E-Fauna BC: Electronic Atlas of the Wildlife of British Columbia

Carapace hard, smooth, about twice as wide as long and with a granular ridge on anterior lateral margins. Chelipeds of adult male robust; palm with a few granules; short fingers with small or no teeth. Chelipeds of female and immature male slender; palm granulate; fingers subequal cutting surfaces with small teeth and tips crossed. 3rd walking leg relatively stout and long, setose with granular margins on merus and propodus. Other walking legs slender and setose; dactyl slightly curved. Abdomen of male with a semicircular telson.

Carapace: male 5.5 x 10 mm, female 6.8 x 12.5 mm.

Colour often masked by muddy setae or stained by rust or sulphurous mud. In recently moulted specimens the carapace and dorsal surfaces of walking legs are blue-grey, black and white mottled; the margins are light coloured, especially posteriorly. Chelipeds white with fine black dendritic chromatophores dorsally; the palm, especially in the male, is mostly white, as are the ventral surfaces. Eyestalk brown; cornea black with gold flecks.