MICROSTRUCTURE, EVOLUTION, AND ONTOGENY OF SCALE SURFACES IN CORDYLIDAND GERRHOSAURID LIZARDS

The distal oberhautchen and proximal beta layer of 41 species and ever y genus of cordylid and gerrhosaurid lizard were examined with a scann ing electron microscope. Scale organs in these families are concentrat ed on the face, and scale organs occur singly or in pairs below the ke el on the dorsals of cordylids but not gerrhosaurids. Most species exa mined possess primitive, lenticular scale organs. Unique and previousl y unknown, projecting scale organs occur in two species of Cordylus. S cale organs appear to be absent in species of Chamaesaura. The scale s urfaces of cordylids are covered in macrohoneycomb. Individual compart ments of cordylid macrohoneycomb are not intracellular structures but may be overlain by apparent oberhautchen cells. In some cordylid speci es, 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 c ordylids in possessing lamellae 1-8 times as wide as long that overlap macrohoneycomb in some regions of the body. The scale surfaces of Cor dylus 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 thr ee species groups and Chamaesaura into two species groups. Synapomorph ies of the species of Chamaesaura, the species of Platysaurus, and the genera of the gerrhosaurids are also described. (C) 1995 Wiley-Liss, Inc.