Zootaxa 3746: 175-193 (2013)

Hsi-Te Shih, Tomoyuki Komai & Min-Yun Liu

A new species of fiddler crab (Brachyura: Ocypodidae), Uca boninensis sp. nov., is described from the Ogasawara (Bonin) Islands, Japan. The new species has previously been identified with the widely distributed U. crassipes (White, 1847), from which it differs by having a slightly differently shaped carapace, and relatively stouter male first gonopods (G1). The recognition of the new species is also supported by differences in the mitochondrial cytochrome oxidase I (COI) and control region (CR) genes. U. boninensis sp. nov., appears to be endemic to the Ogasawara Islands, and as the only known population is small, urgent conservation measures are needed for its protection. Our study brings the total number of the Japanese fiddler crab species to 12.

Key words: fiddler crab, Uca boninensis, U. crassipes, new species, COI, control region.

FIGURE 1. Collection sites for specimens of Uca crassipes (White, 1847), U. boninensis sp. nov. and U. splendida (Stimpson, 1858) used in this study: red solid circles (nos. 1–3, 5, 13–18) for U. crassipes; green rhombus (no. 23) for U. boninensis sp. nov.; blue triangles (nos. 9, 11, 12) for U. splendida; and purple squares (nos. 4, 6–8) for U. crassipes and U. splendida sympatrically. Red empty circles and green empty rhombus mean the additional records of U. crassipes and U. boninensis sp. nov. respectively from other references. Different lines indicate the updated ranges of the three species (modified from Shih et al. 2012). Inserted figure is a map of Chichi-jima I. and Ani-jima I.

FIGURE 2. Uca boninensis sp. nov., holotype, male (CW 19.0 mm), entire animal in dorsal view, CBM-ZC 12094.

FIGURE 3. Uca boninensis sp. nov., holotype, male (CW 19.0 mm), CBM-ZC 12094. A, anterior part of carapace and appendages, frontal view; B, major cheliped, outer view.

FIGURE 4. A–D, Uca boninensis sp. nov., holotype, male (CW 19.0 mm), CBM-ZC 12094; E, F, Uca crassipes (White, 1847), male (CW 17.1 mm), CBM-ZC 7460. A, E, carapace, dorsal view; E, F, left G1, mesial view; C, close up of distal part of left G1, mesial view; D, same, lateral view. Scale bars: 5 mm for A, E; 1 mm for B. F; 0.5 mm for C, D.

FIGURE 5. Carapace in dorsal view. A, Uca boninensis sp. nov., paratype, male (CW 23.5 mm), CBM-ZC 11245; B, Uca boninensis sp. nov., paratype, female (CW 20.5 mm), same lot; C, Uca crassipes (White, 1847), female (CW 16.6 mm), CBMZC 11958 (ex NCHUZOOL 13472).

FIGURE 6. Uca boninensis sp. nov., showing live coloration. A, B, male, NCHUZOOL 13593; C, female, NCHUZOOL 13594. Photographs taken by Tetsuro Sasaki.

FIGURE 7. Morphology of different sizes of male Uca chlorophthalmus (H. Milne Edwards, 1837) (CHL), U. crassipes (White, 1847) (CRA), U. boninensis sp. nov. (BON) and U. splendida (Stimpson, 1858) (SPL). A, CHL: CW 13.1 mm (Kenya; NCHUZOOL 13498), CRA: 13.1 mm (Cocos-Keeling; ZRC), BON: 13.0 mm (Ogasawara Is.; CBM 11245) and SPL: 13.0 mm (New Taipei, Taiwan; NCHUZOOL 13446). B, CHL: 19.2 mm (Mayotte; MNHN-IU-2011-5600), CRA: 19.1 mm (Philippines; NCHUZOOL 13473), BON: 18.8 mm (Ogasawara Is.; CBM-ZC 11245) and SPL: 19.2 mm (Penghu, Taiwan; NCHUZOOL 13456). C, CRA: 23.1 mm (Dongsha, Taiwan; NCHUZOOL 13464); BON: 21.6 mm (Ogasawara Is.; CBM-ZC 11245) and SPL: 23.5 mm (Penghu, Taiwan; NCHUZOOL 13488). Some males' chelae are separated from the body.

FIGURE 8. A minimum evolution (ME) tree for Uca crassipes (White, 1947), U. boninensis sp. nov., U. splendida (Stimpson, 1858) and U. chlorophthalmus (H. Milne Edwards, 1837), based on the combined cytochrome oxidase I and control region genes. Probability values at the nodes represent support values for ME, maximum parsimony (MP) and maximum likelihood (ML). For haplotype names, see Table 1. “*” means the haplotype is heteroplasmic obtained by cloning.

FIGURE 9. Genealogical network for the control region haplotypes observed within the clades of Uca crassipes (White, 1947) (collected from the Ryukyus, Taiwan, the Philippines, Guam, Indonesia, Cocos-Keeling, New Caledonia and Polynesia) and U. boninensis sp. nov. (from Ogasawara Is.). The ancestral haplotype, or root of the network, is indicated by a square. Unlabelled nodes indicate inferred haplotypes not found in the sampled population.

Copyright © 2014 Hsi-Te SHIH