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Orthohantaviruses (genus Orthohantavirus, family Hantaviridae) are the etiologic agents of Hantavirus Pulmonary Syndrome in the Americas. In South America, orthohantaviruses are highly diverse and are hosted by sigmodontine rodents (subfamiliy Sigmodontinae, family Cricetidae), an also diverse group of rodents. The aims of this work were to (1) identify orthohantavirus hosts and (2) to study the spatial and temporal variations in the prevalence of infection and their associations with community, environmental and individual characteristics, in different environments of Misiones province, northeastern Argentina. Live-capture sessions were carried out during two years in different land uses, with a trapping effort of 31,653 trap nights. We captured 719 individuals from the species Akodon montensis, Rattus rattus, Mus musculus, Calomys tener, Thaptomys nigrita, Oligoryzomys nigripes, Euryoryzomys russatus, Oligoryzomys flavescens, Brucepattersonius sp., and Juliomys pictipes. Antibodies against orthohantavirus were detected in Akodon montensis in one natural protected and one periurban areas, and it was the most abundant species in almost every study sites. We observed the presence of spatial focality of orthohantavirus infection and a positive association with host abundance suggesting the existence of a threshold density. At the individual level, large, reproductively active, and male individuals were more likely to have antibodies against orthohantavirus. This is the first record of orthohantavirus infection in A. montensis in Argentina, which shows the importance of investigations about emerging diseases.

The southeastern Atlantic Forest of the Zona da Mata Mineira is located in the extreme north of Minas Gerais state, Brazil. The Serra da Mantiqueira, is a mountainous region with a high diversity of small non-volant mammal species, several of which are rare species or endemic lineages. The presence of cryptic species in small mammals makes the karyotype an excellent tool for identification and detection of new lineages. We analyzed the karyotype of 14 species: 11 rodents – Abrawayaomys ruschii, Akodon cursor, Blarinomys breviceps, Delomys sublineatus, Juliomys ossitenuis, Oligoryzomys nigripes, Oligoryzomys flavescens, Oxymycterus dasytrichus, Rhipidomys tribei, Sooretamys angouya, and Thaptomys nigrita; and three marsupials – Monodelphis scalops, Philander quica, and Marmosops incanus. We described for the first time the fundamental autosomal number and the morphology of sex chromosomes of Abrawayaomys ruschii, a rare sigmodontine species, and described a new karyotype for Blarinomys. The revision of published karyotypes of the species herein studied enabled the expansion of the geographic distribution of Oligoryzomys nigripes and Delomys sublineatus.

Rodents are reservoirs of various types of hantavirus, some of which are agents of hantavirus pulmonary syndrome in humans. Each hantavirus is associated with a single rodent host species but successive spill-over events may eventually lead to host-switching and new species' becoming host of a given pathogen. This study aims to gain an understanding of the spatial ecology of two hantavirus-host species, Akodon azarae, and Oligoryzomys flavescens, by identifying factors modulating their home range sizes and stability, and by evaluating intra- and interspecific spatial aggregation for these species and a third one-Oxymycterus rufus-living in sympatry. For this, eleven capture-mark-recapture surveys were carried out, spanning 22 months. We found that A. azarae males have larger and more mobile home ranges than females, independently of the season. Consequently, males could likely have a more relevant role in the transmission of hantavirus because of their greater exposure both to a higher number of contacts between individuals and viral contamination of the environment. Contrasting, O. flavescens individuals showed negligible displacements of their home range through time, which could limit the range of hantavirus spread in host populations. Since O. flavescens is host to Lechiguanas hantavirus (pathogenic to humans) this result encompasses epidemiological relevance, for it may imply the existence of local foci of infection. Additionally, individuals of both species performed excursions outside their home ranges. These events could enable hantavirus spread over distances beyond the normal range of movements and lead to new hantavirus outbreaks in formerly non-infected rodent populations, favoring the persistence of the virus in nature.

Hantavirus pulmonary syndrome is an emerging infectious disease caused by viruses of the genus Orthohantavirus. The rodent Oligoryzomys flavescens is distributed along four countries of South America. In Argentina, O. flavescens acts as a reservoir of three genotypes of ANDV orthohantavirus. The aims of this work were to estimate home range size and movements-with spool-and-line and radiotelemetry-of infected and non-infected O. flavescens in order to understand the spread and transmission of the virus. O. flavescens use a wide area to satisfice its requirements, reaching a home range of 1.82 ha during spring. Orthohantavirus infection did not change the behaviour of individuals. We observed a great overlapping in the home range of infected and non-infected individuals resulting in a high probability of virus dispersion on rodent population. These results show that human health risks could be high on island environments and knowledge about the movement ecology of O. flavescens provides useful information on prevention.

