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Oxymycterus wayku, new species (holotype CML 7247): dorsal (upper left), ventral (upper right) and lateral (middle) views of skull and labial view (bottom) of mandible. Scale bar = 10 mm.
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Morphological and molecular studies allowed us to recognize a new species of Oxymycterus from the southern end of the Yungas of Argentina. External morphologic traits allow the new species, Oxymycterus wayku, to be differentiated from O. paramensis and O. akodontius, the two currently recognized species for northwestern Argentina, as well as from t...
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... CML 7247, Juvenile male (age 2), collected by J. P. Jayat on 19 June 2005 (original field number JPJ 1407), skin, skull, skeleton, and tissues in alcohol (Fig. 4). Diagnosis: A member of the Subfamily Sigmodontinae (sensu Reig 1980) distinguishable from all other species of the genus Oxymycterus by the following combination of characters: size intermediate for the genus (mean values in mm for two individuals of age 3; length of head and body, 129; tail length, 81; condyloinci- sive length, ...
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... Here, the montane forest is the habitat preferred by the sigmodontines Abrothrix illutea, Akodon caenosus, Akodon simulator, Oxymycterus wayku, Oligoryzomys brendae, and O. cf. O. occidentalis, while A. spegazzinii, Necromys lactens, Calomys musculinus, Phyllotis tucumanus, Reithrodon auritus, and Cavia tschudii show a marked preference for highland grasslands (d 'Hiriart et al., 2015;Jayat et al., 2008aJayat et al., , 2008bJayat et al., , 2010Jayat et al., , 2011Ortiz et al., 2011bOrtiz et al., , 2019. In grassland areas more affected by overgrazing Calomys musculinus is usually the most frequent species (Ortiz et al., 2011b(Ortiz et al., , 2019Ortiz and Jayat, 2007a). ...
... For each sample, the minimum number of individuals (MNI) was determined based on examination of the mandibles and maxillae recovered. For the paleoenvironmental reconstruction, we considered the habitat preferences of current populations of the species recorded in the Late-Holocene sample from Las Chacritas (hereafter LCLH) as well as the environmental characteristics of the areas where they are potentially found in sympatry (d 'Hiriart et al., 2015'Hiriart et al., , 2021a'Hiriart et al., , 2021bJayat et al., 2008aJayat et al., , 2008bJayat et al., , 2010Ortiz, 2003;Ortiz et al., 2011aOrtiz et al., , 2019Ortiz and Jayat, 2007a, 2007b. ...
... Our conclusions would not have been possible without the noteworthy increase in knowledge on taxonomy, distribution, ecological requirements and fossil record of small mammals of the region in recent years, which begins to show general trends on the evolution of these communities in the Quaternary and their close connection with the environmental changes (e.g. d 'Hiriart et al., 2015'Hiriart et al., , 2017'Hiriart et al., , 2021a'Hiriart et al., , 2021bGomez et al., 2012;Guilardi et al., 2020;Jayat et al., 2007Jayat et al., , 2008aJayat et al., , 2008bJayat et al., , 2010Jayat et al., , 2011Jayat et al., , 2016Jayat et al., , 2017Jayat et al., , 2018Jayat et al., , 2020Jayat et al., , 2021Nanni et al., 2012;Ortiz et al., 2000Ortiz et al., , 2011aOrtiz et al., , 2011bOrtiz et al., , 2019Ortiz andJayat, 2007a, 2012;Ortiz and Pardiñas, 2001;Ortiz-Tempel et al., 2022;Teta et al., 2011Teta et al., , 2013Teta et al., , 2022Teta et al., , 2023. Nevertheless, although several Quaternary small mammal assemblages were described for NWA from different periods, our knowledge about short-, medium-, and long-term changes in these communities is still incipient. ...
