To date, four nominal species and several other unidentified species of Zanclea hydrozoans are known to live symbiotically with scleractinians, and recent surveys reported this association also in the Red Sea. Previous molecular studies showed that each coral genus involved in this association hosts only one species or molecular clade of Zanclea, with the only exception being the genus Acropora, which hosts at least two Zanclea species. Moreover, some of the detected genetic lineages were morphologically undistinguishable in the polyp stage, suggesting the presence of cryptic species. In this study, we investigated the morphology and genetic diversity of Acropora-associated Zanclea specimens collected in previous studies in Egypt and Israel, as well as new samples collected in Saudi Arabia. Based on the current data, all the analysed samples were morphologically identical to Zanclea gallii, a species associated with Acropora corals from the Maldives. However, molecular analyses separated the samples collected in the Red Sea from all other coral-associated hydroids. Therefore, phylogenetic reconstructions, haplotype networks, genetic distance analyses and distribution data allowed us to identify a previously unknown cryptic species of Acropora-associated hydroid, here named Zanclea gallii IIa, following a recently proposed molecular nomenclature.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): FCC/1/1973-07
Acknowledgements: This research was undertaken in accordance with the policies and procedures of the King Abdullah University of Science and Technology (KAUST). Permissions relevant for KAUST to undertake the research have been obtained from the applicable governmental agencies in the Kingdom of Saudi Arabia. The authors wish to thank the members of the Reef Ecology Lab at King Abdullah University of Science and Technology and, in particular, Tullia Terraneo (KAUST) and Malek Amr Gusti (KAUST) for logistic support. Many thanks go to the staff of the iDive and Open Ocean Science Centre in Dahab, especially to Inga Dehnert and Hans Lange for their help in the field activities. We also want to thank all the staff of the Interuniversity Institute for Marine Sciences (IUI) in Eilat for their logistic support. Finally, we thank the two anonymous reviewers for their constructive comments. This project was partly supported by funding from KAUST (award # FCC/1/1973-07 and baseline research funds to MLB) and University of Milano-Bicocca (baseline research fund to PG). The samples from Eilat were collected during the project ‘HyDRa’ (ASSEMBLE grant no. 227799).