Platysaurus

Abstract: The first quantitative data on foraging mode in the cordyliform lizards reveal different foraging behaviours between and within families. All species of cordylids studied (four Cordylus, two Pseudocordylus. and one Platysaurus) are ambush foragers. However, the species of Cordylus and Pseudocordylus microlepidotus are the most extreme ambushers. These species spent a significantly lower per cent time moving than did all of the other species studied and made significantly fewer movements per minute than Platysaurus capensis and gerrhosaurids. In addition, P. microlepidotus made significantly fewer movements per minute than did its congener Pseudocordylus capensis. Possible reasons for the high number of movements per minute in Platysaurus capensis are discussed. Very limited observations of two gerrhosaurid species show that Cordylosaurus subtessellatus is an active forager and Gerrhosaurus validus forages actively at least some of the time. A tentative hypothesis of the evolution of cordyliform foraging behaviour based on very limited data hints that active foraging is plesiomorphic in the Gerrhosaurini and further that gerrhosaurids may have retained active foraging from the common ancestor of Scincidae and Cordyliformes. Somewhat stronger data suggest that ambush foraging arose in the common ancestor of Cordylidae or Cordylinae. Further study is needed to trace inter- and intrageneric changes in foraging mode in cordylids.

Abstract: Mitochondrial DNA sequences were obtained for 16 species representing all nominal genera of Cordylidae (Platysaurus, Chamaesaura, Cordylus, and Pseudocordylus). Gerrhosauridae and Teiidae were used as first and second outgroups. Results indicate that the oviparous Platysaurus is the sister taxon of the remaining cordylids (all of which are ovoviviparous). Within the ovoviviparous group Cordylus is paraphyletic with respect to Chamaesaura and Pseudocordylus. No evidence of Pseudocordylus monophyly was discovered. The three species of Chamaesaura and the seven species of Pseudocordylus are transferred to Cordylus to render a monophyletic taxonomy.

Abstract: Studies of niche overlap within communities of lizards have shown that separation may be along the three major dimensions of space, time and food. Space is usually the most important dimension where a range of habitats are involved; there is less information on the importance of microhabitat separation within a single habitat type. This study investigated microhabitat relationships of small diurnal lizard species occupying granitic rock habitat in Zillmbabwe. There was statistically significant niche separation among all species in both the type of rock occupied (size, shape, number of cracks, closeness to other rocks, and vegeta- tion cover) and the position of the lizard in the microhabitat (height on rock, slope angle, and distance to cover). Overlap of microhabitat was lowest between the generalist terrestrial skink Mabuya varia and all other species. The arboreal skink Mabuya striata was found on rocks at one site where the more saxicolous Mabuva quinquetaeniata was absent, due to competitor release. Overlap of microhabitat among rock specialists was lowest between the sit-and-wait foragers Aganma kirkii and Platysaurus intermedius, as in other tropical lizard communities. The high degree of microhabitat separation was attributed to the high structural complexity of the granitic rock habitat.