Could polyp pulsation be the key to species boundaries in the genus Ovabunda (Octocorallia: Alcyonacea: Xeniidae)?

Ovabunda is a common genus of the family Xeniidae in the Red Sea. In the current study, 70 Ovabunda colonies were collected in Eilat (Gulf of Aqaba) and evaluated for inter- and intra-species variation, both morphologically and genetically, using three mitochondrial genes (mtMutS, COI, ND2) and the nuclear 28S rDNA. The purpose of the study was to elucidate species boundaries within the genus and determine which morphological characters are congruent with genetic clades. We found a large intraspecific variation in morphological characters and therefore faced difficulties when trying to assign colonies to species based on classical taxonomy. Genetic analyses revealed that the morphospecies did not cluster according to their classification but, rather, in two groups: one comprising colonies with pulsating polyps and the other with non-pulsating polyps. Comparisons of SNP sites in 28S among parents and their respective offspring suggest that the pulsating and non-pulsating groups are reproductively isolated, as we did not find any of the heterozygotes that would be expected if cross-fertilization existed between the two clades. Based on these findings, we recommend further documentation of polyp pulsation in the study of other genera of the family Xeniidae.