Astacoides

Astacoides
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Crustacea
Class:	Malacostraca
Order:	Decapoda
Family:	Parastacidae
Genus:	Astacoides Guérin-Méneville, 1839
Type species
Astacus Goudotii Bate, 1865

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 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 fallax f. 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.

Astacoides species are large for freshwater crayfish, reaching a carapace length of up to 80 millimetres (3.1 in) 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.

Very little field work has been carried out on Madagascan crayfish, leaving their biology poorly known. They are slow-growing animals, among the slowest of any crayfish; A. crosnieri may take 10 years to reach a carapace length of 30 mm (1.2 in). They appear to breed once a year, with females bearing eggs for around four months, peaking from July to October. The eggs hatch in October or November, and the juveniles are independent by January.

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Wikipedia