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Zootaxa 2345: 43-59 (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

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Kingsley J. H. Wong, Benny K. K. Chan & Hsi-Te Shih*

Sand bubbler crabs of the genus Scopimera are common on sandy shores in East Asia yet the taxonomy of the species remains unclear. Scopimera globosa De Haan, 1835, the type species, was described from Japanese specimens and also occurs in Korea and China. Scopimera tuberculata Stimpson, 1858, described from Japan, has been regarded a junior synonym of S. globosa, but the types had long been lost. Some workers have considered the two taxa distinct and S. tuberculata has been recorded from South China. In the present study, we confirm using male gonopod morphology and molecular analysis, that the early records of S. tuberculata from Hong Kong and S. globosa from Taiwan are in fact S. intermedia Balss, 1934. The present study regards S. tuberculata as a subjective junior synonym to S. globosa. A new species, Scopimera ryukyuensis sp. nov. from the Ryukyus, is identified and described herein. The new species is close to S. globosa but can be separated by carapace characters. The mitochondrial cytochrome oxidase I (COI) gene revealed basepair (bp) difference between the new species and other Scopimera spp. to be at the interspecific level, at least 28 bp (4.3%).

Key words: Scopimera ryukyuensis, Dotillidae, cytochrome oxidase I, taxonomy, Ryukyus, Japan.

FIGURE 1. Scopimera globosa De Haan, 1835: dorsal view of carapace (a) and suborbital ridge and pterygostomian region (b); S. intermedia Balss, 1934: dorsal view of carapace (c) and suborbital ridge and pterygostomian region (d); S. ryukyuensis sp. nov.: dorsal view of carapace (e) and suborbital ridge and pterygostomian region (f). a, c, e: note arrow highlighting relative size of extra-orbital angle and solid line indicating direction of ridge behind the extra-orbital angle (which is diagnostic between S. ryukyuensis sp. nov. and S. globosa). b, d, f: arrow noting raised branchial region viewed from front in S. ryukyuensis sp. nov. (e) and relative conspicuousness of sub-orbital ridge: that of S. ryukyuensis sp. nov. being most pronounced.

FIGURE 2. Scopimera globosa De Haan, 1835: chela (a) and male abdomen (b); S. intermedia Balss, 1934: chela (c) and male abdomen (d); S. ryukyuensis sp. nov.: chela (e) and male abdomen (f). a, c, e: arrow pointing tooth at inner margin of movable finger: that of S. intermedia Balss, 1934, being most rudimentary. b, d, f: large arrows showing dimensions of the sixth abdominal somite and small arrow indicating the convexity of distal border of the fourth somite.

FIGURE 3. Scopimera globosa De Haan, 1835: G1 entire view (a), tip (b) and magnification of setae (c); S. intermedia Balss, 1934: G1 entire view (d), tip (e) and magnification of setae (f); S. ryukyuensis sp. nov.: G1 entire view (g), tip (h) and tip observed under light microscope (i). Scale bars in gm.

FIGURE 4. Photographs in life (aVe). Scopimera globosa De Haan, 1835: male frontal view (a) and dorsal view (b); S. intermedia Balss, 1934: male frontal view (c) and dorsal view (d); and S. ryukyuensis sp. nov.: male frontal view (e) and close-up of external maxillipeds from preserved specimens, showing ring-like marking on merus (f).

FIGURE 5. Photographs in life Scopimera ryukyuensis sp. nov. (aVe): dorsal view (a), frontal view (b) and ventral view (c) of male and dorsal view (d) and frontal view (e) of female. External architecture of burrow at Sedake, Okinawa, the Ryukyus (f).

FIGURE 6. Dorsal view of the neotype of Scopimera tuberculata Stimpson, 1858. A male (cw 9.9 mm, cl 7.6 mm) (CBM-ZC 4195) deposited in Natural History Museum and Institute, Chiba, Japan.

FIGURE 7. A minimum evolution (ME) tree (left) and maximum parsimony (MP) tree (right) of the Scopimera species from East Asia and Dotilla, based on 658 basepairs of the cytochrome oxidase I genes. Probability values at the nodes represent confidence values for ME (left), MP, Bayesian inference (BI) and maximum likelihood (ML) (right). For haplotype names see Table 1. Species name and locality are behind each haplotype name.

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