Guide to Muelleria

The outline of valves of Muelleria is linear, linear-elliptic or panduriform. The external proximal raphe ends are distinctive because they are unilaterally deflected. Distal raphe ends are branched. A longitudinal canal is present on each side of the raphe. Areolae are loculate. Living cells contain four plastids.

Muelleria gibbula and M. terrestris are widespread in aerophilic habitats in North America. These species grow association with soils, mosses and ephemeral pools of the mid-western and western states. Several species are geographically restricted to the Arctic, Antarctic or South America.