Incongruent cladistics reveal a new hydrozoan genus (Cnidaria : Sertularellidae) endemic to the eastern and western coasts of the North Pacific Ocean

Abstract

Molecular phylogenetics provides objective references for zoological systematics which sometimes are inconsistent with morphological data. This applies particularly for some primitive phyla such as Cnidaria. The marine hydrozoan Symplectoscyphus turgidus (Sertularellidae) is a recent questionable case reported to occupy an unexpected phylogenetic position and suggested to belong to a new genus. However, its position, based on a single Californian specimen, seemed doubtful. Here we contributed 16S, 18S and 28S rRNA data of another morphologically related species from the Yellow Sea, forming a monophyletic clade with the Californian sample, confirming the clade stability. Further integrative analyses support describing this clade as the new genus Xingyurella, gen. nov., and lead to a taxonomic revision of species characterised by three hydrothecal marginal teeth and strong gonothecal spines. This resulted in a new species and three new combinations: Xingyurella xingyuarum, sp. nov., X. gotoi, comb. nov., X. pedrensis, comb. nov. and X. turgida, comb. nov. Future investigations are required to understand the evolution and speciation involved in the transoceanic distribution pattern of Xingyurella. The approach used herein for dealing with non-monophyletic conditions may be indicative for further studies by integrating trophosome and gonosome traits for Sertularellidae and other hydrozoans. http://zoobank.org/urn:lsid:zoobank.org:pub:E99F8777-8E31-4C4B-A065-71C71371EEBC.