Note: Up to 50 cm, nocturnal, not common Carpus of first pereiopod with a distinct dorsal groove, and without a conspicuous basal swelling. First abdominal somite with 2 distinct but rather small lateral spots and a large, less dark and irregular median spot. Outline of posterior margin of pleura of second abdominal somite concave in middle through presence of strong tooth. Fourth abdominal somite in adult specimens produced into very strong median hump which is about twice as high as those on second and third somite.