ABSTRACT
We conducted a molecularly based phylogenetic analysis with representatives of the thalassinidean families Axianassidae, Axiidae, Callianassidae, Callianideidae, Calocarididae, Ctenochelidae, Laomediidae, Micheleidae, Strahlaxiidae, Thalassinidae, Thomassiniidae, and Upogebiidae, along with decapod outgroup taxa representing the infraorders Anomura, Astacidea, Brachyura, Caridea, and Achelata. Analyses were based on two datasets, one corresponding to a partial fragment of the 16S mitochondrial gene and a second to a partial fragment of the 18S nuclear gene, representing roughly 1,800 nuclear and 550 mitochondrial characters. We incorporated 34 genera and 50 species in the analysis upon which our molecular phylogenetic trees were based and compared outcomes to morphologically based phylogenies. Our analysis finds the infraorder Thalassinidea to be paraphyletic, as presently comprised. We also find no support for monophyly in either the superfamily Axioidea or the superfamily Callianassoidea. Two large clades into which the infraorder is divided instead recall arrangements that were based upon larvae by Gurney and subsequently supported in some early taxonomic revisions. We conclude that these clades deserve separate infraordinal status, and we draw upon the work of de Saint Laurent for the name of each. One we refer to the infraorder Gebiidea, encompassing representatives of Upogebiidae, Laomediidae, Thalassinidae, and Axianassidae. The other we refer to Axiidea, encompassing Callianassidae, Ctenochelidae, Strahlaxiidae, Micheleidae, Callianideidae, Thomassiniidae, Axiidae, and Calocaridae. We accept previous evidence merging Eiconaxiidae with the Axiidae, and we suggest the Calocarididae should be likewise merged. We also present evidence to support merging of Thomassiniidae back into Callianideidae.
1 INTRODUCTION
