Distribution, ecology, and conservation status of freshwater Idoteidae (Isopoda) in southern New Zealand

Three species of Idoteidae, Austridotea lacustris, A. annectens, and A. benhami, are known from the South Island of New Zealand and some of its outlying islands. All three have largely coastal distributions, with A. lacustris and A. annectens inhabiting both fresh and brackish water. They feed mainly on plant detritus and, to a lesser extent, algae and invertebrates. A. lacustris is known from Stewart Island, Campbell Island, Pitt Island, and the south of the South Island. On Stewart Island, many stream populations of A. lacustris occur immediately above the upper limit of tidal influence, but on Campbell Island, the species penetrates much further inland. A. annectens has been found on Stewart Island, Pitt Island, and the southern South Island as far north as Banks Peninsula. It lives in freshwater streams and brackish lagoons. A. annectens has a 1-year life cycle with young released in spring. A. benhami is known only from a few freshwater streams near Dunedin (South Island) and appears to be the most endangered of the three species. Habitat protection by vegetated riparian strips is proposed to reduce potentially harmful effects on its populations.