Based on a diverse Late-Holocene (1889–1743 cal yrs BP) small mammal assemblage (14 species, 204 individuals) resulting from the trophic activity of owls, we reconstruct the paleoenvironmental conditions of Las Chacritas area, Catamarca Province, northwestern Argentina. Twenty modern and one additional Late-Holocene samples from the region were used as comparative parameters in the paleoenvironmental reconstruction. Through direct comparison with a present-day assemblage from Las Chacritas, and using Nonmetric Multidimensional Scaling, spatial and temporal beta diversity (employing the Sorensen dissimilarity index), and the temporal beta diversity index (TBI) including all the small mammal samples, we quantitatively reconstruct the relationships among modern and Late-Holocene assemblages. Direct comparison showed significant differences, with relative abundances changing markedly over time, with several species of the Late-Holocene assemblage absent in the modern sample whereas many species frequent in the modern community absent in the Late-Holocene. NMDS analysis associated the Late-Holocene assemblage with modern samples of western drier environments. Beta diversity was low for presence-absence and moderate for abundance data, with higher contribution of turnover than nestedness, although for abundance data the proportion of nestedness was higher. TBI showed high variation among both Holocene sites and their present-day counterparts, whereas species gains dominated in modern samples. Our results suggest that the habitats surrounding Las Chacritas have modified markedly since the Late-Holocene. Presence of species today frequent in arid environments and absence of forest-dwelling species suggest that open, dry and relatively rocky habitats characterized this area in that interval.
... The genus Oxymycterus therefore stands as one of the challenges to species delimitation among sigmodontine rodents, demanding integration of distinct lines of evidence provided by morphological and molecular analyses, most particularly including examination of type specimens. In fact, recent species descriptions and taxonomic revisions in the genus largely have employed molecular and morphometric analyses to delimit species within complex species groups (Hoffmann et al. 2002;Gonçalves and Oliveira 2004;Jayat et al. 2008;Peçanha et al. 2019). However, numerous problematic species remain unexamined under the aegis of an integrative taxonomic framework. ...
... Oxymycterus quaestor (sensu Oliveira and Gonçalves 2015) presents highly structured mtDNA diversity within the Oxymycterus radiation, and divergence based on Cytb was higher than, or similar to, interspecific distances observed among recognized species of Oxymycterus (Hoffmann et al. 2002;Jayat et al. 2008;Peçanha et al. 2019). On the other hand, the limited variation in the nuclear marker, coupled with the lack of clear morphological segregation among most mitochondrial lineages in PCA analyses of skull shape, does not support the recognition of more than one species within O. quaestor. ...
... Lineage C presents two subclades with low support, one including sequences from eastern Paraguay (Canindeyú Department) and northeastern Argentina (Misiones Province), associated with Seasonal Dry Forests (Alto Paraná Forest); the other distributed along western Paraná State (in Seasonal Dry Forests), São Paulo and Santa Catarina states, mainly in Dense Ombrophilous Forest (Serra do Mar Coastal Forest). The intraclade distance of 0.5% within lineage C obtained in our analysis is equivalent to the distance found by Jayat et al. (2008) andD'Elía et al. (2008) between specimens from São Paulo and Misiones, or from São Paulo and Canindeyú, Paraguay, respectively, attributed to judex and misionalis. A similar pattern of low genetic divergence between Southeastern Brazilian, Misiones, and Paraguayan, samples also has been detected for Sooretamys angouya, a species with distribution similar to that of O. quaestor (Chiquito et al. 2014). ...
We present a new assessment of the genetic and morphological variation within Oxymycterus quaestor Thomas, 1903, which currently includes the junior synonyms O. judex Thomas, 1909 and O. misionalis Sanborn, 1931. We integrate distinct lines of evidence, including variation of mitochondrial (Cytochrome b [Cytb]) and nuclear (intron 7 of beta fibrinogen gene [Fgb]) sequences, and the assessment of skull quantitative traits based on geometric morphometrics, throughout the Atlantic Forest of Southeastern-Southern Brazil, Argentina, and Paraguay. Phylogenetic relationships based on Cytb indicate that O. quaestor is structured in four well-supported clades (lineages AD), one of them (lineage C) including topotypes of a previously associated nominal form (O. judex). However, these Cytb lineages exhibit lower levels of differentiation based on the Fgb locus, and are not recovered in the genealogies of this nuclear marker, representing a case of mitonuclear discordance. The Cytb lineages also broadly overlapped in the morphospace both in skull shape and size, which sustain the current wider concept of O. quaestor as one single young species (0.947 Myr) that is recently expanding, and ultimately branching out, in the Atlantic Forest. Apresentamos uma nova avaliação da variação genética e morfológica dentro de Oxymycterus quaestor Thomas, 1903, que atualmente abrange os sinônimos júnior O. judex Thomas, 1909 e O. misionalis Sanborn, 1931. Integramos distintas linhas de evidência, incluindo variação em sequências de DNA mitocondrial (Citocromo b [Citb]) e nuclear (intron 7 do gene beta fibrinogênio [Fgb]), e avaliação de características quantitativas do crânio com base na morfometria geométrica, ao longo da Floresta Atlântica do Sudeste e Sul do Brasil, Argentina e Paraguai. As relações filogenéticas baseadas em Citb indicam que O. quaestor está estruturado em quatro clados bem sustentados (linhagens A a D), sendo que um deles (linhagem C) contem topótipos correspondentes a uma forma nominal previamente associada à espécie (O. judex). No entanto, as linhagens apresentam menor nível de diferenciação com base no locus Fgb, e não são recuperadas nas genealogias deste marcador nuclear, representando um caso de discordância mitonuclear. Essas linhagens também se sobrepõem Downloaded from https
... The genus Oxymycterus therefore stands as one of the challenges to species delimitation among sigmodontine rodents, demanding integration of distinct lines of evidence provided by morphological and molecular analyses, most particularly including examination of type specimens. In fact, recent species descriptions and taxonomic revisions in the genus largely have employed molecular and morphometric analyses to delimit species within complex species groups (Hoffmann et al. 2002;Gonçalves and Oliveira 2004;Jayat et al. 2008;Peçanha et al. 2019). However, numerous problematic species remain unexamined under the aegis of an integrative taxonomic framework. ...
