Megacanthopus rotundicollis Cameron, 1912:216, ♂. ♂, British Guiana (Georgetown Museum); Richards, 1978Richards, O.W. 1978. The social wasps of the Americas excluding the Vespinae. British Museum (Natural History), London. 1-567.:281, Holotype ♀, examined (BMNH). - Meade-Waldo & Morley, 1914Meade-Waldo, G. & C. Morley 1914. Notes and synonymy of Hymenoptera in the collection of the British Museum. The Annals and Magazine of Natural History ser. 8: v. 14:402-410. (distribution), 406 ( listed as synonym of Mischocyttarus labiatus drewseni Saussure, 1857). - As Mischocyttarus rotundicollis: - Richards, 1978Richards, O.W. 1978. The social wasps of the Americas excluding the Vespinae. British Museum (Natural History), London. 1-567. (distribution); Starr & Hook, 2003Starr, C.K. & Hook, A.W. 2003. The aculeate Hymenoptera of Trinidad, West Indies. Occasional Papers o the Department of Life Sciences, University of the West Indies 12:1-31. (distribution); Rasmussen & Asenjo, 2009Rasmussen, C. & A. Asenjo 2009. A checklist to the wasps of Peru (Hymenoptera, Aculeata). ZooKeys 15:1-78. (distribution).
Mischocyttarus gracilis Zikán, 1935:158, Lectotype ♂, examined (Inst. O. Cruz), designated by Richards, 1978Richards, O.W. 1978. The social wasps of the Americas excluding the Vespinae. British Museum (Natural History), London. 1-567.:281. - Richards, 1978Richards, O.W. 1978. The social wasps of the Americas excluding the Vespinae. British Museum (Natural History), London. 1-567.:281 ( listed as synonym of Mischocyttarus rotundicollis (Cameron, 1912)).
Mischocyttarus fumigatus Zikán, 1949:46, Lectotype ♂, examined (Inst. O. Cruz), designated by Richards, 1978Richards, O.W. 1978. The social wasps of the Americas excluding the Vespinae. British Museum (Natural History), London. 1-567.:281. Synonymized with Mischocyttarus rotundicollis (Cameron, 1912) by Richards, 1978Richards, O.W. 1978. The social wasps of the Americas excluding the Vespinae. British Museum (Natural History), London. 1-567.:281.
Mischocyttarus fumigatoides Zikán, 1949:236, Lectotype ♂, examined (Inst. O. Cruz), designated by Richards, 1978Richards, O.W. 1978. The social wasps of the Americas excluding the Vespinae. British Museum (Natural History), London. 1-567.:281. Synonymized with Mischocyttarus rotundicollis (Cameron, 1912) by Richards, 1978Richards, O.W. 1978. The social wasps of the Americas excluding the Vespinae. British Museum (Natural History), London. 1-567.:281.
Mischocyttarus graciloides Zikán, 1949:236, Lectotype ♂, examined (Inst. O. Cruz), designated by Richards, 1978Richards, O.W. 1978. The social wasps of the Americas excluding the Vespinae. British Museum (Natural History), London. 1-567.:281. Synonymized with Mischocyttarus rotundicollis (Cameron, 1912) by Richards, 1978Richards, O.W. 1978. The social wasps of the Americas excluding the Vespinae. British Museum (Natural History), London. 1-567.:281.