Holochilus Brasiliensis Research Articles

Hippocrepis fuelleborni (Digenea: Notocotylidae) from Argentina, morphological, molecular and phylogenetic studies

Notocotylidae is a family with a cosmopolitan distribution, with 13 genera parasitizing birds and mammals. Four of these genera were registered in the Americas, and two parasitizing rodents in Argentina. In this paper, specimens of the genus Hippocrepis parasitizing Holochilus brasiliensis from Argentina are studied on the basis of morphological and molecular characteristics. Eleven Ho. brasiliensis specimens were collected in seven localities from the Cuenca del Plata region. A total of 192 specimens of digeneans were found in a single Ho. brasiliensis. Conventional morphological and molecular analyses were used. The digenean specimens were identified as Hippocrepis fuelleborni. Furthermore, the molecular characterization of three genetic markers for Hi. fuelleborni is provided. This study contributes to the first record of the genus Hippocrepis in cricetid rodents. The continuity of the studies on this genus and the incorporation of more haplotypes from different genera of Notocotylidae will allow us to recognize the relationship among genera and provide a new systematic proposal.

Small mammals in the diet of Barn Owls (Tyto furcata) in an urban area in Rio de Janeiro state, Brazil, with a new record of the dwarf mouse opossum (Cryptonanus)

Abstract Several studies emphasize the use of owl pellets in small mammal inventories in natural areas harboring high richness of rare species, but few Brazilian Atlantic forest localities have been surveyed by this method. The present study documents the species composition and abundance of small mammals in the diet of Tyto furcata in an urban area of the municipality of Campos dos Goytacazes, Rio de Janeiro, Brazil, remarking on a new record of the dwarf mouse opossum genus Cryptonanus in the Atlantic forest. We analyzed 265 pellets regurgitated by a pair of T. furcata from November 2016 to September 2017 found in a nesting box. Analysis of the samples enabled finding a total of 596 individuals of four small mammal species. Mus musculus was predominant among the prey items (98.3%), while the native rodents Necromys lasiurus (1.3%) and Holochilus brasiliensis (0,17%) were much rarer. A single specimen of Cryptonanus sp. was identified among the diet items based on distinctive dental characters. The identification of this genus in the present study represents the second record in the state of Rio de Janeiro, and the sixth in the Atlantic Forest biome, suggesting that this marsupial occupies a wider ecological and biogeographic range. The present study underscores the relevance of owl pellets for small mammal surveys, even in urban and highly disturbed areas.

Phenotypic and genomic differences between biomes of the South America marsh rat,Holochilus brasiliensis

AbstractAbiotic factors can influence genetic and phenotypic divergence in several ways, and identifying the mechanisms responsible for generating this variation is challenging. However, when evaluated in combination, ecological characteristics and genetic and phenotypic information can help us to understand how habitat preferences can influence morphological and genetic patterns exhibited by taxa distributed between distinct biomes, such as the Atlantic Forest and Pampas biomes in South America. By combining distributional, environmental, phenotypic and genomic information from a habitat-specialist semi-aquatic rodent (Holochilus brasiliensis), we quantified the relationship between ecological niche differences and the phenotypic and genetic variation. The results demonstrate notable segregation among the ecological niches of H. brasiliensis within each biome, although we could not refute the hypothesis of niche similarity or equivalency. Such differences are consistent with a solid morphometric variation associated with the size of these rodents. However, the ecological and morphometric differentiation is not accompanied by the same pattern of genetic variation. Despite differences in the connectivity patterns in both biomes, the genetic differences corroborate a consistent level of migration history between biomes. Additionally, the association tests show that the environment explains a small and non- significant part of the genetic variation but a significant portion of the morphometric variation.

Orthohantavirus genotype Lechiguanas in Oligoryzomys nigripes (Rodentia: Cricetidae): New evidence of host-switching

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 samples were 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 the complete 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 our knowledge, 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 between rodent reservoirs and orthohantaviruses, and supports the hypothesis that the community structure of sympatric host species may contribute to orthohantavirus dynamics.

