A small species and its habitat is just like that of Deiratonotus japonicum Sakai, living on the flats of river mouth.
The carapace is flat and anteriorly broadened. Against the generic name of this species (Deirato = ridged, notus = dorsum, after Manning and Holthuis), the dorsal surface is flat and no ridges on the gastric and cardiac regions. The antero-lateral border is cut into two or three obtuse teeth. The ischium and merus of the outer maxilliped are very broad, so that the buccal orifice is completely closed.
The tips of the fingers are spoon-shaped, by their aid, the animal can pick up the mud for select the organisms for food. In the ambulatory legs, the posterior border of merus of the first to fourth pairs, and the carpus of the third and fourth pairs are covered with soft hairs on the upper surface.
The first and second segments of the male abdomen are very short, and the third to fourth segments are fused together, and the fifth segment is narrowed in the distal portion. The anterior male pleopod is strongly bent basally and pointed, without long hairs. (Sakai, 1983)
Type locality: Kii Province, Japan.
Range: Japan - Kii Province (Sakai, 1983).