: 0.1 mm.