Published online by Cambridge University Press: 31 May 2011
To date, there have only been two endemic species of the lichen genus Porpidia known from the maritime Antarctic. A new endemic species, Porpidia submelinodes Osyczka & Olech, recognized in the South Shetlands and South Orkneys, is described in this paper. The species is primarily characterized by its rusty orange, sorediate thallus, composed of convex, well separated and rounded areoles, and by the absence of lichen secondary products detectable by TLC. The morphology and soralia of this new species correspond to the arctic-alpine and boreal-mountain lichen Porpidia melinodes. The paper also discusses the differences between these two taxa and all Porpidia species reported from Antarctica.