The Herpetological Journal

Authors: Roberta Ferreira Abecassis, Alfredo P. Santos-Jr, Lucas Vinicius Cavalcante Esteves, Advanio Inácio Siqueira-Silva, Selma Maria Almeida-Santos & Síria Ribeiro

Abstract: We studied the sexual dimorphism and reproductive cycle of Amphisbaena brasiliana, based on specimens from the municipality of Santarém, Pará state, Brazil, and tested whether precipitation affects the cycle. We accessed and analysed 143 individuals (73 males, 70 females), deposited in scientific collections between 1999 and 2021. We analysed: snout-vent length (SVL), testicular length, width and height, condition of the ductus deferens (convoluted or non-convoluted), diameter of the ductus deferens in the medial and distal portion, condition of the oviducts (convoluted or non-convoluted), length of the largest follicle and number of primary and secondary follicles (vitellogenic follicles). The SVL of females ranged from 149.10–363.11 mm, with 46 specimens (66%) being mature (smallest adult female = 246.46 mm). Male SVL ranged from 123.31–337.26 mm, with 42 (58%) being mature (smallest adult male = 242.0 mm). The sample does not present significant variation in sexual dimorphism analysed in SVL (Mann-Whitney: P = 0.932). Testicle volume and ductus deferens diameter varied seasonally, with the highest values recorded from August to December, during the low rainfall period. Spermatozoa were recorded in the ductus deferens during the low rainfall months in the region, especially in September, when we observed more individuals with ductus deferens convoluted, which may indicate spermatozoa storage. The testicular volume and the diameter of the ductus deferens in the medial and distal portions are related to the period of lower precipitation (ANOVA: P = 2.1 x 10-5; P = 5.18 x 10-6; P = 1.56 x 10-5, respectively). We recorded oviductal eggs in one specimen in December, in addition to the record of vitellogenic follicles in September, October and December, which allows us to interpret a peak of development in the period of lower precipitation, coinciding with the results for males of the species. Our results suggest that the reproductive cycle of the population of A. brasiliana analysed may be influenced by regional rainfall, being seasonal.

Keywords: Amazon, Amphisbaenia, natural history, reproductive cycle, spermatogenesis