Keratodont formulae in anuran tadpoles: proposals for a standardization

Abstract

The various systems proposed to describe concisely, in the form of a formula, the number and arrangement of keratodont rows in the oral disk of anuran tadpoles, are reviewed and classified. A distinction is made between individual and collective keratodont formulae. The different systems are compared and evaluated, and proposals are made to standardize the use of various signs, numerals and letters in keratodont formulae. Nine standardized systems (seven all-cardinal and two cardinal-ordinal systems) are finally retained: these should cover all needs according to the kind of use and the level of precision required.