Astrocoryne cabela gen. nov., sp. nov. (Hydrozoa: Sphaerocorynidae), a new sponge-associated hydrozoan

The family Sphaerocorynidae includes two valid genera and five species, most of which have a confusing taxonomic history. Here, a new genus and species, Astrocoryne cabela, gen. et sp. nov., is described from the Maldives and the Red Sea, based on both morphological and molecular evidence. Astrocoryne cabela has an apomorphy represented by the type of tentacles, here named 'dicapitate', and consisting of capitate tentacles with a proximal capitulum-like cluster of nematocysts. Molecular analyses confirmed the monophyly of this species, as well as its belonging to the Sphaerocorynidae, together with Sphaerocoryne spp. and Heterocoryne caribbensis Wedler & Larson, 1986, for which we present molecular data for the first time. Moreover, the high divergence of A. cabela from other species of the family justifies the establishment of a new genus. Interestingly, specimens from the Maldives and the Red Sea showed marked morphological variation in the polyp stage, although only a slight genetic divergence was detected. This study highlights that a comprehensive morpho-molecular assessment of Sphaerocorynidae is strongly needed in order to clarify the taxonomic issues and the diversity of this taxon.