Synopsis of the Oryctini (Coleoptera: Scarabaeidae: Dynastinae) from the Brazilian Amazon Author Alvarez, Héctor Jaime Gasca Instituto Nacional de Pesquisas da Amazônia-INPA Coordenação de Pesquisas em Entomologia Av. André Araújo, 2936 - Petrópolis CEP 69011 - 970 Manaus, Amazonas, Brazil Author da, Claudio Ruy Vasconcelos Instituto Nacional de Pesquisas da Coordenação de Pesquisas em Av. André Araújo, 2936 - Petrópolis CEP 69011 - 970 Manaus, Amazonas Author Fonseca Amazônia-INPA Entomologia Petrópolis, Brazil Author Ratcliffe, Brett C. University of Nebraska State Museum W 436 Nebraska Hall Lincoln, NE 68588 - 0514, USA text Insecta Mundi 2008 2008-12-05 2008 61 1 62 journal article 10.5281/zenodo.5352440 1942-1354 5352440 Key to the species of adult Megaceras of Brazilian Amazonia 1. Apex of clypeus with 2 teeth ( Fig. 59 ). Mandibles with 2 subequal teeth with acuminate apex ... ........................................................................................................... M. philoctetes (Olivier) — Apex of clypeus truncate or slightly emarginate. Mandibles with 2 teeth different in size ....... 2 2(1). Elytra with sutural stria slightly impressed or absent. Head horn with apex rounded or slightly acuminated. Pygidium of females with strong transverse furrow ( Fig. 54 ), anterior half concave in lateral view .......................................................................................... M. laevipenne Prell —- Elytra with sutural stria impressed. Head horn with apex slightly bilobed or strongly bifurcate. Pygidium of females covex in lateral view ............................................................................... 3 3(2). Apex of head horn slightly bilobed. Horns of pronotal prominence subparallel, curved down. Pronotum of females with 2 tubercles. Pronotum of females with 2 tubercles behind anterior margim and with a slight furrow between them ........................................ M. crassum Prell —- Apex of pronotal horn bifurcate. Horns of pronotal prominence divergent, strongly curved down. Pronotum of females with 2 conical tubercles behind anterior margin, without slight furrow between them ............................................................................................. M. stuebeli Kirsch