82 resultados para Small mammals
Resumo:
A key to species groups of the genus Belostoma Latreille, 1807, using new taxonomic characters are presented as well as the revision of the four species included in the denticolle group: B. denticolle Montandon, 1903, and three new species: B. orbiculatum from eastern Argentina and southern Brazil, B. retusum from eastern Argentina and B. amazonum from northern Brazil which are described and illustrated.
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We analyzed the alimentary tract of 66 specimens of Amphisbaena munoai Klappenbach, 1969 from the Serra do Sudeste, state of Rio Grande do Sul, southern Brazil. Forty specimens (60.6%) had prey items in their gut. The diet consisted mainly of small invertebrate prey, such as termites, insect larvae and ants. The most abundant prey item was termites, found in 62.5% of the non empty stomachs. The high number of individual prey items in the majority of stomachs, the small size of the regular prey items, and the absence of gut content in specimens of A. munoai kept alive for about two days, indicate that this species forages very frequently. The predominance of fossorial prey items and the occasional records of nomadic ants lead us to suggest that A. munoai usually feeds underground, and occasionally forages on the surface.
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We studied life history traits of females of the lizard Eurolophosaurus nanuzae (Rodrigues, 1981), an endemic species of rock outcrop habitats in southeastern Brazil. During October 2002 and 2003 we sampled three populations in sites that encompass the meridional portion of the geographic range of the species. Clutch size varied from one to three eggs, with most females carrying two eggs. Clutch size did not vary among populations, but was correlated to female body size. Only larger females produced clutches of three eggs. Females of the small-sized E. nanuzae produce eggs as large as those of medium-sized tropidurids, thus investing a considerable amount of energy to produce clutches resulting in high values of relative clutch mass.
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Between January 2007 and December 2010, the abundance of medium-sized mammals was studied, with special focus on the Molina's hog-nosed skunk, Conepatus chinga (Molina, 1782), at four locations in southern Brazil. In this study, transect line methodology was used to obtain data for Distance Analyses. Transects were traveled by car at night, searching with spotlights along the edges of secondary roads in agricultural landscapes. Along 1,811 km, we obtained 620 observations of 20 mammal species. The most common species was the exotic European hare, Lepus europaeus (Pallas, 1778); the highest abundance estimated for South America was observed in one of the study areas, where its density was estimated as 32 individuals/km². Carnivores were the most commonly recorded mammals, represented by 10 species and comprising 51% of all observations. Molina's hog-nosed skunk occurred in all study areas, but occurred in sufficient numbers to obtain density estimates in only two of the areas. We estimated 1.4 to 3.8 individuals/km², in the first density estimate made by the transect method for a member of Conepatus in the Neotropics. These values are similar to those estimated for North American species of Mephitidae. In Brazil, C. chinga is apparently more abundant in the Pampa biome than in the grasslands of the Atlantic Forest. For two other carnivores, Lycalopex gymnocercus (Fisher, 1814) and Cerdocyon thous (Linnaeus, 1766), we estimated preliminary densities that were similar to those previously cited for different regions.
Resumo:
We assessed the species composition and abundance of medium and large-sized mammals in an urban forest fragment in the Brazilian Amazon, and recorded the preference of some species for particular phytophysiognomies. We placed nine transects with 20 sand plots each in three phytophysiognomies: open rainforest with a dominance of bamboos (OFB), open rainforest with palm trees (OFP), and dense rainforest (DF). We calculated species abundance as the number of records/plot.day, in a total of 2,700 plots.day. We recorded twelve mammal species; Sylvilagus brasiliensis (Linnaeus, 1758) and Dasyprocta fuliginosa (Wagler, 1831) were the most abundant. The results differed among phytophysiognomies: DF presented the highest mammal diversity, whereas the species composition of OFP was less similar than that of other phytophysiognomies. Rodents showed higher preference for OFP and Sylvilagus brasiliensis was more abundant in OFB. The study area showed high species richness, with the occurrence of mesopredators, but there was a predominance of common species adaptable to disturbed environments, which reflects the severe isolation degree of the forest fragment and the hunting pressure that is still present.
