Treefrog toe pads: comparative surface morphology using scanning electron microscopy

Abstract

Scanning electron microscopy of toes and toe pads of a large number of species of frogs reveals many features of possible systematic or functional significance. The adhesive pads evolved through progressive development of specialized columnar epidermis at the digital tips, in tandem with increased arborealism. Mucous pore morphology and density on the pads will distinguish between evolutionarily convergent hylid and rhacophorid treefrogs. Larger pads and accessory adhesive areas on subarticular tubercles allow large treefrogs to compensate for allometric increase in mass relative to surface area. Other characters of potential systematic or evolutionary significance are discussed. As anuran toe pads have been used previously for systematics, the use of scanning electron microscopy in this regard is advocated.