... Oxymycterus quaestor (sensu Oliveira and Gonçalves 2015) presents highly structured mtDNA diversity within the Oxymycterus radiation, and divergence based on Cytb was higher than, or similar to, interspecific distances observed among recognized species of Oxymycterus (Hoffmann et al. 2002;Jayat et al. 2008;Peçanha et al. 2019). On the other hand, the limited variation in the nuclear marker, coupled with the lack of clear morphological segregation among most mitochondrial lineages in PCA analyses of skull shape, does not support the recognition of more than one species within O. quaestor. ...
... Lineage C presents two subclades with low support, one including sequences from eastern Paraguay (Canindeyú Department) and northeastern Argentina (Misiones Province), associated with Seasonal Dry Forests (Alto Paraná Forest); the other distributed along western Paraná State (in Seasonal Dry Forests), São Paulo and Santa Catarina states, mainly in Dense Ombrophilous Forest (Serra do Mar Coastal Forest). The intraclade distance of 0.5% within lineage C obtained in our analysis is equivalent to the distance found by Jayat et al. (2008) andD'Elía et al. (2008) between specimens from São Paulo and Misiones, or from São Paulo and Canindeyú, Paraguay, respectively, attributed to judex and misionalis. A similar pattern of low genetic divergence between Southeastern Brazilian, Misiones, and Paraguayan, samples also has been detected for Sooretamys angouya, a species with distribution similar to that of O. quaestor (Chiquito et al. 2014). ...
We present a new assessment of the genetic and morphological variation within Oxymycterus quaestor Thomas, 1903, which currently includes the junior synonyms O. judex Thomas, 1909 and O. misionalis Sanborn, 1931. We integrate distinct lines of evidence, including variation of mitochondrial (Cytochrome b [Cytb]) and nuclear (intron 7 of beta fibrinogen gene [Fgb]) sequences, and the assessment of skull quantitative traits based on geometric morphometrics, throughout the Atlantic Forest of Southeastern-Southern Brazil, Argentina, and Paraguay. Phylogenetic relationships based on Cytb indicate that O. quaestor is structured in four well-supported clades (lineages A–D), one of them (lineage C) including topotypes of a previously associated nominal form (O. judex). However, these Cytb lineages exhibit lower levels of differentiation based on the Fgb locus, and are not recovered in the genealogies of this nuclear marker, representing a case of mitonuclear discordance. The Cytb lineages also broadly overlapped in the morphospace both in skull shape and size, which sustain the current wider concept of O. quaestor as one single young species (0.947 Myr) that is recently expanding, and ultimately branching out, in the Atlantic Forest.
