The acarine fauna of Heard Island

Abstract.

Forty-five mite species have been reported from Heard Island. Collections made during a 3-month field expedition (from 11 habitat types at over 16 localities) produced 1 new undescribed taxon (Neocalvolia: Astigmata), confirmed the occurrence of 10 species, and revealed 23 new mite records for the island. Most of the newly recorded mites were collected from the supralittoral (eulittoral fringe) and intertidal (eulittoral) zones, and included Halacaridae (Prostigmata), Ameronothridae (Oribatida) and Hyadesiidae (Astigmata). Some unconfirmed records relate to previous apparent taxonomic misidentification or incomplete resolution. Distinctions are noted between shoreline and terrestrial faunas, with the shoreline taxa being more habitat specific, and their diversity being comparable to that on islands north of the Antarctic Polar Frontal Zone. The depauperate terrestrial fauna on Heard, relative to some peri-Antarctic islands, is probably a consequence of the small habitable area (as a result of considerable glaciation) and the absence of introduced species. Glacial scouring of the shoreline is ongoing, though this is spatially limited and some local shorelines have probably been unaffected by glaciation over geological time.