Trilacuna zayu Tong & Li 2025, sp. nov.

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).