Dieta e biologia reprodutiva da cruzeira, Bothrops alternatus (serpentes Viperidae), na Região Sul do Brasil

Abstract

The Bothrops alternatus is a terrestrial pitviper of the Crotalinae sub-family, Bothriopsini tribe, measuring, approximately, 1690mm. It presents a vertical distribution of approximately 700 m above sea level, and is found in Brazil, Paraguay, Uruguay and Argentina. In Brazil, it is found in the states of Minas Gerais, Goiás, São Paulo, Paraná, Santa Catarina, Rio Grande do Sul and Mato Grosso. It inhabits swamps, marshes, riverbanks and other wet habitats, fields and rocky areas, as well as farmlands. In this study, 207 specimens of Bothrops alternatus were analyzed with the objective of broadening the knowledge available about its diet and reproductive biology in the southern region of Brazil. The analysis of the digestive tube content indicated that the species is a specialist in mammals (Muridae: 80,8 %, Caviidae: 9,6 %, and Didelphidae: 9,6%). Most of the snakes began ingesting the prey at the frontal region of their bodies (93,4 %). The reproductive cycle of this species is long. Vitellogenic follicles were found throughout the year, embryos from November to January, and births were registered in February, March, April, June and August. Males possess an aseasonal reproduction and reach sexual maturity with a shorter snout-vent length than females. The smallest mature male (enlarged and opaque efferent ducts) measured 438 mm in snout-vent length and the smallest female (follicles > 10 mm) measured 701 mm. Adult females storage spermatozoids in the uterus. The number of offspring varied from 5 to 20 and their snout-vent length varied from 146 to 252 mm. Mature females possessed a greater snout-vent length than mature males, but their tails were proportionately smaller.