{{Short description|Genus of crayfishes}} {{Automatic taxobox | image = Astacoides_Huxley.png | taxon = Astacoides | authority = Guérin-Méneville, 1839 | type_species = ''Astacus Goudotii'' | type_species_authority = Bate, 1865 | range_map = Astacoides distribution.svg | range_map_caption = }} {{Portal|Crustaceans}}
'''''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 {{convert|80|mm}} in the case of ''A. betsileoensis''.<ref name="Jones"/> Males and females are similar, except for the organs directly involved in reproduction.<ref name="Hobbs"/> 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''.<ref>{{cite book |author=Thomas Henry Huxley |author-link=Thomas Henry Huxley |year=1880 |title=The Crayfish: an Introduction to the Study of Zoology |publisher=D. Appleton & Co. |location=New York |url=https://archive.org/details/crayfishintroduc00huxl}}</ref><ref name="Boyko"/>
==Biology== Very little field work has been carried out on Malagasy crayfish, leaving their biology poorly known.<ref name="Boyko"/> They are slow-growing animals, among the slowest of any crayfish; ''A. crosnieri'' may take 10 years to reach a carapace length of {{convert|30|mm|abbr=on}}.<ref name="Jones">{{cite journal |author1=Julia P. G. Jones |author2=Fortunat B. Andriahajaina |author3=Neal J. Hockley |author4=Kaith A. Crandall |author5=Olga R. Roavohangimalala |year=2007 |title=The ecology and conservation status of Madagascar's endemic freshwater crayfish (Parastacidae; ''Astacoides'') |journal=Freshwater Biology |volume=52 |issue=9 |pages=1820–1833 |doi=10.1111/j.1365-2427.2007.01766.x}}</ref> 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.<ref name="Jones"/>
The fish ''Channa maculata'' is an invasive species in parts of Madagascar, and it is known to feed on young crayfish.<ref name="Jones"/> ''Astacoides'' is also harvested by local people, often before the crayfish are able to reach reproductive age.<ref name="Jones"/> The greater threat to ''Astacoides'' crayfish, however, is from habitat loss. The importance of habitat loss may have been underestimated in the past because most studies have focussed on the Ranomafana National Park, where the forests are largely intact but crayfish are still harvested by local people.<ref name="Jones"/> The introduced marbled crayfish may also be a significant threat, both by outcompeting native crayfish and spreading the devastating crayfish plague to them, although crayfish plague-induced declines have not been noted among native ''Astacoides'' in places where they co-occur with marbled crayfish.<ref>{{Cite journal |last1=Jones |first1=Julia P. G. |last2=Rasamy |first2=Jeanne R. |last3=Harvey |first3=Andrew |last4=Toon |first4=Alicia |last5=Oidtmann |first5=Birgit |last6=Randrianarison |first6=Michele H. |last7=Raminosoa |first7=Noromalala |last8=Ravoahangimalala |first8=Olga R. |date=2009-06-01 |title=The perfect invader: a parthenogenic crayfish poses a new threat to Madagascar's freshwater biodiversity |journal=Biological Invasions |language=en |volume=11 |issue=6 |pages=1475–1482 |doi=10.1007/s10530-008-9334-y |issn=1573-1464}}</ref><ref>{{Cite journal |last1=Andriantsoa |first1=Ranja |last2=Tönges |first2=Sina |last3=Panteleit |first3=Jörn |last4=Theissinger |first4=Kathrin |last5=Carneiro |first5=Vitor Coutinho |last6=Rasamy |first6=Jeanne |last7=Lyko |first7=Frank |date=2019-02-06 |title=Ecological plasticity and commercial impact of invasive marbled crayfish populations in Madagascar |journal=BMC Ecology |language=en |volume=19 |issue=1 |page=8 |doi=10.1186/s12898-019-0224-1 |doi-access=free |issn=1472-6785 |pmc=6366054 |pmid=30727994}}</ref>
