Integrative taxonomy of the genus Buchannan, 1800 (Mollusca, Gastropoda, Pulmonata, Onchidiidae).

In an effort to clarify the species diversity of onchidiid slugs, the taxonomy of the genus Buchannan, 1800 is revised using an integrative approach. New, fresh specimens were collected in a large number of places, including type localities. The genus is redefined here as a clade including only three species which are strongly supported by both morphological and molecular data. All three species were already named: the type species Buchannan, 1800, (Westerlund, 1883), and (J.E. Gray, 1850). With the exception of a re-description of published in 1869, all three species are re-described here for the first time. First-hand observations on the color variation of live animals in their natural habitat are provided. The anatomy of each species is described. Important nomenclatural issues are addressed. In particular, Starobogatov, 1976 is regarded as a junior synonym of and (Labbé, 1935) and (Plate, 1893) are regarded as junior synonyms of . The nomenclatural status of several other species names is discussed as well. Many new records are provided across South-East Asia and precise ranges of geographic distributions are provided for the genus and its three species. Distinctive features that help distinguish the genus from other onchidiids are provided, as well as an identification key for the three species.