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Un articulo sobre el cangrejo violinista que apareció el año pasado en la playa de Las Canteras publicado en la revista británica Marine Biodiversity Records.

A new record of the West African fiddler

crab, Uca tangeri, from Gran Canaria

(Canary Islands)

A specimen of West African fiddler crab, Uca tangeri, was collected in October 2011 on the north-east coast of Gran Canaria (Canary Islands). This species is frequent along the shores of the east Atlantic from Portugal to Angola, but is very rare in the Canary Islands. There is only a previous record from 1971, but that did not report the place where it was found in the archipelago.

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<p>INTRODUCTION</p>
<p>Uca tangeri (Eydoux, 1835) is a common crab in marsh land,</p>
<p>mud flats, often near river mouths, along the west coast of</p>
<p>Africa from Morocco to southern Angola. It is also present</p>
<p>on the coast of Portugal, but it does not occur in the</p>
<p>Mediterranean (Holthuis, 1981; Manning & Holthuis, 1981;</p>
<p>Schneider, 1990).</p>
<p>According to Burggren & McMahon (1988), U. tangeri</p>
<p>with a maximum carapace length of 33 millimetres (47 mm</p>
<p>carapace width) is the largest species in the genus Uca</p>
<p>(Holthuis, 1981; Lloris & Rucabado, 1998). The most</p>
<p>notable feature of this species is the dimorphism of the</p>
<p>chelae. Males have one small chela (smaller than observed</p>
<p>in females) and the other is enormously enlarged. The small</p>
<p>chela is mainly used for feeding while the large one is used</p>
<p>for agonistic and mating displays (Christy & Salmon, 1984;</p>
<p>Burggren & McMahon, 1988). The waving and vertical movements</p>
<p>of the larger chela, together with quick movements of</p>
<p>the small one during feeding, have given the genus its</p>
<p>popular name of ‘fiddler crabs’ (Burggren & McMahon,</p>
<p>1988). Fiddler crabs live in burrows and galleries created</p>
<p>into the mud and used for protection during high tide, emerging</p>
<p>when galleries are exposed at low tide (Altevogt, 1959;</p>
<p>Montague, 1980).</p>
<p>There are no reports of the presence of this crab at Madeira</p>
<p>and Cabo Verde archipelagos. However, Garcı´a-Cabrera</p>
<p>(1971), in a paper about similarities of Canary Islands and</p>
<p>Antilles marine fauna, reported the presence of U. tangeri in</p>
<p>the list of brachyuran species of both areas, but without site</p>
<p>specification. Because of this lack of specificity and because</p>
<p>there are no previous or later references to that of</p>
<p>Garcı´a-Cabrera in this archipelago González – Pérez (1995)</p>
<p>excluded this crab from the species catalogue of crustaceans</p>
<p>of the Canary Islands. Also, the citation of U. tangeri for the</p>
<p>Antilles is probably due to confusion with other species of</p>
<p>the Uca genus.</p>
<p>MATERIALS AND METHODS</p>
<p>On the night of 3–4 October 2011, a single male specimen of</p>
<p>U. tangeri (Figure 1), with carapace length 28.0 mm, carapace</p>
<p>width 33.7 mm, and 33.3 g of wet weight, was collected from</p>
<p>the Las Canteras Beach (20808′27.23′′N–15826′09.42′′W),</p>
<p>north-east of Gran Canaria (Canary Islands, central-east</p>
<p>Atlantic). The crab had the left chela (73.2 mm) 4.2 times</p>
<p>larger than right one (17.2 mm). The specimen was captured</p>
<p>by hand while it was walking on the sand, along the beach</p>
<p>strand, in the limit of sea waves during low tide.</p>
<p>During the night of 3–4 October there was low tide</p>
<p>(20.6 m) and the sea surface temperature was 248C (the</p>
<p>minimal low tide recorded in Gran Canaria had been</p>
<p>21.5 m). The moon was in its first quarter. The weather</p>
<p>was warmer and winds were light and variable from the northeast</p>
<p>at coastal areas, and from the south changing to west at</p>
<p>high areas of the island.</p>
<p>RESULTS AND DISCUSSION</p>
<p>This is the first corroborated record for U. tangeri from the</p>
<p>Canary Islands. According to García-Cabrera (1971), in the</p>
<p>Canary Islands only 15% of marine species are in common</p>
<p>with the neighbouring African coasts. Mainland and island</p>
<p>ecosystems are very different. The African waters are colder</p>
<p>and less saline than the island ones, with shallow bottoms</p>
<p>that extend beyond 120 km without reaching the 500 m</p>
<p>depth. These bottoms are rich in marine vegetation and able</p>
<p>to accommodate populations of great interest and biomass.</p>
<p>However, the islands are of volcanic origin and their shelves</p>
<p>are markedly narrow and steep. The coastal areas are quite</p>
<p>diverse, with predomination of volcanic and stony shores,</p>
<p>and they present a great variety of microclimates and</p>
