Cenozoic Biogeographic History of the Eurythermal Genus Retrotapes, New Genus (Subfamily Tapetinae) from Southern South America and Antarctica

Abstract

Retrotapes, new genus, comprises a group of Neoaustral bivalves that appeared in the southern circumpolar regions by the Eocene and have since been confined to the high latitudes of the southern hemisphere. Its presence in the Tertiary strata of Antarctica and southern South America reflects an active faunal interchange between both regions during the Eocene. Retrotapes is here proposed to include to those Recent and Tertiary representatives of the Subfamily Tapetinae (Family Veneridae) from southern South America and Antarctica that had been previously placed in Venus Linné, 1758, Marcia H. and A. Adams, 1857, Eurhomalea Cossmann,1920, Samarangia Dall,1902, and Kalelysia Römer, 1857. The Argentine Tertiary species Retrotapes ninfasiensis, new species, R. fuegoensis, new species, R. striatolamellata (Ihering, 1897) and R. scutata (Ihering, 1907) are here described and illustrated. The Recent Argentine Venus exalbida Chemnitz, 1795 and Venus lenticularis Sowerby, 1835, the Antarctic V. antarctica Sharman and Newton, 1894 and V. newtoni Wilckens, 1911 (Eocene-early Oligocène?, La Meseta Formation), and the Neogene Chilean species V. navidadis Philippi, 1887 and V. colchaguensis Philippi, 1887 are also included in this new genus.