Chthonopes bifidum Yu & Lin sp. nov.

Figs 1, 2, 6

Type material.

Holotype: ♂, China: Yunnan Province: Xishuangbanna: Mengla County: Menglun Town: Shenmi cave, 21.97°N, 101.24°E, elevation 776 m, 3.X.2017, Y. Lin and Y. Li leg. Paratypes: 15♀11juv., same data as holotype.

Other material examined.

1♂ 24♀ 1juv., China: Yunnan Province: Dehong: Luxi City: Mangliu village: Xianfo cave, 24.33°N, 98.52°E, elevation 1081 m, 25.VIII.2010, C. Wang leg.

Etymology.

The species epithet is taken from the Latin adjective " bifidus " and refers to the forked distal horn of median apophysis.

Diagnosis.

The males of C. bifidum sp. nov. easily differentiated from those of all other congeners by the bifurcate distal horn of median apophysis, the partly membranous or hyaline, whisker-shaped distal apophysis of tegulum, and by the paracymbium with a spine-like tip, vs. distal horn on median apophysis represented by a small needle or spine, not forked, distal apophysis on tegulum relatively sclerotized, lamina-shaped, paracymbium without spine-like tip in C. jaegeri and C. cavernicola (cf. Fig. 2A-D and Wunderlich 2011: 433, figs 13-17, 18b, Fig. 4A-D). The females of C. bifidum sp. nov. can be easily distinguished from other congeners except C. jimudeng sp. nov. by the short and smooth scape, about 1/5 of epigyne length (Figs 1E-G, 5C-E) (vs. scape rugose, longer than 1/2 of epigyne length in all other congeners, including C. jaegeri and C. thakekensis; Fig. 3E-G; Lin et al. 2014: figs 17B-E, 18A-C), but differ from the latter by the: (1) scape triangular, translucent, extending from posterior margin of epigynal plate (Fig. 1E-G) (vs. digitiform, relatively sclerotized, originating from dorsal side of posterior margin of epigynal plate; Fig. 5C-E); (2) accessory spermathecae located anterolaterally to main spermathecae, nearly claviform or tubular (Fig. 1G) (vs. located laterally to main spermathecae, consisting of tubular stalk and globular head; Fig. 5E).

Description.

Male (holotype) (Fig. 1A, B): Carapace nearly pyriform, yellowish brown, without distinct pattern, slightly darker marginally. Anterior eye row recurved, posterior eye row distinctly procurved. Sternum heart-shaped, dark brown, with sparse setae. Mouthparts coloured as sternum. Legs uniformly brown, femora slightly darker. Abdomen round, dorsum centrally beige, marginally coffee coloured with sparse long hairs, weakly ossified at hair base; venter slightly darker than dorsum, posteriorly clothed with short setae. Measurements: Total length 2.1. Carapace 0.8 long, 0.9 wide. Clypeus 0.2 high. Sternum 0.5 long, 0.5 wide. Abdomen 1.4 long, 1.3 wide. Length of legs: I 4.0 (1.3, 0.4, 1.0, 0.9, 0.4); II 3.0 (0.9, 0.3, 0.8, 0.6, 0.4); III 2.4 (0.6, 0.2, 0.7, 0.6, 0.3); IV 3.0 (0.9, 0.3, 0.8, 0.7, 0.3).

Palp (Fig. 2A-D): Tibia small, about 1/5-1/6 length of cymbium, dorsally bears a short trichobothium (TTr). Cymbium narrow, about 2.6 × longer than width, with long setae. Paracymbium (Pc) small, about 1/5-1/6 length of cymbium, with a nearly triangular base and spine-like tip. Tegulum (Te) capacious, 1.5 × longer than wide; sperm duct distinct in ventral view, running a V-shaped course along posterior part of the tegulum. Median apophysis (MA) originating from subbasal portion of tegulum, consisting of broad base and biforked distal horn (DH); base nearly triangular; distal horn heavily sclerotized, tip curved and bifurcate, lateral ramus short claw-shaped, mesal ramus filiform and ca. 2 × longer than lateral ramus. Distal apophysis (DA) located at distal-retrolateral position of tegulum, base partly membranous, and tip hyaline with a truncated apex. Embolus (Em) long and thick, hidden behind conductor, arising at approximately the 9-10 o’clock position, terminating at ca. 2 o’clock position, embolic distal end forked. Conductor (Co) tubular, covering almost whole embolus, apex translucent and pointing retrolaterally.

Female (one paratype). Somatic features as in Fig. 1C, D and coloration slightly lighter than in male. Measurements: Total length 2.5. Carapace 0.8 long, 1.1 wide. Clypeus 0.2 high. Sternum 0.6 long, 0.5 wide. Abdomen 1.9 long, 1.3 wide. Length of legs: I 4.0 (1.4, 0.4, 1.1, 0.7, 0.4); II 3.5 (1.0, 0.4, 1.0, 0.7, 0.4); III 2.6 (0.7, 0.3, 0.7, 0.6, 0.3); IV 3.1 (0.9, 0.3, 0.9, 0.7, 0.4).

Epigyne (Fig. 1C-E). Epigynal plate large, slightly wider than long, with long setae in midline, the arrangement of the various parts of the vulva are indistinctly visible through the tegument; scape (Sc) short, triangular, translucent, extending from posterior margin of epigynal plate, less than 1/5 of epigyne length, apex blunt. The distal part of copulatory ducts (CD) wide, forming two egg-shaped bursae, then connecting with later margin of main spermathecae; the two bursae base closely spaced but anterior surface widely separated by ca. 2 × of bursae width. Main spermathecae (Sp) small, reniform, strongly sclerotized, separated by about 1/10 of their width; accessory spermathecae (Asp) located anterolaterally to main spermathecae, translucent, nearly claviform or tubular, about 1/2 of epigyne length. Fertilization ducts (FD), short, ribbon-shaped, strongly sclerotized, located on dorsal-basal surface of main spermathecae; apical parts separated by about 2.5 × of FD width, apex curved and sharp.

Distribution.

Known from Mengla County and Luxi City, Yunnan, China (Fig. 6).