The Patagonian Herpetofauna José M. Cei Instituto de Biología Animal Universidad Nacional de Cuyo Casilla Correo 327 Mendoza, Argentina Reprinted from: Duellman, William E. (ed.). 1979. The South American Herpetofauna: Its origin, evolution, and dispersal. Univ. Kansas Mus. Nat. Hist. MonOgr. 7: 1-485. Copyright © 1979 by The Museum of Natural History, The University of Kansas, Lawrence, Kansas. 13. The Patagonian Herpetofauna José M. Cei Instituto de Biología Animal Universidad Nacional de Cuyo Casilla Correo 327 Mendoza, Argentina The word Patagonia is derived from the longed erosion. Scattered through the region term “Patagones,” meaning big-legged men, are extensive areas of extrusive basaltic rocks. applied to the tall Tehuelche Indians of The open landscape is dissected by transverse southernmost South America by Ferdinand rivers descending from the snowy Andean Magellan in 1520. Subsequently, this pic­ cordillera; drainage is poor near the Atlantic turesque name came to be applied to a con­ coast. Patagonia is subjected to severe sea­ spicuous continental region and to its biota. sonal drought with about five cold winter Biologically, Patagonia can be defined as months and a cool dry summer, infrequently that region east of the Andes and extending interrupted by irregular rains and floods. southward to the Straits of Magellan and eastward to the Atlantic Ocean. The northern boundary is not so clear cut. Elements of the HISTORY OF THE PATAGONIAN BIOTA Pampean biota penetrate southward along the coast between the Rio Colorado and the Rio In contrast to the present, almost uniform Negro (Fig. 13:1). Also, in the west Pata­ steppe associations in Rio Negro, Chubut, gonian landscapes and biota enter the vol­ and Santa Cruz provinces, during Oligocene canic regions of southern Mendoza, almost and Miocene times tropical and subtropical reaching the Rio Atuel Basin. The Pata­ vegetation occurred along with xerophytic gonian region has a wide ecotonal zone with woodlands with luxuriant mesophytic gallery the Chacoan region (Gallardo, this volume). forests. A comparison of the rich Miocene The monte vegetation (Morello, 1958) with flora of Pichi Leufu, Rio Negro (Berry, 1938) its several formations containing numerous with analagous associations from Mirhoja, subtropical elements extends south to the Chubut; Valcheta, Rio Negro; and Rio Chalia, Peninsula de Valdes; the monte enters the Santa Cruz, shows a mixture of mesic tropical Rio Chubut drainage and extends westward elements (Ficus, Fagara, Nectandra, Tabe- to the Río Neuquén, Río Agrio, and Rio Limay buia, Myristica, Sterculia, tree fems, Erythro- valleys. South of the Rio Negro, the monte xylon, Oreopanax, Maytenus), including associations exist in a system of saline low­ climbers (Buettneria, Banisteria, Bignonia, lands (bajos) and reach irregular spurs of Cissus, Paullinia, Sapindus, Strychnos), to­ the Meseta de Somuncurá, a typical Patagon­ gether with nontropical genera (Araucaria, ian environment (Cei, 1969a,b; Ruiz Leal, Azora, Berberís, Ginkgo, Laurelia, Emboth- 1972). Nevertheless, there is a general, some­ rium, Fitzroya, Libocedrus, Podocarpus, Lo- times remarkable, agreement between the matia, Peumus, Myrceugenia, Drimys). Most phytogeographic boundaries of the Monte- of the latter are characteristic components of Pampean and the Patagonian regions and the the present temperate Valdivian forest. Nev­ distribution patterns of their herpetofaúnas. ertheless, xeric areas in the Middle Tertiary Herein I emphasize the biota of the Cis- of Patagonia are suggested by certain paleo­ Andean steppe to the near exclusion of the floras containing Schinopsis, Schinus, and Cu- Trans-Andean austral forest ecosystems pania. The former is a significant genus of treated by Formas (this volume). trees in the subtropical Chacoan region. Patagonia is a region of sedimentary rocks Nothofagus forests were widespread in and soils, mostly tablelands subjected to pro­ Patagonia in the Eocene and Oligocene, but 309 310 MONOGRAPH MUSEUM OF NATURAL HISTORY NO. 7 Fig. 13:1. Phytogeographic regions of austral South América. Regiones fito geográficas de Sud América austral. 1979 CEI: PATAGONIAN HERPETOFAUNA 311 Fig. 13:2. Paleontological records of the lower Tertiary Patagonian flora and of leptodactylid frogs. Hallazgos paleontológicos de flora patagónica del Terciario inferior y de anuros leptodactylidos. 