[2] A molecular study using the cytochrome oxidase I gene does not support the monophyly of this genus.

[3] Metacarcinus crabs have an oval carapace of about ⅔ of its largest width, with a surface with poorly marked division of smooth or gently colored regions.

The front edge usually does not protrude before orbital, and the total length of these edges is 26–34% of the largest width of the carapace, with five spikes, including inner orbits, of which the middle springs lower than the others.

9–10 spikes are located on both anteroposterior lateral sides of the carapace; they can be of different shapes.

The cutting edges of the pliers' fingers of the claw have sharp teeth.