See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/255483376 Cenozoic Biogeographic History of the Eurythermal Genus Retrotapes, New Genus (Subfamily Tapetinae) from Southern South America and Antárctica Article in Nautilus -Greenville then Sanibel- · July 1997 CITATIONS READS 27 119 1 author: Claudia Julia Del Río National Scientific and Technical Research Council 122 PUBLICATIONS 981 CITATIONS SEE PROFILE Some of the authors of this publication are also working on these related projects: Controles extrínsecos e intrínsecos de los depósitos sedimentarios del Paleógeno y Neógeno temprano en las cuencas patagónicas de San Jorge y Austral, Argentina. PIP- CONICET 523 (2016-2018) View project Contingencies and the assembly of an extant biota - Southwestern Atlantic biogeography in historical perspective. PICT- RAICES 0057 - ANPCyT (2012-2017) View project All content following this page was uploaded by Claudia Julia Del Río on 29 May 2014. The user has requested enhancement of the downloaded file. THE NAUTILUS 110(3):77-93, 1997 Page 77 Cenozoic Biogeographic History of the Eurythermal Genus Retrotapes, New Genus (Subfamily Tapetinae) from Southern South America and Antárctica Claudia Julia del Río Centro de Investigaciones en Recursos Geológicos Ramírez de Velazco 847 (1414) Buenos Aires ARGENTINA and Facultad de Ciencias Exactas y Naturales Universidad de Buenos Aires Ciudad Universitaria Pabellón 2 Nuñez (1428) ARGENTINA ABSTRACT sented by more than seventy species. Most of the Indo- Pacific genera, among them Katelysia Romer, 1857, Retrotapes, new genus, comprises a group of Neoaustral bi- Marcia H. & A. Adams, 1857, Granicorium Hedley, valves that appeared in the southern circumpolar regions by 1906, Hemitapes Rómer, 1864, Notirus Finlay, 1928, the Eocene and have since been confined to the high latitudes Notopaphia Oliver, 1923, Eumarcia Iredale, 1924, Pa- of the southern hemisphere. Its presence in the Tertiary strata of Antárctica and southern South America reflects an active phirus Finlay, 1927, and Gomphinella Marwick, 1927, faunal interchange between both regions during the Eocene. are restricted to New Zealand and Australia. Others, Retrotapes is here proposed to include to those Recent and including Gomphina Morch, 1853, Venerupsis Lamarck, Tertiary representatives of the Subfamily Tapetinae (Family 1818, Ruditapes Chiamenti, 1900, Tapes Mergele von Veneridae) from southern South America and Antárctica that Mühlfeld, 1811, and Paphia Róding, 1798, are also found had been previously placed in Venus Linné, 1758, Marcia H. beyond those regions. and A. Adams, 1857, Eurhomalea Cossmann,1920, Samarangia In contrast, Recent tapetines are poorly represented Dall,1902, and Kalelysia Rómer, 1857. The Argentine Tertiary in the littoral zones along both coasts of the American species Retrotapes ninfasiensis, new species, R. fuegoensis, continents. The subfamily is known from only twelve new species, R. striatolamellata (Ihering, 1897) and R. scutata living North American species distributed among the (Ihering, 1907) are here described and illustrated. The Recent Argentine Venus exalbida Chemnitz, 1795 and Venus lentic- genera Ruditapes, Liocyma Dalí, 1870, Psephidia Dalí, ularis Sowerby, 1835, the Antarctic V. antárctica Sharman and 1902 and Irus Schmidt, 1818, as well as uve South Amer- Newton, 1894 and V. newtoni Wilckens, 1911 (Eocene-early ican taxa assigned to the genera Eurhomalea Cossmann, Oligocene?, La Meseta Formation), and the Neogene Chilean 1920 and Retrotapes, new genus. species V. navidadis Philippi, 1887 and V. colchaguensís Phi- The fossil record in the Americas reveáis that Tape- lippi, 1887 are also included in this new genus. tinae were more abundant in the Tertiary than in the Key words: Tapetinae, Retrotapes, new genus, biogeography, Recent fauna. Two diverse and different assemblages Neoaustral, Tertiary, Argentina, Chile, Antárctica. appeared during the Tertiary, one restricted to North America, the another to austral latitudes. The northern assemblage comprises the endemic genera Liocyma, Cy- clorisma Dalí, 1902, Psephidia and Sinonia Stephenson, INTRODUCTION 1952, as well as taxa with european affinities such as Mercimonia Dalí, 1902, Flaventia Jukes-Browne, 1908, The Subfamily Tapetinae (Family Veneridae) shows a Paraesa Casey, 1952 , Legumen Conrad, 1858 and Tex- moderately high degree of endemism in Recent as well tivenus Cossmann, 1886. The less diverse austral assem- as in Tertiary faunas. The known geographic distribution blage, characterized by Eumarcia, Katelysia, Atamarcia of most living tapetines is mainly restricted to the south- Marwick, 1927 and Retrotapes, appeared during the ear- ern hemisphere. This Subfamily is particularly abundant ly