Oligoryzomys flavescens Karyotype: 2n = 64 and FN = 66. Autosomal complement: two small metacentric and submetacentric pairs, and 29 acrocentric pairs (one very large and the remaining large to small decreasing in size). Sex chromosomes: X, a large submetacentric that presented a variable centromeric index; Y chromosome presented three different morphologies, a medium metacentric, a medium submetacentric, and a small acrocentric (Yonenaga et al. 1976; Myer & Carleton 1981, pp. 16, Fig. 5C; Brum-Zorrilla et al. 1988; Rioja et al. 1988; Espinosa & Reig 1991; Sbalqueiro et al. 1991; Aniskin & Volobouev 1999; Andrades-Miranda et al. 2001a; Weksler & Bonvicino 2005; Di-Nizo et al. 2015). A different diploid number from 65 to 68 were reported due to the presence of 1 to 4 small acrocentric or metacentric supernumerary chromosomes, mosaicism karyotypes with 2n = 64/64+1B and 2n = 64+1B/ 64+2Bs were also reported. These variations in number and presence of supernumerary chromosomes were widely distributed throughout the karyotyped specimens (Table 9, Fig. 19; see Yonenaga et al. 1976; Myer & Carleton 1981; Brum-Zorrilla et al. 1988; Rioja et al. 1988; Espinosa & Reig 1991; Sbalqueiro et al. 1991; Aniskin & Volobouev 1999; Andrades-Miranda et al. 2001a; Weksler & Bonvicino 2005; Di-Nizo et al. 2015). Additional chromosome polymorphisms, reported only for samples from Minas Gerais, state of Brazil, were due to a whole heterochromatic arm occurring in 1 to 3 large to medium-sized acrocentric chromosomes, and a fundamental number of 68 possibly due to a pericentric inversion affecting one small autosomal pair (Yonenaga et al. 1976; Brum-Zorrilla et al. 1988; Rioja et al. 1988; Espinosa & Reig 1991; Bonvicino & Weksler 1998; Aniskin & Volobouev 1999; Sbalqueiro et al. 1991; Weksler & Bonvicino 2005). C-banding metaphases exhibited blocks of constitutive heterochromatin on the pericentromeric region of all autosomes. The X chromosome has a heterochromatic short arm, which was responsible for the observed variable centromeric indexes. The metacentric or submetacentric Y chromosomes presented over half their short arm heterochromatic, while the acrocentric Y chromosome was entirely heterochromatic. The B chromosomes were entirely C-positive, but the staining was less intense in some cases (Rioja et al. 1988; Espinosa & Reig 1991; Sbalqueiro et al. 1991; Aniskin & Volobouev 1999). G-banding was also performed (Brum-Zorrilla et al. 1988; Espinosa & Reig 1991; Sbalqueiro et al. 1991; Aniskin & Volobouev 1999; Di-Nizo et al. 2015). Multiple NORs, varying from two to eight were localized at the telomeric regions of the short arms of small acrocentric pairs (Sbalqueiro et al. 1991)., Published as part of Moreira, Camila Do Nascimento, Ventura, Karen, Percequillo, Alexandre Reis & Yonenaga-Yassuda, Yatiyo, 2020, A review on the cytogenetics of the tribe Oryzomyini (Rodentia: Cricetidae: Sigmodontinae), with the description of new karyotypes, pp. 1-111 in Zootaxa 4876 (1) on page 61, DOI: 10.11646/zootaxa.4876.1.1, http://zenodo.org/record/4423612, {"references":["Yonenaga, Y., Frota-Pessoa, O., Kasahara, S. & Almeida, E. J. C. (1976) Cytogenetic studies on Brazilian rodents. Ciencia e cultura, 28 (2), 202 - 211.","Brum-Zorrilla, N., Fronza, T. G., Wainberg, R., Rioja, L. V. & Zwirner, N. (1988) Oryzomys flavescens and O. Delticola chromosomes (Rodentia, Cricetidae) from Uruguay and Argentina. Caryologia, 41 (3 - 4), 275 - 288. https: // doi. org / 10.1080 / 00087114.1988.10797868","Rioja, L. V., Fronza, T. G., Wainberg, R., Brum-Zorrilla, N., Wallace, F. & Zambelli, A. (1988) C-banding pattern and satellite DNA localization on the chromosomes of Oryzomys flavescens (Rodentia, Cricetidae). Caryologia, 41 (3 - 4), 323 - 328. https: // doi. org / 10.1080 / 00087114.1988.10797872","Espinosa, M. B. & Reig, O. A. (1991) Cytogenetics and karyosystematics of South American oryzomyine rodents (Cricetidae, Sigmodontinae) III. Banding karyotypes of Argentinian Oligoryzomys. Zeitschrift fur Saugetierkunde, 56, 306 - 317.","Sbalqueiro, I. J., Mattevi, M. S., Oliveira, L. F. B. & Solano, M. J. V. (1991) B chromosome system in populations of Oryzomys flavescens (Rodentia, Cricetidae) from southern Brazil. Acta theriologica, 36, 193 - 199. https: // doi. org / 10.4098 / AT. arch. 91 - 18","Aniskin, V. M. & Volobouev, V. T. (1999) Comparative chromosome banding of two South-American species of rice rats of the genus Oligoryzomys (Rodentia, Sigmodontinae). Chromosome Research, 7, 557 - 562. https: // doi. org / 10.1023 / A: 1009245729902","Andrades-Miranda, J., Oliveira, L. F. B., Lima-Rosa, C. A., Nunes, A. P., Zanchin, N. I. T. & Mattevi, M. S. (2001 a) Chromosome studies of seven species of Oligoryzomys (Rodentia: Sigmodontinae) from Brazil. Journal of Mammalogy, 82, 1080 - 1091. https: // doi. org / 10.1644 / 1545 - 1542 (2001) 082 % 3 C 1080: CSOSSO % 3 E 2.0. CO; 2","Weksler, M. & Bonvicino, C. R. (2005) Taxonomy of pigmy rice rats genus Oligoryzomys Bangs, 1900 (Rodentia, Sigmodontinae) of the Brazilian cerrado, with the description of two new species. Arquivos do Museu Nacional, 63, 113 - 130.","Di-Nizo, C. B., Ventura, K., Ferguson-Smith, M. A., O'Brien, P. C. M., Yonenaga-Yassuda, Y. & Silva, M. J. J. (2015) Comparative chromosome painting in six species of Oligoryzomys (Rodentia, Sigmodontinae) and the karyotype evolution of the genus. Public Library of Science one, 10 (2), e 0117579. https: // doi. org / 10.1371 / journal. pone. 0117579","Bonvicino, C. R. & Weksler, M. (1998) A new species of Oligoryzomys (Rodentia, Sigmodontinae) from northeastern and central Brazil. Zeitschrift fur Saugetierkunde, 63, 90 - 103."]}

We investigated the patterns of flea infestation in wild populations of eight Sigmodontinae rodent species: Akodon azarae, Calomys callidus, Calomys venustus, Holochilus chacarius, Necromys lasiurus, Oligoryzomys flavescens, Oligoryzomys nigripes and Oxymycterus rufus. Rodents were captured in systematic trapping sessions carried out along 2 years at two localities from El Espinal Ecoregion, Argentina. Mean flea intensity, occurrence (presence/absence) of flea infestation, richness and diversity were compared for different ages, body condition, sex and rodent tribes (Akodontini, Oryzomyini and Phyllotini). A total of 376 fleas of the following species and subspecies were collected: Craneopsylla minerva wolffhuegeli, Polygenis (Neopolygenis) pradoi, Polygenis (Polygenis) axius axius, and Polygenis (Polygenis) byturus. The most important factor driving flea infestation was the rodent tribe, with Phyllotini showing the highest values of occurrence, abundance and species richness. Only C. m. wolffhuegeli was affected by the sex of the host. Age and body condition of the hosts did not affect flea infestation. Our results contribute to knowledge of the ecology of fleas on rodent hosts in El Espinal Ecoregion. The relevance of host taxonomy as driver of flea dynamics highlight the importance of considering host community structures at the time of studying the ecology of parasites.

Livestock is promoting the global collapse of mammal populations. The discovery of the best management practices that reconcile conservation with production is urgently needed. We evaluated the effect of cattle grazing on the occupation of three rodent species (Akodon azarae, Oligoryzomys flavescens and Oxymycterus nasutus). We collected habitat covariates and sampled rodents, using live traps and tracking tunnels, in 20 paddocks subjected to different grazing pressures, from two research stations, across four seasons. We applied single-season occupancy modeling to determine whether rodent detection and occupation varied as a function of the covariates describing sampling occasions and grazing intensity. We ran sensitivity analyses to evaluate the effect of the differential sampling effort we applied across research stations. All species had higher detection probabilities during the winter. O. nasutus showed a higher detection probability under tall vegetation. A. azarae reached a higher occupation probability in ungrazed areas, although it also had a low probability of occupation in highly grazed paddocks. O. flavescens occupation seemed constant across the grazing gradient. O. nasutus reached a higher occupation probability in ungrazed areas. Decreasing stocking rates and maintaining ungrazed areas might compose the best management practices for small mammal conservation in the grasslands of Southern Brazil.

The nominal species Oligoryzomys flavescens (yellow pygmy rice rat) appears in different phylogenetic reconstructions as paraphyletic, forming a complex together with Oligoryzomys fornesi (Fornes' pygmy rice rat) or Oligoryzomys sp. B. To test if O. flavescens includes cryptic species, we used a phylogenetic and a phylogeographic approach to analyze the evolutionary relationships among the lineages of this complex and estimated their geographical distributions using niche modeling analysis. We analyzed a portion of the mitochondrial cytochrome b (Cytb), exon 1 of the Interphotoreceptor Retinoid Binding Protein (Rhp3), and intron 7 of the beta fibrinogen (Fgb) genes and estimated divergence times among lineages using a fossil-calibrated molecular clock. The Cytb phylogenetic tree shows 2 main clades: 1 clustering individuals distributed predominantly in the east of the study area and the other grouping individuals from the west, which would correspond to the subspecies O. f. occidentalis. The eastern clade includes 5 lineages: Oligoryzomys sp. B, O. fornesi, and 3 clades named O. flavescens (O. flavescens Uruguay and southeastern Brazil, O. flavescens eastern Brazil, and O. f. flavescens). The phylogenetic break between these 2 main clades occurred about 0.89 million years ago. These clades were not recovered when nuclear markers were evaluated, revealing incomplete lineage sorting and retention of ancestral polymorphisms. The spatial distributions of the ecological niche of the clades obtained in the Cytb phylogenetic reconstructions were predominantly parapatric; narrow overlapping zones between some of them were detected. Phylogeographic analyses in O. f. flavescens revealed a population expansion about 100,000 years ago, and conformed to an isolation by distance pattern. Our results, together with morphological differences previously described between populations belonging to the east and the samples referable to O. f. occidentalis, suggest that the latter should be recognized as a full species. Fil: Rivera, Paula Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina Fil: González Ittig, Raúl Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina Fil: Robainas Barcia, Aymée. Pierre Fabre Iberica; España Fil: Trimarchi, Laura Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina Fil: Levis, Silvana. Instituto Nacional de Enfermedades Virales Humanas Dr Julio I. Maiztegui; Argentina Fil: Calderon, Gladys. Instituto Nacional de Enfermedades Virales Humanas Dr Julio I. Maiztegui; Argentina Fil: Gardenal, Cristina Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina

