Published online by Cambridge University Press: 28 March 2007
All species of Antarctic Acarosporaceae (s. lat., including Biatorellaceae) with yellow thalli are revised. Four genera, Acarospora, Biatorella, Biatorellopsis, Eklundia, and ten species, all of them endemic, were previously reported from Antarctica. Our results indicate that in Antarctica Acarospora subgen. Xanthothallia s. str. includes only two species, A. gwynnii Dodge and A. flavocordia sp. nov.; Biatorella does not occur in Antarctica, the species described by Dodge belonging instead in Candelariella; the genus Eklundia is a synonym of Candelariella; Biatorellopsis does not occur in Continental Antarctica, and the genus is a synonym of Pleopsidium; Pleopsidium is represented in Antarctica by one species, P. chlorophanum, which was treated under very different generic and specific names by earlier authors. Altogether, the number of species of yellow Acarosporaceae known from Antarctica is reduced from ten to three, distributed in two genera: Acarospora and Pleopsidium. The two Acarospora species, A. gwynnii and A. flavocordiaare apparently endemic to Antarctica, whereas P. chlorophanum is a widespread bipolar lichen. A comprehensive list of synonyms and a key are provided.