Meeting Abstract

102.3  Saturday, Jan. 7  Phylogenetic implications of the morphology of the braincase of caecilian amphibians (Gymnophiona) MADDIN, HC*; RUSSELL, AP; ANDERSON, JS; University of Calgary; University of Calgary; University of Calgary

Currently, phylogenetic analyses of characters drawn from the morphology of caecilians lack resolution, as well as complementarity, with results of phylogenetic analyses that employ molecular data. Stemming from the hypothesis that the braincase has the potential to yield phylogenetic information, the braincases and intimately associated stapedes of twenty-seven species (twenty-three genera) of extant caecilians, and one fossil stem-caecilian (Eocaecilia micropodia), were examined using images assembled via micro-computed tomography. Thirty-two new morphological characters pertaining to the braincase and stapes were identified and tested for congruence with previously recognized morphological character states. The results reveal that characters of the braincase and stapes resolve generic-level relationships in a way that is largely congruent with the results of molecular analyses. The results of a combined analysis of molecular and morphological data provide a framework for conducting ancestral character state reconstructions and permit the generation of a hypothesis relating to the plesiomorphic condition of the caecilian braincase, which bears relevance to ongoing discussions about lissamphibian phylogeny. The current analyses also resulted in the identification of 70 new synapomorphies for various clades of taxa, 24 of which appear to be unique for the taxa that possess them. Together these data demonstrate the utility of the application of characters of the braincase and stapes for resolving phylogenetic relationships in this group, and provide a framework for future evolutionary studies.