A revision of the Shallow-water Azooxanthellate Scleractinia of the Western Atlantic

CAIRNS, S. D., 2000. A revision of the shallow-water azooxanthellate Scleractinia of the western Atlantic. Studies Nat. Hist. Caribbean Region 75, Amsterdam, 2000: 1-231. This paper constitutes the second of a two part revision of the western Atlantic azooxanthellate Scleractinia — this part addressing the taxonomy and distribution of the 73 species known to occur at depths shallower than 183 m within the tropical and warm temperate realm. Of this number, 27 species occur exclusively shallower than 183 m; these are fully described, figured, and mapped. The remaining 46 species are also known to occur at depths greater than 183 m, most of those species treated more fully in part 1 (CAIRNS 1979). Lists are also provided of the azooxanthellate species that occur exclusively deeper than 183 m (56 species) as well as the western Atlantic zooxanthellate fauna (65 species), resulting in the first comprehensive list of all 192 western Adantic scleractinian species. In the western Atlantic there are approximately twice as many azooxanthellate as zooxanthellate species. One species, Tubastraea coccinea is considered to be introduced; its distribution and chronology of its possible dispersal are mapped and discussed. Approximately 6900 specimens (1100 lots) were examined, collected from over 550 stations. Additional records of all but three of the 73 species are reported herein. Ten species and one subspecies are described as new; ten new combinations are suggested. Among the 73 shallow-water species several patterns of distribution were discerned: widespread insular and continental, primarily insular, primarily continental, endemic to Brazil, and endemic to the Carolinian Province. The most common pattern, shared by 18 species, was a distribution that includes the entire tropical western Atlantic as well as the northern warm temperate region in the northern Gulf of Mexico and/or southeast coast of the US, these ‘eurythermic tropical’ species usually extending no farther than 34°30' to 35°00'N. Among the 27 exclusively shallow-water azooxanthellates, the percentage of species endemic to the western Atlantic (85%) and the amphi-Atlantic component (11%) were considerably higher and lower, respectively, than those components for the deeper water azooxanthellates, but virtually identical to that of the western Atlantic zooxanthellate corals.