Molecular analysis of the commercial deep-sea crabs Chaceon ramosae and Chaceon notialis (Brachyura, Geryonidae) reveals possible cryptic species in the South Atlantic

• Exhaustive phylogenetic analyses of the crab species of genus Chaceon from different areas of southern Atlantic were performed.
• Emphasis was given on molecular phylogenetic context to help the fisheries strategies and stock regulations.
• Our research represents the first description, based on mtDNA, on this relationship between the group of species.

Deep-sea red crabs Chaceon ramosae and Chaceon notialis are commercially and ecologically important crustaceans in South Atlantic waters. With some overlapping occurring at the edge of the crabs’ distribution, the fisheries are managed separately in Brazil and Uruguay, with some differences in the regulations, although the stock is supposedly shared between the two countries. To assess genetic information on these two species, we examined the nucleotide sequence of the mitochondrial 16S rDNA and CO1 mtDNA genes in samples from the southern region. We also compared these data to sequences from other congeners. The genetic analysis revealed a clear separation between C. notialis and C. ramosae. In addition, we detected the existence of at least two different groups within the species that is currently recognized as C. notialis. This might indicate the existence of cryptic species, leading us to speculate about the presence of two different taxonomic entities, although further research is needed to resolve this issue.