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Calomys laucha (Fischer, 1814) is a small phyllotine rodent (

We provide a formal recognition to a tribal level clade composed of Andinomys and Punomys , two extant sigmodontine genera consistently and repeatedly recovered in the phylogenetic analyses of molecular and morphological data. As currently recognized, this tribe is distributed in middle to high elevations in the Andes of Bolivia, Peru, northern Chile, and northwestern Argentina in habitats that range from high elevation grasslands and ecotonal areas to dry Puna. Within this new clade, Punomys appears as the more specialized member as it is fully restricted to rocky outcrops and their immediate surrounding areas at elevations above 4400 m on both sides of the Altiplano. In contrast, Andinomys occupies a broad elevational range (500–4000 m) and multiple habitats, from subtropical mountain forests and semiarid Puna and Prepuna to high altitudinal grasslands. Both taxa share a number of possible synapomorphies (e.g., presence of caudal enlargement of the post-zygapophysis in the second and eighth thoracic vertebrates, unilocular-hemiglandular stomachs with a large corpus and deep incisura angularis, and very similar chromosomal complements) and other diagnostic morphological features. The supratribal phylogenetic relationships of the taxon here named are not resolved even with the moderate amount of molecular data now available. In addition, we present a revised classification for the Sigmodontinae and comment on the content and context of this unique radiation of the Cricetidae. En este trabajo reconocemos formalmente un clado de nivel tribal compuesto por los géneros de roedores sigmodontinos Andinomys y Punomys , el que es consistentemente recuperado en el análisis filogenético de datos moleculares y morfológicos. Los miembros de esta tribu se distribuyen en los Andes de Perú, Bolivia, norte de Chile y el noroeste de Argentina en hábitats que van desde praderas altoandinas y hábitats ecotonales hasta la Puna seca. Dentro de este nuevo clado Punomys parece ser el miembro más especializado, ya que está totalmente restringido a afloramientos rocosos y sus áreas aledañas en elevaciones superiores a 4400 m en ambos lados del Altiplano. En contraste, Andinomys ocupa múltiples ambientes en elevaciones que van desde 500–4000 m y que incluyen bosques subtropicales de montaña, Puna y pre-Puna semiáridas y pastizales de altura. Andinomys y Punomys comparten una serie de posibles sinapomorfías (por ejemplo, ampliación caudal de la postzigapófisis de la segunda y octava vertebras torácicas, estómagos uniloculares y hemiglandulares con incisura y corpus especialmente prominentes y complementos cromosómicos muy similares) entre otras características morfológicas diagnósticas. Las relaciones filogenéticas supratribales del taxón aquí nombrado no se resuelven incluso con una cantidad moderada de datos moleculares. Por último, se presenta una clasificación actualizada para la subfamilia Sigmodontinae y se ofrecen comentarios sobre el contenido y el contexto de esta singular radiación de los Cricetidae. Fil: Salazar Bravo, Jorge. Texas Tech University; Estados Unidos Fil: Pardiñas, Ulises Francisco J.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Diversidad y Evolución Austral; Argentina Fil: Zeballos, Horacio. Pontificia Universidad Católica de Perú; Perú Fil: Teta, Pablo Vicente. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina

El roedor filotino Tapecomys ha sido mencionado con 2 especies en Argentina, la típica Tapecomys primus Anderson y Yates, 2000 y Tapecomys wolffsohni (Thomas, 1902); ambas han sido reportadas como simpátricas en 1 localidad de las Yungas de Jujuy. Una revisión de estos materiales indica que la referencia a T. wolffsohni es incorrecta. En este contexto, en la selva montana solo se registra T. primus con 4 localidades en Jujuy. Otro registro para T. wolffsohni en Argentina, correspondiente a una localidad de Salta, es discutido sobre la base de una nueva aproximación morfológica. En el estado de conocimiento actual no es posible afirmar que T. wolffsohni habite el país. The 2 known species of the phyllotine rodent Tapecomys , the typical, Tapecomys primus Anderson and Yates, 2000 and Tapecomys wolffsohni (Thomas, 1902), have been cited for Argentina, and reported to be sympatric in 1 locality in the Yungas of Jujuy. A review of these materials suggest that the reference for T. wolffsohni is incorrect. In this context, only 1 species— T. primus —is present in 4 localities in the montane forests of Jujuy. A record for T. wolffsohni from 1 locality in Salta, is discussed based on a critical assessment of the morphological variation of these species. Currently it is not possible to confirm that T. wolffsohni inhabits the country. Fil: Pardiñas, Ulises Francisco J.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Diversidad y Evolución Austral; Argentina Fil: Teta, Pablo Vicente. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina Fil: Salazar Bravo, Jorge. Texas Tech University; Estados Unidos

Phylogenetic hypotheses based on molecular markers indicate that the so-called Reithrodon group, including the extant genera Euneomys, Neotomys, and Reithrodon, formerly within the tribe Phyllotini, is not monophyletic. In turn, a new clade of tribal rank is recovered constituted by Euneomys, Irenomys, and Neotomys, comprising a small, mostly Andean sigmodontine radiation. Within the new clade, here named and diagnosed, Irenomys appears as a taxon with many specialized traits, which suggests an early divergence associated with the exploitation of Nothofagus forests. The living members of the new tribe are characterized by several morphological features including grooved upper incisors, narrow and parallel-sided interorbital regions, enlarged interparietals, and simplified and hypsodont molars. This new phylogenetic scenario implies a high degree of craniodental convergence among several lineages of sigmodontine rodents. The tribal position of several highcrowned extinct forms of sigmodontine rodents (e.g., Panchomys, Tafimys), formerly allocated to the Reithrodon group, is in need of revision. Hipótesis filogenéticas basadas en marcadores moleculares indican que el denominado grupo Reithrodon, incluyendo los géneros vivientes Euneomys, Neotomys y Reithrodon, anteriormente dentro de la tribu Phyllotini, no es monofilético. En cambio, un nuevo clado de rango tribal es recuperado, constituido por Euneomys, Irenomys y Neotomys, comprendiendo una pequeña radiación de sigmodontinos mayormente andinos. Dentro de este nuevo clado, aquí nominado y diagnosticado, Irenomys emerge como un taxón con varios rasgos especializados que sugieren una temprana divergencia en el marco de la explotación del bosque de Nothofagus. Los miembros vivientes de la nueva tribu están caracterizados por varios rasgos morfológicos, incluyendo incisivos superiores surcados, regiones interorbitarias angostas y de bordes paralelos, interparietales agrandados y molares simplificados e hipsodontes. Este nuevo escenario filogenético implica un alto grado de convergencia en la morfología cráneo-dentaria entre varios linajes de roedores sigmodontinos. La posición tribal de varias formas extintas de roedores sigmodontinos de coronas altas (e.g., Panchomys, Tafimys), anteriormente ubicadas en el grupo Reithrodon, necesita ser revisada. Fil: Pardiñas, Ulises Francisco J.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Diversidad y Evolución Austral; Argentina Fil: Teta, Pablo Vicente. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Diversidad y Evolución Austral; Argentina Fil: Salazar Bravo, Jorge. Texas Tech University; Estados Unidos

The small vesper mouse (Calomys laucha (Fischer, 1814)) (Cricetidae: Sigmodontinae) ranges widely in Brazil, Uruguay, Paraguay, Argentina, and Bolivia. The species is the reservoir of the Laguna Negra hantavirus (LNV) in Paraguay but not in Argentina, where it is one of the most abundant rodents in agro-pastoral ecosystems. To answer the question if the nominal species C. laucha constitutes a single genetic unit or if it presents genetic discontinuities that may relate to hosting LNV, we sequenced the cytochrome b (cyt b) gene of specimens from throughout the range of the distribution of the species. Phylogenetic analyses revealed two well-supported clades. Twenty-two sequences from Argentina, Paraguay, and Bolivia grouped in clade A, but three sequences from Uruguay and Brazil clustered in a quite divergent clade B. The genetic distance between the two groups is 5.75%. No significant differences between Argentinean, Paraguayan, and Bolivian specimens assigned to C. laucha were detected. The restricted distribution of LNV associated to C. laucha in central Paraguay could be explained by a “natural nidality” phenomenon. Fil: González Ittig, Raúl Enrique. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Cordoba. Instituto de Diversidad y Ecologia Animal; Argentina Fil: Kandel, Narayan. Texas Tech University; Estados Unidos Fil: Levis, Silvana. Instituto Nacional de Enfermedades Humanas; Argentina Fil: Calderón, Gladys. Instituto Nacional de Enfermedades Humanas; Argentina Fil: Salazar Bravo, Jorge. Texas Tech University; Estados Unidos Fil: Gardenal, Cristina Noemi. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Cordoba. Instituto de Diversidad y Ecologia Animal; Argentina

Akodon spegazzinii Thomas, 1897 Akodon spegazzinii Thomas, 1897. Annals and Magazine of Natural History, 6(20): 216. Akodon tucumanensis J. A. Allen, 1901. Bulletin of the American Museum of Natural History, 14: 410. Akodon alterus Thomas, 1919. Annals and Magazine of Natural History, 9(3): 496. Akodon leucolimnaeus Cabrera, 1926. Revista Chilena de Historia Natural, 30:320. Holotype: B.M. 97.5.5.14. Type locality: Lower Cachi (Thomas 1897). Probably Thomas referred to the lower course of the R��o Cachi which passes through the town of Cachi, close to the junction with the R��o Calchaqu��. The town is situated in the Deparment of Cachi, in central Salta Province (25�� 07`11.93``S, 66�� 09`47.00``W, 2341 m). Description: Because of the terse description of the species (Thomas 1897) and the paucity of specimens available to later workers (Myers et al. 1990; D��az 1999), here we offer a more detailed description of A. spegazzinii based on topotypic specimens but including also material coming from the known range of the species. General coloration remarkably variable, with individuals ochraceous brown, ruddy brown, fulvous brown, and buffy brown, and darker or paler depending on individuals and populations. Dorsal coloration uniform from head to rump and with more or less spattered black or dark brown hairs. The yellow eye ring are always present but its development is variable. Ears of same color as dorsum. Flanks with the same coloration as dorsum but some clearer. The venter is buffy, ruddy gray or ochraceous gray and contrast lightly with the dorsum. The chin is covered by a few isolated white hairs that do not form a conspicuous patch. Inguinal region of some individuals with a more intensive hue. Both fore and hind feet covered with bicolored hairs and whitish, buffy or greyish in appearance. Claws covered with tufts of hairs greyish brown at the base and tipped white. Tail conspicuously bicolored, dorsally brown or blackish brown and ventrally whitish or buffy, more or less furred depending