This study aims to characterize the gonads, folliculogenesis, and spermatogenesis processes of male and female Rhinella bergi through anatomical, histological and morphometric analysis. We worked with specimens previously collected in the spring and summer seasons (2014–2015), in which the gonads were studied based on morphological, histological and morphometric analysis. The reproductive system was analyzed using a stereoscopic microscope and a scanning electron microscope (SEM). Histological preparations were made following the conventional protocol of dehydration, inclusion in paraffin and stained with haematoxylin–eosin, Mallory trichrome and PAS histochemical reactions. The anatomical and morphometric characteristics and the gametogenesis in R . bergi agree with what was proposed for other analyzed species of the Bufonidae family. Females with ovaries with oocytes in different stages of maturity and postovulatory females were found. The males presented continuous spermatogenesis. The results of this work serve as a basis for the characterization of the reproductive cycle in R . bergi and, at the same time, provide background information on the analysis of gametogenic activity. Future investigations will be focused on evaluating the reproductive cycle in this species, both in ovaries and testes as well as Bidder's organ, to compare and correlate with the results obtained in this study.

To characterize the reproductive biology of Scinax acuminatus and contribute to the natural history of this species, the morphology of the reproductive system of males and females was analyzed at anatomical, histological and immunohistochemical levels. The individuals were collected fortnightly between August and December (2016) and January to December (2018). The anatomy of the reproductive system was analyzed in a stereoscopic microscope, and histological preparations staining with hematoxylin-eosin and Masson’s trichromic, PAS and Coomassie Blue was performed as well. To characterize the meiotic-active cells in the testes, immunostaining with the PCNA proliferation protein was performed. There were found females with ovaries with oocytes in different stages of maturity and post-ovulatory females. Males presented continuous spermatogenesis, which could be confirmed by the immunostaining of PCNA in spermatogonia during the cycle. The results of this work serve as a basis for the characterization of the reproductive cycle in S. acuminatus and provide background information on the analysis of spermatogenic activity by IHQ from the study of the immunodetection of the PCNA cell proliferation protein. Future studies will focus on the evaluation of cell death processes during the reproductive cycle in the studied species to compare with those obtained in terms of cell proliferation.

Utilizando microscopía electrónica de barrido se describen los principales cambios producidos en el disco oral, branquias externas, órgano adhesivo y desarrollo del opérculo, en larvas de P. biligonigerus durante los estadios 19-25 de Gosner. Se brinda una descripción detallada de estas estructuras en los estadios estudiados y los resultados son comparados con los de Leptodactylus chaquensis, Bufo arenarum, B. americanus y Scaphiopus intermontanus.

La Histología es una disciplina un poco abandonada en el plan de estudios de los colegios secundarios, esto puede deberse principalmente a la falta de material histológico, por lo complejo que les puede resultar acceder a ellos y tener una histoteca y atlas histológico. La histología es el estudio de la estructura microscópica del material biológico y de la forma en que se relacionan tanto estructural y funcionalmente los distintos componentes individuales. Es crucial para la biología por que se encuentra en las intersecciones entre la bioquímica, la biología molecular y la fisiología por un lado y los procesos patológicos y sus consecuencias por el otro. Los histólogos prestan cada día mayor atención a los problemas químicos, Así, por ejemplo, aspiración a determinar con exactitud la composición química de determinadas estructuras de la masa viva, al estudiar las enzimas, iones, proteínas, hidratos de carbono, grasas y lipoides, fermentos y otros componentes en las células y en los tejidos a partir de observaciones que se realizan en el microscopio. Por lo antes descripto desde la cátedra de Histología Animal y Morfología de las carreras Lic. en Cs. Biológicas y Bioquímica respectivamente de la Facultad de Ciencias Exactas y Naturales y Agrimensura surge la iniciativa de crear una Histoteca Popular con el fin de poder brindar a la comunidad de colegios secundarios acceso a material histológico, atlas y blog interactivo.

We present a new record of Amphisbaena trachura (Squamata: Amphisbaenidae) for the northeast of Corrientes province, Argentina. Seven specimens (five females and two males) were identified using morphological and meristic characters. The specimens were found under Eucalyptus sp. logs on 6 December 2014 and 3 March 2015, in General Alvear Department, Corrientes.

Reproductive aspects of Dendropsophus sanborni (Anura, Hylidae) in northeastern Argentina. The aim of this investigation was to characterize reproductive aspects of Dendropsophus sanborni (Schmidt, 1944) (Anura, Hylidae) in the northwest of Corrientes province, in northeastern Argentina. The reproductive cycles of males and females, the existence of sexual dimorphism and the male’s vocalization period were analyzed. Samplings were made from September 2011 to August 2012. Dendropsophus sanborni showed a prolonged reproductive pattern because reproductive activity was observed during most part of the year. Calling males were recorded all months except in July. The spermatogenic cycle can be characterized as potentially continuous. In males, snout-vent length was significantly correlated with mean testicular volume. The species showed sexual dimorphism in body mass, with females larger than males. Post-ovulatory females were found from March to June and most females had oocytes at different stages of maturity, with abundant post-vitellogenic oocytes from August to December.

