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Muroid rodents are the most species-rich superfamily of rodents occurring in Argentina. Increased fieldwork with these mammals depicts the need of adequate keys to identify species on the base of external characters. In this contribution we provide three keys (one for families and subfamilies, and another two for Sigmodontinae and Muridae, respectively) for all known species of Cricetidae and Muridae distributed in Argentina (42 genera and 110 species). In addition to the dichotomous keys, and as a way to facilitate the identification, we include for each species a brief description of its distribution and the main habitats where it occurs. Los roedores muroideos constituyen la superfamilia de roedores con más especies en Argentina. El creciente interés en el trabajo de cam- po con estos mamíferos ha puesto en evidencia la necesidad de contar con claves para identificar sus especies a partir de características exter- nas. En esta contribución se proporcionan tres claves (una para familias y subfamilias y otras dos para Sigmodontinae y Muridae) para todas las especies conocidas de Cricetidae y Muridae que se distribuyen en Argentina (42 géneros y 110 especies). Además de las claves dicotómicas, y como una forma de facilitar la identificación, para cada especie incluimos una breve descripción de su distribución y de los principales hábitats en donde ocurre. 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: Jayat, Jorge Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; Argentina

Se describe el ensamble de roedores sigmodontinos recuperado en el sitio arqueológico “El Divisadero Monte 6”, emplazado sobre la franja de humedales costeros de la Bahía de Samborombón (partido de General Lavalle, provincia de Buenos Aires, Argentina). Una datación de 540 ± 60 años radiocarbónicos antes del presente ubica la muestra en el Holoceno tardío. El ensamble está dominado por sigmodontinos frecuentes actualmente en el área (e.g., Akodon azarae, Oligoryzomys flavescens, Holochilus brasiliensis) y otros extintosregionalmente (e.g., Bibimys torresi, Pseudoryzomys simplex). La disminución de riqueza y diversidad que reflejan las comunidades actuales de sigmodontinos podría estar vinculada con el impacto antrópico que sufrió la región en los últimos siglos. Sigmodontine rodents from “El Divisadero Monte 6” archaeological site (Late Holocene, Buenos Aires, Argentina): Taxonomy and enviromental reconstruction. We describe the assemblage of sigmodontine rodents from the archaeological site “El Divisadero Monte 6”. This site is placed within the fringe of coastal wetlands of the Bahía de Samborombón (General Lavalle county, Buenos Aires province, Argentina). A radiocarbon date of 540 ± 60 years B.P. indicates a Late Holocene age for the studied sample. The studied sample is mostly composed by species still frequent in the area (e.g., Akodon azarae, Oligoryzomys flavescens, Holochilus brasiliensis) and other sigmodontines regionally extinct (e.g.. Bibimys torresi, Pseudoryzomys simplex). The observed decrease both in richness and diversity in recent samples probably was triggered by human-made disturbances over the pampean region during the last centuries. Fil: Teta, Pablo Vicente. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico. Unidad de Investigación Diversidad, Sistemática y Evolución; Argentina; Fil: Pardiñas, Ulyses Francisco J.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico. Unidad de Investigación Diversidad, Sistemática y Evolución; Argentina; Fil: Aldazabal, Veronica Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Multidisciplinario de Historia y Ciencias Humanas; Argentina; Universidad de Buenos Aires. Facultad de Arquitectura y Urbanismo. Instituto de Arte Americano e Investigaciones Estéticas “Mario J. Buschiazzo”. Centro de Arqueologia Urbana; Argentina; Fil: Silveira, Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Multidisciplinario de Historia y Ciencias Humanas; Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Multidisciplinario de Historia y Ciencias Humanas. Unidad de Investigaciones Prehistóricas y Arqueológicas; Argentina; Fil: Eugenio, Emilio Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Multidisciplinario de Historia y Ciencias Humanas; Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Multidisciplinario de Historia y Ciencias Humanas. Unidad de Investigaciones Prehistóricas y Arqueológicas; Argentina

