Molecular phylogenetic reassessment of eastern Atlantic Callinectes (Brachyura, Portunidae)

Abstract Several species from the genus Callinectes are economically important, yet the number of species and their geographic distributions remain unclear. Recently, one of the American species, Callinectes larvatus , was synonymized with one of the African species, C. marginatus , making C. marginatus the only species of the genus regarded to be amphi-Atlantic in distribution. However, there was no formal taxonomic study to support this taxonomic change, which was in contradiction to earlier studies that had provided morphological characters to support the taxonomic separation of the eastern Atlantic species from those of western Atlantic distribution. Callinectes maracaiboensis has also been questionably resurrected. Here we present a molecular based analysis for all species of Callinectes , using the two common mitochondrial genes 16S and 12S. Our molecular data support the presence of three eastern Atlantic, three eastern Pacific, and nine western Atlantic species. Historically, it appears that the separation of Africa and South America with the opening of the Atlantic basin gave rise to sister species distributed on opposite sides of the Atlantic Ocean. In a second isolation event, the emergence of the Panamanian isthmus resulted in pairs of geminate species distributed in eastern Pacific and western Atlantic waters.