Summary
Abstract Isotoma klovstadi Carpenter, 1902 was one of the first Collembola described from the Antarctic continent. It was first collected in November 1899 during the British Antarctic Expedition on the north coast of Victoria Land in the Ross Sea region. It is now known to occur in an extensive area of northern Victoria Land, including the offshore Possession, Coulman, and Foyn Islands. More recently, I. klovstadi was moved to the genus Gnathisotoma Cassagnau, 1957 and has been included in this genus in an unpublished checklist (online) of all described Collembola. Here, we redescribe the species and use morphological and molecular (COI and 18S genes) evidence to investigate its affinities within the Isotominae. We show that it does not belong to Gnathisotoma, or Isotoma s. str. (the viridis group) as currently conceived, but is likely to be part of the species complex of Isotoma s. lat. We discuss reasons for placing it in the genus Desoria Nicolet, 1841. Our results reinforce the already high level of endemicity in the Antarctic fauna and emphasise the value of both morphological and molecular studies in examining relict Gondwanan taxa and their evolutionary relationships with those of other Southern Hemisphere continents.