Trilacuna metok Tong & Li 2025, sp. nov.

Trilacuna metok Tong & Li sp. nov. Figs 5 I, 8, 9, 10, 14 C, D Material examined. Holotype China • ♂ (SYNU -911), Xizang, Nyingchi City, Metok Co., nr Yadong Vill.; 29°20.605'N, 95°20.807'E, 1360 m elev.; 6. VIII. 2013; L. Lin leg. Paratypes. China • 1 ♂ 1 ♀ (SYNU -912–913); same data as holotype • 1 ♀ (SYNU -924); same data as holotype. Other material. China • 1 ♂ 1 ♀ (SYNU -F-955–956); same data as holotype • 1 ♀ (SYNU -F-967); same data as holotype • 1 ♂ 2 ♀ (SYNU -F-976–978); same data as holotype • 1 ♀ (SYNU -F-963); near Metok Co.; 29°19.399'N, 95°20.448'E, 1300 m elev.; 3. VIII. 2013; L. Lin leg. • 1 ♂ 1 ♀ (SYNU -F-973–974); same data as above • 1 ♂ 2 ♀ (SYNU -F-964–966); near Metok Co.; 29°19.382'N, 95°19.016'E, 980 m elev.; 2. VIII. 2013; L. Lin leg. • 1 ♂ 2 ♀ (SYNU -F-957–959); Metok Co., hills nr Nongjiale; 29°19.087'N, 95°18.876'E, 1280 m elev.; 4. VIII. 2013; Q. Cao leg. • 3 ♂ (SYNU -F-960–962); same data as above • 1 ♀ (SYNU -F-968); same data as above • 1 ♀ (SYNU -F-975); same data as above • 4 ♂ (SYNU -F-969–972); 108 km along highway from Bomi Co. to Metok Co.; 29°29.178'N, 95°26.868E, 1360 m elev.; 9. VIII. 2013; L. Lin leg. Etymology. The specific name is a noun in apposition taken from the type locality. Diagnosis. Males of this new species are similar to those of T. triseta Tong & Li, 2000 in the branches of psembolus, but can be distinguished by the fused cymbium and bulb (Fig. 9 A – N) vs. cymbium well separated (Tong et al. 2020: fig. 12 A, B) and the coxae IV connected by radial furrow (Fig. 8 D) vs. not connected (Tong et al. 2020: fig. 11 F). Females of the new species can be distinguished from all congeners by the long, narrow posterior spiracles, which are situated at the anterior corner of the postgastric scutum (Fig. 10 C, E) vs. normal size, far away the anterior corner (e. g., Figs 4 G, 7 G, 13 G). Description. Male. Body: reddish-brown, legs yellow; habitus as in Fig. 8 A, C, E; body length 1.61. Carapace (Fig. 8 B, F): 0.81 long, 0.63 wide; sides smooth. Eyes (Fig. 8 B, H): eyes well developed; ALE separated from edge of carapace by 1.25 diameters. Mouthparts (Figs 8 D, H, 5 I): labium distally not branched, with large membranous area at anterior part. Sternum (Fig. 8 D): surface smooth, with large seta pits; with radial furrows between coxae I – II, II – III, III – IV and IV – IV. Abdomen (Fig. 8 G): 0.87 long, 0.55 wide; surface smooth; sperm pore situated between anterior and posterior spiracles; apodemes present, posterior spiracles connected by groove. Palp (Fig. 9 A – N): orange; 0.58 long (0.16, 0.13, 0.08, 0.21); femur elongated (width / length = 0.48); bulb and cymbium fused; psembolus including slender anterior branch (ab), slender dorsal branch (sdb), broad dorsal branch (bdb), and slender posterior branch (pb). Female (paratype, SYNU -913). As in male except as noted. Body: habitus as in Fig. 10 A, C, E; body length 2.19. Carapace: 0.97 long, 0.79 wide. Abdomen: 1.37 long, 0.74 wide; posterior spiracles narrow and long (psp), situated at anterior corner of postgastric scutum. Epigastric area (Figs 10 G, 14 C): without recurved, strongly sclerotized arches. Endogyne (Fig. 14 D): with narrow, transverse sclerite (tsc); with an anterior large T-shaped sclerite (as) and a posterior small globular structure (glo); transverse bars (tba) with pair of strongly curved, thick lateral apodemes (ap). Comment. All the known species of the genus Trilacuna have a well-separated cymbium and bulb; the fused cymbium and bulb demonstrate that T. metok sp. nov. is quite different from all other species of Trilacuna. But based on the psembolus and somatic characters, e. g., the deeply incised labium and the large setae base on the male chelicerae, it is reasonable to consider this species in Trilacuna. Distribution. Known only from the type locality (Fig. 1).