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Ichthyomyini, a morphologically distinctive group of Neotropical cricetid rodents, lacks an integrative study of its systematics and biogeography. Since this tribe is a crucial element of the Sigmodontinae, the most speciose subfamily of the Cricetidae, we conducted a study that includes most of its recognized diversity (five genera and 19 species distributed from southern Mexico to northern Bolivia). For this report we analyzed a combined matrix composed of four molecular markers (RBP3, GHR, RAG1, Cytb) and 56 morphological traits, the latter including 15 external, 14 cranial, 19 dental, five soft-anatomical and three postcranial features. A variety of results were obtained, some of which are inconsistent with the currently accepted classification and understanding of the tribe. Ichthyomyini is retrieved as monophyletic, and it is divided into two main clades that are here recognized as subtribes: one to contain the genus Anotomys and the other composed by the remaining genera. Neusticomys (as currently recognized) was found to consist of two well supported clades, one of which corresponds to the original concept of Daptomys. Accordingly, we propose the resurrection of the latter as a valid genus to include several species from low to middle elevations and restrict Neusticomys to several highland forms. Numerous other revisions are necessary to reconcile the alpha taxonomy of ichthyomyines with our phylogenetic results, including placement of the Cajas Plateau water rat (formerly Chibchanomys orcesi) in the genus Neusticomys (sensu stricto), and the recognition of at least two new species (one in Neusticomys, one in Daptomys). Additional work is necessary to confirm other unanticipated results, such as the non-monophyletic nature of Rheomys and the presence of a possible new genus and species from Peru. Our results also suggest that ichthyomyines are one of the main Andean radiations of sigmodontine cricetids, with an evolutionary history dating to the Late Miocene and subsequent cladogenesis during the Pleistocene. [ABSTRACT FROM AUTHOR]

The genus Calomys includes several species that have very similar external morphologies, which often leads to confusing field identification and has resulted in conflictive taxonomic histories. One of its clades involves large‐sized body forms, known as the Calomys callosus complex. In a previous study, a biogeographic hypothesis was proposed to explain a south‐to‐north colonisation of South America by species of this complex. However, other studies which not included all members of the complex' members and that used different molecular markers, did not support that biogeographic hypothesis. Here we explore the relationships among C. callosus sensu stricto (s.s.), C. fecundus, C. callidus, C. venustus, C. tocantinsi and Calomys sp. using two mitochondrial genes (Cyt‐b and Control Region) and two nuclear genes (Rhp3 and i7FGB) data. We also applied several gene trees and species delimitation methods to elucidate the taxonomy, distribution and evolutionary relationships among the analysed species. By including sequences of individuals from Argentina, Brazil, Bolivia and Paraguay, we reconstructed the possible ancestral biogeographic origin of the complex. Two main clades were recovered: the western showed the relationships (C. venustus [C. fecundus–Calomys sp.]), while the eastern (C. callidus [C. callosus s.s.–C. tocantinsi]). These results support the original biogeographic hypothesis and suggest the following scenario: in the west, from the Espinal ecoregion, first the Tucumane–Bolivian Yungas and later, the Beni savanna would have been colonised. In the east, from the Espinal, first the Chaco and later the Cerrado ecoregions may have been occupied. [ABSTRACT FROM AUTHOR]

Ecosystems around the world face a variety of threats from anthropogenic activities and drylands are among the most affected due to their unique environmental characteristics. To maintain phylogenetic history and ecological functionality in these areas, it is imperative to preserve community structure and composition by identifying and protecting key conservation areas. Various methods have been used to define these areas in need of protection; in this study, we used patterns of taxonomic and phylogenetic diversity in the arid lands of the Altiplano-Puna Bioregion of South America, using non-volant small mammal communities as a model system. Based on detailed records of species presence in the study area we estimated indices of species richness and phylogenetic redundancy. The geographic distribution of these indices was then compared to the distribution of protected areas in the region. These analyses identified areas around Lake Titicaca as being of exceptional conservation importance and in need of protection efforts. We propose a network of interconnected areas that together would provide high conservation value while allowing genetic exchange and facilitating ecological processes across landscapes. • Small mammals are key components of the Puna-Altiplano bioregion. • Highest species diversity and phylogenetic uniqueness clustered around Titicaca Lake. • High values of phylogenetic diversity are located outside of protected areas. • New protected areas are needed to conserve the evolutionary history of this region. [ABSTRACT FROM AUTHOR]

