{{Short description|Species of snake}} {{Speciesbox | image = Casarea dussumieri IleRonde 860513.jpg | status = VU | status_system = IUCN3.1 | status_ref = <ref name="iucn status 17 November 2021">{{cite iucn |author=Cole, N. |author-link=species:Nik C. Cole |author2=Hector, A. |author3=Roopa, P. |author3-link=species:Premandan Roopa |author4=Mootoocurpen, R. |author4-link=species:Rouben Mootoocurpen |author5=Goder, M. |author5-link=species:Martine Goder |date=2018 |title=''Casarea dussumieri'' |volume=2018 |article-number=e.T3989A152276140 |doi=10.2305/IUCN.UK.2018-2.RLTS.T3989A152276140.en |access-date=17 November 2021}}</ref> | status2 = CITES_A1 | status2_system = CITES | status2_ref = <ref>{{Cite web|title=Appendices {{!}} CITES|url=https://cites.org/eng/app/appendices.php|access-date=2022-01-14|website=cites.org}}</ref> | genus = Casarea | parent_authority = Gray, 1842 | species = dussumieri | authority = (Schlegel, 1837) | synonyms = '''Genus:''' *''Casarae'' <br />{{small|Gray, 1842}} *''Leptoboa'' <br />{{small|A.M.C. Duméril & Bibron, 1844}}<ref name="McD99">McDiarmid RW, Campbell JA, Touré TA (1999). ''Snake Species of the World: A Taxonomic and Geographic Reference, Volume 1''. Washington, District of Columbia: Herpetologists' League. 511 pp. {{ISBN|1-893777-00-6}} (series). {{ISBN|1-893777-01-4}} (volume).</ref> ---- '''Species:''' *''Boa dussumiri'' <br />{{small|Schlegel, 1837}} <br />(typographical error) *''Boa Dussumieri'' <br />{{small|Schlegel, 1837}} *''Boa Dussumieri'' <br />{{small|— Gray, 1842}} *''Casarea dussumieri'' <br />{{small|— Gray, 1842}} *''Leptoboa dussumieri'' <br />{{small|— A.M.C. Duméril & Bibron, 1844}} *''Casarea dussumieri'' <br />{{small|— Boulenger, 1893}}<ref name="McD99"/> }}
The '''Round Island boa''' ('''''Casarea dussumieri'''''),<ref name="ITIS-S">{{ITIS|id=202190|taxon=''Casarea dussumieri ''|accessdate=16 August 2007}}</ref> also known commonly as the '''Round Island keel-scaled boa'''<ref name="iucn status 17 November 2021" /> and the '''Round Island ground boa''',<ref name="iucn status 17 November 2021" /> is a species of nonvenomous snake in the monotypic genus '''''Casarea''''' in the family Bolyeriidae.<ref name="ITIS-G">{{ITIS|id=202189|taxon=''Casarea'' Gray, 1842|accessdate=25 March 2015}}</ref><ref name=RDB/> The species is endemic to Round Island, Mauritius. No subspecies are currently recognized.<ref name="ITIS-S"/><ref name=RDB>{{NRDB species|genus=Casarea|species=dussumieri|accessdate=25 March 2015}}</ref>
==Etymology== The specific name, ''dussumieri'', is in honor of Jean-Jacques Dussumier, a French merchant, ship owner, and collector of zoological specimens.<ref>Beolens, Bo; Watkins, Michael; Grayson, Michael (2011). ''The Eponym Dictionary of Reptiles''. Baltimore: Johns Hopkins University Press. xiii + 296 pp. {{ISBN|978-1-4214-0135-5}}. (''Casarea dussumieri'', p. 78).</ref>
==Description== thumb|left|Adult female Adults of ''C. dussumieri'' are slender and reach a maximum total length (including tail) of 150 cm (5 ft). The males have slimmer, more pointed heads and have shorter bodies than the females. The body is covered in small keeled scales that give the species one of its common names. The genus is unique among extant vertebrates as it has a split jaw (intramaxilliary joint that separates anterior and posterior bones), an adaptation that may be advantageous in catching its main prey of geckos and skinks.
