Systematics and phylogeography of Cerion sensu stricto (Pulmonata: Cerionidae) from Aruba, Curacao and Bonaire
The systematic relationships of the Cerion uva complex and its constituent taxa are reviewed based on partial sequences of the cytochrome c oxidase I and 16S rDNA genes from 19 populations spanning the geographic range of the species complex and including the type localities of 8 of the 9 subspecies and forms. Molecular data support the conclusion of prior morphometric studies that all living Cerion inhabit- ing Aruba, Curacao and Bonaire are members of a single species, C. uva. Sequence variability among and within populations is not sufficiently discontinuous to segregate populations into discrete, species- level taxa. Three of four subspecies, proposed on the basis of geographic isolation during the Quaternary, C. uva uva (Linnaeus, 1758), the nominotypical subspecies from eastern Curacao, C. uva knipensis Baker, 1924, from western Curacao, and C. uva bonairensis Baker, 1924, from Bonaire, are all supported by dis- tinctive haplotypes. Cerion uva arubanum Baker, 1924, a taxon based on living specimens from Aruba, is shown to be a synonym of C. uva uva, with which it shares a preponderance of haplotypes. It is conjec- tured that C. uva was widespread on Aruba during the Quaternary, but had become extinct on that island, and was reintroduced from a population near Willemstad in eastern Curacao by humans (either by Caquetı ́ o Indians or by European settlers) within the past 800 years. Further investigation is needed to determine if Quaternary Aruban Cerion warrant subspecific recognition. On the island of Curacao, molecular data lend support to the partition of the Cerion fauna into C. uva knipensis, which is confined to an isolated western region, as defined by Baker, and C. uva uva, which inhabits a broad, eastern region that is composed of Baker’s central and eastern regions. A population at Ronde Klip in eastern Curacao has remained genetically isolated, and retains subspecific status as C. uva diablensis Baker, 1924. A neotype is designated for Turbo uva Linnaeus, 1758, as is necessary to provide an objective standard of ref- erence for this species-group taxon, and for the genus- and family-level taxa based upon it.