on population. Skull of intermediate size for the boliviensis group and characterized by a well-developed rostrum, relatively narrow zygomatic notches, and lightly swollen frontal sinuses. Interorbital region hourglass shaped, with rounded or slightly squared margins and without overhanging borders. Zygomatic arches not specially flared. The braincase is relatively inflated, but some variation exists among individuals. Temporal and lambdoid crests relatively well developed, mainly in old individuals. Dorsal profile of the cranium relatively arched, especially in young specimens. Zygomatic plate breadth generally intermediate in size but highly variable among individuals. The anterior margin is straight or slightly concave with its dorsal root gently sloping backward. Hamular process generally slender and expanded in its distal end. Posterior ascending process of alisphenoid reaches or surpasses the squamoso-alisphenoid groove. Postglenoid foramen and subsquamosal fenestra are developed, and the ratio between them is highly variable. Incisive foramina relatively long, extended in some specimens to the anterior border of hypocone of M1. Mesopterygoid fossa of intermediate breadth for the group, with the anterior margin slightly rounded or squared and with the lateral borders straight and slightly divergent backward. The medial process of posterior palate can be present but never is well developed. Posteropalatal pits generally tiny and situated at the same level or slightly backward with respect to the anterior margin of mesopterygoid fossa. Parapterygoid fossae of the same breadth or slightly broader than mesopterygoid fossa, relatively shallow, with lateral margins straight or slightly convex, diverging backwards. Tympanic bullae not especially developed with Eustachian tubes generally broad and short. Mandibular ramus delicate. Anterior end of maseteric crest situated just behind the level of the anterior border of M1. The development and position of the capsular projection is variable: in general, it is conspicuous and situated slightly behind the posterior border of the coronoid process. This process is delicate and extends just above the condyloid process. The condyle extends behind the posterior margin of angular process. Upper incisors orthodont, with yellowish orange enamel. Molars with crested crown. M1 with well developed procingulum and anteromedian flexus. The anteroloph is conspicuous, the mesoloph is short and the enteroloph is very small (sometimes missing). A small parastyle can be observed in some specimens. The posteroflexus is poorly developed. M2 with a remnant of anteroloph, which determines a relatively well-developed paraflexus. A weak mesoloph and a very shallow protoflexus and posteroflexus also characterize this molar. M3 with paraflexus and metaflexus clearly visible in most of the examined individuals (excepting very old individuals), sometimes as enamel islands. This molar is not ���8��� shape because the hypoflexus is vestigial and disappears at a very young age. The m1 shows a conspicuous procingulum, well-developed anteromedian flexid and anterolabial cingulum, a tiny ectostylid, and a vestigial mesolophid. The m2 shows a very shallow protoflexid; a tiny ectolophid and a vestigial mesolophid are observable in a few specimens. The m3 presents a remnant of protoflexid, a mesoflexid and a transverse and conspicuous hypoflexid, making it ���S��� shaped. This molar has no trace of posteroflexid. Akodon spegazzinii has 13-14 thoracic ribs; the vertebral column includes 13-14 thoracic, 7-8 lumbar, and 23-26 caudal vertebrae (n = 19). Karyotype: 2n = 40, FN = 40, based on four specimens from Catamarca and one from Tucum��n (Barquez et al. 1980; Myers et al. 1990). Variation: There is considerable variation in external characters among the different populations of A. spegazzinii. Most of these differences probably reflect the different environments from where they were trapped. Populations from humid and low altitude areas are darker, with predominance of black guard hairs. This condition is extreme in populations living in Yungas forest. On the other hand, those populations from open and semiarid environments, such as the Monte desert (e.g. Cachi, type locality of A. spegazzinii) and Puna, are remarkably paler. Moreover, specimens from high altitude localities have fur, ears and tails more densely covered and with longer hairs. Variation within populations includes different color patterns, with ruddy, drabby and dark brown animals. These variations were observable even in mice trapped in the same traplines, in some cases related to reproductive condition or the age of individuals. For example, lactating females were particularly reddish in hue and young individuals darker. Morphometric differences are also conspicuous, even in individuals of the same age class. Some qualitative characters also show some variability. The zygomatic plate is highly variable, with both straight or concave anterior borders more or less sloping backwards. The zygomatic notches can be more or less narrow and shallow. The mesopterygoid fossa can be more or less broad and its anterior border rounded or squared. Our genetic sample includes 17 specimens of A. spegazzinii collected at 10 localities form Catamarca, Salta, and Tucuman provinces. This sample has high haplotypic diversity with 16 haplotypes recovered. However, all are similar as average pairwise comparison among them is 1.2%, and geographic structure is nonexistent. Comparisons: For comparisons between A. spegazzinii and A. boliviensis or A. caenosus please see those accounts. Below we compare it with the remaining species of Akodon present in Yungas of Northwestern Argentina. Jayat et al. (2007a) made detailed comparisons between A. spegazzinii and A. sylvanus. The most relevant differences included general size, with A. sylvanus slightly larger for all the morphometric characters analyzed (Tables 1 and 2). The PCA (Fig. 2) shows some overlap for this species but the DA was very efficient, with only four of 139 individuals not reciprocally well classified. Akodon sylvanus presents also relatively less developed zygomatic notches, more inflated frontal sinuses, broader mesopterygoid fossa, broader and deeper paraterygoid fossa, more developed foramen oval, and conspicuously larger foramen magnum. The general coloration of A. sylvanus is included in the observed variation for the different populations of A. spegazzinii. Notwithstanding, the latter has a more conspicuous eye ring and white spot on the chin. The average percentage of genetic divergence between these species is 4.9% (Table 12). Akodon budini is substantially larger and shows very distinguishable craniodental characteristics. It has a very broad braincase and mesopterygoid fossa, elongated rostrum and relatively narrow and shallow zygomatic notches. The mandible is also distinguishable by the short masseteric crest and lightly developed capsular projection. Moreover, the conspicuous hypsodont molars of A. budini uniquely characterize this species. Akodon simulator and A. spegazzinii are sympatric in parts of their ranges; however, these species are easily differentiable by the larger size of A. simulator and, more importantly, several characteristics of the skin. For example, A. simulator has a more greyish general coloration, more contrast between dorsum and venter, and presents a conspicuous white spot on chin and throat. The skull of A. simulator is more robust, with more divergent and squared interorbital region and broader mesopteryogoid fossa. Furthermore, this species has more proodont incisors. The differences between A. spegazzinii and the new species are considered in detail below. Distribution: A. spegazzinii occurs in southern and central areas of northwestern Argentina, from 24�� 27��� S in central Salta to 28�� 47��� S in southern Catamarca, from 400 to about 3500 m. A single specimen (CNP 1897) is known from southern Mendoza province (Laguna LLancanelo, 1335 m, Malarg��e Department, 35�� 45��� S, 69�� 08��� W); this locality, the first reported for Mendoza province, extends the known distribution of A. spegazzinii 850 km to the south. Records from La Rioja province (Thomas 1920b as A. alterus), corresponding to specimens not examined by us, need confirmation (Fig. 9). Habitat: A. spegazzinii occurs in all altitudinal belts of the Yungas forest (even ecotonal areas with lowland thorn woodlands of Chaco), Monte de Sierras y Bolsones, Puna and Altos Andes. Thus, the species inhabits forests, woodlands and grasslands. In dry areas, such as the Monte desert and Puna, it is only found in grassy zones along streams and rivers. Akodon spegazzinii is especially abundant in cloud grasslands in the upper altitudinal belts of Yungas, where it constitutes the dominant sigmodontine species (Fig. 10). Natural History: Reproduction appears to occur yearlong, with a clear peak between November and April. Most of the individuals were molting in fall and winter (April to August). As it can be expected from the general ubiquity of the species, Akodon spegazzinii coexists with a number of sigmodontine species in the region of interest. In high altitudinal localities, above 3000 m, it has been registered alongside Calomys lepidus (Thomas), Eligmodontia sp., Phyllotis xanthopygus, Reithrodon auritus (G. Fischer) and Neotomys ebriosus Thomas. In cloud grasslands it was caught with Necromys lactens, N. lasiurus and Phyllotis osilae. In forested areas of Yungas A. spegazzinii coexists with Abrothrix illutea, Oligoryzomys sp., Oxymycterus paramensis, O. wayku and Phyllotis anitae. In ecotonal environments of Yungas and Chaco, A. spegazzinii was caugth with Calomys fecundus Thomas, Graomys centralis and Necromys sp. Other species broadly distributted in the region, such as Akodon caenosus, Akodon simulator, Oligoryzomys cf. O. flavescens, Calomys musculinus and Andinomys edax, have also been registered in sympatry with A. spegazzinii. Comments: Myers et al. (1990) viewed spegazzinii as a valid species and considered tucumanensis (type locality Tucum��n, 450 m) as a subspecies. Moreover, Akodon alterus (from Otro Cerro, 3000 m) was considered ���properly allied��� to these forms. Blaustein et al. (1992) studied the status of A. alterus and A. tucumanensis and found weak morphologic and morphometric differences and identical cytogenetic characteristics in the studied populations. Notwithstanding, Mares et al. (1997) listed alterus and tucumanensis as valid species mainly based on their different ecological associations (see also Capllonch et al. 1997; D��az et al. 1997; D��az 1999). In the last ten years the treatment of alterus continued to be confused, alternatively considered as a valid species (D��az 1999; D��az & Barquez 2007), as a subspecies of A. spegazzinii (D��az et al. 2000) or simply as a synonym of this last form (Musser & Carleton 2005; Pardi��as et al. 2006). On the other hand, A. tucumanensis has been recently considered as a synonym of A. spegazzinii (Musser & Carleton 2005), as a subspecies of this last form (Pardi��as et al. 2006) or as a valid species (D��az & Barquez 2007). Cabrera (1926) described A. leucolimnaeus based on two specimens of Laguna Blanca and one from Salar de Antofalla, Catamarca Province. Gyldenstolpe (1932) suggested that this form be included in the genus Necromys Ameghino. For many years this nominal form was considered as a synonym of