New insights into the species diversity of Bartramia Hedw. (Bryophyta) in Antarctica

In Antarctica, the genus Bartramia has been restricted to a single polymorphic species, B. patens. Its status as a separate species or a subspecies of the Northern Hemisphere B. ithyphylla was debated. In the present paper, we combine analyses of chloroplast (trnS–rps4–trnT–trnL–trnF region) and nuclear ITS sequences with a reinvestigation of morphological characteristics to infer the identity of Antarctic Bartramia. Phylogenetic and Automatic Barcode Gap Discovery (ABGD) species delimitation analyses indicate that the species diversity of Bartramia in Antarctica has been underestimated, since two species were identified, both belonging to Bartramia sect. Pyridium. Of these, B. subsymmetrica is a new record of the species for Antarctica, as it has previously only been recorded from Livingston Island, South Shetlands. The other species is B. patens, which is separated from B. ithyphylla by newly inferred morphological characteristics and is a sister species to the latter in the molecular phylogenetic analyses. Consequently, we consider B. ithyphylla to be a Northern Hemisphere instead of a bipolar species. The suggested conspecificity of both taxa into one species in the ABGD analysis is considered to result from overlumping by this species delimitation method. The delimitation of the three species of section Bartramia (B. halleriana, B. mossmaniana and B. pomiformis) and the circumscription of the genus Bartramia are discussed.