Phylogeny of the Decapoda reptantia: Resolution using three molecular loci and morphology

The controversial interrelationships of the major clades of the reptant decapods are resolved by simultaneous analysis of 16S, 18S, and 28S rRNA sequences in combination with morphology. All major reptant clades are represented including the first molecular data for the controversial Polychelidae, Glypheidae, and Enoplometopidae. Interrelations hips of major clades ill the shortest morphological cladograms were identical to those based oil the molecular partition, and were congruent with those of the optimal combined analyses. The optimal tree, namely, that exhibiting minimal overall incongruence between morphological and molecular partitions was achieved under equal transition: transversion weights. Palinura, as traditionally recognised, is polyphyletic corroborating several recent Studies. Infraordinal relationships are robust and insensitive to transition weight variation. For clades previously comprising the Palinura, we recognise Achelata, Polychelida and Glypheidea. Polychelida is sister to the remaining Repantia. Achelata is near basal and sister to Fractosternalia. Contrary to many previous Studies, glypheideans are neither basal reptants, not, are they related to Thalassinidea, Brachyura or Anomra. Glypheidea is sister to Astacidea. A monophyletic Astacidea, comprising the freshwater crayfish (Astacida) and marine clawed lobsters (Homarida), corroborates most previous studies. The enigmatic lobster Enoplometopus (Enoplometopoidea) is confirmed as all astacidean rather than a possible thalassinidean. Unusual characters of the extinct uncinid lobsters, shared with enoplometopids, suggest close affinity, extending the fossil record of the Enoplometopoidea to the Lower Jurassic. The Sterropoda concept, comprising (Thalassinidea (Achelata + Meiura)) is not recognised. The clade formed by Brachyura, Anomura, and Thalassinidea is United by carapace lineae, for which we propose the new name Lineata. Internal relationships of Anomura recovered in our analyses suggest possible paraphyly of Galatheoidea and Paguroidea. Relationships within Brachyura indicate podotreme paraphyly, but greater taxonomic sampling is required to adequately test the status of Podotremata. The anomuran dromiid hypothesis is unsupported. Seven reptantian infraorders are recognised: Polychelida, Achelata. Glypheidea, Astacidea, Thalassinidea, Anomura and Brachyura.