Patterns of geographic variation in 10 morphometric characters were analyzed in a sample of 91 specimens of the batfish, Ogcocephalus vespertilio (L.), from the NE and SE Brazilian coast, using multivariate statistics and randomization tests. The specimens were ordinated by principal components analysis in two groups corresponding to the regions north and south of the 23ºC isotherm, and size variation was found to account for 70.3%, whereas shape differences accounted for 23.6% of the total variation in morphometric characters. The two groups were different at the 1% significance level by multivariate analysis of variance based on the Wilk's criterion, tested by a randomization procedure. Width of illicial cavity and distance from anus to anal fin were the characters most contributing to the differentiation of the population samples.
Ogcocephalidae; Ogcocephalus; geographic variation; multivariate morphometrics; randomization tests