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A revision of the generic classification of the tribe Macrodactylini is provided using morphological characters of adults. The revision is based on a taxonomic analysis of 80 genera historically placed in the tribe and a cladistic analysis of 32 genera conforming to the new tribal definition. Synapomorphies for the newly defined Macrodactylini include: the length of the fifth ventrite longer than the fourth ventrite when viewed ventrally, fifth ventrite lacking a complete suture between the tergite and sternite, and the metathoracic tibial spurs (if present) offset, allowing the metatarsus to move past them. Thirty-two genera constitute the newly defined Macrodactylini: Agaocnemis Moser, Alvarinus Blanchard, Ancistrosoma Curtis, Anomonyx Saylor, Anoplosiagum Blanchard, Astaenosiagum Martínez, Barybas Blanchard, Calodactylus Blanchard, Ceraspis Le Peletier and Serville, Ceratolontha Arrow, Chariodactylus Moser, Chariodema Blanchard, Chremastodus Solier, Clavipalpus Laporte, Ctenotis Burmeister, Dasyus Le Peletier and Serville, Dicrania Le Peletier and Serville, Gama Blanchard, Gastrohoplus Moser, Hercitis Burmeister, Hieritis Burmeister, Isonychus Mannerheim, Issacaris Fairmaire, Macrodactylus Dejean, Manodactylus Moser, Manopus Laporte, Oedichira Burmeister, Pectinosoma Arrow, Plectris Le Peletier and Serville, Pristerophora Harold, Rhinaspis Perty, and Schizochelus Blanchard. Sixteen genera are removed or their removal is confirmed from the historical Macrodactylini: Coenonycha Horn, Dichelonyx Harris, and Gymnopyge Linell (to Dichelonychini), Homalochilus Blanchard, Homoliogenys Gutiérrez, Liogenys Guérin-Méneville, and Pacuvia Curtis (to Diplotaxini), Diphycerus Deyrolle and Fairmaire (to Diphycerini), Hyperius Deyrolle and Fairmaire (to Melolonthini), Apterodemidea Gutiérrez (to Sericoidini), Blepharotoma Blanchard (to Liparetrini ), Diaphylla Erichson (removed from Macrodactylini, and currently unplaced into existing melolonthine tribes), Hilarianus Blanchard, Manonychus Moser, Pseudoisonychus Frey (removed from Macrodactylini, and currently unplaced into existing melolonthine tribes) and Zabacana Saylor (to Epectinaspis (Rutelinae)). Nine new generic synonyms are proposed: Corminus Burmeister, junior synonym of Alvarinus Blanchard; Ctilocephala Burmeister, Eubarybas Gutiérrez, and Pseudohercitis Moser, each a junior synonym of Barybas Blanchard; Byrasba Harold, Rhinaspoides Moser, and Ulomenes Blanchard, each a junior synonym of Rhinaspis Perty; Demodema Blanchard, a junior synonym of Plectris Le Peletier and Serville; and Pachylotoma Blanchard, junior synonym of Gama Blanchard. Eight previously proposed synonyms are confirmed: Amphicrania Burmeister, junior synonym of Clavipalpus Laporte; Chlaeobia Blanchard a junior synonym of Phyllophaga Harris; Dioplia Burmeister, junior synonym of Calodactylus Blanchard; Faula Blanchard junior synonym of Ceraspis Le Peletier and Serville; Dejeania Blanchard, preoccupied name and junior synonym of Dichelomorpha Burmeister; Harpodactyla Burmeister, junior synonym of Gama Blanchard; and Microcrania Burmeister, junior synonym of Barybas Blanchard. The removal of Philochloenia (junior synonym of Dichelonyx) is noted. Fifteen genera remain incertae sedis due to lack of adequate study material or insufficient information on their possible removal from Macrodactylini: Acanthosternum Philippi (junior synonym of Modialis, Smith and Evans 2005), Anomalochilus Blanchard, Astaenoplia Martínez, Aulanota Moser, Canestera Saylor, Dichelomorpha Burmeister, Diphydactylus Thomson, Hadrocerus Guérin-Méneville, Hamatoplectris Frey, Mallotarsus Blanchard, Metaceraspis Frey, Paulosawaya Martínez and D’Andretta, Pseudodicrania Gutiérrez, Pseudoleuretra Martínez and D’Andretta and Xenoceraspis Arrow. A diagnosis for the thirty-two genera comprising the Macrodactylini is presented and key characters are illustrated. A key to the genera and hypothesized phylogeny of Macrodactylini is provided.