Madracis auretenra (Scleractinia: Pocilloporidae) - testing our knowledge of systematics, biology and connectivity in the western North Atlantic

The systematic biology of the Caribbean scleractinian coral Madracis auretenra Locke, Weil and Coates 2007 is presented. This includes a new species description and brief taxonomic history, an explanation for the name Madracis mirabilis (Duchassaing and Michelotti 1860), a biological and bibliographic revision of M. auretenra, and information on this coral's genetic diversity and phylogeography in the greater Caribbean region. Madracis auretenra is described for a common, shallow-water, zooxanthellate coral, previously mis-identified as M. mirabilis. Madracis mirabilis is a subjective junior synonym for the deep-water species Madracis myriaster and according to the International Rules of Zoological Nomenclature, the name M. mirabilis cannot be used for another coral species. The problematic taxonomic history of this coral is presented as a perspective to explain what the binomen M. mirabilis refers to, in order to make this information easy to understand and accept by the community of coral researchers. To ensure earlier work on the species is recognized, a biological and bibliographic review of M. auretenra incorporates literature from more than 170 publications on the species, when it was incorrectly identified as M. asperula, M. mirabilis, or M. mirabilis sensu Wells 1973 during the years 1959-2008. Conspecificity with M. auretenra has been verified by authors of 97 M. mirabilis publications unverified studies are noted. The review includes an extensive description of M. auretenra with new information on colony branch diameter and information on the distribution, ecology, physiology, molecular and experimental research of this common Caribbean species. To inform conservation management of Bermuda's geographically isolated high latitude reef system, assessments of genetic diversity and connectivity were made for the hermaphroditic, brooding coral M. auretenra. Patterns of genetic structure and evolutionary history for the coral in Bermuda, the Florida Keys and Puerto Rico are elucidated using the nuclear intron SRP54. Twenty distinct nDNA haplotypes were determined from a trimmed alignment of 219 bp. Nucleotide and haplotypic diversity in Bermuda exceeded that of Florida and Puerto Rico, suggesting the island could be a coral refugium. Significant population structure was suggested to exist between Bermuda, Florida and Puerto Rico (Fst = 0.153, p < 0.001 Fct = 0.141, p < 0.05). However, a shared historical connection between regions is evident in phylogenetic reconstructions. Distinct SRP54 haplotypes for Bermuda and Puerto Rico support the recent division of these populations. Geographically shared phylogenetic clades for some Bermuda and Florida haplotypes indicate that geographic isolation my be broken periodically by gene flow to Bermuda from Florida via dispersal of coral planulae or settled, rafted individuals caught in Gulf Stream cyclonic eddies. This rare dispersal is predicted to occur too infrequently to sustain Bermuda coral populations indicating that conservation efforts of Bermudian coral species should be focused locally.