Tertiary in the southernmost región of South America in the southern Indo-Paciñ'c región, where it is repre- and Antárctica. Page 78 THE NAUTILUS, Vol. 110, No. 3 Figure 2. Geographic distribution of fossil localities referred to in this paper. Figure 1. Stratigraphic distribution of Retrotapes, new genus, in South America and Antárctica. tica), and the Chilean species V. navidadis Philippi, 1887 (early Miocene), V. colchaguensis Philippi, 1887 (early The species that are here included in Retrotapes occur Miocene-Pliocene) and V. lenticularis (Pliocene-Holo- in the Tertiary rocks of Chile, Antárctica and Argentina, cene), along with the Recent V. exalbida, are also placed and are at present distributed in the littoral zones along in Retrotapes. both coasts of South America (Figure 1), where they are represented by R. lenticularis (Sowerby, 1835) and fí. exalbida (Chemnitz, 1795). MATERIAL AND METHODS This paper includes the systematic description of the The fossil material reported here carne from the thick, Tertiary Argentine representatives of Retrotapes: R. nin- marine, sedimentary, Tertiary sequence exposed along fasiensis new species (Puerto Madryn Formation, middle the eastern coast of Patagonia from San Antonio Oeste Miocene), R. fuegoensis new species (Carmen Silva For- (Río Negro Province), southward to Isla Grande of Tierra mation, late Oligocene-early Miocene), fí. striatolamel- del Fuego, and at Cerro Puntudo (Lago Cardiel), a lo- lata (Ihering, 1897) (Monte León Formation, late Oli- cality situated in the western región of Patagonia (Santa gocene-early Miocene) and El Chacay Formation (late Cruz Province) (Figure 2). Lithostratigraphic units yield- Eocene) and ñ. scutata (Ihering, 1907) (San Julián For- ing representatives of Retrotapes are the Puerto Madryn mation, late Eocene). Venus antárctica Sharman and Formation (Haller, 1978), the Monte León Formation Newton, 1894 and V. newtoni Wilckens, 1911 from the (Bertels, 1970), the Carmen Silva Formation (Codignotto Eocene-early Oligocene? La Meseta Formation (Antarc- & Malumián, 1981), the San Julián Formation (Bertels, Claudia Julia del Río, 1997 Page 79 1970) and the El Chacay Formation (Chiesa & Camacho, documented by del Río (1995). Only one fairly well- 1984). preserved valve of Retrotapes is known from the up- The Puerto Madryn Formation, exposed at Península permost, highly-fossiliferous, orange coquinoid sand- Valdés (Chubut Province), is believed to represent one stones that altérnate with green or yellowish gray silstones of the youngest Tertiary marine units recognized in Pa- and sandstones exposed at Cañadón El Lobo. tagonia, having been reported by del Río (1988, 1992) Retrotapes is poorly represented in the El Chacay as being of middle Miocene age. This formation consists Formation, exposed at Cerro Puntudo (Lago Cardiel). of 150 meter thick, whitish cinerites and yellowish sand- Chiesa and Camacho (1994) placed this unit in the late stones alternating with highly fossiliferous calcareous Eocene based on biostratigraphic correlations with the sandstones and muddy or sandy shelly beds. Retrotapes San Julián Formation. is abundant at the basal ochreous shelly sandstones that Specimens described in this paper are housed in the are exposed at Cerro Prismático (horizon N 2, del Río, Museo Argentino de Ciencias Naturales "Bernardino Ri- 1992), where it is associated with "Chlamys" actinodes vadavia" (MACN), Buenos Aires, Argentina, in the Cen- (Sowerby, 1846), Purpurocardia leonensis del Río,1986, tro de Investigaciones en Recursos Geológicos (CIRGEO- Glycymerita magna del Río, 1992, Aequipecten para- PI), Buenos Aires, Argentina, Facultad de Ciencias Ex- nensis (d'Orbigny, 1842), Dosinia meridionalis (Ihering, actas y Naturales of the Universidad de Buenos Aires 1897) as well as with the gastropod Valdesia valdesiensis (CPBA), Buenos Aires, Argentina, Dirección Nacional del Río, 1985. Retrotapes is less common in the gray, Servicio Geológico (DNSG), Buenos Aires, Argentina and massive, fine sandstones that comprise the base of the in the Department of Earth and Atmospheric Science, section at Punta Norte (horizon PN 2, del Río, 1992), Purdue University (PU), Indiana, USA. where articulated specimens have been found in life positions along with Anadara (Rasia) lirata (Philippi, 1893), Glycymeris longioriformis del Río, 1992, Lucinisa SYSTEMATIC PALEONTOLOGY sp., "Cyclocardia" nortensis del Río, 1986, Dosinia mer- Phylum MOLLUSCA Linné, 1758 idionalis (Ihering, 1897), Dosinia cuspidata del Río, 1994, Class BI VAL VIA Linné, 1758 Ameghinomya meridionalis (Sowerby, 1846) and A. argentina (Ihering, 1897). Retrotapes also occurs in the Subclass HETERODONTA Neumayr, 1884 strata placed at the top of the sequence exposed at Punta