The distribution of locally rare moss species in the Argentine Islands-Kyiv Peninsula region, Maritime Antarctic

Abstract Located in the central part of the Western Antarctic Peninsula, the Argentine Islands-Kyiv Peninsula region is a hotspot of moss diversity, with 51 species and one variety currently known. However, no studies have specifically addressed the distribution of rare mosses in this region. Applying the only definition of moss rarity currently available for Antarctica, we identify very rare (one to two unique occurrences) and rare (three to five unique occurrences) moss species in the region and present a biogeographical analysis of their spatial distribution with corresponding maps, based on a comprehensive synthesis of archival published occurrence data. Of the 51 recorded species, 23 were classified as locally very rare or rare. Cape Tuxen, Galindez Island, Darboux Island and Cape Pérez hosted the highest concentrations of rare moss diversity, with eight, seven, seven and six species, respectively. Five rare species were recorded at Petermann Island, four at Booth and Lahille islands and three each at Diorite, ‘Eight’ and Uruguay islands. Additionally, several locations hosted species with unique characteristics, including their only known occurrence in the Antarctic Peninsula or at their known range edge. Very rare and rare species assemblages showed only partial overlap among sites: the four most species-rich sites shared several taxa, but no species occurred at all sites. Uruguay, Diorite and ‘Eight’ islands together represented a full moss species pool of the four most species-rich sites. In addition, some sites supported distinct species not recorded elsewhere in the region. Notwithstanding the limitations of the available survey data, these findings highlight the regional significance of the Argentine Islands-Kyiv Peninsula region within the Western Antarctic Peninsula for moss diversity in terms of the recognized criteria required for developing proposals for formal protection under the Antarctic Treaty.