Neuroanatomy of the lumbosacral plexus in a highly diversified clade of South‐American lizards. Evolution and phylogenetic implications

QUIPILDOR, ANGEL MATÍAS; QUINTEROS, ANDRÉS SEBASTIÁN; LOBO, FERNANDO JOSÉ

JOURNAL OF MORPHOLOGY

WILEY-LISS, DIV JOHN WILEY & SONS INC

Año: 2020 vol. 281 p. 970 - 985

0362-2525

Only few published studies that describe the neuroanatomy of lizards. Here, wedescribe the neuroanatomy of several Iguanian species belonging to three families(species of Liolaemus and Phymaturus belonging to Liolaemidae, Tropidurus andStenocercus as representatives of Tropiduridae, and Diplolaemus as a representativeof Leiosauridae). Based on Sudan Black B staining and conventional dissections, theneuroanatomy of the lumbosacral region is described. Among the most outstandingresults is the existence of a neuronal pattern of the lumbosacral plexus characteristicof Liolaemidae. In addition, it was found that in the genus Liolaemus the lumbosacralplexus is composed of five pairs of spinal nerves while in Phymaturus, Tropidurus,Stenocercus and Diplolaemus is composed from five to six pairs of spinal nerves (frompre-sacral, sacral, and caudal vertebrae). We find differences in the origin of the spinalnerves that constitute the plexus. In some cases, the pattern of nerves involvedincludes even the caudal vertebrae. Variation among taxa related to the zeugopodialinnervation is described, and the homology of these nervous branches is discussed.Sexual differences were found in some species studied. Based on our results andavailable literature, we found three different patterns of innervation of thezeugopodium. The major contribution of this study is to provide a detailed descriptionof lumbosacral plexus nerves pathways from their origins at the vertebral columnto the muscles that they innervate.