Search

The genus Microcavia includes six species of terrestrial, medium-sized, living cavies that occupy arid to semiarid environments at both high and low elevations in western and southern South America. Among these, Microcavia shiptoni is one of the least known species, being recorded only at two isolated localities from northwestern Argentina. Genetic information and a detailed morphological characterization are lacking for this elusive species. In this work, we start filling these gaps by including M. shiptoni in a phylogenetic analysis based on mitochondrial DNA sequences that includes five of the six currently recognized species and place M. shiptoni as sister to M. niata in a clade of highland species. In addition, using both qualitative and quantitative morphological traits, we provided an emended diagnosis for this taxon and a key for the living species of the genus. Finally, we present, the first notes on the natural history of this species. [ABSTRACT FROM AUTHOR]

The genus Andalgalomys Williams and Mares, 1978 includes three species of small phyllotine rodents: Andalgalomys olrogi Williams and Mares, 1978; Andalgalomys pearsoni (Myers, 1977); and Andalgalomys roigi Mares and Braun, 1996. These mice are distributed from southeastern Bolivia and western Paraguay to west-central Argentina, occupying mostly semi-desert environments, such as the Dry Chaco and High Monte. Available phylogenetic analysis of DNA sequences suggests that Andalgalomys olrogi and Andalgalomys roigi, which also share the same diploid complement, constitute the same species. We tested this hypothesis through a qualitative and quantitative morphological approach, in order to integrate different lines of evidence. Based on the largest sample analyzed to date, we found that some of the supposedly diagnostic traits of both Andalgalomys olrogi and Andalgalomys roigi (e.g., dorsal coloration) are more variable than previously documented. In addition, principal component analysis failed to separate Andalgalomys olrogi from Andalgalomys roigi in the multivariate space, although clearly segregate Andalgalomys pearsoni from these two taxa. Based on these findings, plus previous evidence, we consider Andalgalomys roigi as a junior synonym of Andalgalomys olrogi. [ABSTRACT FROM AUTHOR]

Based on previously published molecular (mitochondrial) and herein provided morphological (qualitative and quantitative data) evidence, we describe a new species of leaf-eared mouse of the genus Phyllotis. The new species is morphometrically distinct when compared with other phylogenetically or geographically close species of Phyllotis, showing several quantitative differences in their external and craniodental characters (e.g., proportionally broader nasals and interorbital region, and proportionally smaller tympanic bullae). The new species is endemic to central Argentina, occurring on rocky grasslands at elevations of 650–2,800 m a.s.l. This is the only species of Phyllotis inhabiting the Central Sierras, a mountain system of medium elevation, isolated from the Andes by low elevation arid and semiarid environments. [ABSTRACT FROM AUTHOR]

Northwestern Argentina (NWA) is a region characterized by a complex geomorphology, and encompasses six ecoregions in a relatively small area. The environmental heterogeneity of NWA and the sensitivity of small mammals towards environmental and landscape changes constitute a good scenario to assess the factors that influence small mammal diversity patterns in the region. We studied small mammal communities obtained from pellet samples in 24 localities of NWA. We identified 50 non-volant small mammal species and obtained topographic, climate and land cover variables. Our results show that small mammal communities respond to environmental factors at a regional scale. Such variations were explained in different proportions by the geographic position of the collecting sites, landscape and climate. Furthermore, the combined effect of these factors was the main determinant of species abundance patterns. Our results support the need of large-scale approaches to study communities, since the explanations of the observed patterns are simpler and more general. We emphasize the importance of considering the combined effect of different environmental predictors, which allows determining the amount of species variation that is spatially structured, and within that, the amount of variation related to the influence of the measured environmental variables. [ABSTRACT FROM AUTHOR]