La tribu Abrotrichini (Rodentia, Cricetidae) es uno de los clados de Sigmodontinae más recientemente diagnosticados. Su distribución es fundamentalmente andino-patagónica, con mayor diversidad de especies en el sur de Argentina y Chile. En esta tesis se evaluaron las relaciones filogenéticas entre sus integrantes, utilizando 21 taxones terminales (20 vivientes y uno fósil) y un grupo externo (Wiedomys). Se realizó un análisis cladístico a través de búsquedas exactas y heurísticas de 99 caracteres morfológicos (16 del tegumento, 42 craneanos, 29 dentarios, 4 postcraneanos, 7 sexuales masculinos y 1 del aparato digestivo) y dos marcadores moleculares (uno mitocondrial [citocromo b; 746 pares de bases] y otro nuclear [IRBP, proteína intersticial de unión al retinol; 1137 pb]). Los datos fueron considerados por separado y en conjunto, bajo pesos iguales e implicados. En todos los casos se recuperó una división mayor entre un clado de formas cursoriales-escansoriales (Abrothrix) y otro de formas semifosoriales a fosoriales (Chelemys, Geoxus, Notiomys, Pearsonomys). El análisis cladístico corroboró la monofilia de Abrothrix, aunque a juzgar por el grado de diferenciación morfológica entre grupos de especies queda abierta la posibilidad de que este taxón pueda escindirse en al menos cuatro entidades de nivel genérico. Dentro del clado de formas fosoriales, las dos especies reconocidas para Chelemys no formaron un grupo monofilético y se confirmó la parafilia de Geoxus con respecto a Pearsonomys. Para ajustar el esquema clasificatorio con la hipótesis filogenética presentada en esta tesis se describe un género nuevo para contener a “Chelemys” macronyx y se incluye a Pearsonomys en la sinonimia de Geoxus. Se ofrecen diagnosis enmendadas para todos los géneros de Abrotrichini, aclarando los límites y contenidos de cada uno. En una segunda instancia, se estudió la taxonomía alfa de Abrothrix longipilis, uno de los abrotriquinos más ampliamente distribuidos en Argentina y Chile. Se realizó un análisis morfológico cualitativo (seis caracteres discretos) y cuantitativo (18 medidas cráneo-dentarias) de 471 especímenes, agrupados primero según un criterio geográfico y luego según su pertenencia a los clados definidos por un estudio filogeográfico previo. Los análisis multivariados (análisis de componentes principales, análisis discriminantes “libres de tamaño”) indican que en su actual concepción, A. longipilis es un complejo que incluye por lo menos dos especies, A. longipilis s.s. (restringida al centro de Chile) y A. hirta (sur de Chile y sudoeste de Argentina). Las poblaciones de A. hirta mostraron una correspondencia moderada entre los patrones filogeográficos y de variación fenotípica. Preliminarmente, puede considerarse que el tamaño en A. hirta se vincula más estrechamente con las características del ambiente (con los individuos más grandes en áreas boscosas, de mayor productividad primaria y los más pequeños en ambientes áridos, de menor productividad) antes que con su pertenencia a los distintos clados. En este escenario, la divergencia morfológica podría estar mayormente determinada por la selección diferencial a lo largo de un gradiente ambiental extremo y sería independiente de la cantidad de flujo génico (modelo de divergencia con flujo génico). Finalmente, se revisaron las formas fósiles Plio-Pleistocénicas de Abrothrix, incluyendo Akodon (Abrothrix) kermacki, A. (Ab.) magnus y aff. Abrothrix. El estudio de la morfología dentaria permitió referir los dos primeros taxones, recuperados de sedimentos pliocénicos del sudeste de la provincia de Buenos Aires, a la tribu Akodontini. El análisis cladístico sugiere que el fósil identificado como aff. Abrothrix del Plioceno-Pleistoceno de la provincia de Jujuy corresponde a una nueva especie que se vincula con A. jelski, que habita actualmente en la misma región. Bajo esta hipótesis taxonómica no habría registros extra-limitales para el género Abrothrix, tal como se infería de esquemas previos. Como corolario, se remarca la importancia de combinar evidencias morfológicas y genéticas, tanto para resolver interrogantes a nivel taxonómico como así también para lograr un esquema clasificatorio refinado a nivel de las especies fósiles por sus profundas implicaciones en la biogeografía histórica y evolución de estos roedores., Facultad de Ciencias Naturales y Museo

El Libro Rojo es una herramienta en el desarrollo de programas de conservación a escala mundial, continental, regional, nacional y local. Desde los inicios de la SAREM impulsamos distintas actividades orientadas a la conservación de los mamíferos del país y refl ejadas en documentos, libros, boletines, talleres y simposia a lo largo de la vida de la Sociedad. Esta nueva edición del Libro Rojo refl eja un proceso hacia la consolidación profesional de la SAREM en la categorización de especies. Fil: Teta, Pablo Vicente. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina Fil: Pardiñas, Ulises Francisco J.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina

The Patagonian and Fuegian regions host a rich assemblage of sigmodontine rodents. In this article, we present a synthesis of our current understanding of their late Neogene diversification. Sigmodontine diversity in this area encompasses 16 genera and about 24 species; however, most belong to the tribes Abrotrichini and Phyllotini. Several abrotrichine genera are endemic to the region, whereas phyllotines are represented mainly by species widely distributed outside Patagonia. Two main ecogeographical assemblages of sigmodontines can be recognized: a lowland northeastern group with species mostly associated with shrub formations of the Monte Desert, and a medium to highland southwestern group of typical Patagonian elements, including several abrotrichines and a diversity of Andean forms. The pattern of latitudinal decline in species’ number in sigmodontine rodents is more complex than the traditionally envisioned north to south pauperization; southern mainland Patagonia is as poor in species’ number as is northern Tierra del Fuego (six species), suggesting that insularity is insufficient to explain the island assemblage. Glacial cycles may have had a major role in the control of sigmodontine richness. The fossil Fuego–Patagonian sigmodontine record is restricted to late Pleistocene–Holocene times. Remarkable events include regional extinctions of several widespread southwestern species during the latest Holocene and a reworking of micromammal assemblages, probably as a result of anthropogenic environmental changes. Two main phylogeographical patterns can be broadly associated with the northeastern and southwestern groups. The northeastern assemblage basically comprises species without phylogeographical structure, whereas the southwestern group involves several lineages with deep phylogeographical breaks. The current Fuego–Patagonian sigmodontine assemblage is mainly composed of species that colonized the area from lower latitudes and by others that have differentiated in situ. La región Patagónico-Fueguina comporta un rico ensamble de roedores sigmodontinos. En este trabajo presentamos una síntesis del conocimiento sobre los procesos de diversificación del grupo durante el Neógeno tardío. La diversidad de sigmodontinos comprende 16 géneros y cerca de 24 especies; sin embargo, la mayor parte de las mismas pertenecen a las tribus Abrotrichini y Phyllotini. Varios géneros de abrotriquinos son endémicos de la región, mientras que los filotinos están en general representados por especies de amplia distribución fuera de Patagonia. Se pueden reconocer dos grandes ensambles eco-geográficos de sigmodontinos: un grupo nor-oriental de tierras bajas, con especies mayoritariamente asociadas a las formaciones vegetales arbustivas del Monte, y otro sud-occidental de tierras de mediana a alta elevación, que agrupa típicos elementos patagónicos, incluyendo abrotriquinos y una diversidad de formas andinas. El patrón de disminución latitudinal en el número de especies de sigmodontinos es más complejo que aquel tradicionalmente supuesto de una pauperización norte a sur. La porción continental más austral de Patagonia es tan pobre en número de especies como la porción norte de Tierra del Fuego (seis especies) sugiriendo que la insularidad es insuficiente para explicar el ensamble isleño. Los ciclos glaciales podrían haber jugado un papel principal en el control de la riqueza específica de sigmodontinos y mamíferos en general. El registro fósil de sigmodontinos en Fuego-Patagonia está restringido al Pleistoceno tardío y Holoceno. Eventos destacables en esta historia incluyen extinciones regionales de especies sud-orientales de amplia distribución durante el Holoceno tardío y una restructuración de las comunidades posiblemente debida a cambios ambientales de origen antrópico reciente. Dos patrones filogeográficos principales pueden ser gruesamente asociados con los grupos nor-oriental y sud-occidental previamente reseñados. Mientras que el ensamble nor-oriental comprende básicamente especies sin estructura filogeográfica, el sud-occidental involucra varios linajes que muestran profundos quiebres. La fauna de sigmodontinos de Fuego-Patagonia está conformada mayoritariamente por especies que colonizaron desde bajas latitudes y por otras diferenciadas in situ. Fil: Pardiñas, Ulises Francisco J.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; 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: D'Elía, Guillermo. Universidad Austral de Chile. Instituto de Ecología y Evolución; Chile. Centro de Investigación en Ecosistemas de la Patagonia; Chile Fil: Lessa, Enrique P.. Universidad de la República. Facultad de Ciencias. Departamento de Ecología y Evolución; Uruguay

Se estudió el holotipo de Graomys hypogaeus Cabrera, 1934, una especie correspondiente al género Eligmodontia de acuerdo a autores previos. Sobre la base de caracteres morfológicos y métricos se concluye que G. hypogaeus debe ser considerado un sinónimo junior de Eligmodontia moreni (Thomas, 1896), una especie ampliamente distribuida en el centro-oeste de Argentina. We studied the holotype of Graomys hypogaeus Cabrera, 1934, a putative species of Eligmodontia according to previous authors. Based on morphology and metrics we concluded that G. hypogaeus must be considered as a junior synonym of Eligmodontia moreni (Thomas, 1896), a species widely distributed in west-central 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: D'Elía, Guillermo. Universidad de Concepción; Chile Fil: Pardiñas, Ulises Francisco J.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina

Teta, Pablo, Pardiñas, Ulyses F. J., Sauthier, Daniel E. Udrizar, D'ElÍa, Guillermo (2009): Loxodontomys micropus (Rodentia: Cricetidae). Mammalian Species (Dordrecht, Netherlands) 837 (3): 1-11, DOI: 10.1644/837.1, URL: http://dx.doi.org/10.1644/837.1

Juliomys pictipes (Osgood, 1933) Holotype. FMNH 26814, adult male (skin and skull) collected by C. C. Sanborn on Sept. 6, 1926. Photographs (skull and mandible) of this individual were recently published by Costa et al. (2007: figs. 4 and 5). Type locality. ���Caraguatay, Rio Parana, 100 miles south of Rio Iguassu, Misiones, Argentina ��� (Osgood, 1933: 11). The exact location of this type locality was recently addressed by Pardi��as et al. (2007: 397). These authors, taking into account the most probable route followed by C. Sanborn and the fact that he worked in Misiones��� Charles Benson property (see Field Museum of Natural History - Reports, 1927), restricted it to Puerto Caraguatay (26 �� 37 ��� S, 54 �� 46 ��� W, Department of Montecarlo, Province of Misiones). However, in a recent inspection of this area, Mr. Benitez, an old resident of the area and with a good knowledge of it, showed us (UFJP and CAG) the exact place where the original house of Mr. Benson was emplaced. The main building is now in ruins and practically subsumed by the forest. Clearly, this is not Puerto Caraguatay, instead Puerto Benson with coordinates 26 �� 37 ��� 13 ��� S and 54 �� 46 ��� 57 ��� W and probably Sanborn trapped around there. Despite those findings, the extreme proximity of these two localities (ca. 0.5 km), the missing of Puerto Benson as toponomy, and the ambiguity around the exact place where Sanborn worked, support our restriction of the type locality of J. pictipes to Puerto Caraguatay. Distribution (Fig. 2). J. pictipes is restricted to tropical and subtropical moist forests of the Atlantic coast in southeastern Brazil and in interior subtropical moist forests of Argentina (Osgood, 1933; Pine, 1980; Costa et al., 2007). New Argentinean specimens (Fig. 2). CIES-M 23, adult female preserved as skin in poor condition and skull, originally identified as Oligoryzomys nigripes. Collected by Silvana Montanelli in Sendero Macuco, Parque Nacional Iguaz�� (25 �� 41 ��� S, 54 �� 26 ��� W, Department of Iguaz��, Province of Misiones). CNP 895, young female, preserved as cleaned skull, carcass in fluid and digestive, collected by Ulyses Pardi��as and Rosario Robles (original number LTU 379) in Arroyo de Salamanca, Parque Provincial ���Ernesto Che Guevara��� (26 �� 36 ��� 53 ��� S, 54 �� 46 ��� 51 ��� W, 147 m asl, Department of Montecarlo, Province of Misiones). MLP 1.I. 03.24, adult pregnant female (3 fetus) preserved as complete fluid, except digestive organs, collected by Graciela Navone and Juliana Notarnicola on 28 August 2006 (original number JN 702) in Balneario de la Reserva Privada de Usos M��ltiples de la Universidad Nacional de La Plata ���Valle del Arroyo Cu��a Pir����� (27 �� 05��� S, 54 �� 57 ��� W, Department of Cainguas, Province of Misiones). Emended diagnosis. The largest known species of Juliomys, characterized by the following combination of traits: body markedly bicolored light orange-brown above and white to cream-white below; tail slightly shorter than head-body length; tail bicolor except for the terminal half-inch, which is dusky all around; feet clear ochraceous-twany, the toes whitish; zygomatic notch moderately expressed; upper free border of the zygomatic plate reduced; incisive foramina short, not reaching the first upper molars; lateral expansion of frontal bones restricted; tympanic bulla small, squamosal-alisphenoid and sphenofrontal foramen absents, sphenopalatine vacuities absents or reduced to a narrow fissures, 2 n = 36. Description. Based on the new Argentinean specimens. A small-sized sigmodontine rodent, externally similar to Oligoryzomys nigripes, but with the head and eyes proportionally larger and with a shorter tail that is nearly equal to head and body (Fig. 3). Dorsal hairs are plumbeous gray at the base and distally reddish. Over hairs on the rump and hind legs are vivid orange at the tip, contrasting with the rest of the body. The venter is covered by bicolored hairs; each hair has a short gray base and is withish at the tip. Orange tipped hairs are visible in the inguinal region around the tail base. The philtrum, genal zone, and chin are covered by whitish hairs. Hairs around the nose are short and orange, contrasting with the rest of the body. The ears are small, covered mainly with short and sparse brownish hairs externally and mostly naked internally; the ear border is covered by short reddish hairs. Mystacial vibrissae are blackish, relatively short anteriorly, and long posteriorly, the latter largely extended beyond the posterior border of the ears. The supercilliary and genal vibrissae are thinner, blackish, and shorter than mystacial, and not surpassing the posterior border of the ears. The tail pelage is sparse, gradually becoming denser toward the tip, where a short tuft is visible. Hairs from proximal and distal halves of tail reach 2���3 scales and 3���6 scales, respectively, with three hairs