==Distribution== thumb|left|A village in the Malagasy highlands 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 {{convert|60000|km2}} and ranges from the Isaha valley south to the Hauts Plateaux (near Anjozorobe).<ref name="Boyko">{{cite journal |author1=Christopher B. Boyko |author2=Olga Ramilijaona Ravoahangimalala |author3=Désiré Randriamasimanana |author4=Tony Harilala Razafindrazaka |title=''Astacoides hobbsi'', a new crayfish (Crustacea: Decapoda: Parastacidae) from Madagascar |journal=Zootaxa |volume=1091 |pages=41–51 |url=http://iz.carnegiemnh.org/crayfish/cfref/download.asp?file=Boyko_etal_2005_Zootaxa1091.pdf |access-date=2010-03-09 |archive-url=https://web.archive.org/web/20170808171917/http://iz.carnegiemnh.org/crayfish/cfref/download.asp?file=Boyko_etal_2005_Zootaxa1091.pdf |archive-date=2017-08-08 }}</ref> In common with other tropical crayfish, ''Astacoides'' only lives at higher altitudes, from {{convert|500|m}} above sea level to {{convert|2000|m|abbr=on}}.<ref name="Boyko"/>
==Biogeography== 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.<ref name="Boyko"/> 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.<ref name="Boyko"/>
==Taxonomic history== [[File:Félix Edouard Guérin-Méneville.gif|thumb|right|Félix Édouard Guérin-Méneville, who was the first to describe a crayfish from Madagascar]] In 1839, the French explorer-naturalist Justin Goudot returned from an expedition to Madagascar bearing specimens of a crayfish he had collected there. He gave some of the material to the Muséum national d'histoire naturelle in Paris and some to Félix Édouard Guérin-Méneville. Both Guérin-Méneville and, at the museum, Henri Milne-Edwards and Jean Victoire Audouin wrote papers describing the new species, with the name ''Astacoides Goudotii'' Guérin, 1839 published on 29 April, and ''Astacus madagascarensis'' Milne-Edwards & Audouin, 1839 published on May 9.<ref name="Hobbs">{{cite journal |author=Horton H. Hobbs Jr. |author-link=Horton H. Hobbs Jr. |year=1987 |title=A review of the crayfish genus ''Astacoides'' (Decapoda: Parastacidae) |journal=Smithsonian Contributions to Zoology |volume=443 |issue=443 |pages=1–50 |url=http://si-pddr.si.edu/dspace/bitstream/10088/5543/2/SCtZ-0443-Lo_res.pdf |doi=10.5479/si.00810282.443}}</ref> Some years later, and apparently unaware of the two French descriptions, Charles Spence Bate published what he thought was the first account of Malagasy crayfish. He had been brought specimens by J. Caldwell, and described them in 1865 under the name ''Astacus Caldwelli'' Bate, 1865.<ref name="Hobbs"/> By the end of the 19th century, scientists had settled on the name ''Astacus madagascarensis'', treating the others as synonyms,<ref name="Hobbs"/> and to preserve nomenclatural stability, the name ''A. goudotii'' was suppressed by the International Commission on Zoological Nomenclature in 1958.<ref name="Holthuis">{{cite journal |author=Lipke Holthuis |author-link=Lipke Holthuis |year=1964 |title=The genus ''Astacoides'' Guérin (Decapoda Macrura) |journal=Crustaceana |volume=6 |issue=4 |pages=309–318 |jstor=20102549 |doi=10.1163/156854064X00074}}</ref>
The next new taxon to be described was the variety ''betsileoensis'' described by Georges Petit in 1923. In 1927, he divided the Malagasy crayfish into the "macrophthalmes", with large eyes, a convex carapace and flattened chelae, and the "microphthalmes", with small eyes, cylindrical carapace and more robust chelae. In their 1929 monograph, Théodore Monod and Petit recognised four "varieties", ''betsileoensis'' and ''madagascariensis'' (the "macrophthalmes") and ''brevirostris'' and ''granulimanus'' (the "microphthalmes").<ref name="Hobbs"/> In 1964, Lipke Holthuis realised that due to the suppression of the name ''goudotii'', the epithet ''caldwelli'' would have to be used, although Holthuis continued to treat the different taxa as subspecies.<ref name="Holthuis"/> In 1974, Horton H. Hobbs Jr. published a monograph which finally raised the various taxa observed to that point to the rank of species, and introduced two new species. Since then, the only change has been the addition of a new species, described in 2005, and commemorating Hobbs, ''Astacoides hobbsi''.<ref name="Boyko"/>
==Taxonomy== [[File:Astacoides betsileoensis 01.jpg|thumb|right|''Astacoides betsileoensis'', seen in the Ranomafana National Park]] Of the seven described species, four are considered vulnerable species (VU), one is "Data Deficient" (DD), and two are of "Least Concern" (LC).
