Three new species of Onthophagus Latreille, 1802 from Bioko Island, Equatorial Guinea, belonging to d'Orbigny's group IX, with a taxonomic note on O. denudatus d'Orbigny, 1902 (Coleoptera: Scarabaeidae: Scarabaeinae: Onthophagini). - Génier F (Zootaxa, 2026)