Rostrum without a dorsal rostral tooth. Outer margin of second segment of antenna as a rule with 5 teeth (Apical tooth not included).
Distance between the orbit and the anterolateral angle of carapace 2/5 or less than 2/5 of the distance between two orbits. The posterior of the two lateral teeth of the carapace before cervical incision smaller, but not very much smaller than the anterior. Transverse groove which separates two parts of abdominal somites narrow and filled with many short hairs. The first abdominal somite with 3 to 5 not sharply defined spots on posterior margin: no second row of spots present. Median carinae of second and third abdominal somites usually almost level with surface of somites. Anterior part of second to fifth abdominal somites with reticular pattern of shallow and narrow grooves.
Type locality: "Kururi District, Tokyo Bay", Honshu, Japan. Holotype male in USNM, no. 18883. Paratypes in RMNH, USNM.
Japan (north-west coast, west of Maizuru, 135°15'E; Pacific coast from Tokyo Bay, 140°E, south-westward to Ryukyu Islands).
Habitat and Biology:
In shallow waters up to20 m depth; the animals live on shore reefs
Carapace lengths from 4 to 7.4 cm; maximum total body length about 16 cm.
Interest to Fisheries:
Minor. The species is caught in gill nets and is sold fresh. Very little information is available.