Phylogenetic analyses were performed on the 17 taxa in the subtribe Brachysternina (Coleoptera: Scarabaeidae: Rutelinae: Anoplognathini) as a means of resolving classification conflicts and of identifying monophyletic groups. Results demonstrated that the subtribe is monophyletic and is composed of three monophyletic genera: Aulacopalpus Guérin-Méneville (nine species), Brachysternus Guérin-Méneville (seven species), and Hylamorpha Arrow (one species). Characters that define the genera are discussed, and the biogeography of the group is discussed.

The genus Aulacopalpus is revised and now includes A. aconcaguensis new species, A. castaneus (Laporte), A. ciliatus (Solier), A. clypealis Ohaus, A. pilicollis (Fairmaire), A. punctatus (Fairmaire and Germain), A. pygidialis Ohaus, A. valdiviensis new species, and A. viridis Guérin-Méneville. The generic name Tribostethes Curtis is placed in synonymy with the valid name Aulacopalpus Guérin-Méneville; the species name Aulacopalpus fulvovirens Ohaus is placed in synonymy with the valid name Aulacopalpus castaneus (Laporte); the species name Amblyterus variabilis Philippi is placed in synonymy with the valid name Aulacopalpus punctatus (Fairmaire and Germain); and the species name Aegolasia michaelseni Kolbe is placed in synonymy with the valid name Aulacopalpus pilicollis (Fairmaire). Aulacopalpus viridis Guérin-Méneville is designated as the type species for the generic name Amblyterodes Germain. Phytholaema herrmanni herrmanni Germain is designated as the type species for the generic name Melicurus Germain, and the genus is transferred from the Brachysternina to the tribe Xylonychini (Scarabaeidae: Melolonthinae) as a junior synonym of the genus Phytholaema Blanchard. A lectotype is designated for each of the following names: Amblyterus variabilis Philippi, Aulacopalpus clypealis Ohaus, Aulacopalpus fulvovirens Ohaus, Aulacopalpus pygidialis Ohaus, Bembegeneius fulvescens Solier, Tribostethes ciliatus Solier, and Tribostethes pilicollis Fairmaire. A neotype is designated for Aegolasia michaelseni Kolbe, Aulacopalpus viridis Guérin-Méneville, Brachysternus castaneus Laporte, Tribostethes punctatus Fairmaire and Germain, and Tribostethes virens Philippi and Philippi. Descriptions of all species are included. A key to the genera of Neotropical Anoplognathini and species in the genus Aulacopalpus is provided.