Abstract
Plagiodontes dentatus (Wood, 1828) is the type species of a South American genus including eight named 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 as inhabiting two disjunct areas with quite different ecological conditions. In this paper the identity of this morphospecies is clarified through a study of shell sculpture and apertural teeth data, and a comparison 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 been confounded. 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.
References
Breure, A.S.H. (1974) Catalogue of Bulimulidae (Gastropoda, Euthyneura). II. Odontostominae. Basteria, 38, 109-127.
Breure, A.S.H. (1979) Systematics, phylogeny, and zoogeography of the Bulimulinae (Mollusca). Zoologische Verhandelingen, 168, 1-215, 3 plates.
Buggisch, W. (1997) Stratigraphy and very low grade metamorphism of the Sierras Australes de la Provincia de Buenos Aires (Argentina) and implications in Gondwana correlations. Zentralblatt für Geologie und Paläontologie, Teil I, 7/8, 819-837.
Cabrera, A.L. & Willink, A. (1972) Biogeografía de América Latina. Monografías, Serie Biología, 13. Organización de los Estados Americanos, Washington, DC., 120 pp.
Cazzaniga, N.J. & Fernández-Canigia, M.V. (1985) Aporte al conocimiento de Plagiodontes patagonicus (d’Orbigny) y P. magnus Hylton-Scott (Gastropoda: Odontostomidae). Spheniscus, 1, 35-51.
Cei, J. M. (1972) Segregación corológica y procesos de especiación por asimilamiento en anfibios de la Pampa de Achala, Córdoba. Acta Zoologica Lilloana, 29, 233-244.
d’Orbigny, A.D. (1835) Synopsis terrestrium et fluviatilium molluscorum in suo per Americam Meridonalem itinere ab A. d’Orbigny collectorum. Magasin de Zoologie, 5, 1-44.
d’Orbigny, A.D. (1835-1846) Voyage dans l’Amérique Méridionale. Vol. 5, Mollusques. P. Bertrand, Paris.
Fernández, D. (1973) Catálogo de la malacofauna terrestre argentina. Monografías 4. Comisión de Investigaciones Científicas de la Provincia de Buenos Aires. La Plata, Argentina, 197 pp.
Figueiras, A. (1963) Enumeración sistemática de los moluscos terrestres del Uruguay. Comunicaciones de la Sociedad Malacológica del Uruguay, 1, 79-96.
Hanley S. (1856). Index Testaceologicus, an illustrated catalogue of British and foreign shells, containing about 2800 figures, accurately coloured after nature by W. Wood, F.R.S., F.L.S. A new and entirely revised edition. London, Willis and Sotheran.
Hylton-Scott, M.I. (1948) Moluscos del biotopo de Cerro Colorado (Salta). Acta Zoologica Lilloana, 6, 229-239.
Hylton-Scott, M.I. (1951) Nuevos moluscos terrestres del norte argentino. Acta Zoologica Lilloana, 10, 5-29.
Iriondo, M.H. & García, N.O. (1993) Climatic variations in the Argentine plains during the last 18,000 years. Palaeogeography, Palaeoclimatology, Palaeoecology, 101, 209-220.
Klappenbach, M.A. & Olazarri, J. (1973) El género Scalarinella Dohrn, 1874 (Moll. Gastropoda) en el Uruguay. In: Congreso Latinoamericano de Zoología, 5. Montevideo, October 18-23, 1971. Trabajos, 1, 111-116.
Marshall, W.B. (1931) New land and fresh-water mollusks from South America. Proceedings of the United States National Museum, 77(2), 1-7 + 2 plates.
Parodiz, J.J. (1939) Revisión de Plagiodontes y Scalarinella (Odontostominae). Physis, 17, 711- 734.
Parodiz, J.J. (1942) Los Odontostominos de la Argentina (Segunda parte). Physis, 19, 319-343.
Parodiz, J.J. (1951) Métodos de conquiliometría. Physis, 20, 241-248.
Parodiz, J.J. (1957) Catalogue of the land Mollusca of Argentina [Second part]. The Nautilus, 71, 22-30.
Pilsbry, H.A. (1898) Notes on the genus Odontostomus. The Nautilus, 12, 57-58.
Pilsbry, H.A. (1902) Manual of Conchology. Second Series: Pulmonata Vol. XIV. Conchological Section, Academy of Natural Sciences of Philadelphia, 302 pp. + 62 plates.
Politis, G. (1984) Climatic variations during historical times in eastern Buenos Aires pampas. Quaternary of South America and Antarctic Peninsula, 2, 133-161. Balkema, Rotterdam.
Richardson, C.L. (1993) Bulimulacea: Catalog of species. Amphibulimidae, Anadromidae, Gangrellidae, Odontostomidae, Orthalicidae. Tryonia, 27, 1-164.
Ringuelet, R.A. (1961) Rasgos fundamentales de la zoogeografía de la Argentina. Physis, 22, 151- 170.
Ringuelet, R.A. (1978) Dinamismo histórico de la fauna brasílica en la Argentina. Ameghiniana, 15, 255-262.
Tonni, E.P. (1992) Mamíferos y clima del Holoceno en la provincia de Buenos Aires. In: Iriondo, M. (Ed.), El Holoceno en la Argentina 1. CADINQUA, Comité Argentino de Investigación del Cuaternario, Buenos Aires, 64-78.
Tonni, E.P. & Fidalgo, F. (1978) Consideraciones sobre los cambios climáticos durante el Pleistoceno tardío-Reciente en la provincia de Buenos Aires. Aspectos ecológicos y zoogeográficos relacionados. Ameghiniana, 15, 235-253.