The colour pattern is dark brown dorsally, the belly being lighter with dark spots. Over a 24-hour period the boa has a shift in colour, changing from "dark" during its relatively inactive day time period to "light" in the early evening through to dawn when it is most active. This effect is created through polychromatic skin cells.
==Geographic range== ''C. dussumieri'' is known to survive on Round Island, but has been recorded on the islands of Gunner's Quoin, Flat Island, Ile de la Pas, and on mainland Mauritius (as subfossil remains).<ref name="McD99"/>
The type locality is "''I'île ronde, près de Maurice'' " (Round Island, Mauritius).<ref name="McD99"/>
Between 11 and 31 October 2012 the boa was reintroduced into Gunner's Quoin as part of a joint collaborative project involving the Durrell Wildlife Conservation Trust, the Mauritian Wildlife Foundation, and the National Parks and Conservation Service of Mauritius.<ref>{{Cite web | url=http://blog.durrell.org/index.cfm/2012/11/22/The-translocation-of-the-Round-Island-keelscaled-boa | title=Blog | Durrell Wildlife Conservation Trust}}</ref>
==Conservation status== The species ''C. dussumieri'' is classified as Endangered (E) on the IUCN Red List for the following criteria: D (v2.3, 1994).<ref name="iucn status 17 November 2021" /> This means that, although it is not critically endangered, for some time it has faced a very high risk of extinction in the wild. In 1996 the population was estimated to number less than 250 mature individuals.<ref name="ICUN-23">[http://www.iucnredlist.org/info/categories_criteria1994#categories 1994 Categories & Criteria (version 2.3)][http://www.iucnredlist.org/ IUCN Red List]. Accessed 16 August 2007.</ref>
Recent conservation efforts have seen an increase in the number of adult Round Island boas to around 1,000. This has been achieved by eradicating goats and rabbits from the island and restoring natural habitat, which has led to an increase of the Round Island boas' natural prey, lizards. In recent breeding efforts, Round Island boas in captivity have been fed by scenting small mice with chicken thigh meat.
==Reproduction== In ''C. dussumieri'', breeding begins during April, although young have been observed throughout the year. A clutch of up to 12 soft-shelled eggs may be laid amongst leaf litter or in hollow palm trunks, and is sometimes attended by the female. Incubation is unusually long for a snake, lasting about 90 days. The young are bright orange at birth and weigh less than 5 grams.
==References== {{Reflist}}
==Further reading== {{refbegin}} *McAlpine DF (1981). "Activity Patterns of the Keel-Scaled Boa (''Casarea dussumieri)'' at the Jersey Wildlife Preservation Trust". ''Dodo, Journal of the Jersey Wildlife Preservation Trust'' '''18''': 74-78. *McAlpine DF (1983). "Correlated physiological color change and activity patterns in an Indian Ocean boa (''Casarea dussumeri'' )". ''Journal of Herpetology'' '''17''': 198-201. *Bloxam, Quentin M. C. (1984). "A preliminary report on the captive management and reproduction of the Round Island Boa, ''Casarea dussumieri'' ". pp. 155–177 '''''In:''''' Tolson P (Editor) (1984). ''Proceeding of 7th Annual Reptile Symposium on Captive Propagation and Husbandry''. Thurmont, Maryland: Zoological Consortium of Maryland, Inc. {{refend}}
==External links== {{Commons|Casarea dussumieri}} *{{NRDB species|genus=Casarea|species=dussumieri|date=16 August|year=2007}} *[https://web.archive.org/web/20060524212534/http://www.arkive.org/species/GES/reptiles/Casarea_dussumieri/more_info.html Round Island keel-scaled boa (''Casarea dussumieri'' )] at [https://archive.today/20160426231847/http://www.arkive.org/ ARKive]. Accessed 18 February 2008. *{{NatGeo ecoregion|id=at0120|name=Mascarene forests|accessdate=18 February 2008}}
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Category:Bolyeriidae Category:Taxa named by Hermann Schlegel Category:Reptiles described in 1837 Category:Reptiles of Mauritius Category:Endemic fauna of Mauritius Category:Taxonomy articles created by Polbot Category:Monotypic snake genera