Appearance
Carapace subhexagonal convex. Front cut into four triangular lobes, projects beyond spiniform supraorbital angle. Submedian frontal teeth separated by deep, V-shaped sulcus. Lateral teeth not extending as far forward a submedian pair and separated from latter by shallow, skewed indentation. Superior orbital angle prominent. Postorbital angle spiniform, inferior orbital angle conical, acute, projecting almost as far forward as lateral frontal teeth. Antero-lateral margins sloping to acute, procurved epibranchial spine. Postero-lateral margins slightly inflated.Interantennular septum triangulate. Anterior margin of buccal frame sinuous, imperceptibly notched medially. Endognath of first maxilliped paddle-shaped, anterior margin straight. Exognath of external maxilliped columnar, tapering distally, obtuse triangular tooth distally on inner margin. Ischium of endognath with posterior margin transverse, anterior internal angle produced, internal margin rounded, prominently tuberculate, setose. Lateral margins of merus subparallel, internal margin setose.
Chelipeds well developed, subequal, dissimilarity more pronounced in adult male. Anterior margin of ischium of cheliped with single spine. Merus about 0.8 carapace length, its anterior margin with 7-10 slender, curved spines increasing in size distally. On interior margin of carpus in juveniles two acute spines; posterior spine smaller, tuberculate in adults. Chela swollen, 1.3 carapace length, granulate posteriorly.
Info : http://species-identification.org/species.php?species_group=crabs_of_japan&id=1487
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