Systematic status of the caridean families Gnathophyllidae Dana and Hymenoceridae Ortmann (Crustacea : Decapoda): a preliminary examination based on nuclear rDNA sequences

Abstract

The systematic positions of the caridean families Gnathophyllidae and Hymenoceridae are inferred based on analyses of nuclear 18S rRNA and 28S rRNA genes. The phylogenetic trees based on 18S rRNA and 28S rRNA from selected species of one genus of the family Gnathophyllidae, two genera of the family Hymenoceridae, one genus of the family Anchistioididae, eight genera of the subfamily Pontoniinae and five genera of the subfamily Palaemoninae show a close relationship between Hymenoceridae, Gnathophyllidae and Pontoniinae, with the last group constituting a paraphyletic assemblage. This result concurs with the morphology of maxilla in the first zoea, but not the shape of the third maxilliped in adults, based on which Gnathophyllidae and Hymenoceridae are treated as families. Molecular analysis supports the similarities in larval morphology between Hymenoceridae, Gnathophyllidae and Pontoniinae and therefore draws into question the familial status of the former two groups.