[1] Armadillidium maniatum is a medium to large sized species, reaching maximum dimensions of about 17 x 8.7 mm.

Its tergites are completely smooth and the body lacks pigmentation, except for the eyes, which are black, and the hind margins of the pereion-tergites, which bear dark stripes.

The secondary antennae have a conspicuously enlarged third segment, trapezoidal lobes and flagellum articles of equal length.

[1] Concerning the sexual characters of the male, the first pereiopod has a ventral brush of spines on the carpus and, to a lesser degree, on the merus.

Armadillidium album, another rarely encountered littoral species of the genus, shows the same combination of characters (decreased pigmentation and endogean type of life), supporting this hypothesis.