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The knowledge of the Ixodidae becomes every day, more and more important owing to the fact of the increasing number of diseases of man and animals they can transmit. In Brasil besides transmitting treponemosis, piroplasmosis and anaplasmosis to several domestic animals, the ticks are also responsible fo the transmission of the brazilian rocky mountain spotted fever (A. cajennense and Amblyomma striatum) and they can also harbour the virus of the yellow fever and even to transmit it in laboratory experiments (A. cajennense, O. rostratus). The Brazilian fauna of ticks is a small one and has no more than 45 well-established species belonging to the genus Argas, Ornithodoros, Ixodes, Haemaphysalis, Rhipicephalus, Boophilus, Amblyomma and Spaelaeorhynchus. The genus Amblyomma is the best represented one, with 67% of all species of ticks known in Brazil. One of the most important species in the Amblyomma cajennense owing to its abundance and its wide parasitism in many vertebrates: reptiles, birds and mammals, incluing man, who is much attacked by the larva, the nymph and the adult of this species. The other ticks who attack the man are the Amblyomma brasiliense (the pecari tick), in the forests, and the Ornithodoros, especially the species. O. rostratus and brasiliensis. Other species can bite the man, but only occasionally, like Amblyomma fossum, striatum, oblongogutatum etc. Argas persicus, Rhipicephalus sanguineus and Boophilus are very important species not only as parasites but specially because they transmit several diseases to animals. Some of the ticks of the brazilian wild animals are now also parasites of the domestic ones and vice-versa. Arga persicus var. dissimilis is very common among the poultry and transmits the Treponema anserinum (gallinarum). Boophilus microplus is very abundant on our domestic and wild ruminants (Bos, Cervus, Mazama etc.) and can also ben found on horse, dogs, Felis onca, Felis concolor etc., and it transmits to cattle piroplasmosis and anaplasmosis. Rhipicephalus sanguineus (an introduced species) is now very common on the dog, over all the country. The author recommend to give popular names to some brazilian ticks in order to make them more acquainted with the non scientific people. The author gives a classification of the superfamilia Ixoidoidea and keys to the determination of the different species of brazilian ticks. He creates a new family of Nuttallielidae to the so interesting tick, described by Bedford with the name of Nuttaliella namaqua in South Africa, a new variety of Argas persicus, the Argas persicus var. dissimilis nov. var. owing to the differences on the segment and on the size and morphology of the peritrema. He describes also the female of Amblyomma fuscum Nn. A great part of the author's work deals with the biology, life conditions and parasitism of many of the brazilian ticks in accordance with his personal and from other author's researches, especially in reference to Argas persicus, Ornithodoros rostratus, O. brasiliensis, Boophilus microplus, Rhipicephalus sanguineus, Amblyomma cajennense, A. pseudoconcolor, A. auriculare, A. rotundatum (= A. agamum) etc. The author gives a detailed report upon the parthenogenesis of A. rotundatum (A. agamum) that he first described in 1912 and gives also many references to other species of brazilian ticks, to teratological forms etc. He also gives a detailed report of the geographical distribution of brazilian ticks and of the peculiar conditions of its parasitism. The last part of this article deals with references to the species of ticks of some of the South American Republics namely Argentina, Bolivia, Colombia, Paraguay and Venezuela. Amblyomma testudinis Conil, A. neumanni Ribaga 1902 (= A. furcula Dõnitz 1909) and A. parvitarsum Nn. 1899 (= A. altiplanum Dios 1917), are found only in Argentina. It is given a special bibliography dealing with the brazilian ticks and four text figures and one plate.
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During an outbreak of cutaneous leishmaniasis in a locality (Las Rosas, Cojedes State, venezuela) previously non-endemic, 12.9% of humans, 7% of dogs and 21.4% of donkeys (Equus asinus) had lesions with paraites. The agent in the three hosts was identified as Leishmania braziliensis, subspecies braziliensis at least in man and donkey. The probable vector was Lutzomyia panamensis. No infection was found in a small sample of wild mammals examined. The outbreak was apparently linked with the importation of donkeys with ulcers, from endemic areas. The Authors call attention to the fact that not only in the foci of "uta", but also in areas of the other forms of American cutaneous leishmaniasis, dogs are frequently found infected. They emphasize the necessity of searching for the infection in donkeys and of performing hemocultures and xenodiagnosis with sandflies in human, canine and equine cases, to verify their possible role as sources of infection, and not merely as dead ends in the epidemiological chain of the disease.
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Characterization is given of a new parasite, Leishmania equatoriensis sp.n. wich was isolated from the viscera of a sloth (Choloepus hoffmanni) and a squirrel (Sciurus granatensis), captured in humid tropical forest onthe Pacific Coast of Ecuador. Data based on biological and molecular criteria, as well as numerical zymotaxonomical analysis, indicate that this parasite is a new species of the L. brasiliensis complex. L. equatoriensis is cleary distinguishable form all other known species within this complex, using the following molecular criteria: reactivity patterns with specific monoclonal antibodies, isoenzyme electrophoresis, and restriction-endonuclease fragment patterns of kinetoplast DNA (k-DNA).
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A taxonomical and ecological study was made on 264 samples of 12 species of ectoparasite ixodides collected on wild mammals from several natural regions of Paraná state, Brazil. These species of ticks as their hosts are listed by their identified evolutive forms and capture locations. A review of the early studies on the Ixodida from South Brazil is made considering the frequency of the parasite species on each host concerning the geographic distribution of such species. This paper is a contribution to the knowledge of the Ixodidae ectoparasites species of wild mammals in Brazil.