312 MONOGRAPH MUSEUM OF NATURAL HISTORY NO. 7 these associations decreased and retreated history of tropical elements in Patagonia. The southward and westward in the Middle and fossil snake Dinilysia patagónica from the Late Tertiary. Chusquea bamboo groves oc­ Upper Cretaceous of Neuquén is related to cur in Cenozoic deposits at Laguna Hunco, boids and aniliids that are widespread in trop­ Chubut. Further evidence of paleoclimatic ical South America. Furthermore, boid snakes conditions in Patagonia is derived from the (Madtsoia), crocodilians (Necrosuchus, Se- extensive paleo-mammal faunas (Báez and becus, Eocaiman), and meiolaniid and pelo- Scillato Yané, this volume) and more limited medusid turtles from Paleocene-Eocene de­ paleo-herpetofaunas ( Báez and Gasparini, posits in Chubut are indicative of tropical this volume). environments (Gasparini and Báez, 1975). Primitive leptodactylid, ceratophrynine, Iguanid (Erichosaurus debilis) and teiid (Di- and bufonid frogs have been recorded by asemosaurus occidentalism lizards lived in Schaeffer (1949), Chaffee (1952), and Casa- southern Santa Cruz in the Miocene. miquela (1963) from the Deseadan, early Oligocene Scarritt Pocket Formation (Can­ quel, Chubut) and from the upper Miocene PATAGONIAN FAUNAL REGIONS of Rio Negro (Fig. 13:2). The living Chilean frog Caudiverbera caudiverbera is almost Two major faunal regions (habitats) can identical to the fossil frogs of the same genus. be defined in Patagonia. These are the north­ A fossil frog from the Oligocene of Chubut ern or ancient region and the southern or referred to Eupsophus by Schaeffer (1949) Santa Cruz region; the border between these has been considered the same as living E. regions is approximately at the Rio Chubut roseus, a species characteristic of the Notho- at 45°S (Fig. 13:3). These habitats corre­ fagus forests of southern Chile ( Bogart, spond to ancient physiographic areas, the 1970). These fossils clearly establish the pres­ Patagonian Massif and the Deseado Massif, ence of telmatobiine frogs in Patagonia in respectively (Figs. 13:4-5). These massifs the Oligocene and Miocene. are ancient structural continental units known as nesocratons (Harrington, 1962). In spite The Oligocene Neoprocoela was provision­ of its less marked subpositive tendency in ally referred to a Batrachophrynus or Telma- comparison with the Pampean Massif, the tobius-iike leptodactylid stock by Schaeffer whole region of the Patagonian Massif has (1949). Tihen (1962) considered it to be a been a site of almost uninterrupted accumu­ species of Bufo in the Palearctic Bufo cala­ lation of continental deposits. More rarely it mita group. The fossil was again associated received shallow marine deposits peripherally with the telmatobiine genera Telmatobufo at times of oceanic transgressions in the and Batrachophrynus by Lynch ( 1971 ). New Eocene-early Oligocene, middle Oligocene, material from the same formation supports and middle Miocene. The smaller Deseado the inclusion of Neoprocoela in Bufo (Estes, Massif had a subpositive tendency even less pers. comm.). The placement of Neoprocoela marked than the Patagonian Massif; accord­ in the Bufo calamita group has interesting ingly, its relief was often depressed, and dur­ biogeographical implications. Serological evi­ ing prolonged subsidences it became a sedi­ dence (Cei, 1977) supports a relationship be­ mentary area like the adjacent pericratonic tween the European Bufo calamita and the basins (Harrington, 1962). small B. variegatus presently restricted to the austral Nothofagus forests of Argentina and The northern or ancient Patagonian re­ Chile (Gallardo, 1962). gion extends through Neuquén, Río Negro, and Chubut provinces (Fig. 13:6). The sub- The presence of a ceratophrynine frog cordilleran area in Neuquén is drained by the (Wawelia gerholdi) in the Miocene provides Río Agrio and Río Neuquén, which flow into herpetological evidence for the southward ex­ the Rio Limay, a tributary of the Rio Negro. tent of tropical elements in the Middle Ter­ Extra-cordilleran mesetas include the large tiary. Reptilian remains substantiate the long Meseta de Somuncurá (1000-1700 m eleva- 1979 CEI: PATAGONIAN HERPETOFAUNA 313 Fig. 13:3. Major herpetofaunal regions of Patagonia. Regiones herpetofaunísticas fundamentales de Patagonia. 314 MONOGRAPH MUSEUM OF NATURAL HISTORY NO. 7 Fig. 13:4. General tectonic structure of South America (after Harrington, 1962). The area in the box is enlarged in figure 5. Estructura geotectónica de Sud América (según Harrington, 1962). El área en el recorte aparece aumentada en la figura 5. 1979 CEI: PATAGONIAN HERPETOFAUNA 315 Fig. 13:5. Location of the southern massifs and their relation to the major Patagonian herpetofaunal regions. Ubicación de los macizos australes y su relación con las regiones herpetofaunísticas fundamentales patagónicas. 316 MONOGRAPH MUSEUM OF NATURAL HISTORY NO. 7 tion) and the Meseta de Canquel, plus small­ Table 13:1.—Characteristic Types of Vegetation in er mesetas of the same lower and middle the Ancient Patagonian Region. Tertiary age along the Andean front; their Herbs Spiny or Sclerotic Plants