Necromys lactens Thomas (Cabrera 1961; Reig 1987; Musser & Carleton 1993; Mares et al. 1997) but Galliari et al. (1996) regarded it a valid species, allied to the A. boliviensis group. This view was maintained by Musser & Carleton (2005) and Pardi��as et al. (2006) but its status was considered provisional. Here we offer the first detailed description for A. spegazzinii (see above). We formally tested the taxonomic status of A. alterus and A. leucolimnaeus and established their conspecificity with respect to A. spegazzinii. Moreover, we corroborated the conspecificity of tucumanesis and A. spegazzinii, as suggested by Myers et al. (1990). No clear or constant morphologic differences in skull characters among the specimens coming from Cachi, Laguna Blanca, vicinities of Otro Cerro, and Yungas forest in Tucum��n were found (Fig. 11). Moreover, haplotypes recovered from specimens collected near the type locality of alterus, and assignable to this form, and at the type localities of leucolimnaeus and tucumanensis form part of the spegazzinii clade (Fig. 1). Therefore, the combination of genealogical, genetic (Table 12), morphologic, and morphometric (Tables 5- 8) evidence prompt us to suggest that A. alterus, A. leucolimnaeus , and A. tucumanensis are conspecific with A. spegazzinii. We submit that the lack of large samples, coupled with the geographic and ecotypic variation in pelage described above, misinformed the original authorities of these nominal forms. Specimens from Tucum��n (type locality of tucumanensis) have very dark tones, almost black in some exemplars, which is typical of humid cloud forest dwellers. On the contrary, specimens from Laguna Blanca, in puna environments, have very clear tones, with buffy brown coloration. Individuals coming from Cachi and Otro Cerro are intermediate in coloration although they also differ among them. Cachi presents the typical environmental features of Monte de Sierras y Bolsones, with arid to semi-arid conditions, while Otro Cerro is dominated by relatively humid grasslands communities that are characteristic of the upper belt of Yungas in transition with high Andean environments (Fig. 10)., Published as part of J. Pablo Jayat, Pablo E. Ortiz, Jorge Salazar-Bravo, Ulyses F. J. Pardi��as & Guillermo D'El��a, 2010, The Akodon boliviensis species group (Rodentia: Cricetidae: Sigmodontinae) in Argentina: species limits and distribution, with the description of a new entity, pp. 1-61 in Zootaxa 2409 on pages 28-32, DOI: 10.5281/zenodo.293461, {"references":["Thomas, O. (1897) On some small mammals from Salta, N. Argentina. Annals and Magazine of Natural History, (6) 20, 214 - 218.","Cabrera, A. (1926) Dos roedores nuevos de las montanas de Catamarca. Revista Chilena de Historia Natural, 30, 319 - 321.","Myers, P., Patton, J. L. & Smith, M. F. (1990) A review of the boliviensis group of Akodon (Muridae: Sigmodontinae) with emphasis on Peru and Bolivia. Miscellaneous Publications of the Museum of Zoology, University of Michigan, 177, 1 - 89.","Diaz, M. M. (1999) Mamiferos de la Provincia de Jujuy: Sistematica, distribucion y ecologia. Unpublished D. Phil. Thesis, Universidad Nacional de Tucuman, Argentina, 640 pp.","Barquez, R. M., Williams, D. F., Mares, M. 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(Eds.) Mammal species of the world: A taxonomic and geographic reference. Third ed. Baltimore: John Hopkins University Press, pp. 894 - 1531.","Jayat, J. P., Ortiz, P. E., Teta, P., Pardinas, U. F. J. & D'Elia, G. (2006) Nuevas localidades argentinas para algunos roedores sigmodontinos (Rodentia: Cricetidae). Mastozoologia Neotropical, 13, 51 - 67.","Gyldenstolpe, N. (1932) A manual of Neotropical sigmodont rodents. Kunglia Svenska Vetenskapsakademiens Handlingar, Stockholm, 11, 164 pp.","Cabrera, A. (1961) Catalogo de los mamiferos de America del Sur. Parte II. Revista del Museo Argentino de Ciencias Naturales \" Bernardino Rivadavia \", Zoologia, 4 (2), 309 - 732.","Reig, O. A. (1987) An assessment of the systematics and evolution of the Akodontini, with the description of new fossil species of Akodon (Cricetidae: Sigmodontinae). Pp. 347 - 399 in Studies in Neotropical mammalogy. Essays in honor of Philips Hershkovitz (Patton, B. D. & Timm, R. M., eds.). Fieldiana, Zoology, new series, 39, 1 - 506.","Musser, G. M. & Carleton, M. D. (1993) Familia Muridae. In: Wilson, D. E. & Reeder, D. M. (Eds.), Mammals species of the world: a taxonomic and geographic reference. Washington: Smithsonian Institution Press, pp. 501 - 756.","Galliari, C. A., Pardinas, U. F. J. & Goin, F. J. (1996) Lista comentada de los mamiferos argentinos. Mastozoologia Neotropical, 3, 39 - 61."]}

Akodon boliviensis Meyen, 1833 Akodon boliviense Meyen, 1833. Verhandlungen der Kaiserlichen Leopoldinisch-Carolinischen Akademie der Naturforscher, 16(2):600, pl. 43, fig. 1. Holotype: no holotype was designated by Meyen. Type locality: ���Auf der Hochebene von Hochperu, in dem Indianer-dorfe Pichu-pichun, auf einer H��he von 14,000 fuss gefangen.��� Pichu-Pich��n, 14,000 ft., Chucuito Province, Puno Department, Peru (as clarified by Myers et al. 1990). Description: Detailed morphological description in Myers et al. (1990). The specimens of northwestern Argentina follow, in general, this description and can be distinguished from the remaining species present in this region by the following combination of characters. Dorsal fur soft and somewhat dense, with dorsal coloration uniform pale brown with an olivaceous tinge and lightly streaked with black hairs. Yellow eyerings well defined. Ears of the same color as dorsum and densely covered with hairs. Coloration of sides similar to or somewhat lighter than dorsum. Venter buffy, clearly contrasting with dorsum. Chin with a small patch of completely white hairs. Inguinal region almost rufous in some individuals. Fore and hind feet of the same general coloration than the venter, with bicolored hairs, brown on base and whitish or pale buff on tip. Tail heavily covered with hairs and bicolored, dark brown dorsally and whitish or pale buffy ventrally. Skull with rostrum short and relatively broad. Zygomatic notches proportionally broad and deep. Frontal sinuses slightly swollen. Interorbital region slightly divergent with margins in posterior half something squared in adult specimens. Zygomatic arches relatively well developed. Braincase inflated with temporal and lambdoidal crests relatively well developed. Zygomatic plate with anterior margin flat or slightly concave, oriented vertically or slopes gently backward from bottom to top. Most of examined specimens shows a posterior ascending process of alisphenoid projected at least to the squamoso-alisphenoid groove. Incisive foramina extending to the level of the hypoflexus of M1 or surpassed it. Mesopterygoid fossa narrow with straight borders and sides either parallel or gradually diverging posteriorly, and anterior margin rounded or squared. Parapterygoid fossae broader than mesopterygoid fossa, diverging backward and with straight to slightly convex lateral margins. Mandibular ramus delicate with masseteric crest extending slightly behind of the anterior border of m1, although in some individuals it only reaches the level of protoflexid. Capsular projection well developed and generally situated below the sigmoid notch. Upper incisors generally orthodont. The M1 with procingulum and anteromedian flexus well developed. The anteroloph and mesoloph are always present, the enteroloph is tiny and present only in some specimens. The M2 shows a well developed mesoloph and the M3 is large and complex, with well developed metaflexus and hypoflexus making it distinctively ���8���-shaped in most specimens. The m1 presents a well developed procingulum and a penetrating anteromedian flexid. Protostylid and ectostylid are always presents but the second is poorly defined in some individuals. A small mesolophid-mesostylid is present in a few specimens. In m2 most of the examined specimens have an ectostylid, and a mesolophid-mesostylid is present only in a few individuals but always vestigial (the only young specimen and two adults individuals). The m3 is proportionally large (nearly a half of m2), showing a poorly developed anterior cingulid in most specimens. Karyotype: 2n = 40, FN = 40-42, from Puno and Tacna Departments, Peru (Gardner & Patton, 1976; Myers et al., 1990). Variation: In the few known specimens from northwestern Argentina most variation is age-dependent. Pelage color of young specimens is slightly darker than that of adults. Young individuals also present a shorter and more delicate rostrum, narrower zygomatic notch, less swollen frontal sinuses, broader interorbital region and more inflated braincase. Moreover, the incisive foramina and the mesopterygoid fossa are narrower and the parapterygoid fossae not as deeply excavated. Some variable characters unrelated with age include the general coloration, with some individuals more richly colored; eye ring, development of the hamular process of the squamosal (i.e., tympanic hook in Myers et al., 1990) and the shape of anterior margin of the mesopterygoid fossa. Representatives of this species in northwestern Argentina are morphometricly indistinguishable from those of Peru and Bolivia although they are slightly smaller in some measurements (e.g. CIL, RL) and slightly larger in others (e.g. IOC, IFL, RW 2). Nine specimens coming from Abra de Cienaga Negra and one from Azul Cuesta show subtle morphologic and morphometric differences respect to the specimens from Rodeo Pampa and Pampa Verde (whose haplotypes were more closely related to that of a Peruvian specimen MVZ 171607). These specimens are more richly colored, have a broader interorbital constriction (IOC) and rostral width (RW 2), and a thiner zygomatic plate (ZP). Comparisons: Akodon boliviensis is a medium sized species within the boliviensis group and is, on average, larger than A. caenosus for most of the analyzed measurements (Table 1). Nevertheless, only braincase breadth (BB), mid rostral width (RW 2) and molars series (MTRL and MdTRL) were statistically different according to the N HSD test (Table 2). The PCA analysis indicates some overlap between these species (Fig 2) but the DA misclassified only one of the specimens of A. boliviensis as A. caenosus. In general, the coloration of A. boliviensis is somewhat paler than A. caenosus and the ears are more densely furred. Cranial traits such as a more developed zygomatic notches and a proportionally narrower interobital region distinguish A. boliviensis. Contrary to that observed in A. boliviensis, only in few studied specimens of A. caenosus in northwestern Argentina the posterior ascending process of the alisphenoid extend to the squamoso-alisphenoid groove. As Myers et al. (1990) recognized, the shape of M3 and the thickness of the hamular process of squamosal also differentiate both species. However, A. caenosus shows a great variability in these traits. Additionally, these species show a relatively high average percentage (7.0%) of genetic divergence (Table 12). The examined skins of Akodon boliviensis are very similar to those of specimens of Akodon spegazzinii from high altitude localities, sharing similar hue and color patterns. However, A. boliviensis is on average smaller than A. spegazzinii for most morphometric measurements (Table 1) with the N HSD test indicating significative differences in seven of these measurements (Table 2). In this sense, A. boliviensis presents a more delicate skull, with shorter rostrum and molar series, narrower braincase, narrower and more shallow zygomatic notches and less flared zygomatic arches. The PCA analysis indicates some overlap (Fig 2) but the DA was efficient in separating these species, with only two misclassified specimens. The genetic distance between these taxa is relatively small (2.8%). The striking morphometric and coloration pattern differences between A. boliviensis and A. sylvanus preclude confusing these species. Akodon boliviensis is conspicuously paler, with a drabby brown color, whereas A. sylvanus is dark brown with a strong olivaceous tinge. The contrast between dorsum and venter is more conspicuous in A. boliviensis. In addition, this species shows a more developed eyering and white spot on the chin. The skull of A. boliviensis is clearly more slender, with a shorter and more delicate rostrum, and narrower braincase, interorbital region and mesopterygoid fossa. The molars in A. boliviensis are smaller and clearly less hypsodont. The morphometric differences between these species are notorious with practically no overlap in PCA and none misclassified specimens in DA (Tables 1, 2 and figure 2). The average percentange of genetic divergence between these species is 4.9 %. The comparison between A. boliviensis and the new species will be addressed under the treatment of the latter. Distribution: In northwestern Argentina A. boliviensis is restricted to northernmost Salta Province, mainly above 2500 m (Jayat et al. 2006). All known records come from the Zenta and Santa Victoria ranges. Thus, it is likely that the species probably reaches adjacent Jujuy province due to the continuity of habitats along these mountain ranges (Fig. 6). Habitat: We captured most specimens in highland grasslands, both in upper forest/humid grassland ecotones as well as in drier grasslands more typical of Andean environments. Most of the collecting localities are characterized by grasslands interspersed with rocky outcrops, although in Pampa Verde (locality 6 on figure 6) the humid grasslands are adjacent to alder (Alnus acuminata) forest along humid ravines. Natural history: Four individuals captured in winter (July and August) were molting with only one of them with reproductive activity signs. All specimens caught in spring (nine specimens collected in November) showed reproductive activity and were molting. Other sigmodontine species registered in northwestern Argentina alongside A. boliviensis include Akodon caenosus, Akodon budini Thomas, Necromys lactens Thomas, N. amoenus Thomas, Oligoryzomys cf. O. flavescens (Waterhouse), Oxymycterus paramensis Thomas, Phyllotis osilae J. A. Allen and P. xanthopygus (Waterhouse). Comments: Cabrera (1961) considered A. spegazzinii and A. tucumanensis as subspecies of A. boliviensis, and A. alterus as a synonym of A. boliviensis tucumanensis, a position followed by many authors through the 1980s (e.g. Apfelbaum & Reig 1989; Barquez et al. 1980; Mares et al. 1981; Ojeda & Mares 1989). In the first revision of these small Andean forms, Myers et al. (1990) defined the Akodon boliviensis group, characterized the morphological and distributional boundaries of A. boliviensis, and considered A. spegazzinii as a valid species (with two subspecies A. s. spegazzinii and A. s. tucumanensis). Jayat et al. (2006) erroneously cited A. boliviensis for Escoipe, in central Salta province. This record was based on one specimen (JPJ 69) whose morphometric characteristics were similar to those of A. boliviensis; however, our molecular studies indicate that this and other small specimens caught in the same locality are referable to A. spegazzinii. D��az (1999) and D��az & Barquez (2007) referred one specimen (MMD 395) from Miyuyoc, at 3700 m, Jujuy province to Akodon alterus. We did not examine this specimen, but based on the latitudinal position and characteristics of the reported locality where the specimen was trapped, we note that it may represent another record of A. boliviensis., Published as part of J. Pablo Jayat, Pablo E. Ortiz, Jorge Salazar-Bravo, Ulyses F. J. Pardi��as & Guillermo D'El��a, 2010, The Akodon boliviensis species group (Rodentia: Cricetidae: Sigmodontinae) in Argentina: species limits and distribution, with the description of a new entity, pp. 1-61 in Zootaxa 2409 on pages 20-23, DOI: 10.5281/zenodo.293461, {"references":["Myers, P., Patton, J. L. & Smith, M. F. (1990) A review of the boliviensis group of Akodon (Muridae: Sigmodontinae) with emphasis on Peru and Bolivia. Miscellaneous Publications of the Museum of Zoology, University of Michigan, 177, 1 - 89.","Gardner, A. L. & Patton, J. L. (1976) Karyotypic variation in oryzomyne rodents (Cricetinae) with comments on chromosomal evolution in the Neotropical cricetine complex. Occasional Papers of the Museum of Zoology, Louisiana State University, 49, 1 - 48.","Jayat, J. P., Ortiz, P. E., Teta, P., Pardinas, U. F. J. & D'Elia, G. (2006) Nuevas localidades argentinas para algunos roedores sigmodontinos (Rodentia: Cricetidae). Mastozoologia Neotropical, 13, 51 - 67.","Cabrera, A. (1961) Catalogo de los mamiferos de America del Sur. Parte II. Revista del Museo Argentino de Ciencias Naturales \" Bernardino Rivadavia \", Zoologia, 4 (2), 309 - 732.","Apfelbaum, L. I. & Reig O. A. (1989) Allozyme genetic distances and evolutionary relationships in species of akodontine rodents (Cricetidae: Sigmodontinae). Biological Journal of the Linnean Society, 38, 257 - 280.","Barquez, R. M., Williams, D. F., Mares, M. A. & Genoways, H. H. (1980) Karyology and morphometrics of three species of Akodon (Mammalia: Muridae) from northwestern Argentina. Annals of Carnegie Museum, 49, 379 - 403.","Mares, M. A, Ojeda, R. A. & Kosco, M. P. (1981) Observation on the distribution and ecology of the mammals of Salta Province, Argentina. Annals of Carnegie Museum, 50, 151 - 206.","Ojeda, R. A. & Mares, M. A. (1989) A Biogeographic analysis of the Mammals of Salta Province, Argentina. Patterns of species assemblage in the Neotropics. Special Publications, The Museum, Texas Tech University, 27, 1 - 66.","Diaz, M. M. (1999) Mamiferos de la Provincia de Jujuy: Sistematica, distribucion y ecologia. Unpublished D. Phil. Thesis, Universidad Nacional de Tucuman, Argentina, 640 pp.","Diaz, M. M. & Barquez, R. M. (2007) The Wild Mammals of Jujuy Province, Argentina: Systematics and Distribution. In: Kelt, D. A., Lessa, E. P., Salazar-Bravo, J. & Patton, J. L. (Eds.), The Quintessential Naturalist: Honoring the Life and Legacy of Oliver P. Pearson. University of California Publications in Zoology 134, pp. 417 - 578."]}

Akodon boliviensis species group The great morphological similarity among species of the A. boliviensis group, as well as high levels of intraspecific variability, has precluded a clear and stable taxonomy for the group and in particular for those forms present in northwestern Argentina. This situation, together with the lack of studies of representative series of specimens, including the holotypes and additional specimens collected at the type localities, resulted in the suggestion, along the years, of different taxanomic scenarios, sometimes quite distinct among themselves. As in previous instances (e.g., Patton et al., 2000), the integration of morphologic and molecular data interpreted in a geographic context has proven usefull to assess species boundaries of a taxonomically confusing group. In this regard, the evidence presented herein indicates the existence of four species of the A. boliviensis group in northwestern Argentina with a new species belonging to this group from central Argentina. The taxonomic status of A. spegazzinii (including alterus, leucolimnaeus, and tucumanensis) with respect to A. boliviensis is the most debatable of the taxonomic decisions we make. Based on a small series of specimens, Myers et al. (1990) had earlier proposed the valid status of this form. In line, much of the available evidence here considered suggests that A. spegazzinii represents a distinct species from A. boliviensis. For example, they form reciprocally monophyletic groups (Fig. 1) that are allopatrically distributed; in addition, they are clearly identifiable in morphometric multivariate space and morphological grounds (see comparison above). Moreover, these species have different karyotypes, including the presence of heteromorphism in the largest autosomal pair and the X chromosome in A. spegazzinii (Gardner & Patton, 1976; Barquez et al., 1980; Myers et al., 1990), and different ecological preferences. Our records indicate disjunct distribution for these forms, with A. boliviensis restricted to high altitudinal grasslands in the extreme north of the region and A. spegazzinii extended over many habitats and large areas in south-central portions of the region. In spite of these differences, the genetic divergence betweem them was the smallest among all species pairs of the A. boliviensis group (Table 12). In addition, some overlap in morphological and morphometric characters was evident. Moreover, we could not evaluate the constancy of these differences because we failed to capture both species in sympatry. So, additional studies are needed in the north of the northwestern Argentinean region and in possible areas of sympatry to test the constancy of the observed differences here reported. The taxonomic status of A. tucumanensis, A. alterus, and A. leucolimnaeus remained controversial despite the pioneering work by Myers et al. (1990). While all these forms were treated as subspecies or allied to A. spegazzinii by some authors (e.g. Myers et al. 1990; D��az et al. 2000; Pardi��as et al. 2006; Jayat et al., 2008a), others considered them as valid species (e.g. Barquez et al., 1991; Mares et al., 1997; D��az, 1999; D��az & Barquez, 2007; but see Galliari et al., 1996 about the status of A. tucumanensis). In spite of the extended usage of the specific epithet alterus in previous works (e.g. Capllonch et al. 1997; D��az et al. 1997; Mares et al. 1997; D��az 1999; D��az & Barquez 2007) none of these references was based on a detailed study of extensive topotypical series nor the use of molecular characters. Blaustein et al. (1992) were the only authors who tested the status of alterus (with respect to tucumanensis). However, they erroneously assumed that specimens from El Infiernillo, Tucum��n, belonged to alterus; then, they did not truly test the taxonomic status of A. alterus. They also failed to separate these specimens from A. tucumanensis from low altitude Yungas forest of Tucum��n. In words of Blaustein et al. (1992, pag. 11) ���... we believe that any conclusion on the taxonomic status of the two forms is untimely.