Sinogone caesuma Muhammad & Wang & Zhang 2023, sp. n.

Sinogone caesuma sp. n. (AEṚḲȐĦ)

Figures 21–23

Type material. Holotype male: CHINA: Chongqing, Wuxi County, YNR, Guan Shanlin, Chang Shizhuzi, 31°32′15.29″N, 109°41′49.82″E, 2147 m, 30 September 2020, Z.S. Zhang et al. leg. (SWUC-T-LIN-32-01). Paratype: 1 female, same data as holotype male (SWUC-T-LIN-32-02).

Etymology. This epithet derives from the Latin noun “ caesum ” meaning “comma” and referring to the commashaped anterior radical process of embolic division.

Diagnosis. See genus diagnosis.

Description. Male (Fig. 23A, B): Total length: 2.23. Carapace 1.11 long, 0.92 wide, cephalic region slightly elevated and extended anteriorly with pits behind PLEs, yellow, fovea, cervical and radial grooves distinct. Clypeus 0.33 high. Chelicerae with 5 promarginal and4 retromarginal teeth. Eye region narrow, AER recurved, PER straight, slightly wider than AER. Eye sizes and interdistances:AME 0.06, ALE 0.08, PME 0.06, PLE 0.06, AME–AME 0.03, PME–PME 0.06, AME–ALE, 0.05, PME–PLE 0.09, AME–PME 0.04, ALE–ALE 0.34, PLE–PLE 0.36, ALE–PLE contiguous. Length of legs: I 3.92 (1.12, 1.35, 1.02, 0.43), II 3.65 (1.05, 1.22, 0.94, 0.44), III 2.84 (0.91, 0.91, 0.70, 0.32), IV 3.97 (1.14, 1.39, 0.98, 0.46). TmI 0.34. Tibial spine formula: 2-2-1-1. Abdomen 1.34 long, 0.83 wide, oval, greenish-grey, mid dorsally with 2 pairs of sigillae, ventral side greenish-grey.

Palp (Fig. 21A–D): Patella 2 times shorter than tibia; tibia 2/3 length of cymbium, with 1 reterolateral trichobothrium, dorsal tibial apophysis with bifurcated apex, pointing retrolaterally in ventral view; paracymbium U-shaped, distal arm with hook-shaped tip; protegulum small and transparent; median membrane with broad frayed end; radix robust, tailpiece short with blunt tip; anterior radical apophysis comma-shaped in prolateral view; embolus long and curved, arc-shaped, extending above the apex of cymbium.

Female (Fig. 23C). Total length: 2.59. Carapace 1.19 long, 0.94 wide, cephalic region slightly elevated, yellow, fovea, cervical and radial grooves distinct. Clypeus 0.26 high. Chelicerae with 5 promarginal and 4 retromarginal teeth. Eye region narrow, AER recurved, PER straight, slightly wider than AER. Eye sizes and interdistances: AME 0.06, ALE 0.07, PME 0.06, PLE 0.06, AME–AME 0.02, PME–PME 0.05, AME–ALE, 0.03, PME–PLE 0.06, AME–PME 0.05, ALE–ALE 0.31, PLE–PLE 0.34, ALE–PLE 0.01. Length of legs: I 3.81 (1.16, 1.32, 0.92, 0.41), II 3.70 (1.14, 1.29, 0.87, 0.40), III 3.06 (0.96, 0.97, 0.75, 0.38), IV 4.02 (1.21, 1.27, 1.10, 0.44). TmI 0.29. Tibial spine formula: 2–2–1–1. Abdomen 1.63 long, 0.95 wide, oval, greenish-grey, mid dorsally with 2 pairs of sigillae, ventral side brown.

Epigyne (Fig. 22 A−F): Ventral plate wider than long, extending posteriorly containing pits with copulatory openings; comprises of strikingly unique vestigial organ as pair of lateral arms originate from the anterior margin of ventral plate of epigyne and extending posteriorly, lateral arms do not have any connection with copulatory ducts or copulatory opening. Dorsal plate reduced in size, D-shaped. Vulva: copulatory ducts extending towards the anterior margin of epigyne and then forming long loop before entering the spermathecae. Spermathecae oval, located between the copulatory ducts; fertilization ducts long, extending mesally.

Distribution. Known only from the type locality.