Molecular phylogeny of porcelain crabs (Porcellanidae:Petrolisthesand allies) from the south eastern Pacific: the generaAllopetrolisthesandLiopetrolisthesare not natural entities

Porcelain crabs from the closely related generaPetrolisthes,Liopetrolisthes, andAllopetrolisthesare known for their diversity of lifestyles, habitats, and coloration. The evolutionary relationships among the species belonging to these three genera is not fully resolved. A molecular phylogeny of the group may help to resolve the long-standing taxonomic question about the validity of the generaAllopetrolisthesandLiopetrolisthes. Using both ‘total evidence’ and single-marker analyses based on a 362-bp alignment of the 16S rRNA mitochondrial DNA and a 328-bp alignment of the Histone 3 nuclear DNA, the phylogenetic relationships among 11 species fromPetrolisthes(6 species),Liopetrolisthes(2 species), andAllopetrolisthes(3 species), all native to the south eastern Pacific, were examined. The analyses supported three pairs of sister species:L. mitra+L. patagonicus,P. tuberculatus+P. tuberculosus, andA. angulosus+A. punctatus. No complete segregation of species, according to genera, was evident from tree topologies. Bayesian-factor analyses revealed strong support for the unconstrained tree instead of an alternative tree in which monophyly of the three genera was forced. Thus, the present molecular phylogeny does not support the separation of the species within this complex into the generaPetrolisthes,Liopetrolisthes, andAllopetrolisthes. Taking into account the above and other recent molecular phylogenetic analyses focused on other representatives from the family Porcellanidae, it is tentatively proposed to eliminate the generaLiopetrolisthesandAllopetrolisthes, and to transfer their members to the genusPetrolisthes.