On the genus Spirobranchus (Annelida, Serpulidae) from the northern Red Sea, and a description of a new species

Species of the genus Spirobranchus, commonly known as Christmas tree worms, are abundant throughout tropical Indo-Pacific and Atlantic Oceans. Information on the species inhabiting the Red Sea in general and the Gulf of Eilat (Gulf of Aqaba) in particular, has so far been very limited. Here we present a multigene phylogenetic analysis, examining both mitochondrial (Cyt-b) and nuclear (ITS2 and 18S) markers, to support the presence of four distinct Spirobranchus species in the Gulf of Eilat: S. corniculatus (including three taxa previously regarded as full species: S. gaymardi, S. cruciger, and S. corniculatus), S. cf. tetraceros, S. gardineri and a new species Spirobranchus aloni, likely endemic to the Red Sea (including two morphotypes with slightly different opercular morphology). The results presented here emphasise that the combination of molecular and in-depth morphological evaluation holds great prospects for a better understanding of species divergence and relationships.