*''Astacoides betsileoensis'' <small>Petit, 1923</small> – 24px|VU<ref>{{cite iucn |author=Jones, J.P.G. |date=2016 |title=''Astacoides betsileoensis'' |volume=2016 |article-number=e.T2188A96555039 |doi=10.2305/IUCN.UK.2016-3.RLTS.T2188A96555039.en |access-date=11 November 2021}}</ref> *''Astacoides caldwelli'' <small>(Bate, 1865)</small> – 24px|VU<ref>{{cite iucn |author=Jones, J.P.G. |date=2016 |title=''Astacoides caldwelli'' |volume=2016 |article-number=e.T2187A96555259 |doi=10.2305/IUCN.UK.2016-3.RLTS.T2187A96555259.en |access-date=11 November 2021}}</ref> *''Astacoides crosnieri'' <small>Hobbs, 1987</small> – 24px|VU<ref>{{cite iucn |author=Jones, J.P.G. |author2=Rasamy, J. |author3=Ranaivoson, C.H. |author4=Cumberlidge, N. |author5=Randrianasolo, H. |date=2016 |title=''Astacoides crosnieri'' |volume=2016 |article-number=e.T2184A96555878 |doi=10.2305/IUCN.UK.2016-3.RLTS.T2184A96555878.en |access-date=11 November 2021}}</ref> *''Astacoides granulimanus'' <small>Monod & Petit, 1929</small> – 24px|LC<ref>{{cite iucn |author=Jones, J.P.G. |date=2016 |title=''Astacoides granulimanus'' |volume=2016 |article-number=e.T2186A96555465 |doi=10.2305/IUCN.UK.2016-3.RLTS.T2186A96555465.en |access-date=11 November 2021}}</ref> *''Astacoides hobbsi'' <small>Boyko, 2005<!--In the original description, A. hobbsi is credited to Boyko alone, even though the paper has other authors--></small> – 24px|VU<ref>{{cite iucn |author=Jones, J.P.G. |author2=Rasamy, J. |author3=Ranaivoson, C.H. |author4=Cumberlidge, N. |author5=Randrianasolo, H. |date=2016 |title=''Astacoides hobbsi'' |volume=2016 |article-number=e.T153654A96555789 |doi=10.2305/IUCN.UK.2016-3.RLTS.T153654A96555789.en |access-date=11 November 2021}}</ref> *''Astacoides madagascarensis''<!--See Holthuis, 1974 for discussion of the orthography--> <small>(H. Milne-Edwards & Audouin, 1839)</small> – 24px|LC<ref>{{cite iucn |author=Jones, J.P.G. |author2=Rasamy, J. |author3=Ranaivoson, C.H. |author4=Cumberlidge, N. |author5=Randrianasolo, H. |date=2016 |title=''Astacoides madagascarensis'' |volume=2016 |article-number=e.T2183A96556065 |doi=10.2305/IUCN.UK.2016-3.RLTS.T2183A96556065.en |access-date=11 November 2021}}</ref> *''Astacoides petiti'' <small>Hobbs, 1987</small> – 24px|DD<ref>{{cite iucn |author=Jones, J.P.G. |date=2016 |title=''Astacoides petiti'' |volume=2016 |article-number=e.T2185A96555673 |doi=10.2305/IUCN.UK.2016-3.RLTS.T2185A96555673.en |access-date=11 November 2021}}</ref>
==References== {{Reflist|2}}
==External links== *{{Cite web |url=http://iz.carnegiemnh.org/crayfish/NewAstacidea/genus.asp?g=Astacoides |title=Genus ''Astacoides'' Guérin, 1839 |author=James W. Fetzner Jr. |date=January 14, 2008 |publisher=Carnegie Museum of Natural History |work=Crayfish Taxon Browser |access-date=August 21, 2007 |archive-url=https://web.archive.org/web/20070927015845/http://iz.carnegiemnh.org/crayfish/NewAstacidea/genus.asp?g=Astacoides |archive-date=September 27, 2007 }}
{{Taxonbar|from=Q4810508}} {{Authority control}}
Category:Parastacidae Category:Endemic fauna of Madagascar Category:Freshwater crustaceans of Africa Category:Taxonomy articles created by Polbot Category:Decapod genera