Resumo Dendropsophus nanus foi descrito de Resistencia, Argentina. Essa espécie está amplamente distribuída na América do Sul a leste dos Andes. Apesar da ampla distribuição, poucas informações sobre seu canto de anúncio estão disponíveis em literatura. Descrições de cantos de localidades tipo são especialmente importantes para a resolução de problemas taxonômicos, assim como para comparações intraespecíficas. Aqui, nós descrevemos os cantos de anúncio e de corte do macho de D. nanus de sua localidade tipo. O canto de anúncio de D. nanus é composto por dois tipos de notas, aqui referidas como “notas A” (nota longa) e “notas B” (nota curta), ambas com frequência dominante similar, mas com diferenças nas durações. O canto de corte é formado por notas que são similares à nota A do canto de anúncio, mas emitidas com menor amplitude. Estudos anteriores demonstraram que os cantos complexos de Eleutherodactylus coqui e Geocrinia victoriana transmitem mensagens separadas para machos e fêmeas. Embora vários experimentos anteriores terem sido realizados a fim de avaliar as interações acústicas de algumas espécies de Dendropsophus, mais estudos são necessários para entender as funções das duas notas do canto de anúncio de D. nanus e dos cantos de outras espécies do grupo de D. microcephalus.

Abstract Dendropsophus nanus was described from Resistencia, Argentina. The species distribution is widespread in South America east of the Andes. Despite its wide distribution, little information about its advertisement call is available in the literature. Call descriptions from type localities are especially important for the resolution of taxonomic issues, as well as for intraspecific comparisons. Herein we describe the advertisement and the male courtship calls of D. nanus from its type locality. The advertisement call of D. nanus is composed of two types of pulsed notes, herein referred to as “note A” (long note) and “note B” (short note), both with similar dominant frequencies, but different durations. The courtship call is formed by notes that are similar to notes A of the advertisement call, but emitted at lower amplitude. Previous studies demonstrated that the complex call of Eleutherodactylus coqui and Geocrinia victoriana convey separated messages to male and female. Although several previous experiments have been conducted to assess the acoustic interactions of some species of Dendropsophus, more studies are necessary to understand the functions of the two notes of the advertisement call of D. nanus and the calls of other species of the D. microcephalus group.

The natural history of the Leptodactylus marmoratus species group is poorly known, and there is scarce available information mainly referred to aspects of the reproductive biology. The objective of this study was to contribute to the knowledge of the trophic biology and of the parasitism of Leptodactylus diptyx populations from Northeastern Argentina. The stomach and intestine contents of 22 adult individuals were analyzed for the trophic study, while the alimentary canal and body cavity of 40 individuals were examined for parasites. The diet consisted of 17 different prey items, including mainly Formicidae hymenopterans, collembolans, coleopterans, and spiders. The values of prey diversity calculated by Shannon's index (H') and niche amplitude by Levins's index were 2.06 and 4.29, respectively. The 57.5% of the examined individuals were parasitized by nematodes and acanthocephalans. Leptodactylus diptyx is a new host for Cosmocerca sp. and Aplectana sp. nematodes.

Diversos aspectos de la historia natural de especies del grupo Leptodactylus marmoratus son escasamente conocidos y la poca información existente aborda principalmente los de la biología reproductiva. El objetivo de este trabajo es aportar información acerca de la dieta y del parasitismo de poblaciones de Leptodactylus diptyx del nordeste argentino. Para el estudio trófico, se analizó el contenido estomacal e intestinal de 22 individuos adultos, mientras que para el estudio parasitario, se examinó el tubo digestivo de 40 individuos. Se registró un total de 91 presas, clasificadas en 17 categorías, entre los cuales los himenópteros formícidos fueron los más numerosos (45%) y frecuentes (55%). Otras presas importantes fueron colémbolos, coleópteros y arañas. Los valores de diversidad de presas (índice de Shannon) y amplitud del nicho (índice de Levins) fueron 2.06 y 4.29, respectivamente. El 57.5% de los individuos examinados resultó positivo al examen de endoparásitos, entre los que se incluyen nematodos y acantocefalos. Leptodactylus diptyx representa un nuevo hospedador para los nematodos Cosmocerca sp. y Aplectana sp.

In this work we analyzed the karyotype of five populations of Adenomera diptyx from Argentina after conventional staining, Ag-NOR and C-banding. All specimens presented 2n = 26 and FN = 34. The karyotype was formed by three submetacentric, one metacentric and nine telocentric pairs. Silver staining revealed that the NOR was located on a secondary constriction in pair 7. C- banding evidenced constitutive heterochromatin at the pericentromeric region of all chromosomes. The karyotype of A. diptyx was similar to that of A. hylaedactyla (2n = 26, FN = 34) and different from that of A. andreae (2n = 26, FN = 40) in the fundamental number and secondary constriction position. It also differed from the karyotypes of A. marmorata (2n = 24, FN = 34 and 36) and of A. aff. bokermanni (2n = 23, FN = 34) in diploid number. Until a comprehensive cytogenetic analysis of all the species of the genus is performed, their chromosome evolution will remain poorly understood.