Ixodes spp. (Acari: Ixodidae) ticks in Rio Grande do Sul state, Brazil

Among the 251 described species of ticks from the genus Ixodes, only eight were previously reported in Brazil, Ixodes amarali, Ixodes aragaoi, Ixodes auritulus, Ixodes fuscipes, Ixodes loricatus, Ixodes luciae, Ixodes paranaensis and Ixodes schulzei. Of those species, I. loricatus is considered commonly found, whereas I. auritulus and I. aragaoi were registered just one time in Rio Grande do Sul (RS) state, Southern Brazil. This paper aims to update the Ixodes species occurring in RS through the investigation of the ixodofauna of small rodents. Data from 314 wild rodents were analyzed from nine municipalities of Pampa biome and five from the Atlantic Rainforest in RS. Rodents belonging to the following species were infested by Ixodes spp. ticks: Akodon azarae, Akodon montensis, Akodon paranaensis, Akodon reigi, Calomys laucha, Delomys dorsalis, Deltamys kempi, Holochilus brasiliensis, Oligoryzomys flavescens, Oligoryzomys nigripes, Oxymycterus nasutus, Scapteromys tumidus (Cricetidae) and Cavia aperea (Caviidae). The tick identification was performed based on morphological dichotomous keys, their updates and by molecular techniques. Considering the ticks from the rodents and those collected directly from the environment, 34 specimens of Ixodes spp. were collected. Our results improved to five the list of Ixodes species that occur in RS: I. loricatus, I. auritulus, I. aragaoi, I. fuscipes and I. longiscutatus. Moreover, the finding of I. longiscutatus increases to nine the number of Ixodes species in Brazil. The occurrence of two species of the Ixodes ricinus complex (I. aragaoi and I. fuscipes) highlights the potential impact of Ixodes spp. ticks on public health.

On the Origin and Evolution of the Extant System of B Chromosomes in Oryzomyini Radiation (Rodentia, Sigmodontinae).

Heterogeneous supernumerary chromosomes (Bs) are recognized in the oryzomyines Holochilus brasiliensis, Nectomys rattus, N. squamipes, Oligoryzomys flavescens and Sooretamys angouya, representing about 10% of all known B-containing rodent species. They provide an outstanding model for understanding the origin, evolution and diversity of Bs in a phylogenetic context. Therefore, whole chromosome-specific probes were generated from flow-sorted Holochilus brasiliensis (HBR) autosomes 11 and 25+26 and chromosomes X, Y and Bs. Hybridizations were performed on male metaphases of 15 Oryzomyini species of which 3 are B-containing species. The results reveal that among the species sampled, 12 of them, belonging to a monophyletic Oryzomiyini subclade, are positive for an anonymous Oryzomyini shared heterochromatic region (OSHR) on both sex chromosomes. The OSHR is also present on Bs of Holochilus brasiliensis, Nectomys rattus and N. squamipes but not on Bs of O. flavescens and S. angouya. Two distinct additional OSHR/autosome associations are observed on S. angouya. The three species that are OSHR negative belong to an outgroup. Molecular dating suggests that the OSHR originated between 7.8 and 3 Mya on ancestral sex chromosomes. A tentative explanation for the OSHR-positive nature of B regions in three species could be that transposable elements (TEs) from this specific sex chromosome region may have invaded existing B chromosomes. The presence of the OSHR on entire Xp and Yp adjacent to interstitial telomeric sequences at pericentromeric positions, as observed in Drymoreomys albimaculatus, show a similar organization as on B chromosomes in Nectomys squamipes. The diversity of the Oryzomyini Bs in number, size, morphology and genetic content may be explained by the independent origin of B chromosomes in different subgroups of species, with Bs in Holochilus brasiliensis, Nectomys squamipes and N. rattus sharing the OSHR with sex chromosomes, and those in Oligoryzomys flavescens and Sooretamys angouya lacking OSHR in Bs. The species-specific pattern of Bs is probably a consequence of their independent evolutionary origin.

