On the identity of Ditrichum validinervium (Bryophyta, Ditrichaceae)

Ditrichum validinervium Kaal., a species described from Île de la Possession and Île de l'Est in the Îles Crozet archipelago in Subantarctica, is assessed and some details of its gametophyte are illustrated. An examination of the type material of this species revealed that it is inseparable from D. conicum (Mont.) Mitt. and D. validinervium is the first heterotypic synonym of this name.