Molecular Phylogenetics of Trapezia Crabs in the Central Mexican Pacific

Abstract

To date, Trapezia spp. crabs have been considered obligate symbionts of pocilloporid corals. They protect their coral hosts from predators and are essential for the health of certain coral species. However, the basic details of this group of crustaceans are lacking, and there is a need for species-level molecular markers. The Tropical Eastern Pacific (TEP) region harbors important coral communities mainly built by corals of the genus Pocillopora, with three known Trapezia species known to associate with them: Trapezia bidentata, T. formosa and T. corallina. Both taxonomic and molecular analyses were carried out with samples of all three crab species collected from Pocillopora spp. in the Central Mexican Pacific. Analysis of both a mitochondrial and a nuclear gene revealed only two species, T. corallina and T. bidentata. T. formosa however appears to be a morphotype of T. bidentata. The use of integrative taxonomy for this group has increased the knowledge of the biodiversity not only of the study area, but of the whole TEP and will enhance the future study of the Trapezia–Pocillopora symbiosis.