... The subfamily Sigmodontinae (family Cricetidae) is the largest lineage, including 438 species (Pardiñas et al. 2017;Hurtado and D'Elia 2018). In the last 10 years, 26 new species have been described (Jayat et al. 2008(Jayat et al. , 2016Percequillo et al. 2008Percequillo et al. , 2011Pardiñas et al. 2009Pardiñas et al. , 2013Pardiñas et al. , 2014Pardiñas et al. , 2016Carleton et al. 2009;Bonvicino et al. 2010Bonvicino et al. , 2014Braun et al. 2010;Andrade-Costa et al. 2011;Tavares et al. 2011;Gonçalves and Oliveira 2014;Quintela et al. 2014Quintela et al. , 2017D'Elía et al. 2015a;Hanson et al. 2015;Christoff et al. 2016;Teta and D'Elía 2016;Brito 2017;Palma and Rodríguez-Serrano 2017;Hurtado and D'Elía 2018;Timm et al. 2018) and a number of phylogenetic units, i.e., lineages divergent at the species level based on at least one molecular marker, were identified (e.g., Ventura et al. 2011;D'Elía et al. 2015b;Suárez-Villota et al. 2017). Despite this high taxonomic diversity, the alpha taxonomy remains uncertain in several groups, for example, within the tribe Akodontini in the genus Oxymycterus Waterhouse, 1837 (Oliveira and Gonçalves 2015). ...
... Oxymycterus is composed of 15 species distributed across a wide geographic range in South America, including strikingly distinct ecoregions, such as forest borders in the Atlantic and Amazon Forests, open areas in the Caatinga (restricted to fertile regions), Cerrado , Pampas (Peçanha et al. 2017), Yungas Montane Forests (Jayat et al. 2008), and regions with elevations above 4,000 m in the Andean Mountains (Hershkovitz 1994). This group also includes terrestrial species with marked habitat preferences, particularly wet grasslands, tall grass, woodland, and near edges of streams or rocky outcroppings (Hershkovitz 1994). ...
... Phylogenetic inferences in Oxymycterus have been made with a combination of molecular and craniometric analyses (Hoffmann et al. 2002;Gonçalves and Oliveira 2004;Jayat et al. 2008), and multilocus sequence data (e.g., Fabre et al. 2012;Parada et al. 2015). However, overall species boundaries have only been delimited through DNA polymorphisms, due to difficulties in detecting discontinuities in cytogenetic and morphological characteristics in this sigmodontine group (Hoffmann et al. 2002;Gonçalves and Oliveira 2004). ...
We describe a new species of the cricetid rodent Oxymycterus (Sigmodontinae), which inhabits a transitional area between the southern Cerrado and the Atlantic Forest in south-southeastern Brazil. Compared to other Oxymycterus, the new species is large-sized with a tawny-brown pelage coloration. The new species could be differentiated from other Oxymycterus species by a combination of cranial characteristics that includes markedly large and inflated auditory bulla; a narrow rostrum and large incisive foramen, with the posterior extremity reaching the posterior region of the M1 protocone or hypoflexus; a wide parapterygoid fossa; the presence of a foramen ovale in the posterior region of the parapterygoid plate; and a thin hamular process of the squamosal. Bayesian analysis based on the mitochondrial and nuclear genes (cytochrome-b and acid phosphatase type V—Intron 2, respectively) recovered from the Oxymycterus sp. nov. showed it to be phylogenetically closely related to O. amazonicus and O. delator, all three species associated with open vegetation. The lineage leading to this clade likely emerged around 1.14 million years ago during the Early-Middle Pleistocene. Genetic distances between the new taxa and these two species calculated from comparison of cytochrome-b sequences are 3.7% and 4.1%, respectively. Currently, Oxymycterus sp. nov. is known from only two unprotected sites, with the type locality inserted in an area under the process of conurbation. Our study raises the number of living species in the genus to 16.
Descrevemos uma nova espécie de roedor cricetídeo Oxymycterus (Sigmodontinae), que habita uma área de transição entre o Cerrado Meridional e a Mata Atlântica no Sudeste do Brasil. Comparativamente aos demais Oxymycterus, a nova espécie possui tamanho médio e coloração marrom-avermelhada. A nova espécie também pode ser diferenciada dos demais Oxymycterus pelo tamanho e forma do crânio. Em particular por uma combinação de características cranianas, que incluem a bula auditiva acentuadamente grande e inflada, um rostro estreito e um grande forame incisivo, com a extremidade posterior alcançando a região posterior do protocone ou hipoflexus do M1; fossa parapterigóide larga; a presença de um forame oval na região posterior da placa parapteritóide; e um estreito processo hamular do esquamosal. Uma análise bayesiana reconstruída com base em genes mitocondriais e nucleares (citocromo-b e o íntron 2 do fosfatase ácida tipo V, respectivamente) demostrou que Oxymycterus sp. nov. é filogeneticamente relacionada a O. amazonicus e O. delator, todas as três espécies associadas a formações savânicas. A linhagem que deu origem a esse clado surgiu, provavelmente, há cerca de 1,14 milhão de anos (MIA) durante o Pleistoceno Médio-Antigo. A distância genética entre o novo táxon e estas duas espécies, calculadas a partir da comparação de sequências do gene citocromo-b, foram de 3.7% e 4.1%, respectivamente. Oxymycterus sp. nov. é conhecido apenas em duas localidades não protegidas, e a localidade tipo encontra-se em uma área em processo de conurbação. Nosso estudo eleva para 16 o número de espécies descritas para o gênero.
