Western Atlantic invasion of sun corals: incongruence between morphology and genetic delimitation among morphotypes in the genus Tubastraea

Abstract

The scleractinian corals of the genus Tubastraea Lesson, 1830 are currently globally dispersed and even so still present a confused taxonomy due to the overlap of morphological characters between the species. In this study, we investigate Tubastraea species previously found in the western Atlantic, based on the molecular marker (ITS gene) and morphology, to determine the accuracy of their descriptions. We identified three morphotypes from Brazil which were genetically delimited into two species: Tubastraea coccinea (Morphotypes I and II) and Tubastraea sp. (Morphotype III). Although morphotype I has morphological patterns of Tubastraea aurea (Quoy & Gaimard, 1833) there was no molecular divergence to support the species differentiation and continue to be recognized as a morphological variant of T. coccinea. The third morphotype is both morphologically and genetically distinct from T. coccinea and is also not representative of the species Tubastraea tagusensis Wells, 1982 despite earlier descriptions describing T. tagusensis in Brazil. Morphotype III exhibited distinct morphological characteristics among the other morphotypes, mainly due to greater polyp projection. In addition, it has fusions between septa, a characteristic that differentiates it from T. tagusensis. Nevertheless, molecular phylogenetic analyses showed that Brazilian Tubastraea fell into two well-supported monophyletic clades, and samples collected in the United States overlapped in both clades. Florida samples exhibited fewer morphotypes and showed greater genetic diversity, presenting haplotypes in four other internal clades. This study highlights the need for an integrative approach to conduct a deeper species delimitation of Tubastraea, essential for managing bioinvasion events by sun corals.

Life history strategy of Tubastraea spp. corals in an upwelling area on the Southwest Atlantic: growth, fecundity, settlement, and recruitment

“…Morphological studies demonstrated that T. coccinea has more polyps per colony area than T. aurea and Tubastraea sp. According to Bastos et al (2022) , T. coccinea presents polyps with smaller calyx diameters than the others, and its skeleton is not as robust as that of T. aurea . Morphology may explain this result because the type of dendroid growth of Tubastraea sp.…”

“…Fecundity rate was monitored during the same period of growth rate sampling. Colonies of three species were collected by visual differentiation mainly based on the size, distance and type of growth of the polyps, as well as the color of the tissue and tentacles, following Bastos et al (2022) . Authorization to collect biological material in Arraial do Cabo was granted by ICMBIO (SISBIO no.…”

“…Currently, different morphotypes of sun coral can be seen all along the Brazilian coast, and in Arraial do Cabo a recent study evaluating morphology integrated with molecular data described the occurrence of three morphotypes— T. aurea , T. coccinea , and Tubastraea sp. ( Bastos et al, 2022 ). This study considered all three morphotypes as species because even though T. aurea did not show molecular support, by the ITS marker, to validate it as a species, it did show enough statistical support to differentiate it morphologically and therefore, demonstrates particular biological attributes.…”

Histological description of new specialized reproductive structures in Atlantic dendrophylliid corals (Anthozoa, Scleractinia)

“…In the eld, colonies with at least 12 polyps were selected and removed with a hammer and chisel, being individually separated in plastic bags according to two major morphotype groups (plocoid vs. dendroid). Identi cations were based on colony aspects related to budding patterns, length and width of the corallites, theca margins (dentate vs. no dentate), and the occurrence of colony anastomosis (Bastos et al 2022; S. Serra et al unpubl data). In this study, four morphotypes of Tubastraea were considered, two dendroid and two plocoid, namely: Tubastraea sp.…”