Sakai, 1974
This species is closely allied to M. carinata Baker, 1907 from south and south-west Australia. The carapace is subhemispherical in outline and the dorsal surface markedly convex, the regions moderately defined. The front is very broad and cristate, its breadth being more than half the extreme breadth of carapace and is obscurely divided into four lobules. Compared with that of M. carinata, the front is apparently broader and produced anteriorly beyond the level of the eyes. The antero-lateral borders are cristate, divided into four lobes, of which the anterior three are subequal and long the last is small and deviated postero-laterally. The postero-lateral borders are extremely concave. The posterior border is also very narrow, approximately a half of the breadth of the front.
Chelipeds are short and not at all robust, the merus is entirely concealed beneath the antero-lateral borders; the carpus and propodus are rugose on the upper and outer surfaces. The ambulatory legs are subequal in length, the merus, carpus and propodus are compressed and their anterior and posterior borders markedly cristate.
Abdomen of male is consisted of seven distinct segments. (Sakai, 1976)
Type locality: coast of Minami-iso, Oga Peninsula, Japan.
Range: Japan - only Oga Peninsula (Sakai, 1976a).