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| Karstarma vulcan
Poupin, Crestey & Le Guelte, 2018
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Abstract
Sesarmid crabs of the genus Karstarma Davie & Ng, 2007 are reported for the first time in the Western Indian Ocean: they were discovered in the lava tubes of the volcano ‘Piton de la Fournaise’, Réunion Island. A new species, morphologically similar to Karstarma jacksoni (Balss, 1934) from Christmas Island, Eastern Indian Ocean, is recognized and described. A redescription of K. jacksoni is also provided. A second species is recognized, but being represented in the collection by a single juvenile, it cannot be identified to species level until more collections are made in the lava tubes.
Key words: Crustacea, Grapsoidea, Indian Ocean, endemic species, cave-dwelling species, taxonomy
Family Sesarmidae Dana, 1851
Genus Karstarma Davie & Ng, 2007
Karstarma vulcan sp. nov.
Sesarmoides ?longipes—ACSP 2014: webpage (Réunion, colour photograph).—Robert 2014: 1, 17 (same color photograph as ACSP). Not Sesarmoides longipes (Krauss, 1843).
Etymology. This new species is named after ‘Vulcan’ (used as an appositive noun) the ancient Roman god of fire, including fire of volcanoes, in allusion to the crab’s being discovered in the lava tubes of the volcano ‘Piton de la Fournaise’.
Distribution. Known only from Réunion Island. This is the first record of Karstarma in the WIO (Fig. 6). This is a cryptic species that has remained unnoticed in Réunion for a long time despite numerous studies of wildlife in the Island in the past. It is probably most active at night and is potentially present in all lava tubes allowing an easy access to the shoreline where the crab is likely to lay its eggs. In WIO it is perhaps also present in the Islands of Madagascar, Mauritius and/or Rodrigues in similar cave biotopes. In Rodrigues Island (~ 820 km east to Réunion Island), for example, karstic caves are known in the wildlife park, ‘François Leguat Giant Tortoise and Cave Reserve’ where more investigations for Karstarma crabs would be interesting.
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| Live colour of Karstarma sp. female juv. 8.6 × 9.8 mm (MNHN-IU-2013-7242), probably from lava tube ‘Brûlé des Citrons Galets’.
photograph: A. Barrère, 19 February 2016
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| Live colour of Karstarma jacksoni (Balss, 1934), Christmas Island.
Photographs outside cave by Hitoshi Takakura.
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Joseph Poupin, Nicole Crestey and Jean-Paul Le Guelte. 2018. Cave-dwelling Crabs of the Genus Karstarma from Lava Tubes of the Volcano ‘Piton de la Fournaise’, in Réunion Island, with Description of A New Species and Redescription of Karstarma jacksoni (Balss, 1934) from Christmas Island (Decapoda, Brachyura, Sesarmidae). Zootaxa. 4497(3); 381–397. DOI: 10.11646/zootaxa.4497.3.3