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Necromys is a genus of sigmodontine rodent that inhabits grasslands and scrublands in South America. Eight extant species are recognized in the genus; one of these is Necromys lactens , which inhabits high-elevation grasslands in the Yungas from south-central Bolivia to northwestern Argentina. Morphological variation in N. lactens has been recognized by the description of three nominal forms. Geographically structured genetic diversity also has been observed, but a thorough revision of these nominal forms within an integrative framework has yet to be performed. We conducted a phylogeographic assessment based on an 801 base-pair fragment of the cytochrome- b gene that guided morphometric analyses (univariate and multivariate comparisons) of patterns of geographic variation in the species, and the distinction of its nominal forms. Haplotypes of N. lactens form a well-supported and geographically structured clade. Within it, there are two main clades; haplotypes from the northern range form a well-supported clade, sister and allopatric to a weakly supported southern clade, which includes variants collected at or near the type localities of three nominal forms. In turn, both main clades are composed by two allopatric subclades. Morphometric analyses indicated no differences in shape of the skull among the three nominal forms or between the recovered clades and subclades. Taking together all the available evidence, we consider N. lactens to be a monotypic species. Necromys es un género de roedor sigmodontino que habita los pastizales y arbustales de América del Sur. Se reconocen ocho especies actualmente en existencia en el género; una de ellas, Necromys lactens , habita pastizales de altura en las Yungas, desde el centro-sur de Bolivia hasta el noroeste de Argentina. Se ha reconocido variación morfológica en N. lactens con base en descripciones de tres formas nominales; también se ha observado diversidad genética geográficamente estructurada, pero una revisión exhaustiva de esas formas nominales dentro de un esquema integrativo aún no se ha llevado a cabo. Realizamos una evaluación filogeográfica basada en un fragmento de 801 pares de bases del gen citocromo b que orientó análisis morfométricos (comparaciones univariadas y multivariadas) respecto al patrón geográfico de variación de la especie y la distinción de sus formas nominales. Los haplotipos de N. lactens forman un clado bien apoyado y geográficamente estructurado. Dentro de este clado, los haplotipos del norte de su área de distribución forman un clado bien apoyado que es hermano y alopátrico con respecto de un clado austral débilmente apoyado, el cual incluye variantes colectadas en las localidades tipo de las tres formas nominales o sus cercanías. A su vez, ambos clados principales están compuestos por dos sub-clados alopátricos. Los análisis morfométricos no revelaron diferencias en la forma del cráneo entre las tres formas nominales ni entre los clados y sub-clados recuperados. Teniendo en cuenta toda la evidencia disponible, consideramos que N. lactens es una especie monotípica. [ABSTRACT FROM AUTHOR]

The nominal species Calomys tener (Winge, 1887) ranges broadly in open lands of the Caatinga, Cerrado, Pantanal and Mata Atlântica of Brazil, and was recently reported from the Pampas of southern Brazil, and in the Selva Paranaense of eastern Paraguay and northeastern Argentina. This rodent can be infected with the pathogenic Araraquara hantavirus in Brazil. Given that most epidemiological studies have not taken into account updated taxonomic findings of their rodent hosts, in this study, we obtained sequence data of the Cyt-b and COI genes of specimens of C. tener from 22 different geographical localities from throughout the currently known distribution of the species (including individuals from Argentina, Paraguay, Bolivia, and Brazil) to test if it constitutes a single genetic unit or if it presents genetic discontinuities that may represent different evolutionary lineages. Phylogenetic analyses including several species of Calomys recovered several clades with strong support. Regarding C. tener, it is recovered as sister to the node that cluster C. laucha (Fischer, 1814) sensu lato, C. expulsus (Lund, 1841) and species in the C. callosus (Rengger, 1830) species complex. At the intraspecific level there are no genetic gaps among haplotypes of C. tener that could suggest more than one species. The recent captures in the Pampas of southern Brazil and in the Selva Paranaense suggest that the species may be colonizing new geographic areas. [ABSTRACT FROM AUTHOR]

Recently, Maestri, Luza, et al. () assessed the effect of ecology and phylogeny on body size variation in communities of South American Sigmodontinae rodents. Regrettably, a cursory analysis of the data and the phylogeny used to address this question indicates that both are plagued with inaccuracies. We urge 'big data' users to give due diligence at compiling data in order to avoid developing hypotheses based on insufficient or misleading basic information. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Mammalogy is the property of Oxford University Press / USA and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Zoology is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article describes the presence of a known specimen of the cricetid genus Punomys, a new rodent genus, for Bolivia based on an adult female caught in 1987. The specific affinities of the specimen are currently unidentified as it shares qualitative as well as quantitative characters with Punomys kofordi and P. lemminus but also differs significantly from both species. It suggests that the levels of intraspecific variation within the known species of Punomys need to be examined critically and the unique Bolivian specimen is damaged badly enough to prevent the comparison of many taxonomically significant characters.