Los roedores sigmodontinos (Cricetidae, Sigmodontinae) pueden transmitir a las personas el virus causante del Síndrome Pulmonar por Hantavirus (SPH). Con el objetivo de evaluar las asociaciones entre la abundancia, movimientos y prevalencia de infección contra hantavirus de la comunidad de roedores sigmodontinos con la dinámica ambiental de las islas del Predelta del río Paraná (Entre Ríos y Santa Fe), se estudiaron la abundancia y diversidad de las especies de sigmodontinos; la prevalencia de anticuerpos contra hantavirus en cada una y el uso del espacio del ratón colilargo chico, Oligoryzomys flavescens, reservorio asociado con los casos de SPH en el área de estudio. Se realizaron muestreos estacionales (2014-2017) con trampas de captura viva en siete islas y se capturaron 367 roedores sigmodontinos pertenecientes a siete especies y una especie de marsupial de la familia Didelphidae. Todas las especies estuvieron presentes en las islas pero en distintos momentos, y la recuperación de las poblaciones de roedores después de las inundaciones se dio de modo heterogéneo. Las condiciones hidrológicas y meteorológicas afectaron al éxito de captura de los roedores, y en particular el de O. flavescens fue mayor cuanto más tiempo transcurrió desde la última inundación del río Paraná, y menor cuanto mayores fueron las temperaturas máximas del mes anterior. Con el objetivo de determinar si hubo presencia de roedores sigmodontinos en un momento puntual en la ciudad de Diamante, el estudio con trampas de captura viva detectó la presencia de especies comensales como Mus musculus (32), Rattus rattus (2) y R. norvegicus (1) y silvestres como Oxymycterus rufus (1) y el marsupial Didelphis albiventris (1). Las especies que presentaron anticuerpos para hantavirus fueron O. flavescens y O. rufus (que hasta el momento no se considera reservorio de SPH), mostrando seroprevalencias máximas del 50% (1 infectado/2 testeados) y del 22% (2 infectados/9 testeados) en verano de 2018, respectivamente. El área de acción de los O. flavescens osciló entre 680,4 m2 y 1,82 hectáreas (con un gran solapamiento interindividual) y dentro de ésta en el 40% de los trayectos (en promedio) los individuos utilizaron la estructura vertical del hábitat, y recorrieron la vegetación ribereña de los arroyos. Los pobladores isleños entrevistados estuvieron altamente expuestos al contacto con roedores en su vida cotidiana pero su conocimiento sobre el SPH fue escaso, demostrando la necesidad de implementar programas de protección de la salud en las islas. Small native rodents (Cricetidae, Sigmodontinae) are reservoirs of the virus that causes Hantavirus Pulmonary Syndrome (HPS) in humans. In order to evaluate the associations between the abundance, movements and prevalence of infection against hantavirus of the community of sigmodontinae rodents with the environmental dynamics of the Predelta islands of the Paraná River (Entre Ríos and Santa Fe), we studied the abundance and diversity of sigmodontine species; the prevalence hantavirus antibodies in each one and the use of the space of the Yellow Pigmy Rice Rat, Oligoryzomys flavescens, reservoir associated with cases of HPS in the study area. Seasonal surveys (2014-2018) were conducted with live traps on seven islands and 367 sigmodontinae rodents belonging to seven species and one marsupial species of the Didelphidae family were captured. All species were present on the islands but at different times, and the recovery of rodent populations after the floods also was heterogeneous. Rodent trap success was affected by hydrological and meteorological conditions. The time elapsed since the last flood of the Paraná River influenced the variations in the trap success of O. flavescens, while higher maximum temperatures were associated with lower trap success a month later. The presence of sigmodontinae rodents in the city of Diamante was also evaluated, and the study with live traps detected the presence of commensal species such as Mus musculus (32), Rattus rattus (2) and R. norvegicus (1) and wild species such as Oxymycterus rufus (1) and the white-eared opossum Didelphis albiventris (1). Hantavirus antibodies were found in O. flavescens and O. rufus (which is not considered an HPS reservoir), showing maximum seroprevalences of 50% (1 infected/2 tested) and 22% (2 infected/9 tested) in summer 2018, respectively. The home range of O. flavescens was between 680,4 m2 and 1,82 hectares (with high overlapping between individuals) and within this in 40% of the paths (on average) individuals used the vertical structure of the habitat, and also use the riparian vegetation of the streams. Interviews with people who live in the islands showed that they are a population highly exposed to rodents, but the knowledge about HPS was scarce, which demonstrates the need to implement health protection programs in the islands. Fil: Maroli, Malena. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

To identify and predict situations of increased risk of orthohantavirus infection in humans, it is necessary to study the relationships between the virus and its rodent hosts. The present study investigated orthohantavirus infection in an assemblage of wild Sigmodontinae rodents of the Paraná Delta, Argentina, and providing new evidence of host-switching events. Rodents belonging to the species Oxymycterus rufus (n=187), Akodon azarae (n=82), Oligoryzomys flavescens (n=80), Oligoryzomys nigripes (n=47), Scapteromys aquaticus (n=38), Deltamys kempi (n=7) and Holochilus brasiliensis (n=2) were captured at 4 sampling sites during 20 trapping sessions. Blood sampleswere analyzed by IgG ELISA and livers by a nested reverse transcription PCR for the diagnosis of orthohantavirus infection. The amplified products of the S and M orthohantavirus genomes were sequenced and analyzed to determine similarities with species of the Orthohantavirus genus. The species of the Oligoryzomys positive to the virus were confirmed by amplifying and sequencing thecomplete cyt b gene. Of the 443 serum samples analyzed by IgG ELISA, A. azarae presented the highest host-specific prevalence value (10/82, 12.2%) followed by Ol. nigripes (4/47, 8.5 %) and Ox. rufus (1/187, 0.5%). All the sero-positive Ol. nigripes (n= 4) were positive to the amplification of the S and M segments of the Lechiguanas genotype (98% nucleotide identity for both segments).This is surprising given that Ol. nigripes has been previously associated with Juquitiba genotype, not Lechiguanas. The latter is generally associated with Ol. flavescens, which in our study were all sero-negative. In addition, the association Ox. rufus ? Pergamino genotype found here is, to ourknowledge, novel and another potential evidence of host-switching considering that Pergamino has been originally associated with A. azarae. These findings contribute to the building evidence that contradicts the one-genotype-one-reservoir species premise in the association betweenrodent reservoirs and orthohantaviruses, and supports the hypothesis that the community structure of sympatric host species may contribute to orthohantavirus dynamics. Fil: Colombo, Valeria Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Santa Fe. Instituto de Ciencias Veterinarias del Litoral; Argentina. Laboratorio de Ecología de Enfermedades; Argentina Fil: Brignone, Juan Jeronimo. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud "Dr. C. G. Malbrán"; Argentina Fil: Sen, Carina. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud "Dr. C. G. Malbrán"; Argentina Fil: Previtali, Maria Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Martin, María Laura. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud "Dr. C. G. Malbrán"; Argentina Fil: Levis, Silvana del Carmen. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud "Dr. C. G. Malbrán"; Argentina Fil: Monje, Lucas Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Santa Fe. Instituto de Ciencias Veterinarias del Litoral; Argentina. Laboratorio de Ecología de Enfermedades; Argentina Fil: González Ittig, Raúl Enrique. Universidad Nacional del Litoral. Facultad de Humanidades y Ciencias; Argentina Fil: Beldomenico, Pablo Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Santa Fe. Instituto de Ciencias Veterinarias del Litoral; Argentina. Laboratorio de Ecología de Enfermedades; Argentina

