Pleistocene evidence of recently discovered cryptic vermetid species from the Mediterranean

Significant genetic differences between populations previously assigned to Dendropoma petraeum (Monterosato, 1884) from diverse Mediterranean localities have been recently highlighted. Molecular analyses disclosed a complex of at least four cryptic species with highly diverging sequences coupled to a low degree of morphological differentiation or stasis in the adult stages. Differences were found in the early development of intracapsular larval shells. In the present paper the use of morphology and size of intracapsular larval shells preserved in the fossil record is proposed in order to trace genetic divergence in the geological past. The application of this research method in the study of Upper Pleistocene representatives of Dendropoma from Eastern Sicily, allowed documentation of the persistence of the expected clade for the area, at least since the Tyrrhenian Stage. This time interval, of the order of one hundred thousand years, is very short, when compared to the 4.5-17 Myr period indicated as a possible time frame for divergence utilizing the molecular clock. It is suggested that examination of protoconchs of Dendropoma specimens from selected older outcrops within the Mediterranean area could in this case provide more precise information with respect to the extremely broad interval obtained utilizing the molecular clock