A tale of lost tails: pseudoautotomy in the Neotropical snake genus Drymoluber (Serpentes: Colubridae)

摘要

Pseudoautotomy (no spontaneous tail breakage without regeneration) occurs in the snakes Drymoluber brazili (Gomes, 1918) and Drymoluber dichrous (Peters, 1863) throughout their geographic range. Examination of 197 specimens of D. dichrous and 60 D. brazili show, respectively, a frequency of tail breakage (FTB) in 26% and 40% of specimens, similar or higher than observed for most species with pseudoautotomy. There is no sexual difference in FTB for D. brazili, and no relationship between tail breakageand snout-vent length (SVL). For D. dicrous, tail breakage is more frequently observed in males when specimens are <710 mm SVL, but for longer specimens, the FTB is higher in females; this strange pattern may not be explained by a single hypothesis. TheFTB does not vary significantly between disjunct populations of D. dichrous, suggesting that they are subject to similar prédation pressures and escape rates, or minor or no effect of habitat structure on prédation risk. The FTB increases with SVL inD. dichrous (but not in D. brazili, probably due to sample size), which is an indication that as the snake grows, the chance of being injured increases and partial tail loss becomes an efficient defense. The multiple tail break hypothesis is not supported for the genus Drymoluber Amaral, 1930, remaining restricted to taxa with specialized pseudoautotomy.