Green spaces in urban areas can play a key role in protecting wildlife. However, the presence of wildlife in urban areas can lead to human health risks. Although the presence of the rodent species Oligoryzomys flavescens (hantavirus reservoir) has been recorded in cities of Argentina, its population dynamics in this type of habitat is still unknown. Here, we evaluated: (1) long-term spatial and temporal patterns of O. flavescens abundance and how these patterns were influenced by weather factors and (2) the seroprevalence of hantavirus and the identity of the viral lineage circulating in the population that inhabits the Costanera Sur Ecological Reserve, a protected area in the city of Buenos Aires. Genetic results confirmed that the pathogenic ANDES Central Lechiguanas virus is present in O. flavescens populations inhabiting this urban reserve. Abundance of O. flavescens showed interannual and seasonal fluctuations, with maximum values in winter and spring and minimum ones in summer and autumn. Summers with the highest abundances of O. flavescens were preceded by warmer winters, while winters with lower abundances were preceded by warmer summers. On the other hand, accumulated precipitations in the previous 6 months positively affected winter abundance. These results could help the authorities in charge of the green spaces of Buenos Aires to identify priority areas and times of the year for the implementation of preventive measures that minimize the contact of rodents with visitors. Such measures could be intensified when winters are warmer than normal, and summers are cooler and wetter than normal. Fil: Muschetto, Emiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentina Fil: Cueto, Gerardo Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentina Fil: Cavia, Regino. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentina Fil: Padula, Paula Julieta. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Suarez, Olga Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentina

The presence of small terrestrial mammals along the commercial cycle of Eucalyptus plantations indicates that silvicultural landscapes can be considered as their habitat. In the present study we evaluated the temporal variation of small terrestrial mammals for more than 10 generations during the first commercial cycle of Eucalyptus in Southeast Brazil. During this period we carried out forty-four monthly campaigns, totaling 10,560 bucket.nights in pitfall traps. Thirteen species (four marsupials and nine rodents) were collected in the Eucalyptus plantations, seven of which (Akodon montensis, Calomys tener, Cryptonanus agricolai, Gracilinanus microtarsus, Necromys lasiurus, Oligoryzomys flavescens, and Oligoryzomys nigripes) persisted for the entire study period. In general, they have an explosive population growth during the first two years of collection followed by a decline in all environments, and an apparent regrowth trend in the fourth year for some species with a trend in dominant species from Cerrado to forest dwellers. Marsupials exhibited a similar trend, but slower and later. The spatio-temporal patterns of variation detected in this study strongly suggest that for most of the remaining species of small rodents and marsupials, silvicultural landscapes have distinct habitats including the Eucalyptus plantations. This means that they should be evaluated in terms of its habitat quality not only its permeability. The perception of the Eucalyptus plantations as habitat should stimulate the development of wildlife-friendly management techniques, which improve their carrying capacity, food web complexity and biological diversity without compromising their primeval mission of biological production. Fil: Verdade, Luciano Martins. Universidade de Sao Paulo; Brasil Fil: Moral, Rafael de Andrade. Universidade de Sao Paulo; Brasil Fil: Calaboni, Adriane. Universidade de Sao Paulo; Brasil Fil: do Amaral, Marcus V. S. G.. Maynooth University; Irlanda Fil: Martin, Paula S.. Itaiti Consultoria Ambiental; Brasil Fil: Amorim, Luana S.. Universidade de Sao Paulo; Brasil Fil: Gheler Costa, Carla. Ecologia Aplicada: Pesquisa, Ensino e Serviços Ambientais; Brasil Fil: Piña, Carlos Ignacio. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; Argentina

From May to September 2011, a total of 138 wild rodents of the Cricetidae family were collected in the cities of Anhembi, Bofete and Torre de Pedra, in São Paulo State. All animals were examined for the presence of ticks, which were collected and identified at species level in the laboratory by morphological examination (for adults, nymphs and larvae) and molecular biology, by sequencing of a fragment of the 16S mitochondrial rDNA (for larvae). A total of 47 ticks (21 larvae and 26 nymphs) were collected from rodents, identified as 21 larvae and 23 nymphs of Amblyomma ovale (collected on Oligoryzomys nigripes , Oligoryzomys flavescens , Sooretamys agouya and Nectomys squamipes ), two nymphs of Ixodes schulzei (O. nigripes and O. flavescens ) and an Amblyomma sculptum nymph in S. agouya . The overall prevalence of parasitism by A. ovale was 4.3% for larvae, and 10.1% for nymphs. The mean intensity of parasitism was 3.5 larvae/parasitized animal, and 1.6 nymphs/parasitized animal. One O. nigripes was found parasitized by both larva and nymph of A. ovale , and another O. nigripes was parasitized simultaneously by an I. schulzei nymph and five A. ovale nymphs. This research reports the following unpublished records: A. ovale on O. flavescens , O. nigripes and S. agouya ; A. sculptum on S. agouya ; and I. schulzei on O. flavescens and O. nigripes . RESUMO: De maio a setembro de 2011, um total de 138 roedores silvestres da família Cricetidae foram coletados nos municípios de Anhembi, Bofete e Torre de Pedra, no estado de São Paulo. Todos os animais foram examinados quanto à presença de carrapatos, os quais foram coletados e identificados ao nível de espécie em laboratório, através de análises morfológicas (para adultos, ninfas e larvas) e por biologia molecular para confirmar estas análises, através do sequenciamento de um fragmento do gene 16S rDNA mitocondrial (para uma parte das larvas). Um total de 47 carrapatos (21 larvas e 26 ninfas) foi coletado dos roedores, sendo identificados como 21 larvas e 23 ninfas de Amblyomma ovale (coletados sobre Oligoryzomys nigripes, Oligoryzomys flavescens, Sooretamys agouya e Nectomys squamipes ), duas ninfas de Ixodes schulzei (em O. nigripes e O. flavescens ) e uma ninfa de Amblyomma sculptum em S. agouya. A prevalência geral de parasitismo por A. ovale foi de 4,3% e de 10,1% para larvas e ninfas, respectivamente. As intensidades médias de parasitismo foram de 3,5 larvas/animal parasitado e de 1,6 ninfas/animal parasitado. Um O. nigripes foi encontrado parasitado simultaneamente por larva e ninfa de A. ovale , e outro O. nigripes estava parasitado simultaneamente por uma ninfa de I. schulzei e cinco ninfas de A. ovale . O presente trabalho reporta os seguintes registros inéditos: A. ovale em O. flavescens, O. nigripes e S. agouya; A. sculptum em S. agouya; e I. schulzei em O. flavescens e O. nigripes.