A más de una década de la primera Lista Roja de herpetofauna propuesta por la Asociación Herpetológica Argentina (Lavilla et al., 2000), se recategorizaron los anfibios a partir de nueva información taxonómica, biogeográfica, bio-ecológica y de modificaciones metodológicas respecto a la evaluación anterior. Mediante la participación de 35 especialistas de toda la Argentina se reevaluaron 175 taxones de anfibios (171 en la anterior) incluyendo 23 taxones nuevos para Argentina y obteniéndose como resultado la inclusión de 51 especies en la Lista Roja (8 En Peligro, 11 Amenazadas, 32 Vulnerables), 21 Insuficientemente Conocidas y 103 No Amenazadas. En relación con la categorización anterior de la AHA, los cambios de categorías han sido: un taxón descendió de las categorías En Peligro a Amenazado, siete taxones descendieron de Amenazados o Vulnerables a Insuficientemente Conocidos y nueve de Insuficientemente Conocidos a No Amenazados. Tres No Amenazados y 10 Insuficientemente Conocidos fueron elevados a distintas categorías de amenaza, nueve taxones Vulnerables fueron elevados a Amenazados, cinco de Vulnerables a En Peligro, y un taxón fue elevado de Amenazado a En Peligro. De 23 taxones no evaluados en el 2000, 16 se ubican en la categoría No Amenazados, tres en Insuficientemente Conocidos y cuatro en Vulnerables. Estas modificaciones son el resultado de: (1) mayor información sistemática, biogeográfica y bio-ecológica disponible para la evaluación, (2) cambios en cuanto a las presiones antrópicas sobre las especies o sus hábitats, (3) modificaciones metodológicas que incluyeron instructivos para aplicar los conceptos, la discusión y consenso entre especialistas y el análisis de las incertidumbres. More than a decade after the first red list of herpetofauna proposed by the Asociación Herpetológica Argentina (Lavilla et al., 2000), we recategorized amphibians based on new taxonomic, biogeographical, bio-ecological information and methodological changes in the former evaluation. Through the participation of 35 specialists from all over Argentina 175 taxa of amphibians (171 in the previous categorization) are reevaluated including 23 new taxa added to Argentina, obtaining as results the inclusion of 51 Red List species (8 Endangered, 11 Threatened, 32 Vulnerable), 21 Insufficiently Known and 103 Not Threatened. In relation to the former categorization of the AHA the changes were: one taxon descended from Critically Endangered to Endangered, seven taxa descended from Endangered orVulnerable to Insufficiently Known, and nine from Insufficiently Known to Not Threatened. Three Not Threatened and 10 Insufficiently Known were elevated to different categories of threat, nine taxa were elevated from Endangered to Vulnerable, five from Vulnerable to Endangered, and one from Threatened was elevated to Critically Endangered. Of 23 taxa not evaluated in 2000, 16 are placed as Not Threatened, three Vulnerable, and four Insufficiently Known. These changes are the result of: (1) more available information for evaluation from systematic, biogeography and bio- ecology, (2) changes in human pressures over the species or over their habitats, (3) methodological changes that included recommendations for applying concepts, discussion and consensus among experts and analysis of uncertainties.

A new two-pored Amphisbaena is described from Formosa and Corrientes provinces of Argentina. The new species has a faint autotomy annulus (with a fracture plane) and two cicatricial precloacal pores separated medially by a pair of nonpored segments: It differs from Amphisbaena dubia, which has a pair of pores on adjacent segments and a fracture plane on the tail, and from Amphisbaena darwini heterozonata, which differs in pore number, coloration, and shape of the autotomy annulus.

Using scaning electron micrographs the principal changes produced in the oral disc, external gills, adhesive organ and opercular development are described, in larvae of P. biligonigerus during stages 19-25 of Gosner. It is offered a detailed description of these structures in the studied stages and the results are compared with those of Leptodactylus chaquensis, Bufo arenarum, B. americanus and Scaphiopus intermontanus. RESUMEN: Utilizando microscopía electrónica de barrido se describen los principales cambios producidos en el disco oral, branquias ex- ternas, órgano adhesivo y desarrollo del opérculo, en larvas de P. biligonigerus durante los estadios 19-25 de Gosner. Se brinda una descripción detallada de estas estructuras en los estadios estudia- dos y los resultados son comparados con los de Leptodactylus cha- quensis, Bufo arenarum, B. americanus y Scaphiopus intermontanus.