Molecular diversity and specificity of acoel worms associated with corals in the Gulf of Eilat (Red Sea)

Epizoic acoel worms are known to inhabit several stony coral genera and one soft coral genus in Eilat (Red Sea). Such acoels were recently found to belong to the genus Waminoa and a new species was described: W. brickneri. Worms isolated from several coral species exhibited variability in size and reproductive state, suggesting the presence of more than one species of Waminoa. In the present study we examined the 18S rRNA gene sequences of worms from 6 genera of stony corals from the Gulf of Eilat to reveal the genetic variability of the worms and to study the specificity between these worms and the corals on which they live. The sequences obtained were found to be genetically similar, and they formed a distinct cluster with the 18S rRNA gene sequence of W. brickneri. Our results demonstrate that corals belonging to 6 different genera harbored genetically similar worms and thus suggest the existence of low specificity between worms and their coral hosts.