��� The status of A. leucolimnaeus was even more dubious and, until the preliminary observations of Galliari et al. (1996), it was considered as a synonym of Necromys lactens (Cabrera, 1961; Reig, 1978, 1987; Mares et al., 1997). However, Galliari et al. (1996) ranked leucolimnaeus as a valid species of Akodon (see also Musser & Carleton [2005] and Pardi��as et al. [2006]), view that contrasts with our results. All the available evidence indicates that the nominal forms alterus, leucolimnaeus, and tucumanensis must be considered junior synonyms of A. spegazzinii. Haplotypes from specimens coming from the type localities of these fall within the spegazzinii clade (Fig. 1). The genetic divergence among haplotypes of this clade is low (1.2% in average) and we found no clear morphological or morphometric differences among these forms. Most of the observed differences in coloration among populations may relate to the great environmental heterogeneity inhabited by A. spegazzinii (Fig. 10). In the A. boliviensis clade, two haplotypes recovered from specimens from northern Salta were more closely related to the haplotype of a Peruvian specimen (MVZ 171607) than to those of other three Argentinean specimens (Fig. 1). This phylogeographic break, together with some morphological, morphometric and genetic differences between these two groups also suggest the possiblity of unrecognized biological diversity within this group. This scenario is similar to that observed in N. amoenus, another highland inhabitant (D���El��a et al., 2008). Notwithstanding, the studied material of A. boliviensis is scarce and the difference between both clades is moderate (2.1% of average genetic divergence), so we point that further research is needed on this area. Myers et al. (1990) considered A. caenosus as a subspecies of A. lutescens (as A. puer caenosus in that publication). They highlighted subtle morphometric, morphologic, and cytogenetic characteristics that distinguished specimens from northwestern Argentina from those of Peru and Bolivia. Our phylogenetic analyses include haplotypes recovered from Argentinean specimens assignable to caenosus and a Peruvian specimen belonging to lutescens. These haplotypes form a paraphyletic group respect to A. subfuscus (Fig. 1). This topology, if lutescens and subfuscus are not to be considered conspecifics, suggests a specific status for A. caenosus. Moreover, the average genetic distance between the Peruvian haplotype of lutescens (MVZ 171612) and those from northwestern Argentinean specimens of A. caenosus is relatively high (3.5%); the average divergence value among specimens of A. caenosus is much lower (1%). Although, there are not clear morphological and morphometric differences among our material of A. caenosus and the values offered by Myers et al. (1990) for A. lutescens, the alternative position of considering A. subfuscus and A. lutescens conspecific seems less supported. These species differ by a substantially high (5.1%) average genetic distance. Furthermore Myers et al. (1990) detailed several morphological characters that distinguish A. lutescens from A. subfuscus. Although we failed to obtain small specimens of Akodon from the type locality of A. aliquantulus (we studied ca. 100 individuals of Akodon from this locality and its surroundings and more than 390 from Tucum��n province), its diagnosis does not permit us to distinguish the two type specimens from A. caenosus. Moreover, the haplotypes of three small Akodon sequenced from Catamarca and Tucum��n were remarkably similar to haplotypes of A. caenosus topotypes (with average genetic distance lower than 1%). On these bases (see also our Species Account discussion above) we place aliquantulus under the synonymy of A. caenosus. This study corroborated the proposition of Jayat et al. (2007a) of placing A. sylvanus as a valid species of the A. boliviensis group. In the MP analysis A. sylvanus appears as the sister species of A. polopi; in accordance to low support of this clade (JKA. polopi is sister to the A. boliviensis - A. spegazzinii clade. Akodon polopi, the new species here described, is a clearly distinct member of the A. boliviensis group, with several diagnostic characters coming from different sources of evidence; not surprinsingly, it was early mentioned as a possible new subspecies by Elio Massoia or a new species (see Polop, 1989). This species, known only from high altitude grasslands of central Argentina, is the only species of the A. boliviensis group inhabiting the Sierras Grandes range, a medium altitude mountain system isolated (ca., 600 km) from the main Andean chain by low elevation arid and semiarid environments. Data at hand are insufficient to pose a biogeographic scenario accounting for the diversification of A. polopi and the remainder species of the A. boliviensis group. Notwithstanding, Pampa de Achala has been mentioned as a biogeographic refuge and an area of endemism for other taxa (Polop, 1989, and references there). Relationships among species of the Akodon boliviensis group are well resolved and mostly coungrent among analyses. Differences relate to the position of A. polopi and A. sylvanus. The present study, as several previous ones, reaffirms the phylogenetic legitimacy of both the boliviensis group and extends our knowledge of its contents, limits, and geographic ranges of its member species. However, we assert that additional research is still needed before an adequate picture of Andean Akodon can be acquired. In this line, more field work coupled with the study of specimen series housed in research institutions is essential., Published as part of J. Pablo Jayat, Pablo E. Ortiz, Jorge Salazar-Bravo, Ulyses F. J. Pardi��as & Guillermo D'El��a, 2010, The Akodon boliviensis species group (Rodentia: Cricetidae: Sigmodontinae) in Argentina: species limits and distribution, with the description of a new entity, pp. 1-61 in Zootaxa 2409 on pages 43-45, DOI: 10.5281/zenodo.293461, {"references":["Patton, J. L., Da Silva, M. D. F. & Malcom, J. R. (2000) Mammals of the rio Jurua and the evolutionary and ecological diversification of Amazonia. Bulletin of the American Museum of Natural History, 244, 1 - 306. Piantanida, M. J. & Barrantes, G. E. (1998) Growth studies in Akodon dolores (Rodentia: Muridae) in captivity. Acta Theriologica, 43, 185 - 193.","Myers, P., Patton, J. L. & Smith, M. F. (1990) A review of the boliviensis group of Akodon (Muridae: Sigmodontinae) with emphasis on Peru and Bolivia. Miscellaneous Publications of the Museum of Zoology, University of Michigan, 177, 1 - 89.","Gardner, A. L. & Patton, J. L. (1976) Karyotypic variation in oryzomyne rodents (Cricetinae) with comments on chromosomal evolution in the Neotropical cricetine complex. Occasional Papers of the Museum of Zoology, Louisiana State University, 49, 1 - 48.","Barquez, R. M., Williams, D. F., Mares, M. A. & Genoways, H. H. (1980) Karyology and morphometrics of three species of Akodon (Mammalia: Muridae) from northwestern Argentina. Annals of Carnegie Museum, 49, 379 - 403.","Diaz, M. M., Braun, J. K., Mares, M. A. & Barquez, R. M. (2000) An update of the taxonomy, systematics, and distribution of the mammals of Salta province, Argentina. Occasional Papers of the Oklahoma Museum of Natural History, 10, 1 - 52.","Jayat, J. P., Ortiz, P. E., Teta, P., Pardinas, U. F. J. & D'Elia, G. (2006) Nuevas localidades argentinas para algunos roedores sigmodontinos (Rodentia: Cricetidae). Mastozoologia Neotropical, 13, 51 - 67.","Jayat, J. P., Ortiz, P. E. & Miotti, M. D. (2008 a) Distribucion de sigmodontinos (Rodentia: Cricetidae) en pastizales de neblina del noroeste argentino. Acta Zoologica Mexicana, 24, 137 - 177.","Barquez, R. M., Mares, M. A. & Ojeda, R. A. (1991) Mamiferos de Tucuman - Mammals of Tucuman. Oklahoma Museum of Natural History, University of Oklahoma, Norman, 282 pp.","Diaz, M. M., Braun, J. K., Mares, M. A. & Barquez, R. M. (1997) Key of Mammals of Salta Province, Argentina. Occasional Papers of the Oklahoma Museum of Natural History, 2, 1 - 10.","Diaz, M. M. (1999) Mamiferos de la Provincia de Jujuy: Sistematica, distribucion y ecologia. Unpublished D. Phil. Thesis, Universidad Nacional de Tucuman, Argentina, 640 pp.","Diaz, M. M. & Barquez, R. M. (2007) The Wild Mammals of Jujuy Province, Argentina: Systematics and Distribution. In: Kelt, D. A., Lessa, E. P., Salazar-Bravo, J. & Patton, J. L. (Eds.), The Quintessential Naturalist: Honoring the Life and Legacy of Oliver P. Pearson. University of California Publications in Zoology 134, pp. 417 - 578.","Galliari, C. A., Pardinas, U. F. J. & Goin, F. J. (1996) Lista comentada de los mamiferos argentinos. Mastozoologia Neotropical, 3, 39 - 61.","Capllonch, P., Autino, A., Diaz, M. M., Barquez, R. M. & Goytia, M. (1997) Los mamiferos del Parque Biologico Sierra de San Javier, Tucuman, Argentina: observaciones sobre su sistematica y distribucion. Mastozoologia Neotropical, 4, 49 - 71.","Blaustein, S. A., Liascovich, R. C., Apfelbaum, L. I., Daleffe, L. Barquez, R. M. & Reig, O. A. (1992) Correlates of systematic differentiation between two closely related allopatric populations of the Akodon boliviensis group from NW Argentina (Rodentia, Cricetidae). Zeitschrift fur Saugetierkunde, 57, 1 - 13.","Cabrera, A. (1961) Catalogo de los mamiferos de America del Sur. Parte II. Revista del Museo Argentino de Ciencias Naturales \" Bernardino Rivadavia \", Zoologia, 4 (2), 309 - 732.","Musser, G. M. & Carleton, M. D. (2005) Superfamily Muroidea .. In: Wilson, D. E. & Reeder, D. M. (Eds.) Mammal species of the world: A taxonomic and geographic reference. Third ed. Baltimore: John Hopkins University Press, pp. 894 - 1531.","Jayat, J. P., Ortiz, P. E., Pardinas, U. F. J. & D'Elia, G. (2007 a) Redescripcion y posicion filogenetica del raton selvatico (Akodon sylvanus: Rodentia: Cricetidae). Mastozoologia Neotropical, 14, 201 - 225.","Polop, J. (1989) Distribution and ecological observations of wild rodents in Pampa de Achala, Cordoba, Argentina. Studies on Neotropical Fauna and Environment, 24, 53 - 59."]}

Akodon caenosus Thomas, 1918 Akodon diminutus Barquez, D��az and Goytia, 1994. Nomen nudum (see Galliari et al., 1996). Akodon aliquantulus D��az, Barquez, Braun and Mares, 1999. Journal of Mammalogy, 80:788. Holotype: BMNH 18.1.1.38, adult male. Type locality: Le��n, Jujuy, 1500 m (Thomas, 1918). Description: Detailed morphological description in Myers et al. (1990) (as A. puer caenosus). Additional morphological and morphometric data for some populations of northwestern Argentina can be found in Thomas (1918; original description of A. puer caenosus), Barquez et al. (1980) and D��az (1999). Here we summarize the characteristics of populations along the latitudinal and altitudinal gradients of northwestern Argentina. Akodon caenosus is the smallest species of the boliviensis group in northwestern Argentina. Dorsal coloration uniform and highly variable, ochraceous brown with yellowish, rufous, or olivaceous casts. Ears of the same color than the dorsum and with a tuft of hairs in front. Laterals clearer than dorsum and more richly colored in some specimens. Venter paler, whitish gray, buffy gray, yellowish or even ruddy, clearly contrasting with dorsum. Chin with few white hairs that do not form a conspicuous patch. Inguinal region with a more intense tinge than the rest of the venter in some specimens. Fore and hind feet covered with whitish or buffy hairs. Tail strongly bicolored, dorsally blackish-brown and ventrally whitish or buffy, densely or sparsely covered depending on the analyzed populations and individuals. The skull is the smallest among the Akodon species of northwestern Argentina. Rostrum short, with very narrow and shallow zygomatic notches and frontal sinuses not well developed. Interorbital region comparatively broad, with hourglass shaped and with margins rounded or slightly squared. Zygomatic arches not flared, braincase small and inflated, with temporal and lambdoid crests not well developed. Zygomatic plate narrow with anterior border straight or slightly concave and generally slopes gently backward from bottom to top. In most of