... Several modern samples of Tyto furcata pellets recovered in Tafí valley were used for comparison in the paleoenvironmental reconstruction. We considered the habitat preferences of current populations of the species recorded in La Mesada as well as the environmental features of the areas where they are found in sympatry (Ortiz, 2003;Jayat et al., 2008aJayat et al., , b, 2010Jayat et al., , 2016Ortiz andJayat, 2007a, b, 2012;Ortiz et al., 2011a;Teta et al., 2011;d'Hiriart et al., 2015;d'Hiriart, 2018). For better interpretation, we ordered the fossil and current samples through a Principal Component Analysis (PCs). ...
... Akodon boliviensis Meyen, 1833. Akodon spegazzinii Thomas, 1897 (Jayat et al., 2008a(Jayat et al., , 2010. Akodon spegazzinii is one of the more frequent small mammal species in the valley, known both from trapping and owl pellet analyzes Ortiz and Jayat, 2007a). ...
... Oxymycterus wayku is only known for a narrow strip of Yungas forests of Sierra del Aconquija and Cumbres Calchaquíes between 800 and 2400 m in Tucumán and neighboring areas of Catamarca and Salta (Jayat et al., 2008a(Jayat et al., , b, 2018d'Hiriart et al., 2015). In Tucumán there are also a few records of O. paramensis, in Yungas forests at low elevation and in the ecotone between montane forest and highland grasslands (Jayat et al., 2008b). ...
We described a fossil small mammal assemblage from La Mesada (2250 m), Tafí valley, Tucumán, Argentina, recovered from levels
referred to late Pleistocene – early Holocene. Gastric corrosion in bones and teeth indicates that the assemblage was generated by the trophic activities of owls. The assemblage is composed by 14 species of rodents: 12 living (Abrothrix illutea, Akodon spegazzinii, Oxymycterus sp., Andinomys edax, Oligoryzomys brendae, Oligoryzomys cf. O. occidentalis, Calomys cf. C. musculinus, Phyllotis sp., Reithrodon auritus, Cavia cf. C. tschudii, Galea leucoblephara, and Ctenomys sp.), one extinct (†Tafimys powelli), and one indeterminate (Sigmodontinae indet.). The sample is characterized by the remarkable dominance of R. auritus (53%) in contrast to its low frequency in other fossil and present-day samples in the area, the presence of †T. powelli, and the absence of one species currently present in the valley (Necromys lactens). The fossil sample shares general similarities with other late Pleistocene – early Holocene assemblages in northwestern Argentina, but there are relevant qualitative and quantitative differences. Although all living species of the fossil sample occur in sympatry in the same area, its quantitative representation (dominance of R. auritus and a higher proportion of herbivore species) is coherent with paleoenvironments with a clear predominance of highland grasslands, involving both the descent and contraction of the vegetation belts on mountain slopes. However, it cannot be discarded that the current scarcity of R. auritus is more related to the anthropic impact than to the prevailing climate in the valley.
... Los sigmodontinos están representados por algo más de 50 especies en el NOA (Patton et al., 2015, con modificaciones), lo que constituye aproximadamente el 30% de los mamíferos registrados en esta región. Esta notable diversidad, reunida en un área pequeña del continente, es en parte el resultado de la confluencia de faunas de distintas afinidades biogeográficas en el gradiente altitudinal (entre áreas abiertas de altura y zonas boscosas de baja altitud) y latitudinal (entre regiones tropicales y templadas) de la región, pero también de la presencia de varias especies endémicas (Jayat et al., 2007(Jayat et al., , 2008a(Jayat et al., , 2010(Jayat et al., , 2016aMares et al., 2008;Ferro & Barquez, 2009, 2014Ferro, 2013). ...
