A phylogeny of Vesiculariidae (Bryozoa, Ctenostomata) supports synonymization of three genera and reveals possible cryptic diversity

摘要

Compared to their calcified sister group, order Cheilostomata, uncalcified ctenostome bryozoans exhibit relatively simple and often inconsistent morphologies, making them particularly suitable candidates for the use of molecular tools to delimit species and examine their interrelationships. The family Vesiculariidae is composed of six genera, three of which, Zoobotryon, Avenella and Watersiana are monotypic, and one, Vesicularia, encompasses four species. The majority of vesiculariid diversity, however, is found in Amathia (39 species) and Bowerbankia (21 species). The respective monophyletic status for Amathia and Bowerbankia has recently been put into question by molecular evidence and is being further examined in this study. Multigene (ssrDNA, rrnL, cox1) phylogenetic analysis revealed that Bowerbankia is paraphyletic to the inclusion of Zoobotryon and Amathia, where the latter was resolved as non-monophyletic. Although Vesicularia also nested within this paraphyletic assemblage in some of the analyses, Bayesian topology testing did not support this result. Our results are discussed within the context of published morphological evidence and lead to the conclusion that Bowerbankia and Zoobotryon should be classified as junior subjective synonyms of Amathia. A revised nomenclature is provided. Furthermore, we examined genetic divergences between widely distributed supposed conspecific species and discovered possible cryptic diversity in the outgroup taxon Anguinella palmata and in Bowerbankia citrina, Amathia vidovici and Amathia crispa.