Redescription, shell variability and geographic distribution of Plagiodontes dentatus (Wood, 1828) (Gastropoda: Orthalicidae: Odontostominae) from Uruguay and Argentina.

PIZÁ JULIA; CAZZANIGA NÉSTOR J.

Zootaxa

Magnolia Press

Año: 2003 vol. 154 p. 1 - 23

1175-5334

Plagiodontes dentatus (Wood, 1828) is the type species of a South American genus including eightnamed species that show a high degree of local endemism. Due to some misidentifications with P.multiplicatus (Doering, 1874) and P. daedaleus (Deshayes, 1851), P. dentatus has been cited asinhabiting two disjunct areas with quite different ecological conditions. In this paper the identity ofthis morphospecies is clarified through a study of shell sculpture and apertural teeth data, and acomparison with the smaller adult specimens (<25 mm long) of its closest species, P. patagonicus(d’Orbigny, 1835) and P. multiplicatus, i.e., the only shells to which P. dentatus could have beenconfounded. A statistical analysis of shell variability revealed that, beyond the qualitative diagnostic characters, there are significantly different shell proportions that also define P. dentatus. The distribution of P. dentatus over two disjunct areas is not supported, its confirmed geographic range being restricted to the Oriental Republic of Uruguay and the Argentine provinces of Entre Ríos and northeastern Buenos Aires. An intraspecific multivariate analysis upholds the opinion that any subspecific discrimination is unwarranted.