Morphological and genetic variability associated with environmental variation in two species of Pseudodiploria Fukami, Budd & Knowlton, 2012 (Cnidaria: Anthozoa: Scleractinia)

Environmental variability often results in morphological plasticity, allowing organisms to acclimate and resist changing environmental conditions. Corals exhibit high morphological variability, possibly influenced by factors such as phenotypic plasticity and hybridization. Pseudodiploria Fukami, Budd & Knowlton, 2012 consists of two species, Pseudodiploria strigosa Dana, 1846 and Pseudodiploria clivosa Ellis & Solander, 1786, which are often differentiated by the colony morphology, number of septa per centimeter, width of valleys, and the presence/absence of coenosteum. In this study, we performed morphological and molecular analyses of 40 Pseudodiploria colonies (20 samples each reef) from the Gulf of Mexico in two reefs Gallega (coastal reef) and Galleguilla (at 2 km of coastline), at the Veracruz Reef System, using univariate analyses of 14 macro- and micro-characters supplemented by examination of mitochondrial (cytochrome b) and nuclear (beta-tubulin) sequences. We confirmed the presence of the two Pseudodiploria species based on micro-morphological results. However, 32 colonies of Pseudodiploria presented high phenotypic plasticity at colony and calice levels (11 of the 14 evaluated characters), and molecular variation of beta-tubulin gene was higher in the colonies that exhibited high morphological variability. Genetic distances of beta-tubulin gene sequences also demonstrated that all colonies collected are most similar to P. clivosa (according to previous studies). Interestingly, we found that colonies collected from a coastal reef had higher variability in morphological characters at colony and calice levels (17 of 20 samples), which may be the evidence of the effect of environmental conditions on phenotypic plasticity of Pseudodiploria colonies.