Microstructure, evolution, and ontogeny of scale surfaces in cordylid and gerrhosaurid lizards.

The distal oberhautchen and proximal beta layer of 41 species and every genus of cordylid and gerrhosaurid lizard were examined with a scanning electron microscope. Scale organs in these families are concentrated on the face, and scale organs occur singly or in pairs below the keel on the dorsals of cordylids but not gerrhosaurids. Most species examined possess primitive, lenticular scale organs. Unique and previously unknown, projecting scale organs occur in two species of Cordylus. Scale organs appear to be absent in species of Chamaesaura. The scale surfaces of cordylids are covered in macrohoneycomb. Individual compartments of cordylid macrohoneycomb are not intracellular structures but may be overlain by apparent oberhautchen cells. In some cordylid species, part of each cell is free and projects away from the scale surface as a pointed flap. Gerrhosaurids lack macrohoneycomb. Instead, their scale surfaces are covered in lamellae without dentate borders, 50-100 times as long as wide. The epidermis of Platysaurus is unique among cordylids in possessing lamellae 1-8 times as wide as long that overlap macrohoneycomb in some regions of the body. The scale surfaces of Cordylus cordylus undergo an ontogenetic change similar to that recently described for the xenosaurid genus Shinisaurus. Phylogenetic analysis of scale surface features allows the partitioning of Cordylus into three species groups and Chamaesaura into two species groups. Synapomorphies of the species of Chamaesaura, the species of Platysaurus, and the genera of the gerrhosaurids are also described. © 1995 Wiley-Liss, Inc.