Morphological and molecular support for Amphithrax verrucosus (H. Milne Edwards, 1832) and Amphithrax aculeatus (Herbst, 1790) (Crustacea, Decapoda, Brachyura) as valid species

The large degree of morphological variations, particularly amongst juveniles, has led to inconsistencies in the literature regarding the taxonomic status of Amphithrax aculeatus (Herbst, 1790) and Amphithrax verrucosus (H. Milne Edwards, 1832). As a result of recent biodiversity sampling initiatives in Barbados, West Indies, multiple specimens of Amphithrax aculeatus and A. verrucosus have been collected. This has prompted us to undertake a thorough reassessment of their morphological and molecular characteristics. Moreover, morphological differences in the carapace, antennae, chelipeds, pereopods and the male first gonopod (G1) supports A. aculeatus and A. verrucosus as separate species. Molecular phylogenetic analysis, based on newly-generated sequences of the 12S rRNA, 16S rRNA and ITS-1 genes also shows that A. verrucosus is a separate species and sister taxa to A. aculeatus. The total number of species within the genus Amphithrax is now brought to eleven. However, our molecular analysis also shows that the taxonomic placement of Amphithrax armatus (Saussure, 1853) within Amphithrax is questionable.