Lung-anatomy: aid in Chameleon-taxonomy

Chamaeleo pumilus is often classified in a separate genus Microsaura or Lophosaura, partly because of differences in lung-structure as compared with a small number of other species. The validity of this assumption, that is questioned, is investigated by studying the lungs of 17 species. Apart from the two lung-types of Chamaeleo chamaeleon and Chamaeleo pumilus already known, many other clearly distinguishable lungtypes were found. As similarities in lung-structure tend to coincide with the relationships distinguished by taxonomists, the lungs proved to be a useful character in this yet systematically difficult group. The extensive variation is discussed in view of various processes in action during the evolution of lungs. Thus it became possible to reconstruct two evolutionary lines, viz. a continental and a Malagasy one, within the genus Chamaeleo. The lung-types of the two species mentioned above represent respectively a primitive type in the one and an advanced type in the other line. Therefore the classification of Chamaeleo pumilus in a separate genus is not justified by the lung-anatomy.