Taxonomic and nomenclatural notes on Didymodon austroalpigenus (Pottiaceae, Bryophyta) from Îles Kerguelen

The taxonomic status of Didymodon austroalpigenus (Müll.Hal.) Broth., a species described as Trichostomum austroalpigenum Müll.Hal. from subantarctic Îles Kerguelen, is discussed. Because the original collection of this species was destroyed, its name is neotypified with a specimen from this archipelago and the species is considered to be conspecific with Bryoerythrophyllum rubrum (Jur. ex Geh.) P.C.Chen. The distribution of this species is briefly reviewed and the present discovery firmly establishes B. rubrum as a bipolar species.