AbstractThe distinction between mamillae and papillae is arbitrary in two of the genera studied, the latter originating as the former inGymnostomum aeruginosumandAnoectangium warburgii. G. aeruginosumandG. calcareumare treated as separate species, both of which can be distinguished fromA. obtusifolium. Moreover, attention is drawn to the fact thatA. obtusifoliumlacks the differentially thickened leaf cells ofMolendoa sendtnerianaand ofM. sendtnerianavar.tenuinervis.