... Sobre la base de los especímenes que hemos podido examinar, incluyendo los aquí reportados, y teniendo en cuenta su patrón de distribución geográfica y ambiental, las localidades confirmadas para esta especie en Argentina son solo 11, la mayoría restringidas a pastizales húmedos altoandinos y al área de ecotono entre estos pastizales y los pastizales de neblina de Yungas de las laderas orientales de la Cordillera Oriental (Fig. 3A). Seis de estas localidades corresponden a la provincia de Salta (Jayat et al., 2006;2008a;2010;Ferro 2010;Sandoval, 2012) y apenas tres a Jujuy (Ferro, 2010;Sandoval, 2012). En este trabajo adicionamos dos localidades para esta última provincia. ...
... Los materiales recuperados de las egagrópilas estuvieron representados por al menos 12 individuos (Fig. 1H). La especie cuenta con apenas 14 registros puntuales para Argentina, la mayoría de ellos muy dispersos y localizados en áreas de pastizales de la Puna y Altos Andes (Barquez, 1983;Díaz et al., 2000;Ortiz et al., 2000;Pardiñas & Ortiz, 2001;Jayat et al., 2008aJayat et al., , 2011aFerro & Barquez, 2017) ( Fig. 4 A). Aquí adicionamos el segundo registro para Tucumán, el cual está situado aproximadamente 50 km al norte de la localidad previamen-te conocida, y suma una cita de la especie para los pastizales de neblina de Yungas en la zona de ecotono con los pastizales altoandinos, en donde es escasamente conocida (Fig. 4A). ...
The Sigmodontinae have radiated to encompass all the terrestrial environments and a wide altitudinal gradient through its large geographic distribution. In Northwestern Argentina (NWA) this group constitutes approximately 30% of the mammals of the region. Several works in the last years have contributed to the knowledge of the geographic distribution of the sigmodontine rodents in NWA. Notwithstanding, many of the species are known only by old and scarce records, most of them heavily biased towards more accessible areas. From surveys conducted in the last three years in the area, which include captures and collections of pellets samples of strigiform birds, in this work we report novel distribution records for the species in this group. We contribute with new record for ten species and eight localities. The new records include the addition of Abrothrix illutea and Oxymycterus wayku for Salta province and Andalgalomys cf. A. olrogi for La Rioja province, the first mentions of Calomys lepidus and Phyllotis tucumanus in high altitudinal grasslands located in Monte de Sierras y Bolsones and Akodon boliviensis in the Puna of Argentina, and several distributional records for Abrothrix andina, Neotomys ebriosus, P. anitae, and Reithrodon auritus, four species not well documented in the study area. Finally, we discussed some methodological and taxonomic aspects, and the relevance of each one of the obtained records.
... Los sigmodontinos están representados por algo más de 50 especies en el NOA (Patton et al., 2015, con modificaciones), lo que constituye aproximadamente el 30% de los mamíferos registrados en esta región. Esta notable diversidad, reunida en un área pequeña del continente, es en parte el resultado de la confluencia de faunas de distintas afinidades biogeográficas en el gradiente altitudinal (entre áreas abiertas de altura y zonas boscosas de baja altitud) y latitudinal (entre regiones tropicales y templadas) de la región, pero también de la presencia de varias especies endémicas (Jayat et al., 2007(Jayat et al., , 2008a(Jayat et al., , 2010(Jayat et al., , 2016aMares et al., 2008;Ferro & Barquez, 2009, 2014Ferro, 2013). ...
... Sobre la base de los especímenes que hemos podido examinar, incluyendo los aquí reportados, y teniendo en cuenta su patrón de distribución geográfica y ambiental, las localidades confirmadas para esta especie en Argentina son solo 11, la mayoría restringidas a pastizales húmedos altoandinos y al área de ecotono entre estos pastizales y los pastizales de neblina de Yungas de las laderas orientales de la Cordillera Oriental (Fig. 3A). Seis de estas localidades corresponden a la provincia de Salta (Jayat et al., 2006;2008a;2010;Ferro 2010;Sandoval, 2012) y apenas tres a Jujuy (Ferro, 2010;Sandoval, 2012). En este trabajo adicionamos dos localidades para esta última provincia. ...
... Los materiales recuperados de las egagrópilas estuvieron representados por al menos 12 individuos (Fig. 1H). La especie cuenta con apenas 14 registros puntuales para Argentina, la mayoría de ellos muy dispersos y localizados en áreas de pastizales de la Puna y Altos Andes (Barquez, 1983;Díaz et al., 2000;Ortiz et al., 2000;Pardiñas & Ortiz, 2001;Jayat et al., 2008aJayat et al., , 2011aFerro & Barquez, 2017) ( Fig. 4 A). Aquí adicionamos el segundo registro para Tucumán, el cual está situado aproximadamente 50 km al norte de la localidad previamen-te conocida, y suma una cita de la especie para los pastizales de neblina de Yungas en la zona de ecotono con los pastizales altoandinos, en donde es escasamente conocida (Fig. 4A). ...
