title: Hidden among sea anemones: the first comprehensive phylogenetic reconstruction of the order Actiniaria (Cnidaria, Anthozoa, Hexacorallia) reveals a novel group of hexacorals.
abstract: Sea anemones (order Actiniaria) are among the most diverse and successful members of the anthozoan subclass Hexacorallia, occupying benthic marine habitats across all depths and latitudes. Actiniaria comprises approximately 1,200 species of solitary and skeleton-less polyps and lacks any anatomical synapomorphy. Although monophyly is anticipated based on higher-level molecular phylogenies of Cnidaria, to date, monophyly has not been explicitly tested and at least some hypotheses on the diversification of Hexacorallia have suggested that actiniarians are para- or poly-phyletic. Published phylogenies have demonstrated the inadequacy of existing morphological-based classifications within Actiniaria. Superfamilial groups and most families and genera that have been rigorously studied are not monophyletic, indicating conflict with the current hierarchical classification. We test the monophyly of Actiniaria using two nuclear and three mitochondrial genes with multiple analytical methods. These analyses are the first to include representatives of all three currently-recognized suborders within Actiniaria. We do not recover Actiniaria as a monophyletic clade: the deep-sea anemone Boloceroides daphneae, previously included within the infraorder Boloceroidaria, is resolved outside of Actiniaria in several of the analyses. We erect a new genus and family for B. daphneae, and rank this taxon incerti ordinis. Based on our comprehensive phylogeny, we propose a new formal higher-level classification for Actiniaria composed of only two suborders, Anenthemonae and Enthemonae. Suborder Anenthemonae includes actiniarians with a unique arrangement of mesenteries (members of Edwardsiidae and former suborder Endocoelantheae). Suborder Enthemonae includes actiniarians with the typical arrangement of mesenteries for actiniarians (members of former suborders Protantheae, Ptychodacteae, and Nynantheae and subgroups therein). We also erect subgroups within these two newly-erected suborders. Although some relationships among these newly-defined groups are still ambiguous, morphological and molecular results are consistent enough to proceed with a new higher-level classification and to discuss the putative functional and evolutionary significance of several morphological attributes within Actiniaria.
authors.affiliation: Division of Invertebrate Zoology, American Museum of Natural History, New York City, New York, United States of America.
authors.forename: Estefanía
authors.initials: E
authors.lastname: Rodríguez
authors.affiliation: Sackler Institute for Comparative Genomics, American Museum of Natural History, New York City, New York, United States of America; Departamento de Zoologia, Universidade Federal do Paraná, Curitiba, Brazil.
authors.forename: Marcos S
authors.initials: MS
authors.lastname: Barbeitos
authors.affiliation: Division of Invertebrate Zoology, American Museum of Natural History, New York City, New York, United States of America; Sackler Institute for Comparative Genomics, American Museum of Natural History, New York City, New York, United States of America; Richard Gilder Graduate School, American Museum of Natural History, New York City, New York, United States of America.
authors.forename: Mercer R
authors.initials: MR
authors.lastname: Brugler
authors.affiliation: Division of Invertebrate Zoology, American Museum of Natural History, New York City, New York, United States of America.
authors.forename: Louise M
authors.initials: LM
authors.lastname: Crowley
authors.affiliation: Division of Invertebrate Zoology, American Museum of Natural History, New York City, New York, United States of America; Richard Gilder Graduate School, American Museum of Natural History, New York City, New York, United States of America.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Grajales
authors.affiliation: Departamento de Zoologia, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Luciana
authors.initials: L
authors.lastname: Gusmão
authors.affiliation: Escuela de Ciencias del Mar, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile.
authors.forename: Verena
authors.initials: V
authors.lastname: Häussermann
authors.affiliation: Department of Molecular Evolution and Genomics, University of Heidelberg, Heidelberg, Germany.
authors.forename: Abigail
authors.initials: A
authors.lastname: Reft
authors.affiliation: Department of Evolution, Ecology, and Organismal Biology, Ohio State University, Columbus, Ohio, United States of America.
authors.forename: Marymegan
authors.initials: M
authors.lastname: Daly
mesh_terms: D000818:Animals; D005075:Biological Evolution; D004272:DNA, Mitochondrial / Q000235:genetics*; D010802:Phylogeny; D012615:Sea Anemones / Q000145:classification / Q000235:genetics*
chemical_list: D004272:DNA, Mitochondrial