Allopatry and anatomical distinctiveness of two puzzling land snails in genus Plagiodontes, from Argentina (Gastropoda: Orthalicidae, Odontostominae)

PIZÁ, JULIA; CAZZANIGA, NÉSTOR J.

MALACOLOGIA

The Field Museum

Lugar: Chicago; Año: 2010 vol. 53 p. 1 - 24

0076-2997

Plagiodontes daedaleus (Deshayes, 1851) is the most widespread species in genus Plagiodontes Doering, 1877. Although some 19th century authors recorded some differences in shell shape between the populations living to the East or to the West of the Pampean Sierras (Argentina), such differences were ignored by later authors. A multivariate statistical analysis on 608 adult shells collected at 29 localities in and around these sierras was used to test if such narratively described shell differences were statistically significant, irrespectively of their taxonomic status. Shells classified as collected from the East or the West of the sierras were correctly identified in 91.9 % of the cases by a Multivariate Discriminant Analysis, leading to recognize the objectivity of two allopatric shell morphologies. These external divergences were found to concur with anatomical differences in the reproductive system that lead us to conclude that two different, allopatric species were merged together under the name Plagiodontes daedaleus in the literature; so we raise the subspecies Plagiodontes daedaleus strobelii (Doering, 1877) to the specific level. Another subspecies living to the west of the sierras, Plagiodontes daedaleus salinicola (Doering, 1877), also showed a simple penis papilla and a non swollen vagina that warrant salinicola not being a member of P. daedaleus but a population of  P. strobelii that do not deserve any subspecific status. The taxonomic significance of the presence of either a simple penial papilla or a papilla bearing an accessory lobe was also confirmed for these Plagiodontes species.