Chromatic anomalies in Bothrops jararaca (Serpentes, Viperidae): Does xanthism affect survival?

Abstract

This article describes, for the first time, the xanthism in two specimens of B. jararaca. It also describes the snakebite caused by one of these specimens, followed by a discussion on the adaptive advantages (e.g. survival) of such colour anomaly. Biometric length and body mass were taken from two Bothrops jararaca: one male (from Jaraguá do Sul – SC) and one female (from São Roque – SP, responsible for a snakebiting accident) both of which had xanthism. The dissection and analysis demonstrated ovarian follicles in early vitellogenesis, indicative of the reproductive period and with features that never had before been reproduced. Dissection and analysis of the male gonads showed the presence of a convoluted deferent duct, indicative of sexual maturity. There was evident accumulation of abdominal fat and lack of stomach and intestinal contents in both specimens. The snakebite case was typically bothropic, presenting the classical changes seen in this type of snakebite. The results corroborate data in the literature for other cases of xanthism in nocturnal snakes, regarding adult specimens at reproductive age. It was found that the loss of cryptic colouration did not confer any advantages, i.e. xanthism probably altered the chances of survival in snakes not predominantly of nocturnal habit.

Keywords

• adaptation
• natural history
• snakes