Worldwide phylogeography of limpets of the order Patellogastropoda: molecular, morphological and palaeontological evidence

Abstract

ABSTRACTA molecular phylogeny, based on sequence data from three mitochondrial (12S rRNA, 16S rRNA and COI) genes, is presented for the Patellogastropoda, including representatives of almost all genera belonging to the Acmaeidae, Lepetidae, Lottiidae, Nacellidae and Patellidae. For comparison, a smaller dataset of sequences from two nuclear (18S rRNA and 28S rRNA) genes is presented. The mitochondrial gene phylogeny shows considerable disagreement with earlier hypotheses derived from morphological data. The Patellidae, Nacellidae and Lepetidae are monophyletic, but the Acmaeidae and Lottiidae are polyphyletic. The family Acmaeidae is divided into two clades corresponding to the subfamilies Acmaeinae and Pectinodontinae, but these two do not form a clade. The Acmaeinae are synonymized with the Lottiidae, and the Pectinodontinae are elevated to familial rank. Our results suggest that the Patelloida profunda group (formerly assigned to the Lottiidae) is the most basal group within the Patellogastropoda. We assign this group to a new genus, Eoacmaea, in the new family Eoacmaeidae. We used a Bayesian Markov-Chain Monte Carlo approach together with the fossil record to estimate divergence times from the combined DNA sequence data. The lineage of extant Patellogastropoda is estimated to have originated as long ago as Late Jurassic. The phylogeny also suggests that the principal clades and antitropical distribution pattern of the Patellogastropoda formed during the Mesozoic to early Cenozoic, in association with the disruption of Pangea and following the establishment and decline of the circumglobal equatorial current.