A survey of Marchantiales from Madagascar

Based on the authors' recent collections and on older herbarium specimens (PC, TAN, EGR), the species of Marchantiidae (Marchantiopsida, Marchantiophyta) of Madagascar are reported with their description based on Malagasy specimens.A distribution map for each taxon is provided.Among the fifteen taxa identified, six are newly recorded for the island, including a new synonymy: Asterella coronata (Steph.)H.A.Mill = Asterella bachmannii (Steph.)S.W. Arnell.Most of Marchantiidae live in xeric areas (Riccia species, Exormotheca pustulosa Mitt.) or in exposed, only temporarily wet stations (Plagiochasma, Asterella).This preliminary study shows the evidence of under-prospection of such areas in Madagascar for bryophytes and the need of taxonomic work to clarify some genera (Riccia, Asterella, Plagiochasma) and to confirm the species hitherto reported.