The genus Euneomys is mostly distributed in the open environments of the central and southern Andes, adjacent Patagonian steppes of Argentina and Chile, and in several islands of the Tierra del Fuego Archipelago. This genus includes three living species: E. chinchilloides, E. fossor, and E. mordax. Euneomys fossor is a poorly known species, with an uncertain geographic provenance and known from a single specimen, whose distinction from the other species of the genus has not been accurately assessed. Here, using qualitative and quantitative morphological evidence, plus published information about karyotypes and genetic variation, we evaluate the taxonomic status of E. fossor and E. noei, a nominal form usually considered a synonym of E. mordax. Based on multivariate analysis of cranial measurements and morphological discrete traits, we recognize two main morphotypes within Euneomys, one referable to E. chinchilloides (with dabbenei, petersoni, and ultimus as synonyms), and another including E. fossor, E. mordax, and E. noei. The recognition of two major groups within Euneomys is also supported by molecular and chromosomal data. By the principle of the priority, the names of E. chinchilloides and E. fossor applies for each one of these morphotypes. In addition, after discussing the pros and cons of replacing the name mordax by fossor, we emended the type localities of both forms. [ABSTRACT FROM AUTHOR]

Akodon oenos, a nominal form with type locality in northern Mendoza province, Argentina, has an intricate taxonomic history. Recently, it was considered a junior synonym of Akodon spegazzinii on the basis of morphological similarities of one individual captured in southern Mendoza with specimens belonging to the type series of A. oenos, plus the genetic similarity of that single specimen with representatives of A. spegazzinii. We compared specimens of the Akodon boliviensis species group recently captured in Mendoza with the type series of A. oenos and series of A. spegazzinii from northwestern Argentina. We conducted an analysis of molecular markers (cytochrome-b gene) and quantitative morphological studies (comparisons of skull measurements). Our results showed that: (1) all sequenced specimens of the A. boliviensis group from Mendoza form a monophyletic clade closely related to A. spegazzinii; (2) contrary to previous hypothesis, specimens of Akodon from Mendoza are morphologically distinctive in size and shape of the skull, from A. spegazzinii; and (3) within the A. boliviensis species group, specimens from Mendoza are distinctive. We argue that the synonymy of A. oenos under A. spegazzinii must await further studies, including molecular markers other than mitochondrial and samples of DNA sequences from topotypical specimens of A. oenos. [ABSTRACT FROM AUTHOR]

The genus Galea Meyen, 1833 includes at least five species of terrestrial, diurnal and herbivorous cavies that occupy grasslands and rocky scrub areas at both high and low elevations in South America. According to the available molecular and morphological data, Galea comes Thomas, 1919 is restricted to highland areas above 2000 m in southern Bolivia and northwestern Argentina. Its distributional range as well as its morphological distinctiveness from other closely related species (Galea leucoblephara and Galea musteloides) is poorly documented. Using both qualitative and quantitative morphological traits, we provided an emended diagnosis for G. comes. In addition, we added six new locality records to its known distribution. [ABSTRACT FROM AUTHOR]

The genus Myoprocta Thomas, 1903 includes two living species of medium-sized caviomorph rodents of the family Dasyproctidae, the red acouchi, Myoprocta acouchy (Erxleben 1777), and the green acouchi, Myoprocta pratti Pocock 1913. Whereas some recent revisionary work has considered both species to be allopatrically distributed, other reports suggest that both taxa co-occur in eastern Colombia. In this contribution, I revaluate some qualitative and quantitative skull traits within Myoprocta to clarify its taxonomy and distribution. Multivariate analyses of quantitative skull characters support the distinction between M. acouchy and M. pratti, contradicting the findings of some previous authors. Based on these results and the examination of ~100 skins, I concur with the hypothesis that the two species are allopatrically distributed. [ABSTRACT FROM AUTHOR]

Ctenomys dorsalis is known only from its type specimen, a female preserved as skin without skull (except for the upper incisors) from an imprecise locality in the "Northern Chaco of Paraguay". Here, we report additional individuals of this species housed, since the 1940s, at the Field Museum of Natural History (Chicago, USA). Based on these specimens, which fully match the original description of this rodent, we provide novel information regarding its phylogenetic position, external and cranial morphology, and distribution. The analysis of mtDNA sequences supports the distinctiveness of this taxon and suggests its placement within the boliviensis group of Ctenomys. Our study highlights once more the importance of museum collections as repositories of biodiversity. [ABSTRACT FROM AUTHOR]

In this note, I discuss the advantages of the usage of subgenera as a practical taxonomic rank in mammalian taxonomy. Use of this category preserves traditional usage, reduces nomenclatural instability and avoids unnecessary change of names. Subgenera are useful to label diagnosable clades of closely related species, especially in morphologically and ecologically diverse monophyletic genera, without alteration of traditional binomial usage. Contrary to informal names such as "divisions" or "groups", subgenera are governed by the rules of the International Commission on Zoological Nomenclature (ICZN), having usage constrained (and stability promoted) by typification and priority. [ABSTRACT FROM AUTHOR]

