A taxonomic revision of occurring in Brazil with an interactive key and remarks on New World Diplotaxini (Coleoptera, Melolonthidae).

Guérin-Méneville, 1831 is the major genus of Neotropical Diplotaxini, with 78 species distributed from Panama to southern Argentina and Chile, except for Ecuador. Due to the large numbers of both described and undescribed species, as well as its agricultural importance, mainly of those in Brazil, was redefined and redescribed. Nine new species are described: Cherman, , Cherman, , Cherman, , Cherman, , Cherman, , Cherman, , Cherman, , Cherman, , and Cherman, All the new species are Brazilian, except for the last one, which is Argentinian. Twenty-three Brazilian species are redescribed and illustrated. Five new synonyms are proposed, and 19 lectotypes are designated. New geographical distribution records for 19 species are presented, as well as a key to New World Diplotaxini and Brazilian species of .