the studied specimens the posterior ascending process of alisphenoid does not reach the squamoso-alisphenoid groove or only touch their lower margin. Hamular process of squamosal delicate, but in a few individuals it is strongly built. Incisive foramina generally extended to the protocone of M1, but in some individuals its reach the hypoflexus or even further back. Mesopterygoid fossa very narrow, its anterior margin rounded or slightly squared and with lateral margins straight and slightly divergent backward. Parapterygoid fossa generally broader than mesopterygoid, with convex border and slightly divergent backward. Mandibular ramus very delicate. Masseteric crest extends slightly behind the anterior margin of m1. Capsular projection generally poorly developed and situated at the same level or behind the coronoid process. Angular process is less extended backward than the condyle. Upper incisors orthodont or slightly opistodont. The procingulum and anteromedian flexus of M1 are well developed. Anteroloph and mesoloph are always present and in some individuals an enteroloph can be observed. The M2 has a conspicuous mesoloph and the M3 shows great variability. In old individuals it is completely oval shaped but in young ones anteroflexus, metaflexus and hipoflexus are present. The m1 has the procingulum and anteromedian flexid well developed and presents protostylid and ectostylid. In some individuals a remnant of metastylid and mesostylid can be observed. The m2 retains only the labial stylid although some specimens have a very small ectostylid. The m3 presents deep labial and lingual flexids. Some individuals show a small protostylid. Karyotype: 2n = 34, FN = 40, based on six specimens from Le��n, Jujuy, and two from El Cadillal, Tucum��n (Barquez et al., 1980; Vitullo et al., 1986 as A. puer). Variation: We have observed substantial morphological variation for this species. Within the same population, we find pale and dark individuals, some of them with striking rufous tones, particularly lactating females. Among the cranial characters, the development of zygomatic notches, zygomatic plate, and the thickness of hamular process show some variability. We also observed morphometric variations for individuals of the same age and population, with remarkable differences among some of the studied localities. In addition, consistent variation in the coloration pattern with elevation and some geographic variation for some morphometric variables are also apparent. The specimens from high altitude populations are conspicuously paler than those from lower localitites, showing more buffy tinges in the coloration of the fur and more developed eyerings. These populations come from open environments characterized as the ecotone between humid grasslands and semiarid areas (e.g., the Prepuna or impoverished grasslands of high-Andean region). Specimens from central Salta and central Tucum��n provinces are on average smaller than individuals from B��rcena and Reyes, southern Jujuy, near the type locality. Comparisons: Externally this species can be confused with A. boliviensis and young individuals of A. spegazzinii. The differences between A. caenosus and A. boliviensis were described in detail by Myers et al (1990) and are summarized above. In areas of sympatry A. caenosus and A. spegazzinii follow similar variation patterns in coloration through altitudinal gradients. However, many morphometric values and several cranial characters are useful in specimen determination. In 15 of the 20 analyzed morphometric variables, A. caenosus is significantly smaller than A. spegazzinii (Tables 1 and 2). This is also verified by the minimum overlap in the PCA analysis (Fig 2) and the lack of missclasifications in the DA. In addition, Akodon caenosus shows narrower and shallower zygomatic notches, comparatively broader interorbital constriction, temporal and mastoid ridges less developed, narrower mesopterygoid fossa and less hypsodont molars. The average percentage of genetic divergence between these species is the greatest (7.7%) observed for the boliviensis group in northwestern Argentina (Table 12). Akodon caenosus and A. sylvanus represent two extremes in the morphometric variation observed within the boliviensis group in northwestern Argentina (Tables 1 and 2; figure 2). Akodon caenosus is, furthermore, paler than A. sylvanus, showing a more evident contrast between dorsum and venter, and has more developed eyerings. The skull of A. caenosus has a shorter and narrower rostrum, less swollen frontal sinuses, narrower braincase and interorbital region and a narrower mesopterygoid and parapterygoid fossa. The upper incisors in A. caenosus are less orthodont and the molars less hypsodont than A. sylvanus. Additionally, these species show a high average percentage of genetic divergence (6.7%). The differences between A. caenosus and the new species are listed under the treatment of the latter. Distribution: Akodon caenosus is the more broadly distributed species of the boliviensis group in northwestern Argentina, with records from northernmost Salta to southern Catamarca, from 400 m to 3100 m elevation (Fig. 7). Habitat: Most of the records come from Yungas environments, from the lower altitudinal belt to high altitude grasslands. Notwithstanding, we have recorded the species in Chacoan environments near the ecotone with Yungas and in the lower altitudinal limit of the High Andean grasslands. Natural history: Although we have recorded specimens in reproductive condition throughout the year, most of the individuals were active between November and January. We observed the highest proportion of molting animals in fall and winter. In their broad distributional range A. caenosus can be found coexisting with many different species depending on the altitudinal or latitudinal sector in northwestern Argentina. Thus, in the north A. caenosus was captured alongside Akodon sylvanus, A. simulator, Oxymycterus paramensis, Oligoryzomys cf. O. flavescens and Oligoryzomys sp. in high altitudinal grasslands at 1400 m. At the same latitude in upper belts above 2000 m, A. caenosus is sympatric with A. boliviensis, Necromys lactens, N. amoenus, Calomys musculinus (Thomas), Phyllotis caprinus Pearson, P. osilae and P. xanthopygus. In the south, in Yungas areas of Tucum��n province, the species was caught together with Akodon spegazzinii, A. simulator, Necromys lactens, N. lasiurus (Lund), Oxymycterus paramensis, Oxymycterus wayku Jayat et al., Oligoryzomys cf. O. flavescens, Oligoryzomys sp., Phyllotis anitae, P. osilae, Andinomys edax and Abrothrix illutea. At this same latitude in Chacoan environments in transition with Yungas A. caenosus is sympatric with Akodon spegazzinii, A. simulator, Necromys sp., Oligoryzomys cf. O. flavescens, Oligoryzomys sp., Calomys sp. and Graomys centralis. Comments: Although originally described as a subspecies of Akodon puer (Thomas 1918), the form caenosus was soon considered as a valid species by Thomas (1920); this latter suggestion was followed by Cabrera (1961), Barquez et al. (1980), and Mares et al. (1981). Vitullo et al. (1986) and Apfelbaum & Reig (1989) considered specimens from Le��n, Jujuy Province (type locality of caenosus) as A. puer and Myers et al. (1990) followed this position (but see Hershkovitz 1990), considering caenosus as the subspecies of A. puer inhabiting northwestern Argentina (see also Barros et al. 1990). Anderson (1997) also recognized three subspecies for A. puer but noted the priority of the name lutescens over puer. Since then, the nomenclature used for this species has been constantly changing. Capllonch et al. (1997) and Mares et al. (1997) listed caenosus as valid species whereas D��az et al. (1999, 2000) recognized caenosus as subspecies of puer for the populations of the northwestern Argentina. Notwithstanding, D��az (1999) and D��az & Barquez (2007) considered again the nominal form caenosus as representing a valid biological species including A. lutescens puer as an additional sigmodontine species in northwestern Argentina. Musser & Carleton (2005) and Pardi��as et al. (2006) followed the conclusions of Myers et al. (1990). D��az et al. (1999) described Akodon aliquantulus, from the ecotone between upper Yungas forest and highland grassland in Tucum��n province (Las Ag��itas, Cumbres del Taficillo, 1700 m, 26�� 42��� S, 65�� 22��� W), and related it to the A. boliviensis group on the basis of its morphology. The unimpressive morphological distinction from A. lutescens, based only on multivariate ordinations and univariate overlap, induced some authors to recommend a revision of the status of this form (Musser & Carleton 2005; Jayat et al., 2008a). This species was diagnosed and differentiated from A. caenosus (as A. puer caenosus) and A. spegazzinii on the account of being smaller in a number of measurements and the ���weakly developed eye ring��� of two individuals originally preserved in fluid and then prepared as skin plus skull. We could not distinguish the type specimens of A. aliquantulus from A. caenosus following the diagnosis provided by D��az et al. (1999). Most of the characters used for the diagnosis of A. aliquantulus (centered, as said, on a few external and cranial dimensions) are subtle, highly variable in many sigmodontine species, and what is most important are age-dependent. Although D��az et al. (1999) considered the two specimens as old individuals (age-class 5) our observations indicate that they must be assigned to the age class 4 of Myers (1989) (Figure 8). The morphometric distinction between A. aliquantulus and A. caenosus was based on a PCA analysis with a relatively low explained variance (63.3%, 7.9% and 5.1% for components 1, 2 and 3 respectively) and the statistic significance of the observed differences was not provided by the authors. We think that the erroneous assignment of age for the two specimens by D��az et al. (1999) misinform their conclusions. The analysis of table 1 of D��az et al. (1999) clearly indicates the overlap between A. aliquantulus specimens and A. caenosus exemplars of ageclass 4 (see also Table 9 of this work). Remarkably, even some of the diagnostic skull measurements (e.g. braincase breadth, maxillary toothrow length) are included in the observed range for age-class 5 individuals of A. caenosus. Moreover, all the characters mentioned in the description of A. aliquantulus are within the levels of morphological variation observed in A. caenosus of Northwestern Argentina. Therefore, we find no defensible argument to consider A. aliquantulus as a distinct species and consider it a junior synonym of A. caenosus., Published as part of J. Pablo Jayat, Pablo E. Ortiz, Jorge Salazar-Bravo, Ulyses F. J. Pardi��as & Guillermo D'El��a, 2010, The Akodon boliviensis species group (Rodentia: Cricetidae: Sigmodontinae) in Argentina: species limits and distribution, with the description of a new entity, pp. 1-61 in Zootaxa 2409 on pages 23-25, DOI: 10.5281/zenodo.293461, {"references":["Thomas, O. (1918) On small mammals form Salta and Jujuy collected by Mr. E. Budin. Annals and Magazine of Natural History, (9) 1, 186 - 193.","Galliari, C. A., Pardinas, U. F. J. & Goin, F. J. (1996) Lista comentada de los mamiferos argentinos. Mastozoologia Neotropical, 3, 39 - 61.","Diaz, M. M., Barquez, R. M., Braun, J. K. & Mares, M. A. (1999) A new species of Akodon (Muridae: Sigmodontinae) from Northwestern Argentina. Journal of Mammalogy, 