Relationships of the Osmeroid Fishes and the Use of Reductive Characters in Phylogenetic Analysis

The phylogenetic relationships of the osmeroid fishes are examined in the context of character congruence. The Osmeroidei is monophyletic, and its sister taxon is the monophyletic Argentinoidei. The division of osmeroids into Northern and Southern Hemisphere groups is largely corroborated. Two problematic taxa, the neotenic Salangidae and the monotypic Lepidogalaxias salamandroides, are hypothesized to be members of the Southern Hemisphere clade, in which reductive evolution has been common. The Northern Hemisphere clade includes the Osmeridae proper and the Japanese Plecoglossus altivelis. The utility of reductive characters in phylogeny reconstruction is discussed, with examples from the osmeroid fishes.