Taphonomic Analysis of Micromammal Remains from Striped Owl (Pseudoscops clamator) Pellets in Northeastern Buenos Aires Province, Argentina: Implications for Archaeological Sites Formation

AbstractThe 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 (<50 g) (e.g. Scapteromys aquaticus, Calomys sp., Oligoryzomys flavescens, Akodon azarae and Mus musculus). Fossil assemblages with a dominance of large‐sized micromammals are commonly associated with humans as agents of accumulation. However, this study demonstrates that this owl produces assemblages with abundant large‐sized micromammals, which introduces an equifinality problem. In that sense, digestive corrosion marks, breakage patterns and the relative abundance of skeletal remains are the main attributes to differentiate P. clamator from humans, as agents of accumulation. Finally, our results might serve as an analytical model for the taphonomic interpretation of the fossil record of micromammals from paleontological and archaeological sites, which fall within the distributional range and habitat of P. clamator. Copyright © 2013 John Wiley & Sons, Ltd.

A remarkable autosomal heteromorphism in Pseudoryzomys simplex 2n = 56; FN = 54-55 (Rodentia, Sigmodontinae)

Pseudoryzomys simplex, the false rice rat, is a monotypic genus of the Oryzomyini tribe (Sigmodontinae) distributed in part of Bolivia, Paraguay, Argentina and Brazil. Its diploid number has been described as 56 acrocentric chromosomes decreasing in size and no karyotype figure has been depicted. Herein, we present karyotypic data on P. simplex, including chromosome banding and molecular fluorescent in situ hybridization using telomeric sequences and the whole X-chromosome of its sister clade Holochilus brasiliensis (HBR) as probes. A case of remarkable autosomal heteromorphism due to the presence of a whole heterochromatic arm leading to the variability of FN is reported, as well as the occurrence of regions of homology between the X and Y chromosomes (pseudoautosomal regions) after chromosome painting with the HBR X probe on P. simplex metaphases.

On the presence of Holochilus brasiliensis (Desmarest, 1819) (Rodentia: Cricetidae: Sigmodontinae) in the late Pleistocene of southern Brazil

Fossil remains of the sigmodontine rodent Holochilus brasiliensis (Desmarest, 1819) from two geographic areas from the state of Rio Grande do Sul, southern Brazil are reviewed and described here. The specimens came from two localities: Quarai River in the western region, which has yielded a dentary with an incisor and molars, and Chui Creek in the eastern region, where a fragmented right dentary and a maxillary fragment with molars were collected. The presence of this taxon in the late Pleistocene of meridional Brazil suggests the existence of perennial water bodies. Keywords : mammals, rodents, late Pleistocene, paleoenvironment, Rio Grande do Sul.

Pequenos mamíferos não-voadores (Didelphimorphia, Rodentia) em dois fragmentos de mata de restinga de Rio Grande, planície costeira do Rio Grande do Sul

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.

Small mammals (Didelphimorphia, Rodentia and Chiroptera) from Pampean Region, Argentina

We studied small mammal assemblages recovered from owl pellets collected at 11 locations throughout the Argentina’s Pampean Region. We identified 21 species, including two marsupials, one bat, and 18 rodents. From the analysis of this dataset, we could distinguish three main groups of small mammals that currently inhabit the Pampean Region: 1) a group of taxa related to Pampean agroecosystems (Calomys spp., Akodon azarae, and Oligoryzomys flavescens); 2) a group of Brazilian species (Cavia aperea, Oxymycterus rufus, Necromys lasiurus, Necromys obscurus, Holochilus brasiliensis, and Monodelphis dimidiata); and 3) a group including species from Patagonia, Espinal and Monte phytogeographic provinces (Microcavia australis, Oligoryzomys longicaudatus, Eligmodontia typus, Graomys griseoflavus, and Akodon molinae). In addition, we documented the first record of a species of the large-bodied group of Calomys in Buenos Aires province, expanding its distribution ca. 420 km southward.

