Cryptic Species Within the Atlantic-Caribbean Genus Meandrina (Scleractinia): A Multidisciplinary Approach and Description of the New Species Meandrina jacksoni

The scleractinian genus Meandrina is unique to the western Atlantic. Species diversity has varied from 12 to two currently recognized taxa, the Caribbean Meandrina meandrites (Linnaeus, 1758) and Meandrina brasiliensis (Milne-Edwards and Haime, 1848), endemic to Brazil. A second Caribbean species, Meandrina danae (Milne-Edwards and Haime, 1848), has been considered a synonym of M. brasiliensis or an ecomorph of M. meandrites. Field observations, examination of specimens, and a literature review indicated the presence of a third, morphologically different Caribbean species. A multi-variable approach, with morphometric, reproductive, and ecological information, was used to clarify the status of M. danae and test the validity of the unrecognized morphology. Three colony-level characters were measured in 779 specimens of M. meandrites, 760 M. danae, and 320 of the cryptic morph (Meandrina sp.) from Puerto Rico. Thirteen calice-level characters were assessed in 45 M. meandrites, 46 M. danae, 32 Meandrina sp., and 98 specimens of all taxa, including M. brasiliensis, from the Smithsonian National Museum of Natural History. Sexual reproductive patterns and modes of development were assessed monthly from at least five colonies of M. meandrites (n = 97), M. danae (n = 138), and Meandrina sp. (n = 99). Results showed consistent and significant differences among characters supporting the separation of three Caribbean species of Meandrina, the common massive, sub-massive, and crustose M. meandrites, the small, free-living M. danae, and a new species, Meandrina jacksoni sp. nov., characterized by small, platy, and mostly pale, medium-to-large crustose, and sub-massive colonies with low ridges, short septa, and wide valleys.