ECOLOGY OF THAMNODYNASTES HYPOCONIA IN SUBTROPICAL-TEMPERATE SOUTH AMERICA

BELLINI, GISELA P.; ARZAMENDIA, VANESA; GIRAUDO, ALEJANDRO R

HERPETOLOGICA

HERPETOLOGISTS LEAGUE

Lugar: Lawrence; Año: 2013 vol. 69 p. 1 - 34

0018-0831

The ecology of the genus Thamnodynastes has received little study and problems 20 with its taxonomy have generated imprecise and incorrect data. We analyzed the reproductive 21 biology, sexual dimorphism, feeding ecology, habitat use and seasonal activity of 22 Thamnodynastes hypoconia, in its subtropical-temperate area of distribution. We discuss its main 23 ecological traits in light of the competition?predation and the deep history hypotheses. Males and 24 females attained sexual maturity at different body sizes, with females the largest. The sexual 25 dimorphism seen in this species is rare among viviparous snakes since the males and females had 26 no difference in the body size and males had more ventral scales than the females do. The 27 females? reproductive cycle was seasonal and not annual, with parturition occurring in summer; 28 while the cycle of the males was continuous. Thamnodynastes hypoconia feeds mainly 29 amphibians (97%) and occasionally on lizards (3%). As in other Thamnodynastes snakes, anuran 30 hylids were the most common type of prey consumed (34%). Thamnodynastes hypoconia is 31 primarily a twilight-nocturnal species that inhabits wetlands (large rivers and its floodplains), 32 where its prey is abundant. Its activity was seasonal, with a high number of individuals 33 encountered during the warm months. The similarity between the natural history traits of T. 34 hypoconia (anurophagy, seasonal reproductive cycle, aquatic and nocturnal habits) and other 35 species of the genus suggests there is phylogenetic conservatism, mainly of its ecomorphological 36 traits, a pattern commonly reported for Dipsadidae snakes.