Amarinus lacustris

Amarinus lacustris is widespread in south-eastern Australia, from Tasmania to the Murray-Darling basin in South Australia and Victoria. It reaches as far inland as Lake Colac, Victoria. In New Zealand, A. lacustris is the only freshwater crab, and is found in a variety of habitats, including lakes, slow-flowing streams and larger rivers. It is found from the lower reaches of the Waikato River to Northland, with a notable population in the Oratia Stream near Auckland. The species is also found on small islands in the Tasman Sea, such as Lord Howe Island and Norfolk Island, ==Description==

Amarinus lacustris grows to a maximum size of across the carapace, with a leg span of 20 mm. The closely related species A. paralacustris was separated from A. lacustris in 1970, ==Ecology==

Amarinus lacustris lives in estuarine, freshwater and shallow subtidal habitats, usually in salinities of 1–6‰, but occasionally to 0.1–9.6‰. It can be found living amongst detritus and vegetation in the shaded edges of rivers and lakes. Remains of both animals and plants have been found in the gut contents of A. lacustris, indicating an omnivorous diet. Its predators include crayfish and introduced trout. ==Taxonomic history==

Amarinus lacustris was first described (as Elamena lacustris) by Charles Chilton in 1882, based on a single juvenile female collected from Lake Pupuke on New Zealand's North Island. The species was later transferred to the genera Hymenosoma ==References==