Reproductive aspects of the semi-aquatic snake Erythrolamprus miliaris (Dipsadidae: Xenodontini) in the state of Rio de Janeiro, southeastern Brazil

Abstract: We analyzed some aspects of reproduction and sexual dimorphism of the semi-aquatic dipsadid snake Erythrolamprus miliaris in the state of Rio de Janeiro, southeastern Brazil. We detected sexual dimorphism in body size (snout-vent length), with females averaging larger than males, but no sexual dimorphism in the relative length of the tail. Oviductal eggs and secondary follicles were found in all seasons, suggesting that female reproductive cycles are continuous, in spite of the tropical seasonal climate in the region. Reproductive males were present throughout the year, suggesting a continuous cycle for males as well. Clutch size averaged 10.3 ± 4.8 (range 4-21) and there was a positive and significant relationship between clutch size and female size. Compared to conspecific populations previously studied in other Atlantic Rainforest areas, populations of E. miliaris from the state of Rio de Janeiro appear more similar overall in their reproductive traits to a more northern population from the state of Bahia than to populations from further south in the states of São Paulo and Paraná.

摘要：我们针对巴西东南部里约热内卢州境内的半水栖钝头蛇科（Dipsadidae）物种米氏红游蛇（Erythrolamprus miliaris）的繁殖与性别二态性特征展开了系统分析。研究发现该物种在体长（吻肛长，snout-vent length）上存在显著性别二态性：雌性个体平均体长大于雄性，但其尾部相对长度未表现出性别差异。尽管该区域属于热带季节性气候，但全年各季节均能检测到输卵管内的卵与次级卵泡，这表明雌性繁殖周期为连续性周期。全年均可发现处于繁殖活跃状态的雄性个体，提示雄性同样存在连续性繁殖周期。该物种的窝卵数平均值为10.3±4.8（范围4~21），且窝卵数与雌性个体体长呈显著正相关关系。相较于此前在其他大西洋热带雨林区域开展研究的同种种群，里约热内卢州的E. miliaris种群在繁殖特征整体上与北部的巴伊亚州种群更为相似，而与更南部的圣保罗州及巴拉那州种群差异更为显著。