The Sigmodontinae have radiated to encompass all the terrestrial environments and a wide altitudinal gradient through its large geographic distribution. In Northwestern Argentina (NWA) this group constitutes approximately 30% of the mammals of the region. Several works in the last years have contributed to the knowledge of the geographic distribution of the sigmodontine rodents in NWA. Notwithstanding, many of the species are known only by old and scarce records, most of them heavily biased towards more accessible areas. From surveys conducted in the last three years in the area, which include captures and collections of pellets samples of strigiform birds, in this work we report novel distribution records for the species in this group. We contribute with new record for ten species and eight localities. The new records include the addition of Abrothrix illutea and Oxymycterus wayku for Salta province and Andalgalomys cf. A. olrogi for La Rioja province, the first mentions of Calomys lepidus and Phyllotis tucumanus in high altitudinal grasslands located in Monte de Sierras y Bolsones and Akodon boliviensis in the Puna of Argentina, and several distributional records for Abrothrix andina, Neotomys ebriosus, P. anitae, and Reithrodon auritus, four species not well documented in the study area. Finally, we discussed some methodological and taxonomic aspects, and the relevance of each one of the obtained records. © 2018 Museo Argentino de Ciencias Naturales Bernardino Rivadavia.
... Most of these changes correspond to the provision of records for NWA of species previously known from other areas (e.g., Barquez et al. 2006b;). However, new species based on material collected in NWA were also described (e.g., Jayat et al. 2007Jayat et al. , 2008aMares et al. 2008). Finally, disagreements on the distinction of different populations have prompted changes in the taxonomic status of some nominal forms (e.g., Ferro & Martínez 2009;Jayat et al. 2010). ...
... In recent years, however, new nominal forms were proposed, as well as the exclusion of one species now placed in the genus Tapecomys (Jayat et al. 2007;Steppan et al. 2007;Ferro et al. 2010;Pacheco et al. 2014;Rengifo & Pacheco 2015) The results here obtained support this idea, revealing a higher species diversity in the P. osilae species group than previously envisioned, even when focusing at a relatively small area of high altitudinal grasslands in NWA. This topographically and environmentally complex area, largely ignored by mammalogists, has been in the last decade the source for many additions to the Argentinean sigmodontine fauna (Jayat et al. , 2008b(Jayat et al. , 2011a, including the discovery of new species (e.g., Jayat et al. 2007Jayat et al. , 2008a. Currently, three species of the P. osilae species group, P. alisosiensis, P. anitae, and P. osilae, are recognized in NWA. ...
... More in general, the complex physiographic and environmental features of NWA coupled with its unique biogeographic history surely have constituted a major driving force for the striking sigmodontine diversity of the region. A recent account mentioned at least 50 species for this relatively small area (Jayat et al. 2011a), many of which are environmentally restricted and thus, confined to narrow distributional ranges (e.g., Jayat et al. 2007Jayat et al. , 2008aMares et al. 2008;Teta et al. 2011). However, as shown in the present study, considerable uncertainties still remain regarding such basic subjects as species boundaries, identity and distribution, while most of the area and environments still are to be appropriately surveyed (Jayat et al. 2011a, b). ...
The taxonomic status of populations of the genus Phyllotis from northwestern Argentina (NWA) has undergone recent changes, with the addition of two species (P. alisosiensis and P. anitae) to the traditionally recognized forms (P. caprinus, P. xanthopygus, and P. osilae). Three of these species (P. anitae, P. osilae, and P. alisosiensis) were included within the Phyllotis osilae species group. Most authors recognized three subspecies of P. osilae for NWA: P. osilae osilae, P. o. nogalaris, and P. o. tucumanus. Morphological, morphometric, and molecular studies based on recently collected specimens suggest that current classification does not reflect the diversity of this group in NWA, revealing the need of some taxonomic reallocations and new distributional delimitations. Here we propose that P. nogalaris must be recognized as a valid species and the restriction of P. osilae to southern Peru and central Bolivia. Following our results, we expect an outstanding improvement in the taxonomic knowledge of the Phyllotis osilae species group in the coming years.