Abstract ContextPig production is increasing in developing countries and is increasing the coexistence of different production systems regarding management practices. Small mammals can cause major economic and sanitary problems on pig farms. The interactions among small mammals, production practices and habitat complexity have been sparsely studied. AimsThe aim was to compare small-mammal assemblages on extensive and intensive pig-production systems, and to analyse the relationship with environmental characteristics and management practices. MethodsSeasonal live-trapping of small mammals within 18 farms (under intensive or extensive management) was performed in central Argentina, simultaneously with a survey of environmental and management practices. Multiple regression analyses were performed to assess the relation between infestation levels and environmental characteristics. Key results In total, 472 small mammals were captured, including the exotic murids Rattus norvegicus, R. rattus and Mus musculus, three native sigmodontines, namely, Akodon azarae, Oligoryzomys flavescens and Oxymycterus rufus, and two native marsupials, namely, Didelphis albiventris and Lutreolina crassicaudata. The location of waste deposits, the density of cats, the frequency of rodent control and the way pig food was stored influenced wild small-mammal abundance; exotic rodent species were lower when the density of cats increased. Rattus norvegicus was more abundant where rodent control was not frequent or null, contrary to M. musculus. Both species were more abundant in food and pig sheds, whereas native species were associated with vegetated areas outside of sheds. Also, A. azarae was associated with the density of pigs. Didelphis albiventris was more abundant on extensive farms, whereas L. crassicaudata was captured on intensive farms. Conclusions Small-mammal abundance did not respond to the type of production system per se, but exotic species abundance was influenced by management decisions. The most important human behaviours related to exotic rodent infestation were the possession of cats, the frequency of rodent control and the way waste and pig feed were managed. Implications Our findings highlighted the need for integrated studies on factors influencing the dynamics of rodent populations in commercial piggery systems, for the development of effective pest management. Management recommendations need to assess environmental complexity and human behaviour as important moderators of the population dynamics of small mammal species in and around piggeries.

Calodium hepaticum (Nematoda; Capillariidae) is a parasitic nematode of mammals with a cosmopolitan distribution. Adults of this nematode can infect the liver of many mammalian species, including humans, but the main hosts are members of the superfamily Muroidea. Among these, Rattus spp. have the highest apparent prevalences reported worldwide. There are only two reports of C. hepaticum infecting Sigmodontinae species (Muroidea: Cricetidae). In this survey, we examined the occurrence of C. hepaticum in two assemblages of Sigmodontinae rodents from Argentina (Santa Fe and Entre Rios provinces). The diagnosis was made by morphological features, histopathological exam, and molecular characterization of 18S ribosomal RNA gene region. Here, we show that C. hepaticum is a common parasite of Sigmodontinae. We report the infection in six species (all new hosts): Akodon azarae, Calomys callidus, Calomys venustus, Oligoryzomys flavescens, Oligoryzomys nigripes, and Oxymycterus rufus. This is the first report of C. hepaticum in Sigmodontinae rodents from Argentina and the second record in this subfamily for South America. It is also the first confirmation of C. hepaticum infection in Sigmodontinae by molecular diagnosis. The genetic findings and the prevalences observed, together with the existing information on C. hepaticum, lead us to propose that Rattus spp. brought C. hepaticum to the New World exposing Sigmodontinae rodents, which are frequently infected by this parasite. The high prevalence of infection in A. azarae (41.2%) suggests that this host may be playing an important role in C. hepaticum dynamics in the New World., Centro de Estudios Parasitológicos y de Vectores

Identifying patterns with sufficient predictive power is a constant challenge for ecologists to address ecological problems related to species conservation, pollution or infectious disease control. During the last years, the amounts of parasitological studies in this sense increased, but they are still scarce in urban environments. The main aim of this study was to investigate if the helminth communities of urban rodents are structured within host assembly (compound community) or they are a result of random events occurring at each individual host scale (infracommunity). A total of 203 rodents belonging to four species, Rattus rattus (Linnaeus), Rattus norvegicus (Berkenhout), Mus musculus Linnaeus and the native Oligoryzomys flavescens (Waterhouse) and captured in different landscape units of the City of Buenos Aires (industrial-residential neighbourhoods, shantytowns and parklands) were analysed. The results showed that infracommunities could be grouped according to composition and relative abundances and that they respond to the structure of the host community. Thus, the component communities defined in this study could be identified as subsets of the compound community (rodent assemblage) and infracommunities (each host) as random samples within each one. Quantitative differences among component communities were denoted by comparing the infection levels of helminths described as central species. Therefore, infracommunities of R. norvegicus and O. flavescens were the most predictable because of the high abundance of the nematodes Heterakis spumosa Schneider, 1866 and Nippostrongylus brasiliensis (Travassos, 1914), and Stilestrongylus flavescens (Sutton et Durette-Desset, 1991), respectively. Several mechanisms contribute to complexity of the structure of parasite communities, where specific parasites, definitive and intermediate hosts, and environmental and anthropogenic factors all play a role in the dynamics of the compound community.

The helminth fauna and metacommunity structure of eight sympatric sigmodontine rodents were investigated at the Serra dos Órgãos National Park, an Atlantic Forest reserve located in the State of Rio de Janeiro, southeast Brazil. Rodents of the species Abrawayaomys ruschii, Akodon montensis, Blarinomys breviceps , Delomys dorsalis, Oligoryzomys flavescens, Oligoryzomys nigripes, Oxymycterus quaestor and Thaptomys nigrita were found infected with helminths. Akodon montensis presented the highest total helminth species richness, with six different species of helminths. The nematode Stilestrongylus lanfrediae was the most abundant and prevalent helminth species observed. The host-parasite network analysis showed little interactions among host species. Akodon montensis seems to act as a keystone-species in the rodent community. This species shared the nematodes Stilestrongylus aculeata with A. ruschii and Protospirura numidica criceticola with T. nigrita, and the cestode Rodentolepis akodontis with D. dorsalis. The congeners host species O. flavescens and O. nigripes shared the nematodes Guerrerostrongylus zetta and S. lanfrediae. The rodents B. breviceps and O. quaestor did not share any helminths with other hosts. The helminth metacommunity showed a random pattern on both infracommunity and component community levels, indicating different responses by each helminth species to the environmental gradient. Resumo Foram investigadas a helmintofauna e suas estruturas da metacomunidade em oito roedores sigmodontíneos simpátricos ao longo do Parque Nacional da Serra dos Órgãos, uma reserva de Mata Atlântica no estado do Rio de Janeiro, Brasil. Roedores das espécies Abrawayaomys ruschii, Akodon montensis, Blarinomys breviceps, Delomys dorsalis, Oligoryzomys flavescens, Oligoryzomys nigripes, Oxymycterus quaestor e Thaptomys nigrita foram infectados por helmintos. Akodon montensis apresentou a maior riqueza total de espécies de helmintos, com seis espécies. O nematoide Stilestrongylus lanfrediae foi a espécie de helminto com maior abundância e prevalência. A análise de rede parasito-hospedeiro mostrou poucas interações entre as espécies hospedeiras e A. montensis atuou como uma espécie-chave na comunidade de roedores. Esta espécie compartilhou os nematoides Stilestrongylus aculeata com A. ruschii e Protospirura numidica criceticola com T. nigrita, e o cestoide Rodentolepis akodontis com D. dorsalis. As espécies congêneres O. flavescens e O. nigripes compartilharam os nematoides Guerrerostrongylus zetta e S. lanfrediae. Os roedores B. breviceps e O. quaestor não compartilharam helmintos com outros hospedeiros. A metacomunidade de helmintos mostrou um padrão aleatório em ambos os níveis, comunidade componente e infracomunidade, indicando diferentes respostas de cada espécie de helminto ao gradiente ambiental.

