Anatomia comparada do neurocrânio em Squatina

Abstract

The Squatiniformes are dorso-ventrally flattened, benthic sharks, and ambush predators. A longstanding debate exists regarding the phylogenetic placement of Squatiniformes relative to other elasmobranchs, with morphological and molecular studies showing extreme divergence. Morphological phylogenetic analyses place Squatiniformes as the sister group to Pristiophoriformes + Batoidea. Molecular phylogenetic analyses position Squatiniformes as the sister group to Pristiophoriformes. Furthermore, the interrelationships among living Squatiniformes are entirely based on molecular studies that exhibit discrepancies. This study conducted a comparative morphological investigation of the neurocranium and brain in Squatina and described the brain of Squatina guggenheim. Despite being relatively well-documented, the neurocranium of elasmobranchs still exhibits morphological variation not explored by previous anatomical studies. The observed variation among Squatina neurocrania was translated into morphological characters, which were subjected to maximum parsimony analysis. The analysis resulted in one more parsimonious tree, which was discussed in comparison with molecular phylogenies.