title: Phylogenetic relationships of Proboscoida Broch, 1910 (Cnidaria, Hydrozoa): Are traditional morphological diagnostic characters relevant for the delimitation of lineages at the species, genus, and family levels?
abstract: Overlapping variation of morphological characters can lead to misinterpretation in taxonomic diagnoses and the delimitation of different lineages. This is the case for hydrozoans that have traditionally been united in the family Campanulariidae, a group known for its wide morphological variation and complicated taxonomic history. In a recently proposed phylogenetic classification of leptothecate hydrozoans, this family was restricted to a more narrow sense while a larger clade containing most species traditionally classified in Campanulariidae, along with members of Bonneviellidae, was established as the suborder Proboscoida. We used molecular data to infer the phylogenetic relationships among campanulariids and assess the traditional classification of the family, as well as the new classification scheme for the group. The congruity and relevance of diagnostic characters were also evaluated. While mostly consistent with the new phylogenetic classification of Proboscoida, our increased taxon sampling resulted in some conflicts at the family level, specially regarding the monophyly of Clytiidae and Obeliidae. Considering the traditional classification, only Obeliidae is close to its original scope (as subfamily Obeliinae). At the genus level, Campanularia and Clytia are not monophyletic. Species with Obelia-like medusae do not form a monophyletic group, nor do species with fixed gonophores, indicating that these characters do not readily diagnose different genera. Finally, the species Orthopyxis integra, Clytia gracilis, and Obelia dichotoma are not monophyletic, suggesting that most of their current diagnostic characters are not informative for their delimitation. Several diagnostic characters in this group need to be reassessed, with emphasis on their variation, in order to have a consistent taxonomic and phylogenetic framework for the classification of campanulariid hydrozoans.
authors.affiliation: Departamento de Zoologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, Travessa 14, 101, 05508-090 São Paulo, Brazil. Electronic address: amanfcunha@gmail.com.
authors.forename: Amanda F
authors.initials: AF
authors.lastname: Cunha
authors.affiliation: National Systematics Laboratory, National Marine Fisheries Service (NMFS), National Museum of Natural History, Smithsonian Institution, Washington, DC, United States. Electronic address: collinsa@si.edu.
authors.forename: Allen G
authors.initials: AG
authors.lastname: Collins
authors.affiliation: Departamento de Zoologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, Travessa 14, 101, 05508-090 São Paulo, Brazil; Centro de Biologia Marinha, Universidade de São Paulo, Rodovia Dr. Manoel Hipólito do Rêgo, Praia do Cabelo Gordo, 11600-000 São Sebastião, São Paulo, Brazil. Electronic address: marques@ib.usp.br.
authors.forename: Antonio C
authors.initials: AC
authors.lastname: Marques
mesh_terms: D000818:Animals; D045304:Cytochromes c / Q000145:classification / Q000235:genetics; D030541:Databases, Genetic; D037402:Hydrozoa / Q000145:classification* / Q000235:genetics; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000145:classification / Q000235:genetics; D012337:RNA, Ribosomal, 18S / Q000145:classification / Q000235:genetics; D012339:RNA, Ribosomal, 28S / Q000145:classification / Q000235:genetics
chemical_list: D012336:RNA, Ribosomal, 16S; D012337:RNA, Ribosomal, 18S; D012339:RNA, Ribosomal, 28S; D045304:Cytochromes c
keywords: Classification; DNA; Diagnosis; Interspecific variation