emerging from each scale. Tail hairs are brown on the dorsum and rufous in the venter, except in the distal tip, which is uniformly brown. Eight mammae are present in a pregnant female examined (MLP 1.I. 03.24) that are arranged in one inguinal, one abdominal, one postaxial and one pectoral pair (see Voss & Carleton, 1993). The hands and feet are short, covered with orange hairs dorsally; the fingers are covered by short white hairs (Fig. 4 b). The hallux is much shorter than other pedal digits. Manal and pedal pads boulbous and enlarged, especially those of the distal phalanxes, remembering the pads of arboreal sigmodontine species of the genus Oecomys and Rhipidomys (Hershkovitz, 1960; Rivas & Linares, 2006). Three large and rounded interdigital and two large and mostly ovale carpal pads are present (Fig. 4 a). The plantar surface of the hind feet has six bulbous tubercles, four interdigitals and two tarsal. The interdigital ones are nearly ovale and large. The thenar pad is more rounded and smaller than the interdigital tubercles. The hypothenar pad is large and is comma-shaped. The distal edge of the thenar just reaches the proximal edge of the hypothenar and is positioned approximately midway along the sole of the foot (Fig. 4 c). The skin between distal pads up to the thenar and hypothenar pad limit is covered by small and rounded scales, while the remainder of the plantar surface is smooth (Fig. 4 a, c). The claws on the hind feet are short and darker in color than the skin of the pes. Ungual tufts are grayish-white and large, reaching or slightly surpassing the claws. The skull is robust with a short rostrum, a rounded braincase and a marked domed profile in its posterior region (Fig. 5,6A-L). The nasals diverge anteriorly, without contrasting expansions and with a slight projection anterior to the incisors, conforming a moderate tube (Fig. 5). The nasofrontal suture is straight but markedly denticulate, positioned anteriorly to the lacrimal level (Fig. 6 A). A clear central depression is present in the anterior part of the interfrontal region (Fig. 6 E); in addition, in this region the interfrontal suture is slightly open, contrasting with the condition of this suture posterior to the depression which appears clearly closed in adult individuals (Fig. 6 B, C). Following Weksler (2006: 28, character 22) the interorbital region can be typified as symmetrically constricted with squared supraorbital margins (Fig. 6 B, C). The lacrimal bone is large. The coronal suture is V-shaped and the squamosal anterior-upper portion is clearly visible from above over the braincase margins (Fig. 6 B). Both parietal and interparietal sutures are meandrous, and the former suture includes supernumerary middle bones (Fig. 6 I). The interparietal is wide and broad (Fig. 6 I). The occipital region is dorso-ventrally compressed producing a oblique position of the foramen magnum (Fig. 6 H). Lateral parietal and lambdoid crests are inconspicuous (Fig. 5). The zygomatic plate is high and narrow showing a much reduced upper free border and having a masseteric tubercle well developed in their base (Fig. 6 D). Contrasting with the general solid construction of the skull, the zygomatic arches, well expanded, are gracile (Fig. 5). A moderate postorbital ridge is present. The lateral portion of the parietals is reduced (Fig. 6 H). Ventrally, the incisive foramina are wide and moderately long and their posterior ends almost reach the M 1 anterior face (Fig. 5, 6 G). The palate is bombed and finely foraminate with two posterior palatine foramina and paired posterolateral palatal pits side by side the mesopterygoid fossa anterior region (Fig. 6 F). The mesopterygoid fossa is broad and has a lire-shape (Fig. 6 F). The mesopterygoid roof is almost totally ossified; the sphenopalatine vacuities remain as narrow fissures (Fig. 6 G). The parapterygoid fossae are broad, well ossified, and show the small posterior openings of the alisphenoid canal (Fig. 6 G). The anterior ends of the parapterygoid fossae are located at the level of M 3 protocones (Fig. 6 F). Otic capsules are reduced and auditory meatus are clearly enlarged (Fig. 6 J). The carotid canal is big and without pteriotic participation; the stapedial foramen is minute and the petrotympanic fissure absent (Fig. 6 J). The tegmen tympani is well developed, superposed to the squamosal bone, and partially filling the postglenoid foramen (Fig. 6 K). The narrow hamular process is distally spatulated and directly applied on the mastoid (Fig. 6 K). The mastoid capsule is small but not flattened with a large mastoid fenestra. Cranial foramina related with cephalic arterial pattern include a well developed oval foramen and a small anterior opening of the alisphenoid canal; the alisphenoid strut is absent, and the same is true for the squamosal-alisphenoid groove while the trough for the masticatory-buccinator nerve is shallow but well expressed (Fig. 6 G, K). These traits coupled with the absence of the sphenofrontal foramen characterizing the carotid circulatory pattern 2 of