 |
| Astacoides Madagascariensis |
 |
| Madagascar Freshwater Crayfish |
Madagascar Freshwater Crayfish
Madagascar Crayfish
The "Macrophthalmes"
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Order: Decapoda
Family: Parastacidae
Genus: Astacoides
Species : Astacoides Madagascariensis, A Madagascariensis
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 and overexploitation by local people. 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 Madagascariensis has been assessed as Data Deficient. This species has possibly undergone declines in abundance due to habitat degradation and loss. It is likely to undergo further declines in the future due to introduced species. This species is likely to qualify for a threat category, however there is no available estimate on the rate of population decline. Further research is needed to determine population decline before a more accurate assessment of conservation status can be made.
Astacoides Madagascariensis is endemic to Madagascar, and extends a little further north than that of any other Malagasy crayfishes. The distribution of this species lies at latitudes 18° to 21° S, longitudes 47° to 49° E. Type specimens were probably collected in the vicinity of Tananarive (Hobbs 1987). This species is found in the Toamasina and Antananarivo provinces (Boyko et al. 2005). This species has an estimated extent of occurrence of 3,697 km2.
Native : Madagascar
Crayfish are only found in a relatively small area of Madagascar, covering parts of Toamasina, Antananarivo, Fianarantsoa and Toliara provinces; the total area they inhabit is around 60,000 square kilometres (23,000 sq mi) and ranges from the Isaha valley south to the Hauts Plateaux (near Anjozorobe).[4] In common with other tropical crayfish, Astacoides only lives at higher altitudes, from 500 metres (1,600 ft) above sea level to 2,000 m (6,600 ft)
The presence of Astacoides on the island of Madagascar is difficult to explain. The other members of the family Parastacidae are found in South America and Australasia, suggesting a Gondwanan origin for the family. However, there are no native crayfish in either Africa or India, the two landmasses with the most recent connections to Madagascar in the geological past.The genus which shares the greatest similarities with Astacoides is the Tasmanian genus Astacopsis. Given the large distance between Tasmania and Madagascar, it has been suggested that although the freshwater crayfish are a monophyletic group, their common ancestor may have lived in the seas, with separate crayfish lineages colonising the rivers separately
0 comments:
Post a Comment