Data from: Molecular evidence shows low species diversity of coral-associated hydroids in Acropora corals

A novel symbiosis between scleractinians and hydroids (Zanclea spp.) was
recently discovered using taxonomic approaches for hydroid species
identification. In this study, we address the question whether this is a
species-specific symbiosis or a cosmopolitan association between Zanclea
and its coral hosts. Three molecular markers, including mitochondrial 16S
and nuclear 28S ribosomal genes, and internal transcribed spacer (ITS),
were utilized to examine the existence of Zanclea species from 14 Acropora
species and 4 other Acroporidae genera including 142 coral samples
collected from reefs in Kenting and the Penghu Islands, Taiwan, Togian
Island, Indonesia, and Osprey Reef and Orpheus Island on the Great Barrier
Reef, Australia. Molecular phylogenetic analyses of the 16S and 28S genes
showed that Acropora-associated Zanclea was monophyletic, but the genus
Zanclea was not. Analysis of the ITS, and 16S and 28S genes showed either
identical or extremely low genetic diversity (with mean pairwise distances
of 0.009 and 0.006 base substitutions per site for the 16S and 28S genes,
respectively) among Zanclea spp. collected from diverse Acropora hosts in
different geographic locations, suggesting that a cosmopolitan and
probably genus-specific association occurs between Zanclea hydroids and
their coral hosts.