Voss (1988). The mandible is robust and short (Fig. 7 A���B). The anteriormost point of the diastema is well below the alveolar plane (Fig. 7 A). The mental foramen is scarcely visible from lateral view. Both upper and lower ridges of masseteric crest are clearly expressed; the same is true for the capsular projection of the incisor. The angular process is short with respect to the condyloid process (Fig. 7 B). Upper incisors are robust and deep, opisthodont, with bright orange frontal enamel. Both upper and lower molars are brachyodont, crested and with the main cusps slightly alternate. M 1 (Fig. 6 L): subrectangular in outline; main cusp slightly alternating; procingulum almost wide as the remainder portion of the tooth; deep and penetrating anteromedian flexus with their fund engulfed producing two conules being the lingual smaller than labial one; anteroloph and mesoloph transverses in orientation with their labial tips spatulated and showing medium point-connections to the anterior structures (anterolabial conule and paracone, respectively) like displaced paralophules; short posteroloph transverse in orientation; very wide and penetrating protoflexus, subequal in morphology to hypoflexus; protostyle and enterostyle present, the latter with a short enteroloph (developed also in the young individual CNP 895). M 2: subcuadrangular in outline; gross morphology very similar to the M 1 comparable portion; main cusp something more alternating than M 1. M 3: about 0.7 of the M 2 length; anteroloph conspicuous. Lower molars are crested and the main cusp slightly alternating. m 1: procingulum wide; anteromedian flexid well developed producing subequal conulids; anterolophid transverse in orientation with tendency to fusion to anterolingual conulid; protoflexid externally obliterate by a sharp anterolabial cingulum; mesolophid narrow but independent and clearly developed well projected lingually; broad hypoflexid showing a small but marked ectostylid. m 2: quadrangular in outline and subequal to the m 1 comparable portion; mesolophid well developed; ectolophid plus ectostylid. m 3: almost large as m 2 (0.9); hypoflexid flanqued by oblique proto- and hypoconid walls resulting in a triangular outline, with their fund oriented to a bifid structure composed by fused mesolophid plus entoconid; annular posterofossetid. We examined the stomach gross anatomy of one juvenile specimen (CNP 895). The morphology is of the type unilocular hemiglandular (see Carleton, 1973); in this morphology the glandular epithelium from the antrum extends to the corpus, near the esophagus opening (Fig. 8). Measures of the thick intestine and caecum are 3.5 and 1.8 cm, respectively. Measurements. See Table 2. a Holotype; measurements taken from Osgood (1933: 12) Habitat. All specimens were collected in the Interior Atlantic Forest of the Misiones Province, Argentina. This biotic unit, also known as ���Selva Paranaense,��� is part of the South American Atlantic Forest macroregion (Plac�� & Di Bitetti, 2005). Three of four specimens were collected in the vicinity of watercourses of the Paran�� river basin. One individual from Sendero Macuco, Parque Nacional Iguaz��, was collected in a mature forest of ���Laurel and Guatambu��� (Mart��nez-Crovetto 1963), where the predominant arboreal species were Matayba elaeagnoides, Balforoundendron riedelianum, Sorocea ilicifolia, Cordia ecaliculata, and Prumus sphaerocarpa. Dense underbrush vegetation at Sendero Macuco includes the bamboos Merostachys clausseni and Chusquea ramossisima. The individual CNP 895 was collected ca. 2 km of the type locality. The rainforest in this area is highly disturbed by human activities, including wood extraction and timber plantations. In fact, the small provincial park ���Ernesto Che Guevara��� (18 ha), where the specimen was trapped, constitutes one of the last patches of forests in this area. The mean height of the trees in this place is 10-12 m, with a discontinuous dosel. The vegetal community is dominated by the Lauraceae Ocotea spp. and Nectandra spp. and other tree species like Inga sp., Luehea divaricada, Fagara hyemalis, Peltophorum dubium, and Balfourodendron riedelianum. Vegetation in the underbrush includes dense communities of bamboo Chusquea ramosissima. Finally, the individual MLP 1.I. 03.24 was caught in a riverine forest of Ocotea acutifolia and Nectandra megapotamica. The mean hight of the trees in this place is ca. 20 m, with a discontinuous dosel. Other tree species present there include Luehea divaricada, Chrysophyllum marginatum, Balfourodendron riedelianum, Bastardiopsis densiflora, Inga affinis and Peltophorum dubium. At this place, the specimen was caught in dense underbrush of the bamboo Merostachys clausseni. Genetic variation. Only five cytochrome- b sequences of J. pictipes are available; these specimens were collected in one Argentinean and three Brazilian (one in Minas Gerais and two in S��o Paulo States) localities. Observed genetic variation among these cyt- b haplotypes is moderate; it ranges form 0.3 to 2.3 %. In