188 resultados para amphibia


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The karyotype of a new species of Paratelmatobius from the P cardosoi group is described. As with other Paratelmatobius and Scythrophrys karyotypes, Paratelmatobius sp. (aff. cardosoi) shows a diploid number of 24 chromosomes, in addition to other similarities with the former karyotypes. The Paratelmatobius sp. (aff. cardosoi) karyotype differs from that of P. cardosoi in the morphology of pair 4, the NOR location and the C-bands in pairs 3 and 8 (exclusive to Paratelmatobius sp.) and those of pairs 7 and 9 (exclusive to P. cardosoi). Both karyotypes also differ in the amount of heterochromatin in pair 1. The presence of interstitial heterochromatin in the long arm of pair 1 and the interstitial C-bands in both arms of chromosome 5 are apparently synapomorphic characters of P. cardosoi and Paratelmatobius sp. (aff. cardosoi), since they are absent in the other Paratelmatobius and Scythrophrys karyotypes. In Paratelmatobius sp. (aff. cardosoi), the nucleolus organizer region is on the short arm of a small metacentric chromosome (pair 9), an arrangement similar to the NOR-bearing chromosome pair in the karyotype of P. poecilogaster and in karyotype 11 of Scythrophrys. A conspicuous heteromorphism unrelated to the sex determining mechanism was also observed and probably arose from a pericentric inversion.

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Amphibian skin is characterized by the presence of mucous glands, related to cutaneous breathing, reproduction and water balance, and granular glands, related to the production of toxins used in defence. In some species the granular glands can form accumulations in certain regions of the body. This is the case for inguinal macroglands of the leptodactylid frog Physalaemus nattereri, where these structures form a pair of black discs associated with deimatic behaviour. The morphology of the inguinal macroglands and their secretion were studied in this species and correlated to deimatic behaviour. The inguinal macroglands are formed from elongated granular glands that, in contrast with the granular glands of the rest of the skin, have small spherical granules with a proteinic content. In the dermis of the whole body, except for the inguinal macroglands and the inguinal region, a well-developed calcified dermal layer is observed. During deimatic behaviour these macroglands discourage a potential predator from attacking, but if visual cues are insufficient and the predator persists in the attack, atoxic secretion is eliminated in its mouth. This elimination is favoured by the absence of a calcified dermal layer in the macroglands, which makes the dermal region softer than the rest of the dorsal skin.

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Males of the South American treefrog Aplastodiscus perviridis construct concealed subterranean nests. Using a complex courtship behavior that involves tactile stimuli and vocalizations, males guide the females to the subterranean nests where eggs are laid. Embryos and facultatively oophagous tadpoles (at least in stage 25) stay in subterranean nests until flooding transports them to ponds or streams. This is a rare reproductive mode previously known for few species in the Hyla albosignata and H. albofrenata complexes. Based on similarities of reproductive mode we suggest a monophyletic origin for Aplastodiscus and these complexes of Hyla.

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Two new species of brachycephalid frogs are described from Pico Marumbi, municipality of Morretes, and Pico da Igreja, municipality of Guaratuba, Parana State, southern Brazil. The new species share the following attributes: body bufoniform; skin on top of the head, and central part of the back body smooth with no dermal co-ossification; outer metatarsal tubercle distinct; dermal roofing bones of skull unornamented; all paired cranial bones distinct and not fused; quadratojugals, and maxillary odontoids present. The new species from Pico Marumbi is characterized by male SVL = 11.6-12.5 and female SVL = 13.0-14.5 turn; and general color orange with dorsal reddish-brown irregular markings, lateral surfaces with small dark brown spots, and belly with brownish spots and small dots. The new species from Pico da Igreja is characterized by male SVL = 12.6-13.9 and female SVL = 14.6-15.3 mm; and general color orange, lateral surfaces with small dark brown spots, and belly with brownish coalescent spots and small dots. Comparisons with other brachycephalid species and osteological data are provided.

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Feeding habits and habitat use of the colubrid snakes Philodryas olfersii and P patagoniensis in southern Brazil are presented here. Philodryas olfersii and P patagoniensis are sympatric in the study area and both dwell in open and forested areas. Specimens preserved in collections and observations of snakes in the field yielded the data. Both species are diet generalists, feeding on small vertebrates, mainly frogs. Philodryas patagoniensis has a broader diet, a less variable frequency of food items, and fed on heavier prey than R olfersii. Seasonal variation in diet occurs in both species. The semi-arboreal Philodryas olfersii is more slender and has a longer tail than the terrestrial R patagoniensis, characters that may reflect differences in microhabitat use. There are a strong relationship between habitat use and frequency of a given food type. Differences in the use of food resources between P. olfersii and P patagoniensis seem to reflect differences in foraging microhabitats used by each species.