El síndrome pulmonar por hantavirus (SPH) es una enfermedad zoonótica. La principal causa en Argentina es el virus Andes. Oligoryzomys flavescens (Sigmodontinae) uno de los reservorios de SPH. El objetivo de esta investigación fue estimar la seroprevalencia de hantavirus en O. flavescens en la Ciudad de Buenos Aires. Se colocaron trampas de captura viva en tres parques y una reserva ecológica de la Ciudad para detectar individuos con diagnóstico positivo para virus Andes. Se capturaron un total de 286 roedores, O. flavescens fue la especie más capturada (49,65%). Se encontró serología positiva para virus Andes (genotipo Lechiguana) en ejemplares capturados en uno de los sitios en estudio (seroprevalencia = 6,62%) si bien encontramos al hospedador en otros dos parques de la Ciudad. El presente estudio confirma la presencia de roedores infectados con el virus Andes en la Ciudad de Buenos Aires, lo que implica un riesgo de transmisión en un ambiente urbano Hantavirus pulmonary syndrome (HPS) is a zoonotic disease. The main cause in Argentina is Andes virus. Oligoryzomys flavescens (Sigmodontinae) was identify as one of the HPS reservoir. The objective of this research was to estimate the seroprevalence of hantavirus in O. flavescens in Buenos Aires City. We set rodents live trapping in three parklands and one ecological reserve in Buenos Aires City in order to screen hantavirus Andes infected rodents. A total of 286 rodents were captured, O. flavescens was the most frequently captured species (49.65%). Positive serology for Andes virus (Lechiguanas genotype) was found in O. flavescens in one site studied (seroprevalence = 6.62%) and we found the host in other two parks within the City. The present study confirms the presence of rodents infected with Andes virus in Buenos Aires City, which implies transmission risk in an urban environment.

Abundance, distribution, movement patterns, and habitat selection of a reservoir species influence the dispersal of zoonotic pathogens, and hence, the risk for humans. Movements and microhabitat use of rodent species, and their potential role in the transmission of hantavirus were studied in Otamendi Natural Reserve, Buenos Aires, Argentina. Movement estimators and qualitative characteristics of rodent paths were determined by means of a spool and line device method. Sampling was conducted during November and December 2011, and March, April, June, October, and December 2012. Forty-six Oxymycterus rufus, 41 Akodon azarae, 10 Scapteromys aquaticus and 5 Oligoryzomys flavescens were captured. Movement patterns and distances varied according to sex, habitat type, reproductive season, and body size among species. O. flavescens, reservoir of the etiologic agent of hantavirus pulmonary syndrome in the region, moved short distances, had the most linear paths and did not share paths with other species. A. azarae had an intermediate linearity index, its movements were longer in the highland grassland than in the lowland marsh and the salty grassland, and larger individuals traveled longer distances. O. rufus had the most tortuous paths and the males moved more during the non-breeding season. S. aquaticus movements were associated with habitat type with longer distances traveled in the lowland marsh than in the salty grassland. Hantavirus antibodies were detected in 20% of A.azarae and were not detected in any other species. Seropositive individuals were captured during the breeding season and 85% of them were males. A. azarae moved randomly and shared paths with all the other species, which could promote hantavirus spillover events. Fil: Maroli, Malena. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; Argentina Fil: Vadell, María Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentina Fil: Iglesias, Ayelén Aluminé. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: Padula, Paula Julieta. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: Gomez Villafañe, Isabel Elisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentina

446. Yellow Pygmy Rice Rat Oligoryzomys flavescens French: Colilargo doré / German: Gelbe Zwergreisratte / Spanish: Rata arrocera pigmea dorada Other common names: Flavescent Colilargo Taxonomy. Mus flavescens Waterhouse, 1837, “Maldonado,” Maldonado, UruBUY. Genetic data suggests that O. flavescens may be a composite of at least two, if not three, species. At least two forms, both with type localities in Argentina, occidentalis and antoniae, are available for binomial or trinomial classifications. Monotypic. Distribution. E & S Brazil, extreme SC Bolivia (Tarija Department), Paraguay, N & C Argentina, and Uruguay. Descriptive notes. Head—body 81-93 mm, tail 97-130 mm, ear 15-16 mm, hindfoot 22-24 mm; weight 15-21 g. The Yellow Pygmy Rice Rat is a small species, characterized by bright brownish orange dorsum, finely intermixed with dark hair; sides are brighter orange. Skull has long incisive foramina that usually reach M' and short mesopterygoid fossa that does not reach M*. Habitat. Pampas, Chaco, Atlantic Forest (pristine and second-growth communities), and gallery forests in Cerrado near limits with Atlantic Forest. The Yellow Pygmy Rice Rat is also found along cropland borders in Argentina, Uruguay, and southern Brazil. It was captured at sites with low dry shrub cover and high green grass cover. In Argentina, it is rarely trapped in forests, replaced there by the Black-footed Pygmy Rice Rat (O. nigripes) or the Chacoan Pygmy Rice Rat (O. chacoensis). Food and Feeding. The Yellow Pygmy Rice Rat is omnivorous, with proportions of food items varying seasonally. Breeding. Reproduction of the Yellow Pygmy Rice Rat occurs from spring to autumn. Litters have 3-7 young (average five). Activity patterns. The Yellow Pygmy Rice Rat is nocturnal and manily terrestrial; strong ability to climb has been reported. Movements, Home range and Social organization. In a study in central Argentina, the Yellow Pygmy Rice Rat was the only species (of four) that did not overlap or cross paths with conspecifics or individuals from other species. Population explosions have been reported in relation to flowering of bamboo (Merostachys skvortzovii, Poaceae) in Brazil, but little demographic change was associated with harvesting or plowing. Nevertheless, social organization appears to change after harvesting because most adult males disappeared, presumably due to increased emigration or mortality. Status and Conservation. Classified as Least Concern on The IUCN Red List. The Yellow Pygmy Rice Rat has a broad distribution and presumably large and stable populations. Bibliography. Bilenca et al. (1995), Bonaventura et al. (2003), Busch & Kravetz (1992, 1993), Busch et al. (1997), Calderén et al. (1999), Canepuccia et al. (2008), Cantoni et al. (2001), Carballido et al. (2011), Cavia et al. (2009), Cittadino et al. (1997), Coda et al. (2015), Contreras & Rosi (1980), Courtalon & Busch (2010), Crespo (1966), Ellis, Mills, Childs et al. (1997), Ellis, Mills, Glass et al. (1998), Ellis, Mills, Kennedy et al. (1994), Fernandez et al. (2012), Fornes & Massoia (1965), Gomez et al. (2012), Gonzalez et al. (2012), Jayat, Ortiz & Miotti (2008), Kufner et al. (2004), Langguth (1963), Lareschi (1996), Maroli et al. (2015), Massoia (1983), Mills, Alva et al. (2007), Mills, Barrera et al. (1996), Mills, Ellis, McKee, Ksiazek et al. (1991), Mills, Ellis, McKee, Maiztegui & Childs (1991, 1992), Mills, Schmidt et al. (2007), Mino, Cavia, Gémez, Bilenca & Busch (2007), Mino, Cavia, Gobmez, Bilenca, Cittadino & Busch (2001), Palma et al. (2012), Polop (1989), Reig (1965), Rosario et al. (2015), Vadell & Gomez (2016), Vadell et al. (2011), de Villafane, Bonaventura et al. (1988), de Villafane, Merler et al. (1992), Weksler & Bonvicino (2015b), Weksler, Bonvicino, D’Elia et al. (2016)., Published as part of Don E. Wilson, Russell A. Mittermeier & Thomas E. Lacher, Jr, 2017, Cricetidae, pp. 204-535 in Handbook of the Mammals of the World – Volume 7 Rodents II, Barcelona :Lynx Edicions on page 437, DOI: 10.5281/zenodo.6707142