addition, there is not a pattern of isolation by distance. The most distinct haplotype is the one recovered at the Minas Gerais locality and not the one from the Argentinean locality that is the most apart of the four (see Fig. 1). Comparisons involving the haplotype from Minas Gerais and the other J. pictipes haplotypes range from 1.6 to 2.3 %, while comparisons between the Argentinean haplotype and the others range from 0.4 to 1.6 %. Future studies involving more haplotypes, especially from intermediate localities will test the pattern of genetic structure described here, and explain its biological meaning if any. Conservation status. D'El��a et al. (2006) categorized J. pictipes in Argentina as data deficient. Due to the lack of primary data about J. pictipes natural history and the fragmentary knowledge about its distribution we prefer to maintain this category for the populations in Misiones Province. Globally, J. pictipes was treated by Baillie (1996) as Lower risk, least concern., Published as part of Pardi��as, Ulyses F. J., Teta, Pablo, D'El��a, Guillermo & Galliari, Carlos, 2008, Rediscovery of Juliomys pictipes (Rodentia: Cricetidae) in Argentina: emended diagnosis, geographic distribution, and insights on genetic structure, pp. 29-44 in Zootaxa 1758 on pages 33-41, DOI: 10.5281/zenodo.181855, {"references":["Osgood, W. H. (1933) Two new rodents from Argentina. Zoological Series of Field Museum of Natural History, 20 (321), 11 - 14.","Costa, L. P. Pavan, S. E., Leite, Y. R. L. & Fagundes, V. (2007) A new species of Juliomys (Mammalia: Rodentia: Cricetidae) from the Atlantic forest of southeastern Brazil. Zootaxa, 1463, 21 - 37.","Pardinas, U. F. J., Teta, P., D'Elia, G., Cirignoli, S. & Ortiz, P. E. (2007) Resolution of some problematic type localities for sigmodontine Rodents (Cricetidae, Sigmodontinae). In: Kelt D. A., Lessa, E., Salazar-Bravo, J. A. & Patton. J. L. (Eds.) The quintessential naturalist: honoring the life and legacy of Oliver P. Pearson. University of California Publications in Zoology, Berkeley, 391 - 416.","Pine, R. H. (1980) Notes on rodents of the genera Wiedomys and Thomasomys (including Wilfredomys). Mammalia, 44, 195 - 202.","Voss, R. & Carleton, M. (1993) A new genus for Hesperomys molitor Winge and Holochilus magnus Hershkovitz (Mammalia, Muridae) with an analysis of its phylogenetic relationships. American Museum Novitates, 3085, 1 - 39.","Hershkovitz, P. (1960) Mammals of northern Colombia, preliminary report Nº 8: arboreal rice rats, a systematic revision of the Subgenus Oecomys, Genus Oryzomys. Proceedings of the United States Natural Museum, 110 (3420), 513 - 568.","Rivas, B. A. & Linares, O. J. (2006) Cambios en la forma de la pata posterior entre roedores sigmodontinos segun su locomocion y habitat. Mastozoologia Neotropical, 13, 205 - 215.","Weksler, M. (2006) Phylogenetic relationships of oryzomine rodents (Muroidea: Sigmodontinae): separate and combined analyses of morphological and molecular data. Bulletin of the American Museum of Natural History, 296, 1 - 149.","Voss, R. (1988) Systematics and ecology of ichthyomyine rodents (Muroidea): patterns of morphological evolution in a small adaptative radiation. Bulletin of the American Museum of Natural History, 188, 259 - 493.","Baillie, J. (1996) Wilfredomys pictipes. In: IUCN 2007. 2007 IUCN Red List of Threatened Species. . Accesed on 12 February 2008."]}

Juliomys Gonz��lez, 2000 Type species. Juliomys pictipes (Osgood, 1933). Included species (in order of nomination). J. pictipes (Osgood, 1933), J. rimofrons Oliveira and Bonvicino, 2002; J. ossitenuis Costa, Pavan, Leite and Fagundes, 2007. Emended diagnosis. Small to medium Sigmodontinae rodents (total length ~ 200, Occipto-nasal length ~ 27) with large head, conspicuous eyes, and tail equal or slightly larger than head and body; dorsal pelage soft dark-brown to light-orange brown; feet rather short and broad with 6 plantar pads and scutelated surface; skull with short rostrum (Fossil record. No fossil of Juliomys is known., Published as part of Pardi��as, Ulyses F. J., Teta, Pablo, D'El��a, Guillermo & Galliari, Carlos, 2008, Rediscovery of Juliomys pictipes (Rodentia: Cricetidae) in Argentina: emended diagnosis, geographic distribution, and insights on genetic structure, pp. 29-44 in Zootaxa 1758 on pages 32-33, DOI: 10.5281/zenodo.181855, {"references":["Gonzalez, E. M. (2000) Un nuevo genero de roedor sigmodontino de Argentina y Brasil (Mammalia: Rodentia: Sigmodontinae). Comunicaciones Zoologicas del Museo de Historia Natural de Montevideo, 12, 1 - 12.","Osgood, W. H. (1933) Two new rodents from Argentina. Zoological Series of Field Museum of Natural History, 20 (321), 11 - 14.","Oliveira, J. A. de & Bonvicino, C. R. (2002) A new species of sigmodontine rodent from the Atlantic forest of eastern Brazil. Acta Theriologica, 47, 307 - 322."]}

