Abstract Two dimensions of the ecological niche (diet and habitat) of a snake assemblage from an endemic rich area in east-central Argentina, the Sierras de Ventania mountain chain, were analyzed. Field data collection was performed in 15-week study periods between 2010 and 2014. Snakes were hand-captured using transect surveys. Field observations on diet were analyzed together with stomach content data from museum specimens. Our results supported the partitioning of the snake assemblage by both habitat use and diet into at least three functional groups: species restricted to microhabitats under rocks and with a diet composed exclusively of ants (Epictia australis); species found mostly in stream microhabitats and feeding mainly upon anurans (Erythrolamprus poecilogyrus and Lygophis elegantissimus); and species found mostly in grassland microhabitats, with specialized diets of terrestrial prey items (Philodryas patagoniensis and Bothrops alternatus). Consistent with previous work, diet was more important than habitat in explaining ecological niche partitioning of this snake assemblage. Our results showed that high overlap values of microhabitat use were compensated by low overlap values of the trophic niche dimension, thus matching the traditional complementary niches hypothesis.

For millennia the turtles and tortoises have been part of the mythical universe of several human cultures. In consequence, the empirical knowledge of oral transmission, the contextualized use, and the symbolic meaning of these animals exceed in antiquity and extension to the academic knowledge on them, which has not impeded, however, that chelonians are currently the most threatened vertebrates on the Earth. This paper deals with the work of explorers and naturalists who laid the foundations of the South American herpetology, in general, and the cheloniology, in particular, with emphasis in Argentina. The work of Marcos Freiberg is recognized as pivotal to the development of the scientific study of the chelonians in this country. Lastly, the progress of cheloniology in recent decades is summarized.

Desde hace milenios las tortugas forman parte del universo mítico de diversas culturas humanas. En consecuencia, el saber empírico de transmisión oral, el uso contextualizado y el significado simbólico de estos animales superan en antigüedad y extensión al conocimiento académico sobre ellos lo que no los exceptúa, sin embargo, de ser actualmente los vertebrados más amenazados del planeta. Este trabajo compendia la labor de exploradores y naturalistas que sentaron las bases de la herpetología sudamericana en general y el estudio científico de los quelonios, en particular, con énfasis en la Argentina. Se reconoce la tarea de Marcos Freiberg como fundamental para el desarrollo en nuestro país de la queloniología como disciplina en sí misma, y se expone brevemente el avance de ésta en las últimas décadas.

Through the participation of nine specialists from different institutions from all over Argentina and after more than a decade from the first Red List of threatened herpetofauna proposed by Asociación Herpetológica Argentina in 2000, we assessed the conservation status of the argentine Testudines taxa, adding the new taxonomic, biological and ecological knowledge progresses made since then as well as applying methodological changes in the former assessment. As a result from the 14 turtles taxa recognized as present in Argentina, nine were included in the actual Red List under some degree of risk (three Critically Endangered, three Endangered, three Vulnerable). From the remaining ones, three were classified as Insufficiently Known and two as Not Threatened. In the classification of the three marine turtles that are frequently found in argentine coasts we adopted the IUCN (2011) Red List criteria. In relation with the former categorization, we included a new species registered in Argentina (Phrynops geoffranus, Insufficiently Known), added two synonymies, increased from one to three the species within the Vulnerable Category and decreased from three to two the Critically Endangered species number. The few changes between the two assessments of the argentine turtle´s conservation status are due to the scarcity of new scientific contributions made to the knowledge of this group in the last decade.

