A. alterniloba is a common wet forest to rainforest species. The thallus is dark glossy green and the apex of the thallus are usually bent downwards. Sporophytes are rare. This species can easily be mistaken for a hornwort but unlike hornworts, the cells of A. alterniloba have numerous chloroplasts. The related Riccardia is similar as well but A. alterniloba is a much more robust taxon with a wider thallus.

A. rodwayi is a species of alpine bogs which has margins curved upwards, making the thallus look concave.

The occurrence of a third species, A. stolonifera, is doubtful and has not been included in the key.