Ecology: Montane forest to shrubby páramo and humid puna; on branches of treelets and trees, probably also on shrubs. Elevation: 2000-3200 m (Ecuador: 2310-3080 m, Peru: 3000 m, Bolivia: 2000-3200 m). Distribution: Endemic to the tropical Andes (Ecuador to Bolivia).

A distinguishing feature of Acidodontium pallidum is the moderately to strongly irregular, spinose-dentate marginal teeth of the leaves; other features include the loose tufted plants to 2 cm, tomentose below, elongate, indistinct border cells in 2-3 rows, setae to 3 cm long, inclined, clavate capsules to 7.5 mm, apiculate hemispherical operculum. The type of this species was collected by Herzog from Florida de San Mateo near to Comarapa (Department of Santa Cruz). Acidodontium spinicuspis Broth., a synonym but aptly named, was also collected by Herzog in the same area, at Laguna Verde above Comarapa.