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URI permanente desta comunidadehttps://bdc.icmbio.gov.br/handle/cecav/1401
Centro Nacional de Pesquisa e Conservação de Répteis e Anfíbios
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Resultados da Pesquisa
Item Nesting of Phrynops geoffroanus (Testudines: Chelidae) on sandy beaches along the Upper Xingu River, Brazil.(Zoologia, 2011-10) Ferreira Júnior, Paulo D.; Balestra, Rafael A. M.; Moreira, José R.; Freitas, Fábio de O.; Lustosa, Ana P. G.; Jorge, Rafael F.; Rosa, Artur J. de M.; Sampaio, Antônio A.; Gomes, Aline S.This work presents the first data on incubation temperature of Phrynops geoffroanus (Schweigger, 1812) in a natural environment, and provides information on nest predation, hatching success and size of offspring born in the nests on sandy beaches along the Upper Xingu River. Thirty-one P. geoffroanus nests were found, of which eleven were completely predated, mainly by Cerdocyon thous (Linnaeus, 1766). Incubation was completed in nine out of the 17 nests protected by netting. The nests presented an average of 13.1 eggs and were distributed over the various geomor phological sectors of the nine sampled beaches. The size and weight of the hatchlings varied significantly between nests, and the incubation period in protected nests lasted for 76.5 days, less than reported for controlled incubation in the laboratory. Daily variation in incubation temperature in the three nests monitored for temperature was lower in those situated in fine sand sediments. Incubation temperature varied from 22 to 39 C and may have affected hatching success, which reached 60.8% in protected nests. Nest distribution in different geomorphological sectors indicated the plasticity of P. geoffroanus in terms of variation in nesting environment, which partly explains the species’ broad geoographical distribution.Item Description of embryonic stages in Melanosuchus niger (Spix, 1825) (Crocodylia: Alligatoridae).(J. Morphol. Sci, 2011) Vieira, L.G.; Lima, F.C.; Santos, A.L.Q; Mendonça, S.H.S.T.;; Moura, L.R.,; Iasbeck, J.R.; Sebben, A.The determination of embryonic stages is very useful in comparative and evolutionary anatomy, experimental research and ecological studies. Although tables of development stages already exist for some crocodilian species, no table has yet been published for Melanosuchus niger. Therefore, the aim of this work is to monitor the development of this species of Alligatoridae and characterize its stages based on the main morphological transformations the embryo undergoes during the incubation process. Under natural conditions, two samples were collected daily in the Lake Cuniã Extractive Reserve in Rondônia, Brazil, making a total of 186 eggs. The incubation period was 90 days at an ambient temperature varying from 25.2 to 31.7 °C. We established 24 embryonic stages between the formation of the pharyngeal arch and hatching. Primordia for the sensory organs and somites were observed in the early stages. The buds of the pelvic and thoracic limbs emerged simultaneously, also in the early stages. An analysis of these structures showed evidence of considerable evolutionary modifications when compared with embryos of different species. In stage 12 we observed subtle pigmentation in the region of the head and, in stage 25, the pigmentation and striped pattern were typical of the newly hatched specimen. The eyetooth was visible in stage 18, disappearing within the first few weeks after hatching. The vitellus was completely absorbed in the penultimate stage. Direct comparisons of the table of embryonic stages were made between M. niger and other crocodilian taxa, and the main differences identified were chronological variations.