Three new species of glass sponges (Porifera: Hexactinellida) from the West Indies, and molecular phylogenetics of Euretidae and Auloplacidae (Sceptrulophora)

Abstract

Three new species and a new genus of dictyonal Hexactinellida (Hexasterophora: Sceptrulophora: Euretidae and Auloplacidae) are described from hard-bottom communities of the West Indies. The holotypes were all collected by manned submersibles operated by the Harbor Branch Oceanographic Institute between 2006 and 2011, and remained in excellent physical condition at the time of their examination and description. As a result of their relatively recent collection and ethanol storage, molecular markers established previously for the phylogenetics of glass sponges were retrievable from all three holotypes. These are the first sequences for their respective genera, Conorete, Verrucocoeloidea, and Dictyoplax gen. nov. In addition, the first sequences of the genus Lefroyella could be obtained. Because the only (alleged) member of the family Euretidae previously included in molecular phylogenetic studies turned out to belong to the recently resurrected family Auloplacidae (i.e. Dictyoplax gen. nov.), in the present study the phylogenetic position of Euretidae within Sceptrulophora could be inferred for the first time. Furthermore, the increased taxon sampling allowed us to conduct a first test of the monophyly of Euretidae and one of its two subfamilies, Euretinae, with molecular data. Maximum-likelihood phylogenetic analysis revealed a close relationship between Euretidae and Farreidae, but also indicated that Euretidae might be paraphyletic with respect to Farreidae. The monophyly of subfamily Euretinae, at least in its current scope, was strongly rejected by the molecular data, in line with results from other hexactinellid families with a subfamilial division. The genus Sarostegia, which was only recently provisionally moved to Euretidae, is here transferred to an incertae sedis position within the classification of Sceptrulophora, because it is clearly unrelated to the other three included euretids. Besides from that, we refrain from any changes to the classification of Euretidae until more genera of this most diverse but poorly defined sceptrulophoran family are sampled for molecular systematic studies. © 2014 The Linnean Society of London