Mitochondrial genomes of two brachyuran crabs (Crustacea: Decapoda) and phylogenetic analysis

Abstract

The brachyuran crabs are highly diverse and characterized by wide ecological distributions. Brachyura contains Podotremata and Eubrachyura, the latter encompassing Heterotremata and Thoracotremata. Phylogenetic relationships within the Eubrachyura remain controversial, especially regarding monophyly of Heterotremata, and recent morphological and molecular analyses have yielded contrasting results. Phylogenetic reconstruction of Decapoda using mitochondrial genomes has the potential to clarify relationships within Eubrachyura, but have thus far relied on limited sampling. Here, we sequenced the mitochondrial genomes of two basal eubrachyurans, Sinopotamon yangtsekiense (Potamoidea: Potamidae) and Ilyoplax deschampsi (Ocypodoidea: Dotillidae) from subsections Heterotremata and Thoracotremata, respectively. The translocation of tRNAHis compared to the pancrustacean ground pattern was found in mitochondrial genomes of both species. After ruling out the effect of long-branch attraction, our phylogenetic analyses using both nucleotide and amino acid data sets show that the heterotreme crabs G. dehaani and S. yangtsekiense of Potamoidea are associated more closely with thoracotreme crabs, suggesting a paraphyletic Heterotremata. The acceptance of the former implies that the coxal male gonopores combined with sternal female apertures typical of Heterotremata would be a convergent acquisition of true freshwater crabs and the "true heterotreme crabs." © Copyright 2014 by The Crustacean Society.