Molecular phylogeny of the mud lobsters and mud shrimps (Crustacea : Decapoda : Thalassinidea) using nuclear 18S rDNA and mitochondrial 16S rDNA

Abstract

Partial sequences of the 18S nuclear and 16S mitochondrial ribosomal genes were obtained for 14 species of thalassinidean shrimp (families Callianassidae, Laomediidae, Strahlaxiidae, Thalassinidae and Upogebiidae) and a further six species in related decapod infraorders (families Aeglidae, Astacidae, Lithodidae, Palinuridae, Raninidae and Scyllaridae). Maximum-likelihood and Bayesian analyses show equivocal support for the monophyly of the Thalassinidea, but show strong support for division of the infraorder into two major clades. This dichotomy separates representatives in the Upogebiidae, Laomediidae and Thalassinidae from those in the Strahlaxiidae and Callianassidae. The Laomediidae is shown to be paraphyletic, with the thalassinid species, Thalassina squamifera, being placed on a branch between Axianassa and a clade comprising Jaxea and Laomedia, the three current laomediid genera. For a monophyletic Laomediidae, the family Axianassidae should be resurrected for the genus Axianassa.