The Gastropod Genus Nerita in the Neogene of Tropical America

The neritid neritaemorph gastropod genus Nerita Linnaeus, 1758, is represented by two new species in the Cantaure Formation (Early Miocene: Burdigalian) of Venezuela. Nerita (Nerita) rugulosa n. sp. is the earliest known member of Nerita s.s., a clade of tropical American species that also includes the Recent West Indian N. peloronta Linnaeus, 1758, and N. versicolor Gmelin, 1791, and the eastern Pacific N. scabricosta Lamarck, 1822. Nerita rugulosa differs from these species by having fewer, more prominent spiral ribs and a conspicuously ridged, pustulose septum. Nerita (Theliostyla) paucigranosa n. sp. is related to the Recent western Atlantic N. fulgurans Gmelin, 1791, and the eastern Pacific N. funiculata Menke, 1850, but differs from these species by its larger size and by having fewer, more prominent septal pustules. We report N. (T.) exuvioides Trechmann, 1935, previously known from the Point Hilaire beds of Carriacou and the Gatun Formation of Panama, from the Baitoa Formation (early Middle Miocene) of the Dominican Republic. Nerita oligopleura Dali & Ochsner, 1928, from the Pliocene of the Galapagos Islands, is here tentatively assigned to the subgenus Ilynerita von Martens, 1887. Members of the Nerita ascensionis Gmelin, 1791, complex in the southwest Atlantic are removed from Theliostyla Mörch, 1852, and recognized as related to N. magdalenae Gmelin, 1791. from the southwestern Indian Ocean. Nerita magdalenae Collignon & Cottreau, 1927, from the Miocene of Madagascar, is renamed N. valdespinosa. We assign Nerita chilensis Philippi, 1887, from the Navidad Formation of Chile, to the subgenus Lisanerita Krijnen, 2002; and we more tentatively assign Nerita joaquinensis Addicott, 1970, from the Round Mountain Silt (Middle Miocene) of California to the same subgenus.