Comprehensive Description

Eriphia sebana, red eyed rock crab belonging to superfamily Eriphoidea, Malacostraca, Crustacea. Adult size is approximately 70mm width of carapace; body is stocky, with a thickly built abdomen and stocky periopods. The carapace is ovate shaped and coloured either light grey or dark brown; it is smooth, however covered in vesiculous granules that are not visible to the naked eye. The body is divided into the frontal, hepatic and branchial regions, each of which bears these granules. Carapace defined by anterior lateral margin and posterior lateral margin, by which a transverse ridge separates. The orbit, which is one of two sections of the anterior margin on the carapace that opens to accommodate for an eyestalk, is bordered by spines on both side and fine grooves behind; grooves that mark the beginning of the hepatic region. The anterior lateral margin exhibits five to six small spines.

Periopods are typical of any species of crab, segmented into sections known as the dactyl, propodus, carpus and merus. E. sebana exhibits asymmetrical chelipeds, which are the anterior most claws. Claws reach a size of approximately 35mm in length. The back four pairs of walking appendages, otherwise known as ambulatory legs, are stout to accommodate for the stockiness of the carapace, and hairy in the outermost segments.

Sexual dimorphism exhibited by E. sebana is mostly in the size and shape of the carapace; the male abdomen is narrow and long with a triangular shaped posterior segment, whereas the female is oblong in shape. Males are generally of larger size with carapace size up to approximately 70mm in comparison to female carapace size of 45mm.