Fur mites of the family Listrophoridae (Acariformes: Sarcoptoidea) associated with South American sigmodontine rodents (Cricetidae: Sigmodontinae)

Six species of 3 genera belonging to the fur mite family Listrophoridae were recorded on skins of South American rodents of the cricetid subfamily Sigmodontinae housed in the Bavarian State Collection of Zoology (Munich, Germany). Among them, Amlistrophorus geoxus sp. nov. from Geoxus valdivianus from Chile is described as a new for science, and males of Prolistrophorus amazonicus amazonicus Fain, 1971 are recorded for the first time. The full generic status for the subgenus Amlistrophorus of the genus Prolistrophorus proposed by Fain et al. (1996) is not supported, and Prolistrophorus musculinus Fain, 1973 stat. nov. (formerly a subspecies of P. amazonicus) from Mus musculus (Rodentia: Muridae) from Suriname is raised to species status. New hosts are recorded for the following species: Prolistrophorus argentinus (Hirst, 1921) from Holochilus brasiliensis and H. chacarius from Argentina, P. amazonicus from Calomys callosus from Argentina and Bolivia, C. laucha and C. musculinus from Argentina, P. akodon Fain and Lukoschus, 1982 from Akodon montensis from Argentina, P. nectomys Fain, 1971 from Nectomys palmipes from Peru and Melanomys caliginosus from Panama, and Sclerolistrophorus oxymycteris Fain, 1976 from Oryzomys laticeps from Brazil.

Historia fósil de las ratas palustres de los géneros <i>Holochilus</i> y <i>Lundomys</i> (Cricetidae, Sigmodontinae) en el Cono Sur de América del Sur

Los géneros hermanos Holochilus y Lundomys, junto con las formas extintas Carletonomys y Noronhomys y la viviente Pseudoryzomys, constituyen un pequeño clado de sigmodontinos de hábitos anfibios, que habitan en ambientes tropicales y subtropicales del Neotrópico. Basándonos en la totalidad de la evidencia fósil disponible para Argentina, Bolivia, sudeste de Brasil y Uruguay se revisó el registro paleontológico de Holochilus y Lundomys de la porción austral de América del Sur. Las distribuciones en el pasado y sus cronologías indican las siguientes ocurrencias para el área de estudio: Holochilus brasiliensis (Pleistoceno Medio-Reciente en Argentina, Pleistoceno Tardío-Reciente en Brasil), H. chacarius (Holoceno Tardío-Reciente en Argentina, Holoceno Temprano-Reciente en Bolivia), †H. primigenius (Pleistoceno Medio en Bolivia) y Lundomys molitor (Pleistoceno Medio-Pleistoceno Tardío en Argentina, Pleistoceno Tardío-Reciente en Uruguay). Considerando en conjunto las distribuciones actuales, los requerimientos ambientales de estos taxones y los registros fósiles, se verifican varios episodios de expansión y retracción de sus poblaciones, posiblemente vinculados con pulsos climáticos húmedos y secos alternantes durante el Pleistoceno-Holoceno.

Study of types of some species of “Filaria” (Nematoda) parasites of small mammals described by von Linstow and Molin

Parasitic nematodes from the Berlin (ZMB) and Vienna (NMW) Museum collections referred to the genus Filaria Mueller, 1787 by von Linstow or Molin were studied. Three samples were in good condition and the specimens redescribed. Litomosa hepatica (von Linstow, 1897) n. comb., sample ZMB Vermes Entozoa 3368, from the megachiropteran Pteropus neohibernicus, Bismarck Archipelago, resembles L. maki Tibayrenc, Bain & Ramanchandran, 1979, from Pteropus vampyrus, in Malaysia, but the buccal capsule differs. Both species display particular morphological characters which differ from species of Litomosa parasitic in microchiropterans. The remaining material originates from Brazil. The spicule morphology of Litomosoides circularis (von Linstow, 1899) Chandler, 1931, sample ZMB Vermes Entozoa 1059 from Hesperomys spec. (= Holochilus brasiliensis), Porto Alegre, confirms that it belongs to the sigmodontis group; the microfilaria presents characters of the genus Litomosoides, e.g. body attenuated at both extremities and salient cephalic hook. Taxonomic discussions by others confirm that species of Litomosoides belonging to the sigmodontis group and described subsequently are distinct from L. circularis. Litomosoides serpicula (Molin, 1858) Guerrero, Martin, Gardner & Bain, 2002, is redescribed, sample NMW 6323 from the bat Phyllostoma spiculatum (= Sturnira lilium), Ypanema. It is very close to L. brasiliensis Almeida, 1936, type host Moytis sp., but distinguished by a single ring in the buccal capsule, rather than two, supporting previous conclusions that the taxon L. brasiliensis, as generally regarded, may represent a complex of species. Samples NMW 6322 and NMW 6324, from other bats and also identified by Molin (1858) as Filaria serpicula, contain unidentifiable fragments of Litomosoides incertae sedis. Filaria hyalina von Linstow, 1890, sample ZMB Vermes Entozoa Q 3905 from Sorex vulgaris (= Sorex araneus), is incertae sedis because it contains two unidentifiable posterior parts of male, which might be an acuarid, Stammerinema sp. Filaria vesperuginis von Linstow, 1885, sample ZMB Vermes Entozoa Q 3929, from the bat Vesperugo serotinus (= Eptesicus serotinus), contains encysted nematode larvae and is a nomen dubium.

Small mammal remains recovered from two archaeological sites in the middle and lower Negro River valley (Late Holocene, Argentina): Taphonomic issues and paleoenvironmental implications

This paper presents the results of a taphonomic and paleoenvironmental analysis of small mammal remains recovered from the Negro Muerto and Angostura 1 archaeological sites. These sites (ca. 0.5 and 0.95 ka BP, respectively), are located in the middle and lower Negro River valley in northern Patagonia, Argentina. Based upon the presence of several types of evidence (cut marks, bone tools, and thermal alteration), it is proposed that Holochilus brasiliensis and cavies were acumulated by humans. At the Angostura 1 site, some remains also show evidence of having been generated by carnivores (digestion, breakage patterns, and relative skeletal element abundances). This indicates that carnivores (e.g., Puma concolor) could have contributed to the formation of the small mammal assemblages. Other small mammal species recovered at both sites (e.g., Galea leucoblephara, Microcavia australis, Akodon molinae, and Graomys griseoflavus) suggest semi-desert environmental conditions, similar to those found today. The presence of Reithrodon auritus and Oligoryzomys sp. indicate the development of open herbaceous steppe environments in proximity to bodies of water. However, the discovery of H. brasiliensis at both sites, an orizomyine of amphibious habitats and subtropical origin, and which is now absent in the area, suggests warmer and wetter conditions during this period.

Hair structure of small rodents from central Argentina: A tool for species identification

Mammal hairs differ among species and may therefore be used for diagnoses at the species level. We characterized dorsal guard hairs of most small rodent species that may be found in central Buenos Aires province (Argentina), according to their geographic distribution: Cavia aperea , Rattus rattus , R. norvegicus , Mus musculus , Holochilus brasiliensis , Scapteromys aquaticus , Oxymycterus rufus , Oligoryzomys flavescens , Akodon azarae , Deltamys kempi , Calomys laucha and C. musculinus . We provide discriminant functions and a dichotomic key to identify hairs at the species level based on hair length and width and scale morphology observed in specific sections of dorsal guard hairs. Discriminant functions require fewer measurements and are faster than the use of the key.

