Brewed in the African pot: the phylogeography of the toothed barnacle Chthamalus dentatus (Chthamaloidea: Chthamalidae)

The toothed barnacle Chthamalus dentatus has a wide distribution in the intertidal zone along the coasts of Africa, ostensibly occurring from Madagascar and Mozambique in the West Indian Ocean to Senegal in the Eastern Atlantic Ocean. We studied the differences in the mitochondrial COI gene of 287 individuals from 15 different locations and found that this taxon, which morphologically is considered a single species, actually compromises three genetically distinct clades – the South African, the Namibian, and the Cameroonian. The genetic differences between these units are similar or larger than those found between different species of Chthamalus. We suggest that the nominal species C. dentatus is a cluster of three cryptic species. These cryptic species are separated by a series of upwelling systems that are likely to act as barriers to the distribution of propagules of C. dentatus. Based on molecular and morphological data, we indicate that C. dentatus is probably a close relative of the Caribbean and Central American species of Chthamalus.