Deep-water Scleractinia (Cnidaria: Anthozoa) from Namibia, South Africa, and Walvis Ridge, southeastern Atlantic

Abstract

[EN] A collection of Scleractinia from three Spanish cruises in 1982 and 1984 VALDIVIA I, BENGUELA VI and VII) comprises ca. 600 specimens in 11 species from 22 stations, depths 145-1398 m: Fungiacyathus hydra n. sp.. Caryophyllia profundu, C. buluenacea n. sp., C. valdiviac n. sp., Stephanocyathus campaniformis, Deltocyathus conicus, Desmophyllum cristagalli, Lophelia pertusu, Flubellurn alabastrum, Truncatoflabellum sp., Enallopsammia rosrraru. Five species were obtained off southern Namibia and northernmost South Africa (23º-29º S) and nine species on Walvis Ridge (25º-26º S), three species being common to both areas, on each side of the Cape Basin. The species are very unequally represented (from 1 to ca. 300 specimens each). most being first records from the southeastern Atlantic. Four patterns of zoogeographical distribution can be distinguished: 1) species widely distributed throughout the Atlantic (North and South) and extending to the Pacific and Indian Ocean; 2) species known throughout the North Atlantic. with new records representing a considerable range extension in the southeastern Atlantic; 3) species probably limited to the southeastern Atlantic including Walvis Ridge; 4) southern species (New Zealand to Tristan da Cunha) extending north along Walvis Ridge. No representative of the typically southern South African fauna was found. Two species typical of about 2000 m depth in the northeastern Atlantic inhabit lesser depths in the southeastern Atlantic, the corresponding low water temperatures being of the same order in both areas. The coral fauna on Walvis Ridge shows a depth zonation correlated with the water temperature. Fungiacyathus hydra appears parasitized by an ascothoracid crustacean. Enallopsammia rostrata bears crypts inhabited by the cryptochirid crab Cecidocarcinus brychills at depths exceeding 500 m (association having its counterpart in the southwestern Indian Ocean). The series of crab dwellings gives evidence that crypt ontogeny depends on both coral skeleton dissolution and induced skeleton growth. Breakage by predators, followed by repair or regeneration, is frequent in four species of the deeper stations on Walvis Ridge. In the particularly fragile Fungiacyathus hydra, high frequency of regeneration from dislocated pieces may be an efficient mode of asexual reproduction compensating the loss by predation and by free larvae being swept away from the ridge

[ES] La colección de seleractiniarios recolectados en las campañas VALDIVIA I, BENGUELA VI and VII comprende, aprox. 600 ejemplares agrupados en 11 especies. Las campañs se realizaron entre 1982 y 1984 y cubrieron unas 22 estaciones con un margen de profundidad de 145 a 1398 m. Las especies recolectadas son: Fungiacyathus hydra n. sp.. Caryophyllia profundu, C. buluenacea n. sp., C. valdiviac n. sp., Stephanocyathus campaniformis, Deltocyathus conicus, Desmophyllum cristagalli, Lophelia pertusu, Flubellurn alabastrum, Truncatoflabellum sp., Enallopsammia rostrata. Cinco especies provienen de la zona sur de Namibia y norte de Sudáfrica (23º-29º S), nueve de la cordillera de Walvis (25º-26º S) y tres son comunes en ambas zonas. Las especies están desigualmente representadas (desde unos pocos a más de 300 ejemplares por especie) y la mayoría se han recolectado por primera vez en el Atlántico sudoriental. desde el punto de vista zoogeografíco se pueden distinguir cuatro pautas: 1) especies de amplia distribución en todo el océano Atlántico y conocidas en los océanos Pacífico e Índico; 2) especies distribuidas por el Atlántico norte pero cuya recolección amplía su margen de distribución a la parte sudoriental del mismo océano; 3) especies de distribución restringida al Atlántico sudoriental y probablemente al área de la cordillera de Walvis; 4) especies de distribución en el hemisferio sur (Nueva Zelanda y Tristan de Cunha) y que se extienden algo hacia el norte por la cordillera de Walvis. No se han recolectado especies típicas de la fauna de la zona sur de Sudáfrica