Habitat associations of small mammals in southern Brazil and use of regurgitated pellets of birds of prey for inventorying a local fauna

We inventoried terrestrial small mammals in an agricultural area in southern Brazil by using trapping and prey consumed by Barn Owls (Tyto alba) and White-tailed Kites (Elanus leucurus). Small mammals were trapped in three habitat types: corn fields, uncultivated fields ("capoeiras"), and native forest fragments. A total of 1,975 small mammal specimens were trapped, another 2,062 identified from the diet of Barn Owls, and 2,066 from the diet of White-tailed Kites. Both trapping and prey in the predators' diet yielded 18 small mammal species: three marsupials (Didelphis albiventris, Gracilinanus agilis, and Monodelphis dimidiata) and 15 rodents (Akodon paranaensis, Bruceppatersonius iheringi, Calomys sp., Cavia aperea, Euryzygomatomys spinosus, Holochilus brasiliensis, Mus musculus, Necromys lasiurus, Nectomys squamipes, Oligoryzomys nigripes, Oryzomys angouya, Oxymycterus sp.1, Oxymycterus sp.2, Rattus norvegicus, and Rattus rattus (Linnaeus, 1758)). The greatest richness was found in the uncultivated habitat. We concluded that the three methods studied for inventorying small mammals (prey in the diet of Barn Owls, White-tailed Kites, and trapping) were complementary, since together, rather than separately, they produced a better picture of local richness.

HISTOPATHOLOGY OF Holochilus brasiliensis(RODENTIA: CRICETIDAE)INFECTED WITH Schistosoma mansoni(SCHISTOSOMATIDA: SCHISTOSOMATIDAE)

Schistosomiasis prevalence in swamplands of North-eastern Brazil is complicated by the presence of alternative hosts, such as the marsh rat Holochilus brasiliensis . However, the effects of Schistosoma mansoni on this host – at both individual and population levels - are unknown. We investigated the pathological effects of S. mansoni invasion in the liver and spleen of H. brasiliensis . Ten infected (5 males; 5 females) and 6 healthy (3 males; 3 females) animals had their liver and spleen extracted 42 days post-treatment. Histological slides were prepared and examined under light microscope. The livers of infected males were seen to contain parasite eggs with moderate or intense granulomas, whereas females showed slight or moderated tissue damage. Parasite eggs were also observed in the spleen of both male and female rodents. There appeared to be a different response to parasite invasion according to host sex.

Feeding habits of Geoffroy's cat ( Leopardus geoffroyi) in southern Brazil

The present study was carried out from 2001 to 2005, with the objective of analyzing the diet of Leopardus geoffroyi in extreme southern Brazil, through analyses of stomach contents and scats. The importance of each prey type found in the scats ( n=66) was determined from the frequency of occurrence and percentage of occurrence. In the stomachs ( n=9), the importance of each prey was determined using Pianka's index of relative importance (IRI). The food spectrum of L. geoffroyi included mammals, birds, serpents, amphibians and insects. Mammals were the most abundant items, present in 95.5% of the scats and representing 74.4% of the total prey, reaching an IRI of 13296.3 in the stomachs. The principal prey types found in the stomachs and scats were small rodents ( Cavia spp., Oligoryzomys spp., Necromys spp. and Holochilus brasiliensis) and large-sized rodents ( Myocastor coypus), of terrestrial, arboreal or semi-aquatic habit. Probably, the high percentage of these prey items in the diet is related to their availability and abundance. The index of niche breadth was low in both the stomach and scat analyses (respectively, B sta=0.18 and 0.17), demonstrating the high degree of specialization of these cats.

Graphidioides subterraneusn. sp. (Nematoda: Trichostrongyloidea) from the South American subterranean rodentCtenomys talarumThomas, 1898 (Rodentia: Octodontidae)

A new nematode species, Graphidioides subterraneus n. sp., found in the stomach of C. talarum from Argentina is described. The new species more closely resembles G. mazzai Lent & Freitas, 1935, parasite of Galea leucoblephara from Argentina, and G. kravetzi Sutton & Durette-Desset, 1995, parasite of Holochilus brasiliensis from Uruguay. It can be distinguished by shorter spicules, by the shape of the gubernaculum, by shorter uterine branches, and by a different number of ridges of the synlophe all along the body.