Con la participación de nueve especialistas de diferentes instituciones de Argentina y transcurridos más de 10 años desde la primera Lista Roja de la herpetofauna de la República Argentina realizada por la Asociación Herpetológica Argentina en el año 2000, se recategorizaron los taxones de Testudines presentes en el país incorporando nueva información taxonómica, biológica y ecológica y, aplicando correcciones metodológicas. Como resultado, de los 14 taxones de tortugas continentales y marinas, nueve quedaron incluidas en la presente Lista Roja bajo algún grado de amenaza, tres En Peligro, tres Amenazadas y tres Vulnerables, mientras que dos fueron categorizadas como No Amenazadas y tres son Insuficientemente Conocidas. En la evaluación de las tres especies de tortugas marinas, que frecuentan las costas del Mar Argentino, se homologaron las categorías con las de IUCN (2011). Respecto de la categorización anterior, se agregó la especie Phrynops geoffranus (Insuficientemente Conocida), se sinonimizaron dos especies, disminuyó el número de especies En Peligro de tres a dos y se incrementó el de Vulnerables de una a tres. Los pocos cambios resultantes de la presente categorización de las tortugas de Argentina respecto de la anterior podría reflejar la escasez de estudios realizados sobre este grupo en la última década y la necesidad de promoverlos.

The first fossil record at central Argentina of both the turtle genus Trachemys Agassiz, 1857 and the family Emydidae Rafinesque, 1815 is described. The fossil material, of late Pleistocene - early Holocene age, is composed of the proneural plate, the right pleurals IV and VIII, and fragments of the left pleurals III and IV, parts of the right epiplastron, hyoplastron and hypoplastron, and three indeterminate fragments. These shell elements were discovered at El Silencio Site (30°53'20" S, 62°49'29" W), southern coast of the saline Mar Chiquita Lake, Córdoba province, Argentina, in a siltite level with calcium carbonate intercalations assigned to the Tezanos Pinto Formation, whose deposition occurred between 36000 and 8000 years BP. The fossil record is related to a humid event between 16500 and 15500 years BP that, if marked and temporarily sustained enough, may have favoured the colonization by Trachemys (as well as other vertebrate taxa) during the Pleistocene into this area where the genus do not live today, 220 km far to the west of its present distribution.

En este trabajo se describen restos del caparazón de una tortuga que constituyen el primer registro del género dulceacuícola Trachemys Agassiz, 1857 y de la familia Emydidae Rafinesque, 1815 en la provincia de Córdoba, y el hallazgo más occidental de ambos en la Argentina. Los materiales recuperados consisten en la placa proneural, las placas pleurales IV y VIII derechas y fragmentos de las placas pleurales III y IV izquierdas, epiplastron, hioplastron e hipoplastron derechos, más tres fragmentos indeterminables. Los restos provienen del Sitio El Silencio (30°53'20" S, 62°49'29" W), un yacimiento paleontológico de edad Pleistoceno tardío - Holoceno temprano, expuesto en la costa de la actual laguna Mar Chiquita, en un nivel de limo con intercalaciones de carbonato de calcio asignado a la Formación Tezanos Pinto, cuya depositación se produjo entre los 36.000 y 8.000 AP. El registro es relacionado con un evento húmedo acontecido entre los 16.500 y 15.500 años AP, que pudo haber sido lo suficientemente marcado y sostenido como para posibilitar el ingreso de Trachemys (y otros taxones vertebrados) durante el Pleistoceno a cercanías de la laguna Mar Chiquita, unos 220 km hacia el oeste de su distribución actual.

The plastral spotting variation in the chelid turtle Phrynops hilarii (Duméril & Bibron, 1835) in relation to sex, size, and geographic procedence of individuals was analyzed. States for qualitative characters were analyzed using non-parametric tests. Quantitative characters (shell and scute measurements) were standardized for body size by linear regression against carapace length, and were subjected to principal components analysis and canonical discriminant function analysis. Results suggest that increased plastral spotting is a polymorphic ontogenetic trait in P. hilarii. Neither hatchlings nor juveniles have plastral pattern moderately or heavily pigmented. The simplest pattern, however, may persist without changes in some adults. There are no differences between sexes. The spatial distribution of the plastral pattern is not ordered latitudinally or longitudinally, showing no relationship with gradients of elevation, temperature, or precipitation. This pattern trait lacks of taxonomic significance. The morphometric analysis failed to reveal any character of diagnostic utility in the plastron to support the possibility that these patterns correspond to different sympatric taxa.