A Preliminary Survey of Dermatoglyphic Variation in the Lizard Genus Sceloporus

Abstract

Scanning electron microscopy of the outer surface of midlateral scales of 51 species of Sceloporus (%3/4 of those now known), representing all 15 groups (as of Smith, 1939) of the genus, suggests that dermatoglyphics are of no apparent diagnostic value at higher taxonomic levels in the genus Sceloporus, but may be very useful at the subspecies, species and species-group levels. Microornamentation of scale surfaces is seemingly unidirectional in evolution. Three variables are useful in systematic considerations in Sceloporus: degree of concavity of Oberhautchen cell surfaces, degree of overlap of cell boundaries, and degree of loss of spinules and reduction of surface pits; cristae occur in those species with the greatest cell-surface cavitation. All species examined exhibit Oberhautchen cell boundaries, much the same in size and shape. Dense spinulation, flat cell surfaces and lack of imbrication are primitive character-states in Sceloporus. * ** Most of the recent contributions to the rapidly-growing body of literature on the squamate integument centers upon the morphology of the ecdysis cycle (summarized by Maderson et al., 1972) and the range of dermatoglyphic variation as revealed by scanning electron microscopy (SEM) of scattered samples from lizards and snakes (summarized by Stewart and Daniel, 1973). No attempt has hitherto been made to explore the systematic significance of dermatoglyphic (DG) variation in either a broad (higher category) or narrow (intrageneric) perspective. Because of the long-standing interest of one of us in the systematics of Sceloporus (e.g., Smith, 1939), and the current explosion of investigation in that topic, we have attempted a survey of variation among the some 70 species now recognized in this genus