Scopimera ryukyuensis Wong, Chan & Shih, 2010, sp. nov.
Creators: name: Wong, Kingsley J. H.
name: Chan, Benny K. K.
name: Shih, Hsi-Te
Publisher: name: Zenodo
Year: 2010
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Dotillidae
Scopimera
Scopimera ryukyuensis

description: Scopimera ryukyuensis sp. nov.
(Figs. 1 e, f, 2e, f, 3g –i, 4e, f, 5a–f)
Scopimera globosa — Takeda 1975: 144, 243 (in part, Okinawa, the Ryukyus). – Sakai 1982: 714 (in part, the Ryukyus). – Miyake 1983: 168, pl. 56(8) (in part, Ishigaki, the Ryukyus). – Nagai & Nomura 1988: 56. – Ng et al. 2008: 235 (in part).
Material examined. Holotype: 1 male (RUMF-ZC-00865), Awase, Okinawa, Ryukyus, Japan, 11 April 2008, coll. H.-T. Shih, T. Naruse & N.-H. Jang-Liaw. Paratypes: 1 male (RUMF-ZC-00866), data same as for holotype; 2 males (NSMT-Cr 18234, 18235), data same as for holotype; 1 female (NSMT-Cr 18236), Sedake, Okinawa, Ryukyus, Japan, Jun. 2007, coll. B. K. K. Chan; 1 male (NMNS-5687-001), data same as for holotype; 1 male (ASIZCR000199), data same as for holotype; 2 females (ASIZCR000200, 000201), Sedake, Okinawa, Ryukyus, Japan, Jun. 2007, coll. B. K. K. Chan; 1 male (NCHUZOOL 13230), data same as for holotype; 1 male (ZRC 2008.0024), data same as for holotype.
Additional material: 2 males, 10 females (CEL-SG-OK 062007), Sedake, Okinawa, Ryukyus, Japan, Jun. 2006, coll. B. K. K. Chan; 14 males, 13 females (inc. 1 ovig.) (NCHUZOOL 13224), data same as for holotype; 4 males (CEL), south of Naha, Okinawa, Ryukyus, Japan, Nov. 2008, coll. B. K. K. Chan.
Diagnosis. External maxillipeds merus shorter than or subequal to ischium; branchial regions raised (Fig. 1 f), external orbital angle prominent, crest behind which subparallel (Fig. 1 e); cheliped length less than twice of carapace length for mature males, rectangular tooth on inner margin of movable finger (Fig. 2 e); male sixth abdominal somite as broad as long, posterior margin shorter (Fig. 2 f); G1 similar to S. globosa, tip rounded, with inward radiating setae of similar length (Fig. 3 g–i).
Description. Carapace inflated, slightly broader than long, regions indistinct, surface covered by rounded tubercles, more prominent on branchial region, nearly smooth on cardiac and intestinal regions (Fig. 1 e); branchial regions extremely raised (Fig. 1 f), length of posterior margin subequal to distance between both external orbital angles. Suborbital ridge composed of at least 20 equal-sized rounded granules (Fig. 1 f); external orbital angle triangular, notch behind which prominent, followed by roughly parallel longitudinal crest extending most of carapace length (Fig. 1 e). Pterygostomian regions covered with rounded granules (Fig. 1 f). External maxillipeds convex, outer surface covered with rounded tubercles, merus slightly smaller than ischium, suture between them slightly oblique, dactylus of palp approximately reaching suture between merus and ischium. Ventral surface glabrous, smooth, except for short dense tufts of light-colored soft setae between bases of first and second ambulatory legs.
Entire cheliped covered with fine granules, total length less than twice of carapace length on adult male; single longitudinal ovate tympana on outer surface of merus; carpus ovate, shorter than merus; palm as long as merus and fingers; tips of fingers tapered to sharp tips, inner margins weakly serrated, inner margin of movable finger with small rectangular tooth (Fig. 2 e). Ambulatory legs relatively elongated, slender; first and second legs longest, subequal in length, fourth leg shortest; merus laterally compressed, tympana entire, occupying most of segment; dactylus tapered to sharp tip, length subequal to respective propodus, fourth dactylus curved slightly upwards. Anterior border of merus, carpus and both margins of propodus, dactylus lined sparsely with long stiff dark-colored setae.
Male abdomen elongated, telson distally rounded, sixth somite as long as broad, lateral margins converging slightly posteriorly; fifth elongated, slightly narrower than the anterior segment; fourth somite broad, distal margin very convex (Fig. 2 f). G1 largely resembling that of S. globosa, slender, curved dorsally, distal end rounded with brush of longer inward-dorsal radiating setae of roughly same length, and a row of short setae around opening on the inner surface (Fig. 3 g–i).
Size. cw 7.4 mm, cl 6.5 mm for the holotype.
Coloration. Dorsal carapace appears brownish gray, appendages yellow with brownish bands except palm and fingers of chelipeds (Figs. 4 e, 5a–e). A brownish circular pattern on merus of external maxillipeds (Fig. 4 f) (not observed in any S. globosa individual).
Etymology. The name denotes the Ryukyu Archipelago, where the new species was discovered.
Habitat and ecology. On mid-low shores of open, exposed sandy shores. Burrow opening with small radiating sand balls (Fig. 5 f) (also see Nagai & Nomura 1988: 56). Smallest female collected that was ovigerous had a carapace width of 5 mm.
Distribution. The present localities are recorded from Okinawa (present study) and Ishigaki (Miyake 1983) in the Ryukyus. This species is probably endemic to the Ryukyu Archipelago.
Remarks. Scopimera ryukyuensis sp. nov. morphologically resembles S. globosa but there are several diagnostic features. Although both species share a similar G1 morphology, S. ryukyuensis has a more prominent or pointed triangular external orbital tooth and notch behind, and a subparallel ridge which follows along the lateral margin.
description: Published as part of Wong, Kingsley J. H., Chan, Benny K. K. & Shih, Hsi-Te, 2010, Taxonomy of the sand bubbler crabs Scopimera globosa De Haan, 1835, and S. tuberculata Stimpson, 1858 (Crustacea: Decapoda: Dotillidae) in East Asia, with description of a new species from the Ryukyus, Japan, pp. 43-59 in Zootaxa 2345 on pages 50-54, DOI: 10.5281/zenodo.205328