Trilacuna metok Tong & Li, 2025

Trilacuna metok Tong & Li sp. nov.

Figs 5 I View Figure 5 , 8 View Figure 8 , 9 View Figure 9 , 10 View Figure 10 , 14 C, D View Figure 14

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. GoogleMaps Paratypes. China • 1 ♂ 1 ♀ ( SYNU -912–913 ); same data as holotype GoogleMaps • 1 ♀ ( SYNU -924 ); same data as holotype GoogleMaps .

Other material.

China • 1 ♂ 1 ♀ ( SYNU -F-955–956 ); same data as holotype GoogleMaps • 1 ♀ ( SYNU -F-967 ); same data as holotype GoogleMaps • 1 ♂ 2 ♀ ( SYNU -F-976–978 ); same data as holotype GoogleMaps • 1 ♀ ( SYNU -F-963 ); near Metok Co.; 29°19.399'N, 95°20.448'E, 1300 m elev.; 3. VIII. 2013; L. Lin leg. GoogleMaps • 1 ♂ 1 ♀ ( SYNU -F-973–974 ); same data as above GoogleMaps • 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. GoogleMaps • 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. GoogleMaps • 3 ♂ ( SYNU -F-960–962 ); same data as above GoogleMaps • 1 ♀ ( SYNU -F-968 ); same data as above GoogleMaps • 1 ♀ ( SYNU -F-975 ); same data as above GoogleMaps • 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. GoogleMaps

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 View Figure 9 ) vs. cymbium well separated ( Tong et al. 2020: fig. 12 A, B) and the coxae IV connected by radial furrow (Fig. 8 D View Figure 8 ) 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 View Figure 10 ) vs. normal size, far away the anterior corner (e. g., Figs 4 G View Figure 4 , 7 G View Figure 7 , 13 G View Figure 13 ).

Description.

Male. Body: reddish-brown, legs yellow; habitus as in Fig. 8 A, C, E View Figure 8 ; body length 1.61. Carapace (Fig. 8 B, F View Figure 8 ): 0.81 long, 0.63 wide; sides smooth. Eyes (Fig. 8 B, H View Figure 8 ): eyes well developed; ALE separated from edge of carapace by 1.25 diameters. Mouthparts (Figs 8 D, H View Figure 8 , 5 I View Figure 5 ): labium distally not branched, with large membranous area at anterior part. Sternum (Fig. 8 D View Figure 8 ): surface smooth, with large seta pits; with radial furrows between coxae I – II, II – III, III – IV and IV – IV. Abdomen (Fig. 8 G View Figure 8 ): 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 View Figure 9 ): 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 View Figure 10 ; 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 View Figure 10 , 14 C View Figure 14 ): without recurved, strongly sclerotized arches. Endogyne (Fig. 14 D View Figure 14 ): 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 View Figure 1 ).