In a project aiming to determine the lichen biodiversity of James Ross Island which is located in the NE Antarctic Peninsula, 3 specimens growing on basaltic rocks were identified as Rinodina gennarii, a cosmopolite bipolar species which was never reported from Antarctica. This species is characteristic by having Dirinaria-type ascospores lacking a distinct torus and swelling around the septa in KOH. Detailed morphological and anatomical properties of this species along with photographs based on the Antarctic specimens are provided here. Our study and newly reported R. gennarii suggest that the lichen biodiversity of Antarctica is far from being fully known and detailed floristic and taxonomical revision studies should be carried to determine it. Keywords: Antarctic Peninsula; biodiversity; James Ross Island; lichens; Physciaceae.