... The rodent genus Oxymycterus Waterhouse, 1837, is a diverse and widely distributed group of the tribe Akodontini Jayat et al. 2008a), ranging from the Amazon Basin (Hershkovitz 1994) to central Argentina (Buenos Aires Province), and Uruguay. Only three nominal species have been mentioned for northwestern Argentina: O. akodontius Thomas 1921, O. paramensis Thomas 1902, and O. wayku Jayat, D'Elía, Pardiñas, Miotti, and Ortiz, 2008(Thomas 1921, 1925Barquez 1976;Díaz et al. 2000;Díaz and Barquez 2007;Jayat et al. 2008aJayat et al. , 2008b. ...
... The rodent genus Oxymycterus Waterhouse, 1837, is a diverse and widely distributed group of the tribe Akodontini Jayat et al. 2008a), ranging from the Amazon Basin (Hershkovitz 1994) to central Argentina (Buenos Aires Province), and Uruguay. Only three nominal species have been mentioned for northwestern Argentina: O. akodontius Thomas 1921, O. paramensis Thomas 1902, and O. wayku Jayat, D'Elía, Pardiñas, Miotti, and Ortiz, 2008(Thomas 1921, 1925Barquez 1976;Díaz et al. 2000;Díaz and Barquez 2007;Jayat et al. 2008aJayat et al. , 2008b. However, Oliveira and Gonçalves (2015) considered O. akodontius as synonym of O. paramensis. ...
... Oxymycterus wayku is restricted to southern Yungas, in Tucumán province, where it has only been recorded at four localities on the humid eastern slopes of Cumbres Calchaquíes and Sierra del Aconquija (Jayat et al. 2008a). This species probably lives only in a narrow belt of humid forest, from about 800 m elevation in Selva Montana (sensu Brown et al. 2001) to the ecotone between Alnus woodland (Bosque Montano; sensu Brown et al. 2001) and highland grasslands, at about 2200 m elevation (Jayat et al. 2008a). ...
Oxymycterus wayku Jayat, D’Elía, Pardinãs, Miotti & Ortiz, 2008, a rodent species recently described, is known in only four localities within the Subtropical Mountain Forests of the Yungas eco-region in Tucumán, northwestern Argentina. Specimens were recorded in an owl pellet sample during a recent survey. This record represents the first for Oxymycterus in Catamarca Province, extending approximately 60 km south its southern distribution in the region. Sixteen other small non-volant mammal species were recorded there, turning this area into one of the most diverse for this understudied group in Argentina.
... Mean Cytb genetic distance between the two Neusticomys haplogroups (8.5 %) is in the order of mean genetic distances shown between species in other groups of sigmodontine rodents (e.g., Abrothrix ca. 5 to 10 % [Feijoo et al. 2010;D'Elía et al. in press]; species of the Akodon boliviensis species group: 2.8-7.7 % [Jayat et al. 2010]; Eligmodontia: 4.6-11.4 % [Mares et al. 2008]; Juliomys: ca. 12 % ; Melanomys: 4.5-7.6 % [Hanson and Bradley 2008]; Nectomys: 7.36 % [Hanson and Bradley 2008]; Oligoryzomys: 4.45-15 % [Hanson et al. 2011;Palma et al. 2010;Richter et al. 2010;Rogers et al. 2009]; Oryzomys: 4.5-12.1 % ; Oxymycterus: 2.5-9.6 % [Jayat et al. 2008 [Henson and Bradley 2009]). Although the species used for comparison are not the closest possible relatives to Neusticomys, all belong to other sigmodontine tribes and provide a diverse array of reference points. ...
Background: In this study, the genetic substructure and morphology of the species Neusticomys monticolus was evaluated. A nuclear marker and mitochondrial maker were used to examine phylogeographic structure and to estimate genetic distances. Two statistical measurement analyses were applied to morphological data.
Results: These data recovered two morphologically distinct phylogeographic groups corresponding to populations on the eastern and western slopes of the Andes. Further, these eastern and western Andean slope populations of N. monticolus are 8.5 % divergent using sequence data from cytochrome-b (0.8 % divergent in the interphotoreceptor retinoid-binding protein gene).
Conclusions: Populations currently assigned to N. monticolus constitute a species complex. The name N. monticolus is here restricted to western Andean slope populations. Populations on the eastern slope of the Andes are assigned to a new species, to which the authors assign the name Neusticomys vossi sp. nov.