We documented the first record of Andalgalomys pearsoni (Myers 1978) in Argentina, based on one individual caught at Cerro Colorado (Metán department, Salta province, Argentina). This new record enlarges the distribution of this species, to date only known from Bolivia and Paraguay, ca. 530 km SW and fills a gap without records for Andalgalomys of approximately 850 km between Paraguay and NW Argentina. The finding of this mouse, caught more than 50 years ago, highlights the importance that biological collections have in our understanding of biological diversity. [ABSTRACT FROM AUTHOR]

Abrawayaomys chebezi is a spiny sigmodontine believed endemic to the Atlantic Forest of Misiones Province, Argentina. The available knowledge is largely restricted to the holotype, the only fully vouchered specimen. Here, we detail a second specimen, a subadult male obtained in the Parque Provincial Urugua-í (Misiones). The morphology of this animal confirms several diagnostic traits of A. chebezi, such as its smaller size relative to Abrawayaomys ruschii, the type species of the genus, and the simplified occlusal structure of its molars. New data on soft anatomy indicate that chebezi has a unilocular-hemiglandular stomach, no gall bladder, and a complex tridigitate penis with an external surface covered by rounded spines. A rich parasite assemblage including fleas and mites was recorded from this animal. A preliminary review of the alpha taxonomy of Abrawayaomys suggests the possible existence of three different species in the genus, one still unnamed. [ABSTRACT FROM AUTHOR]

The southern distribution of the small cavies Galea leucoblephara and Microcavia australis is reviewed. It has been enriched through the addition of 36 new locality records for G. leucoblephara and 176 for M. australis. Both caviomorph rodents are widespread in Patagonia - the former occurs in the northern portion of the territory, whereas the latter is recorded up to the Strait of Magellan. The reference of Patagonian Galea populations to leucoblephara is still subject to confirmation. Therefore, the status of negrensis must be addressed in future studies. For southern Microcavia australis populations, a rich subspecifical scenario is proposed, including the names australis, kingii, and nigriana. The alpha taxonomy of this cavy needs a fresh approach that is based on a larger sample set coupled with the analysis of molecular markers. [ABSTRACT FROM AUTHOR]

Chelemys macronyx is a medium-sized, long-clawed sigmodontine of fossorial habits, distributed between 33°20′ and 51°30′S in the central and southern Andes of Argentina and Chile. Phylogeographic studies based on the analysis of mitochondrial DNA showed that this rodent has a shallow genealogy geographically structured into two main clades: one in the northern part of its range, at high-Andean localities in the Argentinean provinces of Mendoza and northern Neuquén, and the other covering medium- to low-elevation areas from northwestern Neuquén to southern Chile and Argentina. Qualitative and quantitative morphological characters show the existence of two main morphotypes of C. macronyx. Northern populations are characterized by a mesopterygoid fossa rounded at its anterior border and by a large and nearly circular foramen ovale, whereas in central and southern populations the mesopterygoid fossa is quadrate with an ovate to piriform foramen ovale. The described morphological variation is in congruence with the phylogeographic patterns identified by molecular markers. In light of these results, we suggest a simplified taxonomic arrangement on which two subspecies are recognized within C. macronyx, a northern one and a southern one for which the names C. m. macronyx and C. m. vestitus correspond, respectively. [ABSTRACT FROM AUTHOR]

This study aims to describe landscape evolution in two contiguous ecoregions with different land use intensity, to assess changes in small mammal assemblages. Rodent remains in pellet samples from barn owls were used to estimate the attributes of rodent assemblages. Two major biomes were considered in this study, a mosaic of wetlands (Delta and Paraná Islands ecoregion) and a mosaic of grasslands and cultivated fields (Pampa ecoregion). Environmental characterization was based on the analysis of satellite images and weather data. Fourteen rodent species in 28 sampling sites were identified, totaling 7645 prey items. Linear combinations of variables that characterized the landscape explained 66.6% of variation in the composition of rodent assemblages. A positive linear relationship between rodent diversity and the number of different patches was found in the Pampa. Our results suggest that landscape disturbances caused by agricultural intensification favor the increase of generalist and competitively subordinated species. In turn, changes in rodent diversity at the Paraná Delta were negatively associated with the percentage of water-covered area and the number of patches. The hydrological regime of this ecoregion acts as a filter for species establishment, restricting the richness of the rodent assemblages. [ABSTRACT FROM AUTHOR]