<p>marine biotopes (Bas et al., 1995; Brito et al., 1996, 2001).</p>
<p>And, probably due to the microclimates and marine biotopes,</p>
<p>the absence of river estuaries, adequate muddy areas, and that</p>
<p>beaches support a high human pressure (tourism is the main</p>
<p>industry in the Canaries), the population of U. tangeri in the</p>
<p>island should be very low, and limited to few individuals</p>
<p>that live restricted to some small areas.</p>
<p>On the other hand, it is possible that this specimen could be</p>
<p>a consequence of occasional larvae drifting transport between</p>
<p>the African coast and the Canary Archipelago, as it has been</p>
<p>documented for fish larvae (Rodrı´guez et al., 1999, 2004),</p>
<p>and the subsequent process of settlement and growing of an</p>
<p>isolated individual.</p>
<p>ACKNOWLEDGEMENT</p>
<p>I thank Desire´e Herna´ndez-Hormiga for her assistance in the</p>
<p>specimen collection, measuring and rearing.</p>
<p>REFERENCES</p>
<p>Altevogt R. (1959) Okologische und ethoilogische studien an Europas einziger</p>
<p>winkerkrabbe Una tangeri Eydoux. Zeitschrift fu¨r Morphologie</p>
<p>und O¨ kologie der Tiere 48, 123–146.</p>
<p>Bas C., Castro J.J., Lorenzo J.M., Herna´ndez-Garcia V., Moreno T.,</p>
<p>Pajuelo J.G. and Ramos A.G. (1995) La pesca en Canarias y a´reas</p>
<p>de influencia. Madrid: Ediciones del Cabildo Insular de Gran</p>
<p>Canaria, 331 pp.</p>
<p>Brito A., Lozano I.J., Falco´n J.M., Rodrı´guez F.M. and Mena J. (1996)</p>
<p>Ana´lisis biogeogra´fico de la ictiofauna de las Islas Canarias. In Llinas</p>
<p>O., Gonza´lez J.A. and Rueda M.J. (eds) Oceanografia y Rercursos</p>
<p>Marinos en el Atla´ntico Centro-oriental. Gran Canaria: Instituto</p>
<p>Canario de Ciencias Marinas, pp. 241–270.</p>
<p>Brito A., Falco´n J.M., Aguilar N. and Pascual P. (2001) Fauna vertebrada</p>
<p>marina. In Ferna´ndez-Palacios J.M. and Martı´n-Esquivel J.L. (eds)</p>
<p>Naturaleza y conservacio´n en las Islas Canarias. Santa Cruz de</p>
<p>Tenerife: Ediciones Turquesa, 474 pp.</p>
<p>Burggren W.W. and McMahon B.R. (1988) The biology of land crabs.</p>
<p>Cambridge: Cambridge University Press, 479 pp.</p>
<p>Christy J.H. and Salmon M. (1984) Ecology and evolution of mating</p>
<p>systems of fiddler crabs (Genus Uca). Biological Reviews 59, 483–509.</p>
<p>Garcı´a-Cabrera C. (1971) Interrrelaciones entre las faunas marinas de las</p>
<p>Antillas y Canarias. Anuario de Estudios Atla´nticos 17, 37–55.</p>
<p>Gonza´lez-Pe´rez J.A. (1995) Cata´logo de los crusta´ceos deca´podos de las</p>
<p>Islas Canarias: gambas, langostas y cangrejos. Santa Cruz de</p>
<p>Tenerife: Turquesa Ediciones, 282 pp.</p>
<p>Holthuis L.B. (1981) True crabs. In Fischer W., Bianchi G. and Scott W.B.</p>
<p>(eds) FAO species identification sheets for fishery purposes. Eastern</p>
<p>central Atlantic: Fishing areas 34, 47 (in part). Canada</p>
<p>Funds-in-Trust, Ottawa, Department of Fisheries and Oceans</p>
<p>Canada, by arrangement with the Food and Agriculture</p>
<p>Organization of the United Nations, Volumes 1–7; pag. var.</p>
<p>Lloris D. and Rucabado J. (1998) Guide d’identification des ressources</p>
<p>marines vivantes du Maroc. Guide FAO d’identification des espe`ces</p>
<p>pour les besoins de la peˆche. Rome: Food and Agriculture</p>
<p>Organization, 263 pp.</p>
<p>Manning R.B. and Holthuis L.B. (1981) West African brachyuran crabs</p>
<p>(Crustacea Decapoda). Smithsonian Contributions to Zoology 306,</p>
<p>1–379.</p>
<p>Montague C.L. (1980) A natural history of temperate western Atlantic</p>
<p>fiddler crabs (Genus Uca) with reference to their impact on the salt</p>
<p>marsh. Contributions in Marine Sciences 23, 25–55.</p>
<p>Rodrı´guez J.M., Herna´ndez-Leo´n S. and Barton E.D. (1999) Mesoscale</p>
<p>distribution of fish larvae in relation to an upwelling filament of</p>
<p>Northwest Africa. Deep-Sea Research I: Oceanographic Research</p>
<p>Papers 46, 1969–1984.</p>
<p>Rodrı´guez J.M., Barton E.D., Herna´ndez-Leo´n S. and Arı´stegui J.</p>
<p>(2004) Taxonomic composition and horizontal distribution of the</p>
<p>fish larvae community in the Canaries-Coastal Transition Zone, in</p>
<p>summer. Progress in Oceanography 62, 171–188.</p>
<p>and</p>
<p>Schneider W. (1990) FAO species identification sheets for fishery purposes.</p>
<p>Field guide to the commercial marine resources of the Gulf of Guinea.</p>
<p>Prepared and published with the support of the FAO Regional</p>
<p>Office for Africa. Rome: FAO, 268 pp.</p>
<p>J.J. Castro</p>
<p>Departamento de Biología</p>
<p>Universidad de Las Palmas de Gran Canaria</p>
<p>Edificio Ciencias Ba´sicas, Campus de Tafira</p>
<p>35017 Las Palmas de Gran Canaria, Canary Islands, Spain</p>
<p>email: jcastro@pesca.gi.ulpgc.es</p>
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