Astacoides is a genus of freshwater crayfish endemic to Madagascar. The first specimens were brought to Europe in 1839, and seven species are now recognised, most of which are considered as threatened on the IUCN Red List. They are large and slow-growing, and are threatened by habitat loss, overexploitation by local people and by spread of introduced non-indigenous marbled crayfish (Procambarus virginalis). They are only found in a relatively small part of the island, mostly in undisturbed upland areas. They belong to the Gondwana-distributed family Parastacidae, but their nearest relatives li
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Astacoides is a genus of freshwater crayfish endemic to Madagascar. The first specimens were brought to Europe in 1839, and seven species are now recognised, most of which are considered as threatened on the IUCN Red List. They are large and slow-growing, and are threatened by habitat loss, overexploitation by local people and by spread of introduced non-indigenous marbled crayfish (Procambarus virginalis). They are only found in a relatively small part of the island, mostly in undisturbed upland areas. They belong to the Gondwana-distributed family Parastacidae, but their nearest relatives live in Australasia, there being no native crayfish in mainland Africa or India.
==Description== Astacoides species are large for freshwater crayfish, reaching a carapace length of up to in the case of A. betsileoensis. Males and females are similar, except for the organs directly involved in reproduction. Thomas Henry Huxley, in his book The Crayfish, noted that Astacoides has fewer pairs of gills than any other crayfish, with only 12 pairs compared to 21 pairs in Astacopsis.
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