Polymorphism and synonymy of Brookesia antakarana and B. ambreensis, leaf chameleons from Montagne d'Ambre in north Madagascar.

We examine the taxonomic status of two Malagasy leaf chameleon taxa, Brookesia antakarana Raxworthy & Nussbaum, 1995 and B. ambreensis Raxworthy & Nussbaum, 1995, integrating morphological and genetic evidence. Specimens assigned to these species occur in syntopy in Montagne d'Ambre, northern Madagascar, and were originally described based on differences in the shape of their pelvic shields. We found that the shape of these shields falls on a continuous spectrum, and detected only weak differences between the two taxa in a few other morphological features, all of which were correlated with shield length. Members of the two taxa (as assigned based on pelvic shield morphology) also showed extensive haplotype sharing in one nuclear and one mitochondrial marker. We conclude that at present there is no convincing evidence that these species are distinct, and act as first revisers in the sense of the International Code of Zoological Nomenclature to place B. ambreensis into the synonymy of B. antakarana [ABSTRACT FROM AUTHOR]