MONOPHYLY AND RELATIONSHIPS OF THE ARGENTINOID FISHES

Evidence of monophyly and relationships of the Argentinoidei is provided, based on a phylogenetic analysis including aregentinoids, osmeroids, and other euteleosts. the Argentinoidei is monophyletic and is composed of two monophyletic clades, Argentinoidea and Alepocephaloidea. The evidence for monophyly of the Argentinoidei is largely drawn from anatomy of the branchial basket, and other potentially corroborating evidence is presented. The Argentinoidea is monophyletic. In this analysis, bathylagids are the sister taxon of opisthoproctids, argentinids the sister of these two. The Alepocephaloidea, usually composed of three to four families, is restricted here to a single family, Alepocephalidae. The highly derived Platytroctidae is more closely related to some alepocephalids than others, and is not recognized as a separate family. The monotypic Bathylaconidae, Bathyprionidae, and Leptochilichthyidae are not recognized, because doing so would both obscure the shared history of these taxa and render the Alepocephalidae paraphyletic. The sister taxon of the Argentinoidei is the Osmeroidei. Together they comprise the Osmerae. Previous hypotheses have placed either the Salmonidae or the highly derived galaxioid Lepidogalaxias as the sister taxon of the Neoteleostei. It is hypothesized here that the Osmerae is the sister taxon of the Neoteleostei on the basis of two synapomorphies: presence of a postmaxillary process of the premaxilla and loss of laminar bone on the anterior margin of the hyomandibula. The relationships of other euteleostean clades to the Osmerae and Neoteleostei are as yet unresolved.