El conocimiento existente sobre los roedores y marsupiales del norte de Patagonia argentina extra andina es escaso tanto en aspectos taxonómicos, distribucionales como en la relación de las comunidades de micromamíferos con las unidades fitogeográficas. Aquí se presenta un análisis basado en el estudio de 58 localidades con información de egagrópilas de aves rapaces. Se detectaron 19 especies de roedores sigmodontinos y al menos cinco de roedores caviomorfos y dos de marsupiales marmosinos. Se revisó la taxonomía alfa y distribución de estos taxones, destacándose los problemas que aún subsisten, especialmente vinculados a los géneros Akodon, Oligoryzomys y Calomys. Numerosas y novedosas localidades se reportan aquí por primera vez, demostrando la existencia en Norpatagonia central de poblaciones relictuales para roedores típicamente restringidos al bosque de Nothofagus y estepas ecotonales (e.g., Loxodontomys micropus, Chelemys macronyx). El análisis de la riqueza específica, la diversidad y la equitatividad de los agregados indica un moderado pero significativo incremento de los valores de este a oeste, en correspondencia con el aumento de la heterogeneidad ambiental y las precipitaciones medias. La relación entre las muestras de micromamíferos y las unidades fitogeográficas (según el esquema de León et al., 1998), abordada mediante análisis de agrupamiento y ordenamiento, indica una división mayor que involucra a las localidades emplazadas en la Provincia Fitogeográfica del Monte y el Ecotono de la Península de Valdés que se separa claramente de las restantes localidades de la Provincia Fitogeográfica Patagónica. Los ensambles de micromamíferos son consistentes en delimitar unidades fitogeográficas menores, resultado que contrasta con las conclusiones de trabajos previos. Zoogeográficamente, en Norpatagonia ocurren dos grandes grupos de micromamíferos, uno con neta influencia de los bosques andinopatagónicos y el otro asociado a la diagonal árida sudamericana. Las distribuciones de las especies del primer grupo se comprimen sobre el contrafuerte andino en Norpatagonia occidental, expandiéndose progresivamente hacia el este, hasta alcanzar, en latitudes más australes, la costa atlántica. Paralelamente, las geonemias de los micromamíferos del segundo grupo exhiben un efecto simétricamente opuesto. Se pone de manifiesto la necesidad de emprender un plan mastozoológico integral en la Patagonia extra andina, situación imperiosa ante el avance del impacto antrópico y los cambios que éste genera en los ecosistemas patagónicos. Current knowledge of the taxonomy and distribution of rodents and marsupials from northern Extra Andean Patagonia of Argentina is scarce; the same is true regarding the relationship between micromammal communities and phytogeographic units. Here we present an analysis based on micromammals recovered from owl pellets from 58 localities. We registered 19 species of muroid native rodents and, at least, five species of caviomorph rodents and two marmosine marsupials. The review of the alpha taxonomy and distribution of these taxa allowed us to identify numerous problems related to the genera Akodon, Oligoryzomys and Calomys. Several new localities for the taxa under study are reported here. Among these, relictual populations in north central Patagonia of rodents traditionally restricted to the Nothofagus forest and western ecotonal steppes (e.g., Loxodontomys micropus, Chelemys macronyx) are worth noting. Analysis of community structure shows a moderate but significant increase of species diversity and richness across an east west gradient which is positively correlated with both environmental heterogeneity and mean precipitation. The relationship among micromammal samples and phytogeographic units (following León et al., 1998), assessed by means of cluster and ordinal analyses, indicates the existence of two main groups: one including localities located in the Monte Phytogeographic Province and Península de Valdés Ecotone and the other in the remaining localities of Patagónica Phytogeographic Province. At the same time, micromammalian assemblages are correlated with minor phytogeographic units, a result that contrasts with conclusions of previous studies. Zoogeographically, in northern Patagonia concur two main groups of terrestrial non-volant micromammals, one composed mainly of forms from Andean-Patagonian forest and the other, of forms related to the South American arid diagonal. Species of the former group have a distribution compressed against the Andes in northern Patagonia that gradually expands to the east in southern latitudes. The distribution of the species in the second group is the opposite. Finally, we note the need for an extensive mammal survey in Extra Andean Patagonia as a first step to solve the questions discussed in this work. Implementation of such a survey is mandatory if one considers the great impact of human activities on Patagonian ecosystems. Fil: Pardiñas, Ulises Francisco J.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; 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: Cirignoli, Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; Argentina Fil: Podestá, Darío Hector. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentina