Alexandre Uarth Christoff

Diet of crab-eating fox, Cerdocyon thous (Linnaeus) (Carnivora, Canidae), in a suburban area of southern Brazil

The crab-eating fox, Cerdocyon thous (Linnaeus, 1766), is a small canid with twilight and nocturnal habits from savannas and forests of South America. In this study, we seasonally determined and quantified the diet of C. thous in Lami Biological Reserve, a conservation unit with 179.78ha situated in a suburban area in the municipality of Porto Alegre, southern Brazil. During the year 2000, we collected 80 fecal samples - 20 for each season - in two or three week sampling intervals, along trails inside the Reserve. Samples were dried in an oven for 24h at 60oC, immersed in 70% alcohol, and prey items were identified using a stereomicroscope. The diet of the crab-eating fox was essentially carnivorous (87.62% composed by vertebrates), with seasonal variation (p = 0.0009) and absence of fruits. Small non-flying mammals and birds were the most frequent prey, being proportionally more preyed in autumn and summer, respectively. Arthropods were more preyed in winter and spring and bird/reptile eggs only in summer and spring, in the reproduction period of these groups.

A New Species of Atlantic Forest Tree Rat, Genus Phyllomys (Rodentia, Echimyidae) from Southern Brazil

Abstract Phyllomys is the most diverse genus of the subfamily Echimyinae, and is represented by 12 described species endemic to the Atlantic forest of eastern South America. We name and describe a new species of Phyllomys based on specimens collected in southern Brazil. This species is closely related to P. dasythrix and has been referred to as “Phyllomys aff. dasythrix” in the literature. Chromosomal restructuring was probably involved in their speciation because genetic and morphological similarities of the 2 contrast with their karyotypic distinctiveness. The new species of Phyllomys is diagnosed by a unique combination of external, cranial, and karyotypic characters. We propose the conservation status of “Least Concern” for Phyllomys sp. nov., but “Vulnerable” for P. dasythrix. We present an identification key to the living species of Phyllomys.

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

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.

Feeding habits of Molina's hog-nosed skunk, Conepatus chinga (Carnivora: Mephitidae) in the extreme south of Brazil

Feeding habits of the Molinas hog-nosed skunk, Conepatus chinga (Molina, 1782) in the extreme south of Brazil. We analyzed 60 stomachs of road-kills of C. chinga in the extreme south of Brazil. The contents revealed 808 prey parts, including invertebrates (frequency of occurrence - FO = 96.7% and relative abundance - RA = 94.7%), vertebrates (FO = 18.3% and RA = 2.8%) and plants (FO = 31.7% and RA = 2.3%). We identified 18 kinds of food, including the invertebrate order Coleoptera which showed the highest FO (86.7%) and RA (75.2%). Other important orders were Orthoptera (FO = 35% and RA = 10.4%) and Araneae (FO = 41.7% and RA = 4%). The combination of occurrence and abundance of the preys consumed allowed classifying C. chinga as an omnivorous with a predominance of insects, especially Coleoptera, consuming other invertebrates, vertebrates and plants in smaller numbers. Behavioral and morphological adaptations of C. chinga favor the predation of insects, which are preys that offer low physical resistance and are available in all terrestrial environments.

Anatomia comparada e morfometria de oligoryzomys nigripes e o. flavescens (rodentia, sigmodontinae) no Rio Grande do Sul, Brasil

Oligoryzoms flavescens and O. nigripes are widely distributed and sympatryc in many biomes. The diagnostic characters used to recognize these are not clearly established. In this study description and comparison was conducted of external morphology, anatomy of the skull, teeth, postcranial skeleton, as well as stomach and penis morphology. Statistical analysis was generated from morphometric data. The sample consisted of 208 specimens from 24 localities in Brazil. O. nigripes was found to be larger, with dorsal pelage darker and ventral pelage whitish with black specks, the skull being larger and more robust than O. flavescens. O. flavescens is smaller, with slightly clearer dorsal pelage and yellowish belly. The pattern of cephalic circulation is derived from the second type in both species. Comparison of postcranial skeleton reveals prominent accidents in scapula and humerus in O. flavescens. On the other hand O. nigripes demonstrated numerous differences localized in the iliac blade, orientation of the ischium and prominent accidents in tibia and fibula. The stomach morphology of both taxa had the same unilocular-hemiglandular pattern. The penis consisted of distal baculum tri-digited. Analysis of the discriminant function clearly indicates the distinction of two homogeneous groups represented by the species. According to t test, two morphometric variables (width of the zigomatic plate and width of first upper molar)are irrelevant (P > 0.05) to the discrimination of taxa. Sexual dimorphism based on morphometry was supported by t test for O. nigripes. In O. flavescens this condition was not supported.

