Description
Holotype male. Total length 4.20 (habitus). Carapace: 2.15 long/2.20 wide, dark reddish-brown, round, slightly wider than long, clothed sparsely with serrated setae especially along the cervical furrow, cephalic region of prosoma flat with a pair of light stripes along the median line, numerous warts present, cervical and radial furrows distinct, dark longitudinal fovea slightly depressed (Fig. 2A and, C-E). Eyes: ALE 0.10, AME 0.06, PLE 0.14, PME 0.06, ALE-AME 0.17, AME-AME 0.30, PLE-PME 0.37, PME-PME 0.31, ALE-PLE 0.30, AME-PME 0.37, AER 0.58, PER 0.59, all eyes on the eye tubercle and lateral eye tubercles conspicuously developed, eight eyes in two rows, AER almost straight and PER recurved from above, AER strongly procurved and PER slightly procurved from front, PER longer than AER (Fig. 2E and, F). Chelicera; 0.62 long/0.35 wide, dark reddish-brown, light stripe and cross-shaped pattern on dorsal surface (Fig. 2C), no cheliceral teeth, fang very short. Endite: 0.45 long/0.18 wide, dark reddish-brown. Labium: 0.28 long/ 0.25 wide, dark reddish-brown. Sternum: 1.00 long/0.98 wide, mottled with dark and light reddish-brown, subcordate, clothed sparsely with long blackish-brown setae, pointed anteromedial margin protrudent, posterior end round and not protrudent between the coxae of leg IV (Fig. 2B). Legs: I 7.67 (2.40, 0.80, 1.67, 1.90, 0.90), II 6.84 (2.07, 0.80, 1.50, 1.65, 0.82), III 3.92 (0.87, 0.60, 0.85, 0.93, 0.67), IV 4.40 (1.00, 0.52, 0.90, 1.18, 0.80), ivory, stout and strongly developed, I and II mottled severely with dark reddish-brown, III and IV mottled weakly with dark reddish-brown (Fig. 2A and, D), femur with ventral stripe (Fig. 2B), femur I with two small rod-like proximal protuberances on prolateral surface (Fig. 2G), leg formula I-II-IV-III. Abdomen: 2.10 long/2.03 wide, ivory, flat and mottled with blackish-brown, yellowish-brown and reddish-brown, trapezoidal, slightly longer than wide, a pair of dark reddish-brown triangular markings paramedianly, numerous round or irregular pits on dorsal surface, clothed densely with semi-transparent clavate and serrated setae (Fig. 2A, C and, D; Fig. 3E and, F). Palp: 2.57 (0.46, 0.41, 0.20, - , 0.70), bulb round and simple, left margin of tegulum slightly constricted, no tegulum apophysis, embolus thick with a pointed embolus tip straight rotating largely clockwise and close to the tegulum, thumb-like VTA large with a bent tip, thumb-like blunt RTA large (Fig. 3A–D).
Female. Unknown.
Diagnosis
The male of the new species can be easily distinguished from congeners of this genus, except B. ora by the thumb-like blunt RTA without a terminal spur (Fig. 3B and, C); versus thumb-like RTA with a spine-like terminal spur in B. baudueri (Simon, 1877) (Breitling et al. 2016: 44, figs. 8–9), B. decorata (Karsch, 1879) (Paik 1974: 120, figs. 5–6), B. floridana (Banks, 1896) (Bowling and Sauer 1975: 188, f. 4), B. utahensis (Gertsch, 1932) (Dondale and Redner 1978: 136, figs. 439 and, 441), and B. versicolor (Dondale and Redner 1978: 139, figs. 443 and, 445). The male of the new species is most similar to B. ora in the shape of the palpal organ, but can be easily distinguished from the latter by the body appearance, the shape of VTA, tegulum, and embolus: males of B. birudis sp. nov. have no white patterns on the carapace and abdominal dorsum (Fig. 2A), a thick thumb-like VTA (Fig. 3C), a slightly constricted tegulum (Fig. 3B), and an embolus close to the tegulum (Fig. 3B), versus white marginal patterns on the carapace and abdominal dorsum, a slender finger-like VTA, a round tegulum, and an embolus separated from the tegulum in B. ora (Seo 1992: 79, figs. 1–4).