Phylogenetic analyses were conducted on cytochrome b sequence data of the most geographically and taxonomically broad sampling of Cavia taxa to date. Primary objectives included providing the first extensive molecular phylogenetic framework for the genus, testing the taxonomic and systematic hypotheses of previous authors and providing insight into the evolutionary and biogeographic history of the genus. Support was found for the morphologically defined species C. aperea, C. tschudii, C. magna and C. fulgida and the taxonomic placement of taxa previously subject to conflicting taxonomic opinions (e.g. C. nana, C. anolaimae and C. guianae) was further resolved. Additionally, we elevate the Ecuadorian C. a. patzelti to species status, restrict the distributional limits and suggest taxonomic affiliations of some C. tschudii subspecies, and provide strong evidence for the geographic origin of guinea pig domestication. Finally, we provide an estimated evolutionary timeline for the genus Cavia, which appears to extend well into the late Miocene. [ABSTRACT FROM AUTHOR]

González-Ittig, R. E., Salazar-Bravo, J., Barquez, R. M. & Gardenal, C. N. (2010). Phylogenetic relationships among species of the genus Oligoryzomys (Rodentia, Cricetidae) from Central and South America. - Zoologica Scripta, 39, 511-526. The genus Oligoryzomys includes several species very similar in external morphology, which has resulted in a confusing specific taxonomy. Accurate species identification is particularly important because several species of Oligoryzomys act as natural hosts of hantaviruses affecting humans. Here, we assign specific status to individuals from a wide geographical area of Argentina and Chile using sequences of the mtDNA control region. We also compare cytochrome b sequences of 14 species recognized from Central and South America to infer the phylogenetic relationships within the genus. In addition, the results were analysed using available data on chromosome numbers, and the host-parasite relationships reported for the genus Hantavirus. We confirm the geographical distribution of Oligoryzomys longicaudatus (Argentina, Chile), Oligoryzomys nigripes (Argentina, Paraguay, Brazil), Oligoryzomys chacoensis (Argentina, Bolivia, Paraguay), Oligoryzomys fornesi (Argentina, Paraguay), Oligoryzomys destructor (Argentina, Bolivia) and Oligoryzomys microtis (Bolivia, Brazil). Oligoryzomys longicaudatus is strongly related to the Oligoryzomys flavescens complex, which comprises four clades; O. nigripes is closely related to Oligoryzomys stramineus, and Oligoryzomys vegetus, to Oligoryzomys fulvescens from Central America. Oligoryzomys chacoensis, O. destructor, O. fornesi, O. longicaudatus, O. microtis, O. nigripes, O. stramineus, Oligoryzomys moojeni, Oligoryzomys rupestris, O. fulvescens and O. vegetus are confirmed as valid species, whereas O. flavescens, Oligoryzomys magellanicus, Oligoryzomys griseolus, Oligoryzomys victus, Oligoryzomys andinus and Oligoryzomys arenalis need exhaustive revision. The sister species to all the remaining entities of the genus was O. microtis, suggesting an Amazonian origin for the genus. [ABSTRACT FROM AUTHOR]

The article reports on the discovery of Juliomys, a rare sigmodontine rodent, in Paraguay. A specimen of the said rodent was obtained while a study on the effects of habitat fragmentation on the Atlantic Forest in the eastern part of the country was being held. The captured rodent was seen to have orange rump and nose and a slightly bicolored tails. It is noted that the foot pads were big and had long whiskers. The discovery led to the conclusion that the Atlantic Forest in Paraguay has significant mammal diversity and needs to be conserved.

Phylogeographic relationships were evaluated at the intraspecific level using nucleotide sequence data from the mitochondrial cytochrome b gene of representative specimens of "colilargo" (Oligoryzomys longicaudatus) from 31 localities, along its distributional range over a large part of the western Andes and southern Argentina. Based on approximately 1.000 base pairs (bp). we recognized a single species on both the Chilean and the Argentinean side as far as at least latitude 51°S, rejecting the subspecific distinctiveness of longicaudatus and philippi. We thus placed the latter in full synonymy with O. longicaudatus as earlier studies proposed, and enlarged its range as far as Torres del Paine, about 51°S. The occurrence of subspecies in this range is doubtful given the low sequence divergence values and the absence of significant associations between haplotypes and their geography. Additionally, we hypothesized that the entrance of this species into the Chilean side of the Andes mountains occurred through the Patagonian forests of southern Argentina, with further dispersal to the north from the south. [ABSTRACT FROM AUTHOR]

Abstract: With about 400 living species and 82 genera, rodents of the subfamily Sigmodontinae comprise one of the most diverse and more broadly distributed Neotropical mammalian clades. There has been much debate on the origin of the lineage or the lineages of sigmodontines that entered South America, the timing of entrance and different aspects of further diversification within South America. The ages of divergence of the main lineages and the crown age of the subfamily were estimated by using sequences of the interphotoreceptor retinoid binding protein and cytochrome b genes for a dense sigmodontine and muroid sampling. Bayesian inference using three fossil calibration points and a relaxed molecular clock estimated a middle Miocene origin for Sigmodontinae (∼12Ma), with most tribes diversifying throughout the Late Miocene (6.9–9.4Ma). These estimates together results of analyses of ancestral area reconstructions suggest a distribution for the most recent common ancestor of Sigmodontinae in Central-South America and a South American distribution for the most recent common ancestor of Oryzomyalia. [Copyright &y& Elsevier]