Aspects of reproduction and sexual dimorphism of Lygophis flavifrenatus (Dipsadidae: Xenodontinae)

Abstract

Lygophis flavifrenatus Cope, 1862 is a terrestrial dispsadid distributed in subtropical Brazil, Paraguay, Uruguay, and Argentina. Herein, we present data on sexual dimorphism and reproductive biology of this very poorly studied species. A total of 108 specimens (55 females, 50 males, three hatchlings with unidentified sex) from Brazilian states of Rio Grande do Sul, Santa Catarina and Mato Grosso do Sul were analyzed. Sexual dimorphism by size, body dimensions (tail length, head length, head width) and a number of ventral and subcaudal scales is not well marked in the species. Mature females attain the greater size and have a higher number of ventral scales than mature males. Mature males, in turn, presented longer tail, longer and wider head and a higher number of subcaudal scales. Meanwhile, marked overlaps were observed in ranges of all body dimensions proportions and a number of ventral and subcaudal scales. Females attained sexual maturity at a greater size than males. The smallest mature female showed snout-vent length (SVL) = 402 mm while the smallest mature male presented SVL = 285 mm. Females presented a seasonal reproductive cycle, with advanced stages (advanced development of secondary follicles and development of eggs) occurring in late winter and spring. Hatchlings were found in late summer. It is supposed that only one clutch is laid per cycle, considering that the great majority of secondary follicles found in females carrying eggs were irregular or lamellar shaped (possibly atresic). Clutch sizes varied from 6 to 12 eggs (mean = 8.2) and presented a tendency for positive correlation with progenitors SVL. The present study adds new information to the knowledge about the natural history of snakes from subtropical Neotropics.