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We review the information currently available on the reproduction of the Amphisbaenia and provide original data on the reproductive biology of four Neotropical species: Amphisbaena alba; A. mertensi; Cercolophia roberti, and Leposternon infraorbitale. In total, we compiled data for 22 species: 17 Amphisbaenidae, 1 Rhineuridae, 3 Bipedidae, and 1 Trogonophidae. The majority of the species were oviparous with the exceptions of Loveridgea ionidesii, Monopeltis anchietae, M. capensis, and Trogonophis wiegmanni. Viviparity was interpreted as a derived trait that evolved independently for at least 3 times within the Amphisbaenia. In most species, reproduction is synchronized with the hot and rainy season and seems to vary with latitude. Although Amphisbaenia eggs have been found in ant nests, it remains disputable whether this is an obligatory or even a preferable location for egg-laying. Incubation time in A. mertensii lasts 59 days and this is the first report encompassing egg-laying to hatching for any Amphisbaenia species. Nonetheless, a two months incubation period seems to be the common rule for oviparous Amphisbaenia. The general pattern of reproductive output in Amphisbaenia is characterized by a low number of eggs/embryos per clutch whose individual size is comparatively large in relation to adult body size. Eggs are markedly elongated on the long axis and arranged in-line within the abdominal cavity possibly to prevent/diminish biomechanic drawbacks of egg bearing. Hatchlings of A. mertensi possess an egg-tooth implanted at the upper jaw, exhibit positive geotropism, and display defensive behaviors known to be present in adults. Our review shows that our current knowledge of Amphisbaenia reproduction is fragmentary, often based on the examination of small samples, and heavily dependent on the publication of anedoctal observations. Future publications on this subject are encouraged.

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Poison frogs of the family Dendrobatidae contain cryptic as well as brightly colored, presumably aposematic species. The prevailing phylogenetic hypothesis assumes that the aposematic taxa form a monophyletic group while the cryptic species (Colostethus sensu lato) are basal and paraphyletic. Analysis of 86 dendrobatid sequences of a fragment of the 16S rRNA gene resulted in a much more complex scenario, with several clades that contained aposematic as well as cryptic taxa. Monophyly of the aposematic taxa was significantly rejected by SH-tests in an analysis with additional 12S and 16S rDNA fragments and reduced taxon sampling. The brightly colored Allobates femoralis and A. zaparo (Silverstone) comb. nov. (previously Epipedobates) belong in a clade with cryptic species of Colostethus. Additionally, Colostethus pratti was grouped with Epipedobates, and Colostethus bocagei with Cryptophyllobates. In several cases, the aposematic species have general distributions similar to those of their non-aposematic sister groups, indicating multiple instances of regional radiations in which some taxa independently acquired bright color. From a classificatory point of view, it is relevant that the type species of Minyobates, M. steyermarki, resulted as the sister group of the genus Dendrobates, and that species of Mannophryne and Nephelobates formed monophyletic clades, corroborating the validity of these genera. Leptodactylids of the genera Hylodes and Crossodactylus were not unambiguously identified as the sister group of the Dendrobatidae; these were monophyletic in all analyses and probably originated early in the radiation of Neotropical hyloid frogs.

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No presente estudo foi realizado um inventário das espécies de anfíbios anuros que ocorrem em um fragmento de mata ciliar do Córrego do Espraiado, localizado na Universidade Federal de São Carlos (UFSCar), Município de São Carlos, estado de São Paulo, sudeste do Brasil. Durante os meses de março de 2009 a fevereiro de 2010 foram realizadas saídas de campo semanais nas quais foram registradas 13 espécies de anuros. A atividade reprodutiva das espécies de anuros componentes da comunidade estudada mostrou-se sazonal, sendo que houve correlação positiva e significativa entre o número de espécies em atividade reprodutiva e o fotoperíodo. Verificamos que a comunidade estudada mostrou-se mais semelhante a comunidades de anuros de florestas de transição entre Mata Atlântica e Cerrado do que a fragmentos de Cerrado próximos da região.

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