Ecology and distribution. Open premontane to lower montane, infrequent in adjoining Amazon; exposed, often wet sites, on soil and rock. At elevations from 320-2200 m (Venezuela: ?m. Colombia: 1380-2000 m, Ecuador: 365-450 m, Peru: 700-1000 m, Bolivia: 320-2200 m). Pantropical (absent in Africa).
Barbula arcuata is characterized by the lax habit, narrowly lanceolate-triangular leaves, generally decurrent leaf bases, plane to more commonly recureved leaf margins (often to near the apex), and smooth laminal cells. Some authors have placed this taxon in the genus Hydrogonium. Barbula subulifolia Sull. is a synonym.