Challenges and opportunities for the use of integrative taxonomy for invasive Scleractinian coral species identification: the sun coral puzzle

Recent research in the Brazilian coast and China Sea, and the identification of taxonomic discrepancies from earlier studies, resulted in the need for a taxonomic review of the sun coral genus Tubastraea. Henceforth, this study comprehensively reviews publications evaluating ecological and morphological aspects, molecular data and geographic distribution species of the genus Tubastraea in order to evaluate their phylogenetic and biogeographic relationships. Tubastraea corals are considered invasive in Brazil, yet some studies may have underestimated species numbers due to the misinterpretation of a dichotomous model that differentiates between dendroid versus plocoid corallite development. Results revealed high local species diversity on the western Atlantic coast and the presence of cryptic diversity in the southwestern Atlantic. We made biogeographical inferences comparing provinces and phylogenetic relationships between Tubastraea species using the ecoregion scheme derived of the MEOW classifications of the geographic distributions of closely related species. We found several widely distributed species that are closely related to recently described species with restricted distributions in the South China Sea. We also observed that some species and morphotypes in the tropical southern Atlantic province appear to be phylogenetically close to T. aurea specimens from the warm temperate northeast Atlantic and tropical northwestern Atlantic, whereas other morphotypes and recently described species in tropical and temperate southern Atlantic provinces are more closely related to T. coccinea and T. micrantus specimens from the western Indo-Pacific realm. Our comparative evaluation of published molecular phylogenies suggests that erroneously and unidentified specimens and/or incomplete lineage sorting of molecular markers used in phylogenetic reconstructions of species of Dendrophylliidae have made phylogenetic inference difficult across many lineages of populations or species, as seen in the published trees of Tubastraea. Also, phylogenies suggest that the T. coccinea specimens from Japan are distinct from the specimens sampled on the Atlantic coast and thus, may represent different species.