A new species of Juliomys (Rodentia, Cricetidae, Sigmodontinae) from the Atlantic Forest of Southern Brazil

Sigmodontinae is a very rich clade of rodents that is widespread throughout the Neotropics. The arboreal mice Juliomys comprise a poorly known branch, with incomplete information about species richness, phylogenetic position, and geographic distribution. Based on a sample from the Atlantic Forest of Southern Brazil, we name and describe a new species for the genus. This new species can be distinguished from others in the genus by its karyotype, morphological traits, and cytochrome b (Cytb) gene sequence. It has a unique karyotype (2n = 32, FN = 48), and forms a well-supported monophyletic haplogroup, which is phylogenetically distant from the remaining species of Juliomys. The genetic differentiation ranges from 11.1% to 19.7%, and there are 24 molecular autopomorphies in the Cytb gene. The new species can be distinguished from J. pictipes by morphological and morphometric analyses. However, we consider the new species as cryptic, not easily recognized by morphological characteristics of other species of Juliomys. This taxon seems to be endemic to the Brazilian Araucaria Forest in the Atlantic Forest biome, occurring in sympatry with its congeneric species J. ossitenuis and J. pictipes. In this research, we describe a new species for the genus and extend species distributions in the Atlantic Forest.

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

ABSTRACT 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.

Trophic relationships of sympatric small carnivores in fragmented landscapes of southern Brazil: niche overlap and potential for competition

Abstract Between 2000 and 2010, digestive tracts collected from carnivore carcasses found in southern Brazil were analyzed to determine the frequency and proportion of items constituting the diets of each species. Material was collected and analyzed from 194 animals of 10 species: Cerdocyon thous, Lycalopex gymnocercus (Canidae), Procyon cancrivorus (Procyonidae), Galictis cuja (Mustelidae), Conepatus chinga (Mephitidae), Leopardus colocolo, Leopardus geoffroyi, Leopardus guttulus, Leopardus wiedii, and Puma yagouaroundi (Felidae). Most of these species are sympatric, which makes them potential competitors when sharing, to a greater or lesser degree, the same resources. The food niche breadth was relatively narrow, demonstrating that even generalist species, such as the crab-eating raccoon, used food resources rather unequally. An extensive overlap (>90%) in food niches was found among the cat species, the grison, and the Pampas fox, which had diets based on rodents. Crab-eating raccoons occupied a different food niche, based on aquatic or semiaquatic prey and fruits. Conepatus chinga was unique in exploiting arthropods and insect larvae as basic dietary items.

New distribution records of Serra do Mar Grass Mouse Akodon serrensis Thomas, 1902 (Mammalia: Rodentia: Sigmodontinae) in the southernmost Brazil

Geographic distribution is critical information for conservation of the species. In this note we report the southernmost record of Akodon serrensis , a Neotropical terrestrial rodent endemic of the Brazilian Atlantic Forest, but yet with undefined distribution limits.

Identificação de marsupiais do Rio Grande do Sul através da microestrutura dos pelos-guarda

The analysis of mammalian hairs is a non-invasive technique that may help in the identification of Brazilian marsupials. Our objective was to identify microscopic patterns of marsupial guard-hairs (cuticle and medulla) from species with occurrence in the state of Rio Grande do Sul, southern Brazil. We also present a hair-based identification key for this group. Specifically for Monodelphis, a still taxonomically obscure genus that needs revision, we present detailed description of observed hair patterns. We obtained the analyzed material by collecting hair samples of marsupials captured in field or else deposited in different zoological collections. We identified hair patterns of ten marsupial species: Caluromys lanatus, Chironectes minimus, Didelphis aurita, Didelphis albiventris, Cryptonanus guahybae, Gracilinanus agilis, Gracilinanus microtarsus, Lutreolina crassicaudata, Micoureus paraguayanus and Philander frenatus. Individuals of the Monodelphis genus were analyzed together, considered as part of the dimidiata group. We found three distinct patterns for this group, suggesting the possible occurrence of a third species besides the two already recognized (M. brevicaudis and M. dimidiata). These morphs show distinct distribution in the state, with some degree of distribution overlap. The analysis of microscopic patterns of mammal hairs allowed the successful identification of the great majority of marsupials that occur in the Rio Grande do Sul state. Our results suggest that the two Monodelphis species of the dimidiata group might occur with a distinct distribution in the state, one of them occupying mainly the northern part and the other one the eastern region, with some overlap in the central part of the state.