Observations on the distribution of surface-living land arthropods on the Subantarctic Île de la Possession, Îles Crozet

Summary

Collecting by various methods in Jan.–April, 1968, of surface-living arthropods on Île de la Possession, Îles Crozet most of which were already known from the efforts of previous collectors, were made in order to determine to what extent the 46 species are confined to the three main land habitat types distinguished. The results were as follows: The sea-edge habitat is relatively rich, with 10 species, 8 apparently confined to it. Peat-clothed moorland and bog occupying lower ground (about 25–40 km² in area) has 26 species, including 6 species of Diptera, while the fell-field habitat above about 100 m altitude (120–135 km² area) with very scanty vegetation, has 24 species. The relatively species-rich fell-field was surprisingly rich in individuals, particularly ectemnorrhine weevils totalling 7 species (some rare), of carabid beetles (3 spp.). About 8 species showed wide distribution in both moorland and fell-field.

The existence in the depauperate fauna of the island of at least 5 pairs or triplets of congeneric endemic species pose important problems in understanding its history and ecology.