80, 786 - 798.","Myers, P., Patton, J. L. & Smith, M. F. (1990) A review of the boliviensis group of Akodon (Muridae: Sigmodontinae) with emphasis on Peru and Bolivia. Miscellaneous Publications of the Museum of Zoology, University of Michigan, 177, 1 - 89.","Barquez, R. M., Williams, D. F., Mares, M. A. & Genoways, H. H. (1980) Karyology and morphometrics of three species of Akodon (Mammalia: Muridae) from northwestern Argentina. Annals of Carnegie Museum, 49, 379 - 403.","Diaz, M. M. (1999) Mamiferos de la Provincia de Jujuy: Sistematica, distribucion y ecologia. Unpublished D. Phil. Thesis, Universidad Nacional de Tucuman, Argentina, 640 pp.","Vitullo, A. D., Merani, M. S., Reig, O. A., Kajon, A. E., Scaglia, O., Espinosa, M. B. & Perez-Zapata, A. (1986) Cytogenetics of South American Akodont Rodents (Cricetidae): new kariotypes and chromosomal banding patterns of argentinian and uruguayan forms. Journal of Mammalogy, 67, 69 - 80.","Thomas, O. (1920 a) A further collection of mammals from Jujuy. Annals and Magazine of Natural History, (9) 5, 195 - 196.","Cabrera, A. (1961) Catalogo de los mamiferos de America del Sur. Parte II. Revista del Museo Argentino de Ciencias Naturales \" Bernardino Rivadavia \", Zoologia, 4 (2), 309 - 732.","Mares, M. A, Ojeda, R. A. & Kosco, M. P. (1981) Observation on the distribution and ecology of the mammals of Salta Province, Argentina. Annals of Carnegie Museum, 50, 151 - 206.","Apfelbaum, L. I. & Reig O. A. (1989) Allozyme genetic distances and evolutionary relationships in species of akodontine rodents (Cricetidae: Sigmodontinae). Biological Journal of the Linnean Society, 38, 257 - 280.","Hershkovitz, P. (1990) Mice of the Akodon boliviensis size class (Sigmodontinae, Cricetidae), with the description of two species from Brazil. Fieldiana, Zoology, new series, 57, 1 - 35.","Barros, M. A., Liascovich, R. C., Gonzalez, L., Lizarralde, M. S. & Reig, O. A. (1990) Banding pattern comparison between Akodon iniscatus, and Akodon puer (Rodentia, Cricetidae). Zeitschrift fur Saugetierkunde, 55, 115 - 127.","Anderson, S. (1997) Mammals of Bolivia, taxonomy and distribution. Bulletin of the American Museum of Natural History, 231, 1 - 652.","Capllonch, P., Autino, A., Diaz, M. M., Barquez, R. M. & Goytia, M. (1997) Los mamiferos del Parque Biologico Sierra de San Javier, Tucuman, Argentina: observaciones sobre su sistematica y distribucion. Mastozoologia Neotropical, 4, 49 - 71.","Diaz, M. M., Braun, J. K., Mares, M. A. & Barquez, R. M. (1997) Key of Mammals of Salta Province, Argentina. Occasional Papers of the Oklahoma Museum of Natural History, 2, 1 - 10.","Diaz, M. M., Braun, J. K., Mares, M. A. & Barquez, R. M. (2000) An update of the taxonomy, systematics, and distribution of the mammals of Salta province, Argentina. Occasional Papers of the Oklahoma Museum of Natural History, 10, 1 - 52.","Diaz, M. M. & Barquez, R. M. (2007) The Wild Mammals of Jujuy Province, Argentina: Systematics and Distribution. In: Kelt, D. A., Lessa, E. P., Salazar-Bravo, J. & Patton, J. L. (Eds.), The Quintessential Naturalist: Honoring the Life and Legacy of Oliver P. Pearson. University of California Publications in Zoology 134, pp. 417 - 578.","Musser, G. M. & Carleton, M. D. (2005) Superfamily Muroidea .. In: Wilson, D. E. & Reeder, D. M. (Eds.) Mammal species of the world: A taxonomic and geographic reference. Third ed. Baltimore: John Hopkins University Press, pp. 894 - 1531.","Jayat, J. P., Ortiz, P. E., Teta, P., Pardinas, U. F. J. & D'Elia, G. (2006) Nuevas localidades argentinas para algunos roedores sigmodontinos (Rodentia: Cricetidae). Mastozoologia Neotropical, 13, 51 - 67.","Jayat, J. P., Ortiz, P. E. & Miotti, M. D. (2008 a) Distribucion de sigmodontinos (Rodentia: Cricetidae) en pastizales de neblina del noroeste argentino. Acta Zoologica Mexicana, 24, 137 - 177.","Myers, P. (1989) A preliminary revision of the varius group of Akodon (A. dayi, dolores, molinae, neocenus, simulator, toba and varius). In: Redford, K. H. & Eisenberg, J. F. (Eds.), Advances in Neotropical Mammalogy. Gainesville, Florida: Sandhill Crane Press, Inc., pp. 5 - 54."]}

Akodon polopi, new species Akodon sp. sensu Polop, 1989:53. Studies on Neotropical Fauna and Environments 24:53���59. Akodon boliviensis sensu Polop, 1991:115. Revista de la Universidad Nacional de R��o Cuarto 11:115���121. Akodon sp. sensu Pinna-Senn et al., 1992 Mendeliana 10: 59���70. Akodon alterus sensu Priotto et al., 1996:135. Facena 12: 135���138. Akodon boliviensis sensu Morando & Polop, 1997:132. Mastozoolog��a Neotropical 4 (2): 129���136. Akodon spegazzinii sensu D���El��a, 2003: 310. Cladistics 19:307���323. Akodon spegazzinii sensu D���El��a et al., 2003:354. Mammalian Biology 68:351���364. Akodon spegazzinii sensu Kufner et al., 2004:120. Ecolog��a Aplicada 3 (1,2):118���121. Akodon spegazzinii sensu Pardi��as et al., 2005: 473. Journal of Mammalogy 86 (3):462���474. Akodon spegazzinii sensu Rodrigues Gon��alvez et al., 2007: 23. Miscellaneous Publications of the Museum of Zoology, University of Michigan 197: 1���24. Akodon spegazzinii sensu Smith & Patton, 2007: 831. University of California Publications in Zoology 134:1���981. Akodon sp. sensu Jayat et al., 2007a: 203. Mastozoolog��a Neotropical 14 (2):201���225. Holotype: MACN 23486, Adult male (age class 4), collected by J. Pablo Jayat, Pablo E. Ortiz, Daniel Garc��a Lopez, and Rodrigo Gonzalez on August 17, 2008 (original field number JPJ 2125), skin, skull, skeleton and tissues in alcohol (Figs. 12 and 13). Type locality: Pampa de Achala, 6 km E (by highway 34) from antena repetidora La Posta, 2200 m (31�� 36��� 44.5��� S, 64�� 48��� 48.7��� W), San Alberto Department, C��rdoba Province, Argentina (Fig. 14). Diagnosis: A member of the Subfamily Sigmodontinae distinguishable from all other species of Akodon by the following combination of characters: size intermediate for the genus (mean values in mm for individuals of age class 4; length of head and body, 100; tail length, 70; condyloincisive length, 24.53; maxillary toothrow length, 4.40); fur dense and soft; general coloration uniform, buffy brown; chin with a small but distinguishable white patch; claws on fore and hind feet somewhat long (mean values in mm for 10 individuals of age class 4 in the medial finger: 2.81 and 3.26 respectively); skull with the rostrum relatively short and broad; interorbital region hour-glass shaped but with sharply squared posterior margins; temporal and lambdoid ridges well developed; zygomatic plate relatively broad; mesopterygoid fossa narrow. Upper incisors slightly proodont; first lower molar with a conspicuous metastylid and mesostylid. Molecular apomorphies are listed in Table 13 (note that sequences of some Akodon species were not analyzed, and that only three haplotype of Akodon polopi, new species were available; therefore, these character states should be taken with caution). Measurements of the holotype: External measurements (in mm): length of head and body, 103; tail length, 76; length of hind foot (with claw), 25; ear length, 15; weight (in g): 35. Cranial measurements (in mm): greatest length of skull, 26.80; condyloincisive length, 25.50; zygomatic breadth, 13.84; braincase breadth, 11.84; interorbital constriction, 4.58; maxillary toothrow length, 4.60; nasal length, 10.10; mid rostral width, 5.00; diastema length, 7.12; length of incisive foramen, 6.54; width across occipital condyles, 6.70; breadth of zygomatic plate, 2.50. See Table 14 for measurements of paratypes. Paratypes: Seven specimens collected at the type locality (CNP 1927, 1928; CML 7672, 7673; and MACN 23487, 23488, 23489) (Table 14). Other referred specimens: Twenty one specimens from the type locality (JPJ 2118, 2120, 2121, 2123, 2126 to 2129, 2131, 2133 to 2135, 2139, 2141, 2144, 2146, 2147, 2149, 2150, 2158, 2159); four specimens from Pampa de Achala (CUNRC 2805, 10145, 10178, 50151); three specimens from Pampa de Achala, 2163 m (CUNRC 44748, 44749, 44750); three specimens from Pampa de Achala, 2247 m (CUNRC 44744, 44745, 44747), and nine specimens from Repetidora La Posta, Pampa de Achala, 2171 m (CNP 1500 to 1508). Distribution: The new species is only known from few localities in C��rdoba Province, Argentina: Pampa de Achala, a highland plateau situated in the Sierras Grandes (Polop 1989, 1991), three localities in R��o Cuarto Department (Cerro de Oro, Puesto Gonzalez and La Ventana, all above 1500 m elevation; Priotto et al. 1996), and two additional sites in Pampa de San Luis, Cruz del Eje Department (SW of Pampa de San Luis, 1900 m, and near Cuchilla Nevada, 1700-1800 m; Kufner et al. 2004) (Fig. 14). Etymology: Dedicated to our friend and colleague Jaime Jos�� Polop (Universidad Nacional de R��o Cuarto, C��rdoba, Argentina) for his invaluable contributions to the understanding of the ecology of sigmodontine rodents from central Argentina. In addition, Jaime collected many of the specimens used in the characterization of the new species and even pointed-out the distinctiveness of this form (Polop 1989: 58). Morphological description: Fur dense and soft. Dorsal coloration uniform, buffy brown lightly spattered with black hairs. Guard hairs generally black excepting those from the rump, which are distally whitish. In this region, the guard hairs extend beyond the level of the fur hairs by approximately 5 mm. Flanks coloration clearer and more richly colored. Ventral side clearly contrasting with dorsum and flanks, with buffy or tawny tinges. Chin with a small but distinguishable white patch. Ears densely covered by hairs of the same general color as the dorsum. Fore and hind feet whitish or buffy and densely furred. Tail clearly bicolored, blacky brown dorsally and whitish ventrally. Claws on fore and hind feet somewhat longer than in the other species of the boliviensis group and densely covered by a whitish tuft. Skull heavily constructed in the context of the boliviensis group, with the rostrum relatively short and broad. Nasals short, not acuminate, and extended almost to the anterior face of incisors; frontal sinuses clearly inflated and zygomatic notches broad and deep. Interorbital region hour-glass shaped, with rounded or lightly squared borders and with posterior margins having a greater tendency to be sharply squared than is usually the case for the boliviensis group. Temporal and lambdoid ridges well developed for this group. Zygomatic plate relatively broad, with its anterior margin straight and vertical in most of the individuals. Hamular process relatively robust but showing a variable development, with distal end expanded. Incisive foramina long, with posterior ends reaching the hypoflexus of M1. Mesopterygoid fossa narrow, with its anterior margin rounded and lateral borders slightly divergent backward. Posterior palatal pits small and variable in position. Parapterygoid fossae slightly excavated and broader than mesopterygoid fossa, with lateral margins generally straight and divergent posteriorly. Auditory bullae of intermediate size for the genus, with short and wide Eustachian tubes. Mandible similar to the remaining species of the boliviensis group but somewhat more robust, with the horizontal ramus higher and the coronoid process broader. The capsular projection clearly posterior to the coronoid process. Anterior point of diastema located below the alveolar plane. The angular process ends just ahead the condyloid process. Masseteric crest reachs the level