Background Understanding the ecological processes that are involved in the transmission of zoonotic pathogens by small mammals may aid adequate and effective management measures. Few attempts have been made to analyze the ecological aspects that influence pathogen infection in small mammals in livestock production systems. We describe the infection of small mammals with Leptospira spp., Brucella spp., Trichinella spp. and Cysticercus fasciolaris and assess the related intrinsic and extrinsic factors in livestock production systems in central Argentina at the small mammal community, population and individual levels. Methodology/Principal findings Ten pig farms and eight dairy farms were studied by removal trapping of small mammals from 2008 to 2011. Each farm was sampled seasonally over the course of one year with cage and Sherman live traps. The 505 small mammals captured (14,359 trap-nights) included three introduced murine rodents, four native rodents and two opossums. Leptospira spp., anti-Brucella spp. antibodies and Trichinella spp. were found in the three murine rodents and both opossums. Rattus norvegicus was also infected with C. fasciolaris; Akodon azarae and Oligoryzomys flavescens with Leptospira spp.; anti-Brucella spp. antibodies were found in A. azarae. Two or more pathogens occurred simultaneously on 89% of the farms, and each pathogen was found on at least 50% of the farms. Pathogen infections increased with host abundance. Infection by Leptospira spp. also increased with precipitation and during warm seasons. The occurrence of anti-Brucella spp. antibodies was higher on dairy farms and during the winter and summer. The host abundances limit values, from which farms are expected to be free of the studied pathogens, are reported. Conclusions/Significance Murine rodents maintain pathogens within farms, whereas other native species are likely dispersing pathogens among farms. Hence, we recommend preventing and controlling murines in farm dwellings and isolating farms from their surroundings to avoid contact with other wild mammals., Author summary Some rodents and opossums can transmit zoonotic diseases, thereby causing economic losses and sanitary problems, including damage to livestock production systems worldwide. Identifying the factors affecting pathogen transmission will contribute to a better understanding of the mechanisms involved. In this study, the infection of four zoonotic pathogens in small mammals captured on intensive pig and dairy farms in central Argentina and potential environmental drivers of those infections were studied. Seven rodent and two opossum species were trapped on these farms. Murine rodents and opossums were infected with Leptospira spp. and Trichinella spp. and carried anti-Brucella spp. antibodies. Rattus norvegicus was also infected with C. fasciolaris, and some native rodents were infected with some of the studied pathogens. Each pathogen occurred on at least 50% of the farms, and two or more pathogens occurred on 89% of the farms. These results reflect a high circulation of zoonotic pathogens relevant to public health on intensive livestock farms. Moreover, all pathogen infections increased with host abundances. Murine rodents maintain pathogens within farms, whereas other native species are likely dispersing pathogens among farms.

Laelaps schatzi sp. nov. (Mesostigmata: Laelapidae) is described on the bases of mites collected from the sigmodontine Oligoryzomys flavescens Waterhouse, 1837 (Rodentia: Cricetidae) in Pereyra, Buenos Aires, Argentina, based on morphological, morphometric and molecular data. Two DNA fragments, mtDNA cytochrome oxidase subunit I (COI) and nuclear 18.S-ITS1-5.8S-ITS2 partial gene sequence were deposited in the public Genbank datebase. The DNA extraction was conducted nondestructively using Chelex®100 modified for this study, to prevent vouchers for further microscopically examination. Laelaps schatzi sp. nov. is similar in general appearance to Laelaps paulistanensis Fonseca, 1936 and Laelaps fonsecai Gettinger, 1992, but the new species is unique in presenting a reticulated surface pattern on the genital shield from level of Zv1 up to posterior margin, and in the presence of one or two additional impair seta/e between J4 setae of dorsal shield. Also, the phylogenetic analyses separate the new species from all other species available in the GenBank of Laelaps. Fil: Savchenko, Ekaterina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; Argentina Fil: Lareschi, Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; Argentina

The main objective of this study was to determine the taxonomic and taphonomic characteristics of the micromammal remains recovered from pellets of Pseudoscops clamator (striped owl), collected at three localities in northeastern Buenos Aires Province, Argentina (Punta Lara Natural Reserve, 34°49'02,6''S, 58°03'03,9''W; Costanera Sur Ecological Reserve, 34°36'6,44" S, 58°21'33,22" W; Los Robles Park, 34°40'22,03''S, 58°52'18,88''W). The main taphonomic variables (e.g. evidence of digestive action, breakage patterns and relative abundance of skeletal elements) suggest that this owl mainly produces intermediate to moderate modification. On the other hand, P. clamator preyed mainly upon large-sized (>150 g) micromammals (e.g. Lutreolina crassicaudata, Cavia aperea, Holochilus brasiliensis and Rattus sp.), and to a lesser degree on medium- (50–150 g) and small-sized species (

As matas de restinga representam formações vegetais originais na Planície Costeira do estado do Rio Grande do Sul. O objetivo deste trabalho foi avaliar a composição de espécies de pequenos mamíferos não-voadores em dois fragmentos de matas de restinga (mata palustre e mata arenosa ciliar) no município de Rio Grande, região sul da Planície Costeira do Rio Grande do Sul. Um total de 234 indivíduos pertencentes a três espécies de marsupiais (Didelphidae: Cryptonanus guahybae, Didelphis albiventris, Lutreolina crassicaudata) e oito espécies de roedores (Cricetidae: Deltamys kempi, Holochilus brasiliensis, Oligoryzomys flavescens, O. nigripes, Oxymycterus nasutus, Scapteromys tumidus; Muridae: Mus musculus, Rattus rattus) foi capturado. As espécies C. guahybae, D. albiventris, D. kempi, H. brasiliensis, O. nigripes, S. tumidus e M. musculus foram registradas no fragmento de mata palustre, enquanto que C. guahybae, D. albiventris, Lutreolina crassicaudata, D. kempi, O. flavescens, O. nigripes, S. tumidus e R. rattus ocorreram no fragmento de mata arenosa ciliar. Oligoryzomys nigripes e S. tumidus foram as espécies mais abundantes no fragmento de mata palustre, representando respectivamente 40,4 e 22,1% do total de indivíduos capturados. No fragmento de mata arenosa ciliar, as espécies mais abundantes foram O. nigripes e D. albiventris, representando respectivamente 63,4 e 12,4% do total de indivíduos capturados. Indivíduos de C. guahybae e O. nigripes foram capturados em estrato arbóreo(alturas entre 0,50 e 1,65 m) enquanto que todos os indivíduos das demais espécies foram capturados no solo. The restinga forests represent original vegetal formations in Coastal Plain of Rio Grande do Sul state. This work aimed to evaluate the species composition of non-volant small mammals in two restinga forests (peat forest and sandy riparian forest) in Rio Grande, Southern Rio Grande do Sul Coastal Plain. A total of 234 individuals belonging to three species of marsupials (Didelphidae: Cryptonanus guahybae, Didelphis albiventris, Lutreolina crassicaudata) and eight species of rodents (Cricetidae: Deltamys kempi, Holochilus brasiliensis, Oligoryzomys flavescens, O. nigripes, Oxymycterus nasutus, Scapteromys tumidus; Muridae: Mus musculus, Rattus rattus) was captured. The species C. guahybae, D. albiventris, D. kempi, H. brasiliensis, O. nigripes, S. tumidus and M. musculus were recorded in the peat forest while C. guahybae, D. albiventris, Lutreolina crassicaudata, D. kempi, O. flavescens, O. nigripes, S. tumidus and R. rattus occurred in the riparian sandy forest. Oligoryzomys nigripes and S. tumidus were the most abundant species in the peat forest, representing 40.4 and 22.1% of the total of captured individuals, respectively. The most abundant species in the riparian sandy forest were O. nigripes e D. albiventris, representing 63.4 and 12.4% of the total of captured individuals. Individuals of C. guahybae and O. nigripes were captured on trees (heights between 0.50 and 1.65 m) while all individuals of the remaining species were captured on the ground.

