Thyropygus chelatu s n. sp.

(Figs. 4, 14 A–D, 19A)

Material: HOLOTYPE male THAILAND, Nakhonsrithammarat Province, Khanom district, Koh Rab, 9° 18ˏ 30˝ N, 99° 57ˏ 30˝ E. 26 August 2007. H. Enghoff and S. Panha leg., (CUMZ). – Paratypes: 10 males, 40 females, same data as holotype (CUMZ), 2 males, 2 females, same data as holotype (ZMUC), 3 males, 2 females, THAILAND, Nakhonsrithammarat Province, Khanom district, Koh Wangnok, 9° 14ˏ 41˝ N, 99° 54ˏ 48˝ E. 26 August 2007. H. Enghoff and S. Panha leg., (CUMZ).

Etymology: The name refers to the chela-like gonopodal anterior coxal fold.

Diagnosis: A species of the opinatus subgroup. Spatulate lobe (sl) at the apical part of telopodite rounded, spoon-like. Similar in this respect to T. inflexus, T. bearti, T. cristagalli, T. brachyacanthus and T. loxia . Differs from these species by the mesal process of anterior coxal fold (amp) being directed obliquely mesodistad from the mesal margin of anterior coxal fold (ac).

Description: Adult males with 56–58 podous rings, no apodous rings. Length ca. 9–12 cm, width ca. 6.8–7.2 mm. Adult females with 54–60 podous rings, no apodous rings. Length ca. 10–12 cm, width ca. 7.2–8.0 mm. Overall color of living animal (Fig. 19A) medium brown. Prozona, legs and antennae brown, metazona dark brown, head reddish brown, tip of epiproct, margins of paraprocts, and hypoproct yellow.

Gonopods (Figs. 14 A–D): Sternum (st) somewhat larger than in the other subgroup members. Anterior coxal fold (ac) (Fig. 14 A): lateral process (alp) stout, regularly sickle-shaped; mesal process (amp) much shorter than lateral process, directed obliquely disto-mesad, slender, straight, and pointed. Posterior coxal fold (pc) (Fig. 14 B) basally with moderately high lateral paracoxites (px), distally truncate, forming shelf (sh) for accommodation of telopodite; laterally with an erect, digitiform process (plp). Telopodite (Figs. 14 C–D) leaving coxite over shelf of posterior coxal fold; femoral spine (fe) long, slender, excavated along its outer curvature, curving almost exclusively in horizontal plane, its outer curvature in situ resting against the processes alp and amp; tibial spine of same size and shape as femoral spine, but curving in the opposite direction in the horizontal plane, its tip in situ resting against mesal corner of shelf (sh); apical part: spatulate lobe (sl) basally slender, distally expanded, rounded, spoon-like; palette (pa) simple, gutter-like, distally with about twelve brownish blepharochaetae (bp).

Distribution (Fig. 20): Known only from Koh Rab and Koh Wangnok, two small islands in the Gulf of Thailand, where it was very abundant on the day of collecting.