Ctenomys Blainville, 1826 (known as tuco-tucos) is considered one of the most diverse genus within mammals; however, its taxonomy is far from resolved. In recent years, new species have been described, and many other forms have been synonymized, while other lineages remain as candidate species. In this work, based on molecular and morphological evidence, we proposed that C. "rosendopascuali", a taxon considered as a nomen nudum, is in fact a synonym of C. bergi Thomas, 1902. The molecular phylogeny based on the mitochondrial cytochrome b gene showed that individuals from populations a priori assigned to C. bergi and C. "rosendopascuali" were not reciprocally monophyletic. Additionally, geometric morphometric analyses based on cranial morphology showed significant overlap in the morphospace of these two taxa. Our results also show a high genetic similarity among C. bergi, C. "yolandae", and C. bonettoi Contreras and Berry, 1982, questioning the taxonomic status of the latter two taxa and highlighting the need for exhaustive comparison with C. bergi. We also identified a second locality for a highly divergent lineage within the Mendocinus group (Quijadas lineage). Our study confirms the divergence of this lineage and highlights the need to further taxonomic studies in order to evaluate whether it represents a possible undescribed Ctenomys species.

In this work, we examined the relationship of Oligoryzomys longicaudatus' (the Andes virus [ANDV] host, commonly known as the colilargo) occupancy and the cover of dominant woody and herbaceous plant species recorded in censuses along traplines for mice. We found that O. longicaudatus occupancy probability increased with high percentages of Rosa rubiginosa, Plantago lanceolata, Rumex acetosella, and Holcus lanatus, while it decreased with an increased cover of Mulinum spinosum and Ochetophila trinervis. The four positively related species are exotic plants. R. rubiginosa, the most conspicuous one, is capable of invading all types of habitats and forms dense shrublands in the ecotone between forest and steppe. These results are partly consistent with diet studies indicating that sweet briar fruits are the main item consumed by colilargos. The relationship of the ANDV main host with such an invasive plant poses a likely increased ANDV transmission risk to local communities making use of sweet briar's fruits. We discuss further implications of this problem in relation to hantavirus epidemiology in southern Argentina.

Ctenomys es uno de los géneros más diversos de roedores sudamericanos y el conocimiento de su taxonomía alfa es aún incompleto. En la provincia de Córdoba se han citado cinco especies vivientes. Una de ellas, el tuco-tuco de Reig, fue reportada sólo para su localidad tipo. En este trabajo se reportan poblaciones previamente no documentadas de esta especie sobre la base de colectas de especímenes y registros de actividad. La identificación de los especímenes se basó en comparaciones con la serie tipo y otras especies (vivientes y fósiles) presentes en Córdoba. Finalmente, se discute el estado del conocimiento del género y la necesidad de incrementar relevamientos de campo.

Ctenomys (tuco-tucos) is one of the most speciose genera of mammals, and the number of species that compose it continues to increase. Of the 65 species currently recognized for the genus, 15% have been described in the last 10 years. In this work, based on morphological and molecular evidence, we describe a new species of tuco-tuco for Central Argentina. This new species inhabits stony soils in the foothills of Sierras Grandes in Córdoba province and is distinguished from its congeners by a combination of anatomical characters, including a unique morphology of the posterolateral extension of the palatine. The molecular phylogeny based on the mitochondrial cytochrome b gene showed that this new species does not belong to any species complex described for Ctenomys. On the contrary, this new taxon shows a high genetic divergence with the rest of the species and species groups of Ctenomys and was recovered as an independent lineage within the phylogeny of the genus. This finding increases the richness of Ctenomys to 66 species. Our results highlight the need to increase the geographic sampling of studies in this genus to achieve a more complete understanding of its diversity.

Several studies in European and North American agroecosystems conclude that organic farming benefits birds compared to conventional farming. Nevertheless, there are some biases toward these geographic regions and farm size. Argentinian agroecosystems are particularly homogeneous with large arable fields and sparse uncultivated field margins (i.e. large-scale homogenous cropping systems). In Argentina only 0.55% of the total farmland is under organic farming. Thus, our aims were to assess differences in bird occupancy between organic versus conventional farming regimes, and whether bird occupancy varied in relation to annual crop proportion in both farming regimes in central Argentina agroecosystems. We surveyed 156 points in farms under conventional and 154 in organic farming regimes during two bird-breeding seasons. We used multi-species occupancy models with a Bayesian approach to estimate bird occupancy. We observed that the type of farming regime (organic in relation to conventional) had a weak effect on avian occupancy, varying by species and groups. Probability of occupancy was higher for a few insectivorous and omnivorous species but lower for carnivores in organic farms in relation to conventional ones. The proportion of annual crops was positively correlated with occupancy of an insectivore aerial forager, some insectivore foliage gleaners, a granivore, and some omnivorous species in organic farms, but not conventional farms. This work contributes to reducing geographic and small-scale heterogeneous cropping system biases in the avian agroecological literature. Our results, together with future studies needed to assess landscape configuration and composition, and resource availability for birds in each farming regime, will allow the evaluation of organic farming as a tool for the conservation of bird species in large-scale homogeneous cropping systems in temperate regions.

The responses of organisms to organic farming depend on the taxonomic group and landscape complexity. Following the intermediate landscape complexity hypothesis, organic farming can compensate for the lack of complexity in simple landscapes. Argentinian farmlands are simple with large fields and scarce linear habitat array, and conventional agriculture is almost the only agriculture practice. We hypothesize that there is an interaction effect of landscape complexity and farming practices on occupancy and species richness of small mammals in farmland of central Argentina. We selected circular landscapes under organic farming and low- and high-intensity conventional farming and quantified heterogeneity in each landscape considering different cover types (crops, resting plots, fallow land, border habitats, grasslands and man-made structures). We used multi-species occupancy models accounting for multiple seasons with a Bayesian approach to make the estimates. Landscapes under organic farms had the highest level of landscape heterogeneity. In simple Argentinian farmlands, organic farming benefited species richness and occupancy of all small mammal species. Some management strategies used in organic farming (wide and vegetated border habitats, diversity in types of production, winter cover crops, natural or semi-natural patches) should be taken into account to increase landscape complexity in conventional farming.