Reproductive and feeding biology of the common lancehead Bothrops atrox (Serpentes, Viperidae) from central and southwestern Brazilian Amazonia

ABSTRACT The pitviper Bothrops atrox is a widely distributed and medically important snake in Amazonia. Given that the reproductive and feeding biology of snakes varies geographically, we aimed to characterize the natural history of individuals from the central and southwestern portions of the biome. We analyzed museum-preserved specimens collected in the region between the metropolitan areas of the Brazilian cities of Manaus and Porto Velho. We took morphometric measurements and performed the analysis of gonads and digestive tracts of 109 individuals. Females attain sexual maturity with larger body sizes. Adults of the species show pronounced sexual dimorphism in body size, with females being larger. The reproductive cycle, especially in males, appears to be synchronized with regional rainfall, which markedly differed across the biome. The pitvipers had a generalist diet, consuming a wide range of prey such as centipedes, frogs, lizards, snakes and mammals. We provide the first record of predation of the snake Imantodes cenchoa (Dipsadidae) by B. atrox. There was an ontogenetic shift in the diet: smaller individuals fed mainly on ectothermic prey (centipedes, frogs, lizards and snakes), while adults tended to incorporate endothermic prey (mammals) to their food repertoire.

摘要 矛头蝮（Bothrops atrox）是亚马逊流域分布广泛且具有重要医学意义的蛇类。鉴于蛇类的繁殖与摄食生物学特征存在地理变异，本研究旨在阐明该生物群系中部及西南部地区该物种的自然历史特征。我们对采集自巴西马瑙斯（Manaus）与波多韦柳（Porto Velho）两市都市区之间区域的馆藏标本展开研究，对109个个体进行了形态测量学分析，并对其生殖腺与消化道开展了解剖分析。结果显示，雌性个体性成熟时的体型更大；该物种成体存在显著的体型性二态性，雌性体型大于雄性。其繁殖周期（尤其是雄性个体）似乎与区域降雨节律同步，而该生物群系内不同子区域的降雨特征差异显著。该矛头蝮为广食性物种，摄食类群广泛，涵盖蜈蚣、蛙类、蜥蜴、蛇类及哺乳类等多种猎物；本研究首次报道了矛头蝮（B. atrox）捕食钝头蛇科（Dipsadidae）物种Imantodes cenchoa的现象。其食性存在显著的个体发育转变：小型个体主要以变温猎物（蜈蚣、蛙类、蜥蜴及蛇类）为食，而成体则倾向于将恒温猎物（哺乳类）纳入自身食谱范围。