Phylogenetic position of two Patagonian Cibicididae (Rotaliida, Foraminifera): Cibicidoides dispars (d’Orbigny, 1839) and Cibicidoides variabilis (d’Orbigny, 1826)

Cibicidoides dispars and Cibicidoides variabilis are two neritic cibicidids commonly found on the Patagonian coasts. Phylogenetic analyses of partial SSU rDNA sequences show that they both belong to the genus Cibicidoides. Cibicidoides dispars branches close to Cibicidoides wuellerstorfi, whereas C. variabilis clusters with Cibicidoides pachyderma. In both cases, species clustering together are well separated morphologically and ecologically but close genetically. Molecular data indicate clearly that C. dispars and C. variabilis are well separated genetically from Cibicidoides lobatulus, another shallow water cibicidid sharing a similar ecology and morphology. Moreover, our molecular results show that neritic and bathyal or abyssal species are found together in different clades, suggesting multiple colonization events from shallow to deep water or vice versa. The analysis of more variable ITS rDNA region, on the other hand, reveals small differences between individuals of C. variabilis sampled in the south and north of Chilean Patagonia, which could indicate a cryptic speciation undergoing in this species.