Head co-ossification, phragmosis and defence in the casque-headed tree frog Corythomantis greeningi

Some anurans have a peculiar casqued head with the skin co-ossified with the underlying bones. This type of skull usually is associated with phragmosis, a protective behaviour in which the animal enters a hole and closes it with the head. Although co-ossification of the head in lissamphibians frequently has been associated with water economy, recent studies of Corythomantis greeningi, a casque-headed tree frog from semi-arid areas in north-eastern Brazil. suggest that cranial co-ossification contributes little to conservation of water in the frog. Instead. during phragmatic behaviour. the co-ossified head protects the animal against predators and indirectly enhances water balance. Thus, the primary role of co-ossification is defence, a hypothesis that is the focus of this study which describes die morphology of the head of C. greeningi with all emphasis on the co-ossification and the venom glands. We report on behavioural features and on the toxicity of the cutaneous secretion produced by the abundant venom glands that are associated with large spicules oil the skull.Inst Butantan, Lab Biol Celular, BR-05503900 São Paulo, BrazilUniv São Paulo, Inst Biociencias, Dept Fisiol, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Morfol, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Ctr Microscopia Eletron, São Paulo, BrazilInst Butantan, Lab Imunoquim, BR-05503900 São Paulo, BrazilUniv São Paulo, Inst Biociencias, Dept Zool, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Morfol, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Ctr Microscopia Eletron, São Paulo, BrazilWeb of Scienc