We report new recent and fossil records in Patagonia for six and three bat species, respectively. These findings significantly increase the previously known number of localities for these mammals in this entire region, filling gaps between previous references for some species (e.g., Histiotus macrotus) and/or extending by 140-350 km the range of others (e.g., Myotis chiloensis, M. levis, Lasiurus varius). In addition, we report for the second time the vespertilionid bat Lasiurus blossevillii in Patagonia. Fossils are mostly restricted to the Late Holocene epoch, and the recorded assemblages are similar to the recent ones. A preliminary analysis of richness indicates that bat diversity south of the Colorado River (around 39°S) decreases from five to six species in the northwestern to one species in the southeastern, changing abruptly around 43°S-46°S. Compared with similar latitudes of the Northern Hemisphere, bat diversity in the Neotropics follows a similar pattern, with <20 taxa occurring south of 35°S. [ABSTRACT FROM AUTHOR]

Mus talpinus, a fossil sigmodontine rodent exhumated by P. W. Lund from Quaternary deposits in the Lagoa Santa area, Brazil, has been varyingly allocated to the genera Oxymycterus, Blarinomys or Juscelinomys. After our examination of the holotype, an anterior fragment of the skull from Lapa da Serra das Abelhas, Minas Gerais, Brazil, we refer the name talpinus to the genus Brucepattersonius. These mice are sylvan akodontines, widespread in the Atlantic Forest, with the nearest extant record approximately 250 km southeast of Lagoa Santa. The addition of Brucepattersonius to the fossil sigmodontine fauna of Lagoa Santa suggests a non-analogous assemblage of species in this area during the Late Pleistocene. [ABSTRACT FROM AUTHOR]

Lestodelphys halli and Thylamys pallidior are southernmost representatives of the Order Didelphimorphia. We analyzed their southern distribution compiling locality records south of 42°S (Chubut and Santa Cruz provinces). We found 87 locality records for L. halli and 105 for T. pallidior. The distribution of L. halli reaches the central plateaus of Santa Cruz province but avoids the northeastern corner of the Deseado Massif. We report the southernmost locality for this species. The eastern and southern distribution of T. pallidior follows the courses of major rivers and coastal areas and it was not found at altitudes >700 m. Its southern distribution is more reduced than in L. halli, not reaching latitudes south of 46°S. We have recorded 20 localities of sympatry between both taxa, all of them from owl pellet samples; however, we have not found conclusive evidence of syntopy by trapping at any site. Both marsupials have widespread distribution in south-central Patagonia with two different histories: one, that of L. halli, related to Patagonian steppes and the other one linked to arid and semiarid lowlands represented by T. pallidior. [ABSTRACT FROM AUTHOR]

The article discusses a study on the geographic distribution of Leaf-eared mouse Graomys griseoflavus in Patagonia. The study used such factors as literature records, small mammal trappings carried out during the past ten years and the study of owl pellets to review this distribution. It also compiled a list of recorded localities of G. griseoflavus in Patagonia to depict their distribution.

No abstract available [ABSTRACT FROM AUTHOR]

A first step in understanding the ecology of rodents as reservoirs and their relation with the disease they transmit is to determine their geographical distribution. This distribution can be modeled as a function of environmental variables. We georeferenced an extensive database of hantavirus reservoir Oligoryzomys nigripes (Muridae: Sigmodontinae) records in Argentina and used generalized linear models (GLMs) and genetic algorithm for rule-set prediction (GARP) to model the presence probability of this rodent as a function of multiple environmental variables. The GLMs correctly classified 86% of the sites and gave a good prediction area. The GLMs with a spatial term resulted in a probable presence area that matched the rodent occurrences too tightly, and thus was not useful to speculate on potential distribution. The GARP model resulted in a broader probable presence area for the black-footed colilargo than regression models. We suggest that the GLMs without spatial term reflect the actual distribution and should be considered for hantavirus most urgent control plans, whereas the GARP model could be regarded as the most widespread potential distribution and thus considered in long-term plans. [ABSTRACT FROM AUTHOR]