The seasonal dynamics and host usage of Amblyomma triste in Argentina were analyzed. Adults of A. triste were present from early winter to mid-summer, with the peak of abundance from late winter to mid-spring (August to October). Larvae and nymphs were found from December to June, with the peak of abundance in summer. There were no differences among the biological parameters (pre-moult period of larvae and nymphs, pre-oviposition period of females, and minimum incubation period of eggs) of engorged ticks exposed to different photoperiod regimens at the laboratory, but the periods for each biological parameter obtained from ticks exposed in the field were significantly longer than those from the laboratory. Field results fit better with the data of seasonal distribution of each stage. Morphogenetic diapause was not detected, but complementary studies should test the presence of behavioral diapause. Rodents of the subfamily Sigmodontinae (Akodon azarae, Oligoryzomys flavescens, Oligoryzomys nigripes, Oxymycterus rufus and Scapteromys aquaticus) are the principal hosts for immature stages of A. triste, the caviid Cavia aperea could be another potential host for these stages, and birds are exceptional hosts for larvae and nymphs. Regarding hosts of adults in Argentina, domestic and wild large-sized mammals belonging to different orders (cattle, dog, horse, Blastocerus dichotomus and Hydrochoerus hydrochaeris) serve as hosts for adults of this tick species. In conclusion, A. triste has a life cycle of 1 year with adults feeding on large endemic and introduced mammals and immature stages using sigmodontine and caviid rodents as hosts.

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

Grazing and fire, used in pasture regeneration practices, are inter-related activities in livestock management. Both activities affect habitat characteristics by changing the structure of the herbaceous and shrubby vegetation, reducing their biomass and litter cover. This study evaluated the effect of fire and livestock grazing on the assemblage of non-flying small mammals in grassland-Araucaria forest ecotones in southern Brazil. We compared four areas frequently affected by livestock management with four protected areas. Surveys were carried out in four sampling periods, one in each season of 2004. We captured a total of 325 individuals from 12 species of rodents - Akodon montensis Thomas, 1913, Akodon paranaensis Christoff, Fagundes, Sbalqueiro, Mattevi e Yonenaga-Yassuda, 2000, Akodon sp. 1, Akodon sp. 2 (2n = 34), Brucepattersonius iheringi (Thomas, 1896), Delomys dorsalis (Hensel, 1872), Oligoryzomys flavescens (Waterhouse, 1837), Oligoryzomys nigripes (Olfers, 1818), Oxymycterus nasutus (Waterhouse, 1837), Scapteromys sp. (2n = 34), Sooretamys angouya (Fischer, 1814) and Thaptomys nigrita (Lichtenstein, 1829) - and two species of marsupials - Monodelphis dimidiata (Wagner, 1847) and Philander frenatus (Olfers, 1818) -, in a total effective effort of 5254 traps.day-1. The abundance, biomass and diversity of non-flying small mammals were significantly higher in the protected areas than in those affected by fire and livestock grazing. Species strictly associated with grassland habitats were not found in the impacted area. These results indicate that the presence of herds of domestic ungulates negatively affect the assemblage of non-flying small mammals in grassland and Araucaria forest areas in southern Brazil.

We analyzed the relation between rodent communities composition and diversity and the landscape structure in the city of Buenos Aires. Between October 2002 and December 2005 rodent samplings were conducted in a natural reserve, three parklands, three shantytowns and two industrial–residential neighborhoods. Landscape structure at each site was characterized by the proportion of the surface occupied by different land-cover types, and the proportion covered by buildings. We caught 413 rodents of the following species: the native Oligoryzomys flavescens, Deltamys kempi, Calomys musculinus and Cavia aperea; and the introduced Rattus norvegicus, R. rattus and Mus musculus. Native species were dominant in the natural reserve but were also present in parklands. R. rattus, R. norvegicus and/or M. musculus were the dominant species in parklands, shantytowns or industrial–residential neighborhoods. Differences in landscape structure contributed to explain differences in community composition. Diversity, richness and representation of native species decreased with increasing urbanization. Our findings may be useful for planning decisions for either conservation or pest control goals, based on the rodent community composition inferred from the landscape structure.

The role of positive and indirect interactions is often crucial in communities with intense abiotic stress such as salt marshes. The burrowing crab, Neohelice (=Chasmagnathus) granulata, is the dominant benthic macroinvertebrate of southwest Atlantic marshes (southern Brazil to Northern Argentinean Patagonia), having strong direct and indirect effects on marsh soil and, in consequence, on marsh vegetation and primary consumers. In this work, we investigate if this crab indirectly modifies habitat use by the granivorous rodents, Akodon azarae and Oligoryzomys flavescens, by increasing nutrient availability and thus enhancing seed production by the marsh plant Spartina densiflora. The study was conducted at the Mar Chiquita Coastal Lagoon, Argentina (37°32′ S). Rodent frequencies in S. densiflora were positively correlated with crab densities throughout the low and middle marsh. Additionally, the highest quality of S. densiflora and inflorescence density was recorded at the highest crab densities. Experimental manipulation of crab densities shows that N. granulata indirectly enhances the performance of S. densiflora (e.g., decreased fiber content and C/N ratios) and increases density of seeds. Moreover, N. granulata also facilitates S. densiflora seed availability to rodents by concentrating them in sediment mound at their burrows entrances. Experimental rodent exclusions showed that rodent species used S. densiflora seeds, a variable positively related to crab burrow density. Thus, our results show that N. granulata drives the granivorous rodent distribution and the intensity of seeds–rodent interaction trough facilitative and indirect interactions in marsh community.

We established chromosome homology maps between Mus musculus (MMU) and five species of the Akodontini tribe, Akodon cursor (2n = 14, 15 and 16), A. montensis (2n = 24), A. paranaensis (2n = 44), A. serrensis (2n = 46) and Oligoryzomys flavescens (2n = 66) by Zoo-FISH (fluorescence in situ hybridization) using mouse chromosome-specific probes. The aims of this study were (1) to detect the chromosomal rearrangements responsible for the karyotype variation in this tribe and (2) to reconstruct the phylogenetic relationships among these species. We observed four common syntenic associations of homologous chromosome segments, of which the MMU 7/19 has been described previously in other rodents from Africa, Asia and Europe, and might represent a phylogenetic link between the Old World and Neotropical rodents. The remaining three associations (3/18, 6/12 and 8/13) have been observed exclusively in Neotropical rodents so far, which at present can be considered synapomorphic traits of this group. Five further mouse chromosomes (MMU 4, 9, 14, 18 and 19) were each found evolutionarily conserved as a separate syntenic unit. Our phylogenetic analysis using parsimony and heuristic search detected one consistent group, separating the Akodontini from other rodents.