of the anterior margin of m1 or slightly behind. Teeth of typical Akodon pattern (Fig. 15). Upper incisors approximately orthodont, but many individuals somewhat proodont. M1 with procingulum and anteromedian flexus well developed. A small anteroloph and mesoloph are present on the labial side and on the lingual side a tiny enteroloph is visible in some young specimens. M2 with a reduced procingulum and a vestigial mesoloph present. The posteroflexus not well developed. M3 shows the paraflexus and metaflexus always present in young specimens. The hypoflexus is present in only a few individuals. Lower molars crested and transversally compressed. The m1 has a well developed procingulum with a deep anteromedian flexid and a clearly defined anterolabial cingulum. All the young individuals bear a well-developed ectostylid. On the lingual side, young individuals (age classes 1 and 2) show a well-developed metastylid and a relatively robust mesolophid. The m2 preserves an anterolabial cingulum and a small ectostylid but the mesolophid is vestigial. The m3 is large and ���S��� shaped. Akodon polopi has 13-14 thoracic ribs; the vertebral column includes 13-14 thoracic, 8 lumbar, and 26-27 caudal vertebrae (n = 6). Karyotype: 2n = 40. The autosomal pairs 1 to 18 are telocentric and the pair 19 is metacentric. The X chromosomes are subacrocentric and the Y is small metacentric (Polop 1989; Pinna-Senn et al. 1992). Variation: In spite of marked uniformity in fur coloration, we observed slightly darker and more richly colored specimens. Some individuals have a more slender zygomatic plate, with a slightly concave anterior margin, which determine shallower zygomatic notches. The hamular process also shows a variable development, more delicate in some specimens. The posterior palatal pits also vary in position with regard to the anterior border of the mesopterygoid fossa. Comparisons: Akodon polopi is one of the largest and more robust species of the A. boliviensis group. The species is distinguishable from the remaining species by their denser and softer fur, a large skull, with broad rostrum, deep and broad zygomatic notches, and well-expanded zygomatic arches. However, the new species has a comparatively short rostrum, narrow interorbital constriction and a not inflated braincase. A comparatively well developed metastylid in m1 of young individuals is another distinctive feature of A. polopi. In addition to the previously mentioned characteristics, the new species can be differentiated from Akodon boliviensis by the interorbital region with its posterior margins sharply squared, temporal and lambdoid ridges well developed, and the M3 that does not show an ���8��� shape. The numerous morphometric differences between these species include 17 of the 20 measurements analyzed (Table 2). Cyt b haplotypes of A. polopi and A. boliviensis differ by an average of 5.0% (Table 12). Akodon boliviensis was registered in Argentina only in its northernmost end, always above 2400 m, whereas A. polopi lives below 2300 m on isolated mountain ranges from central Argentina, almost 900 km toward the south. Like A. boliviensis, Akodon caenosus does not have a sharply squared interorbital posterior region or well developed temporal and lambdoid ridges. A. caenosus is unmistakable because it is situated at the opposite end in the morphometric range values, with no overlap in most of the analyzed measurements (Table 1) being all of them statistically different (Table 2). Likewise, cyt b haplotypes of A. polopi and A. caenosus are very divergent (6.2%). A. polopi can be differentiated from Akodon spegazzinii by many characteristics. The former has an interorbital region with posterior margins more sharply squared, temporal and lambdoid ridges more developed and a proportionally shorter molar series. The morphometric differences between these species include 14 of the 20 analyzed measurements (Table 2). Cyt b haplotypes of A. spegazzinii and A. polopi differ by on average 5.5%. Akodon sylvanus is very similar to A. polopi in many of the variables we measured, with less than 50% (9 of 20) significantly different. However, the DA efficiently separated both species and no reciprocally misclassified specimens occurred. The anterior region of the skull of A. polopi is shorter and more robust, the zygomatic notches are deeper and broader, and the braincase is less inflated. In ventral view, the mesopterygoid fossa in A. polopi is narrower, and the upper incisors tend to be more prodont. The cyt b haplotypes of A. sylvanus and A. polopi differ on average by 4.7 %. Like A. boliviensis, A. sylvanus appears to show a disjunct distribution with regards to A. polopi; thus far, A. sylvanus is known from only the neighborhood of its type locality in the Sierra de Santa B��rbara in Yungas forest habitats almost 800 km to the north of the type locality of A. polopi. Natural history: The habitat in Pampa de Achala is characterized by extensive highland grasslands dominated by Festuca and Stipa, between 1800 and 2300 m elevation (Fig 16). Intermingled with the grasslands there are scattered small patches of woodlands of Polylepis australis, Heterothalamus alienus, Eupatorium buniifolium, Berberis ruscifolia, Baccharis myrtilloides and Cassia hockeriana, and rocky outcrops (Polop 1989, 1991). None of the specimens that we captured during the end of winter 2008 (August) showed signs of reproductive activity. These data suggest that the species is reproductively active in the late spring and summer seasons and agree with previous studies where the largest number of pregnancy were in Novembre and December (Polop 1989). This author registered an average number of embryos per female of 4.7 (range 3 to 7). Few of the specimens captured in winter show signs of pelage molting. Other sigmodontine species registered at the type locality and surroundings, in the same habitat, include Oxymycterus rufus (as O. paramensis in Polop 1989), Oligoryzomys flavescens, Phyllotis xanthopygus, and Reithrodon auritus. Akodon polopi, new species is the dominant cricetid in the places where it was registered. In previous studies (Kufner et al. 2004) and our surveys, it constituted more than 70% of the captured animals but Polop (1989, 1991) indicated a minor percentage (53% and 34% respectively). Comments: Although early considered as an undescribed species (Polop 1989), Akodon polopi was alternatively treated as A. boliviensis (Polop 1991; Morando & Polop 1997), A. alterus (Priotto et al. 1996) or A. spegazzinii (D���El��a 2003; D���El��a et al. 2003; Kufner et al. 2004; Pardi��as et al. 2005; Rodrigues Gon��alvez et al. 2007 and Smith & Patton 2007)., Published as part of J. Pablo Jayat, Pablo E. Ortiz, Jorge Salazar-Bravo, Ulyses F. J. Pardi��as & Guillermo D'El��a, 2010, The Akodon boliviensis species group (Rodentia: Cricetidae: Sigmodontinae) in Argentina: species limits and distribution, with the description of a new entity, pp. 1-61 in Zootaxa 2409 on pages 34-42, DOI: 10.5281/zenodo.293461, {"references":["Polop, J. (1989) Distribution and ecological observations of wild rodents in Pampa de Achala, Cordoba, Argentina. Studies on Neotropical Fauna and Environment, 24, 53 - 59.","Polop, J. (1991) Distribucion de cricetidos en las Sierras de Achala (provincia de Cordoba, Republica Argentina). Revista de la Universidad Nacional de Rio Cuarto, Zoologia, 11, 115 - 121.","Pinna-Senn, E., de Barale, D. D., Polop, J. J., Ortiz, M. Y., Provensal, M. C. & Lisanti, J. A. (1992) Estudio cariotipico y morfometrico en una poblacion de Akodon sp. (Rodentia, Cricetidae) de Pampa de Achala. Mendeliana, 10, 59 - 70.","Priotto J. W., Morando, M. & Avila, L. (1996) Nuevas citas de roedores de los pastizales de altura de la Sierra de Comechingones, Cordoba, Argentina. Facena, 12, 135 - 138.","Kufner, M. B., Gavier, G. & Tamburini, D. (2004) Comunidades de roedores de pampas de altura en las Sierras Grandes en Cordoba, Argentina. Ecologia Aplicada, 3, 118 - 121","D'Elia, G., Pardinas, U. F. J. & Myers, P. (2005) An introduction to the genus Bibimys (Rodentia: Sigmodontinae): phylogenetic position and alpha taxonomy. In: Lacey, E. & Myers, P. (Eds.), Mammalian Diversification: From Chromosomes to Phylogeography (A Celebration of the Career of James L. Patton). California: University of California Publications in Zoology, pp. 211 - 246.","Smith, M. F. & Patton, J. L. (2007) Molecular phylogenetics and diversification of South American grass mice, genus Akodon. In: Kelt, D., Lessa, E. & Salazar-Bravo, J. (Eds.), Studies in Contemporary Mammalian Biology. Papers Honoring the Remarkable Career of Oliver P. Pearson, 1915 - 2003. California: University of California Publications in Zoology, pp. 827 - 858.","Jayat, J. P., Ortiz, P. E., Pardinas, U. F. J. & D'Elia, G. (2007 a) Redescripcion y posicion filogenetica del raton selvatico (Akodon sylvanus: Rodentia: Cricetidae). Mastozoologia Neotropical, 14, 201 - 225."]}

Akodon, with about 42 living species, is the most diverse genus of the subfamily Sigmodontinae. The Akodon boliviensis species group includes small-bodied, morphologically similar forms inhabiting Altiplano grasslands and grassland/forest ecotones of the eastern slope of the Andes, from central Peru to central Argentina. Northwestern Argentina contains the largest diversity of species of the group; the taxonomic treatment of these species has been based largely on unsupported and some weakly based opinions as underscored by recurrent changes. Based on morphologic and molecular data we assessed species limits among Argentinean populations of the Akodon boliviensis species group. We conclude that four species of the A. boliviensis species group inhabit northwestern Argentina. These are: A. boliviensis; A. caenosus (under which we synonymyze A. aliquantulus); A. spegazzinii (of which the nominal forms alterus, leucolimnaeus, and tucumanensis are junior synonyms); and A. sylvanus. Additionally, we described here a new species of the A. Boliviensis species group, Akodon polopi, which inhabits central Argentina. This is the only species of the A. boliviensis species group inhabiting the Sierras Grandes range (ca. 2000 m), mountain system of medium height isolated (ca., 600 km) from the main Andean chain by low elevation arid and semiarid environments. Additionally, our phylogenetic analysis suggests that the Akodon varius species group is polyphyletic. Fil: Jayat, Jorge Pablo. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Laboratorio de Investigaciones Ecológicas de las Yungas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Ortiz, Pablo Edmundo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Tucuman. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto Miguel Lillo; Argentina Fil: Salazar Bravo, Jorge. Texas Tech University; Estados Unidos Fil: Pardiñas, Ulises Francisco J.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina Fil: D’Elía, Guillermo. Universidad de Concepción; Chile

Palma, R. Eduardo, Rodríguez-Serrano, Enrique, Rivera-Milla, Eric, Hernandez, Cristian E., Salazar-Bravo, Jorge, Carma, Maria I., Belmar-Lucero, Sebastian, Gutierrez-Tapia, Pablo, Zeballos, Horacio, Yates, Terry L. (2010): Phylogenetic relationships of the pygmy rice rats of the genus Oligoryzomys Bangs, 1900 (Rodentia: Sigmodontinae). Zoological Journal of the Linnean Society 160 (3): 551-566, DOI: 10.1111/j.1096-3642.2009.00621.x, URL: http://dx.doi.org/10.1111/j.1096-3642.2009.00621.x