Micromitrium Aust., Musci Appalach. 10. 1870.

Nanomitrium Lindb., Not. Sällsk. Fauna Fl. Fenn. Förh. 13: 408. 1874, nom. illeg. 

Plants scattered and sparse to gregarious and abundant, with sparse protonemata. Leaves shrunken and contorted when dry; ecostate or nearly so; leaf cells thin-walled, smooth. Synoicous. Capsules sessile, globose, not apiculate, dehiscing along a median line of thin-walled cells, or infrequently rupturing irregularly. Calyptrae minute, delicate, consisting of only the remains of the archegonia, persistent.