Rostral horn evolution among agamid lizards of the genus Ceratophora endemic to Sri Lanka.

The first phylogenetic hypothesis for the Sri Lankan agamid lizard genus Ceratophora is presented based on 1670 aligned base positions (472 parsimony informative) of mitochondrial DNA sequences, representing coding regions for eight tRNAs, ND2, and portions of ND1 and COI. Phylogenetic analysis reveals multiple origins and possibly losses of rostral horns in the evolutionary history of Ceratophora. Our data suggest a middle Miocene origin of Ceratophora with the most recent branching of recognized species occurring at the Pliocene/Pleistocene boundary. Haplotype divergence suggests that an outgroup species, Lyriocephalus scutatus, dates at least to the Pliocene. These phylogenetic results provide a framework for comparative studies of the behavioral ecological importance of horn evolution in this group.