Appearance
Carapace distinctly constricted behind postorbital spines, with convex antero-lateral and rounded postero-lateral margins. Epibranchial spine prominent, projecting outward. Submedian frontal sulcus wide and shallow, lateral teeth reaching as far forward as submedian pair.Chelipeds massive. Merus little shorter than carapace, and strongly granulate on anterior margin, with the distalmost tooth largest. Carpus rounded, anterior spine on interior margin prominent, posterior spine appears no more than tubercle in adult. Chela 1.5 carapace length, swollen, tuberculate, tubercles increasing in size posteriorly, giving posterior margin serrate appearance.
First ambulatory leg more than twice carapace length. Curved cornute spines on posterior margin of propodi. On posterior margin of fourth ambulatory dactyl sixteen triangular teeth, proximally diminishing in size. Interiorly, eight distalmost teeth each with an additional spine. Short irregular rows of spinules anteriorly.
First male pleopod slightly sinuous, subdistally spinose. (Galil & Takeda, 1985)
Info from : http://species-identification.org/species.php?species_group=crabs_of_japan&id=1488
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