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Six Plasmodium falciparum protein fractions, isolated under reducing conditions, were used to immunize mice, rabbits and the squirrel monkey Saimiri sciureus. Five or seven subcutaneous injections of each antigenic preparation, in conjunction with Freund's complete or incomplete adjuvants, were administered. This led to the development of specific antibodies detected by IFAT, ELISA or immunobloting which inhibited merozoite reinvasion in in vitro P. falciparum cultures. This activity seems to be associated with rhoptry proteins contained in fractions Pf F2 and Pf F4.
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The marsupial and placental mammals originated at a time when the pattern of geographical barriers (oceans, shallow seas and mountains) was very different from that of today, and climates were warmer. The sequence of changes in these barriers, and their effects on the dispersal of the mammal families and on the faunas of mammals in the different continents, are reviewed. The mammal fauna of South America changed greatly in the Pliocene/Pleistocene, when the newly-complete Panama Isthmus allowed the North American fauna to enter the continent and replace most of the former South American mammal families. Marsupial, but not placental, mammals reached Australia via Antarctica before Australia became isolated, while rats and bats are the only placentals that dispersed naturally from Asia to Australia in the late Cenozoic. Little is known of the early history of the mammal fauna of India. A few mammal families reached Madagascar from Africa in the early Cenozoic over a chain of islands. Africa was isolated for much of the early Cenozoic, though some groups did succeed in entering from Europe. Before the climate cooled in the mid-Cenozoic, the mammal faunas of the Northern Hemisphere were much richer than those of today.
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Eleven species of fleas were collected from 601 small rodents, from November 1995 to October 1997, in areas of natural focus of bubonic plague, including the municipalities of Nova Friburgo, Sumidouro and Teresópolis, State of Rio de Janeiro, Brazil. Among 924 fleas collected, Polygenis (Polygenis) rimatus (Rhopalopsyllidae) was the predominant species regarding the frequency, representing 41.3% (N:382), followed by P. (Neopolygenis) pradoi, representing 20% (N:185) and Craneopsylla minervaminerva (Stephanocircidae), representing 18.9% (N:175). The host Akodon cursor harbored 47.9% of these fleas. Other six host species were infested by 52.1% of the remaining fleas. Fleas were found on hosts and in places within the focus not previously reported by the literature.
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Tabanid females are better known as hematophagous on man and other mammals, and linked to mechanical transmission of parasites. The association between tabanids and reptiles is poorly known, but has been gaining more corroboration through experiments and occasional observation in the tropics. The present study was conducted at a military base (CIGS/BI-2), situated 54 km from Manaus, Amazonas, in a small stream in a clearing (02°45'33"S; 59°51'03"W). Observations were made monthly, from April 1997 to March 1998, during two consecutive days. At the same time, other vertebrate animals were offered, including humans. However in this paper only data obtained on a common caiman, Caiman crocodilus (Linn.), and an anaconda, Eunectes murinus (Linn.), in diurnal observations from 05:30 a.m. to 18:30 p.m., will be discussed. A total of 254 tabanid specimens were collected, 40 from the anaconda and 214 from the caiman. Four tabanid species were recorded on these two reptiles: Stenotabanus cretatus Fairchild, S. bequaerti Rafael et al., Phaeotabanus nigriflavus (Kröber) and Tabanus occidentalis Linn. Diurnal activities showed species-specific patterns. The first three species occurred only in the dry season. T. occidentalis occurred during the whole observation period, and with increased frequency at the end of the dry season. We observed preferences for body area and related behavior of the host. Observations on the attack of tabanids on one dead caiman are also presented.
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The effects of mucosally added Escherichia coli heat stable enterotoxin (STa 30 ng ml-1) on the basal short-circuit current (Isc in µA cm-2) across stripped and unstripped sheets of jejuna and ilea taken from fed, starved (4 days, water ad lib) and undernourished (50% control food intake for 21 days) gerbil (Gerbillus cheesmani) were investigated. The effect of neurotoxin tetrodotoxin (TTX 10 µM) and the effects of replacing chloride by gluconate or the effects of removing bicarbonate from bathing buffers on the maximum increase in Isc induced by STa were also investigated. The maximum increase in Isc which resulted from the addition of STa were significantly higher in jejuna and ilea taken from starved and undernourished gerbils when compared with the fed control both using stripped and unstripped sheets. In the two regions of the small intestine taken from fed and starved animals TTX reduced the maximum increase in Isc induced by STa across unstripped sheets only. Moreover in jejuna and ilea taken from undernourished gerbils TTX reduced significantly the maximum increase in Isc induced by STa across stripped and unstripped sheets. Replacing chloride by gluconate decreased the maximum increase in Isc induced by STa across jejuna and ilea taken from undernourished gerbils only. Removing bicarbonates from bathing buffer decreased the maximum increase in Isc across the jejuna and ilea taken from starved and undernourished gerbils.