Ichneumon atratus Fabricius, 1781:436, sex not indicated.America boreali (Mus. Dom. Yeats); Townes & Townes, 1960Townes, H.K. & M. Townes 1960. Ichneumon-flies of America North of Mexico: 2. Subfamilies Ephialtinae, Xoridinae, Acaenitinae. Bulletin of the United States National Museum 216 (2):1-676.:427, Type ♀ (lost). - As Megarhyssa atrata: - Merrill, 1815Merrill, J.H. 1815. On some genera of the pimpline ichneumonidae. Transactions of the American Entomological Society 91:109-154.:128 (listed); Dalla Torre, 1901-1902Dalla Torre, C.G. 1901-1902. Catalogus Hymenopterorum hucusque descriptorum systematicus et synonymicus. — Volumen III: Trigonalidae, Megalyridae, Stephanidae, Ichneumonidae, Agriotypidae, Evaniidae, Pelecinidae. Pars II. Breitkopf & Härtel, Leipzig. VIII + 1141. (distribution); Rohwer, 1920Rohwer, S.A. 1920. The North American Ichneumon-flies of the tribes Labenini, Rhyssini, Xoridini, Odontomerini, and Phytodietini. Proceedings of the United States National Museum 57:405-474. (distribution); Krombein et al., 1979Krombein, K.V., P.D. Hurd, D.R. Smith & B.D. Burks 1979. Catalog of Hymenoptera in America North of Mexico. Volume 1. Symphyta and Apocrita (Parasitica). Smithsonian Institution Press, Washington D.C. 1-1198. (distribution). - As Megarhyssa atrata atrata: - Townes & Townes, 1960Townes, H.K. & M. Townes 1960. Ichneumon-flies of America North of Mexico: 2. Subfamilies Ephialtinae, Xoridinae, Acaenitinae. Bulletin of the United States National Museum 216 (2):1-676. (distribution).
Ichneumon tenebrator Thunberg, 1822:322 - Townes & Townes, 1960Townes, H.K. & M. Townes 1960. Ichneumon-flies of America North of Mexico: 2. Subfamilies Ephialtinae, Xoridinae, Acaenitinae. Bulletin of the United States National Museum 216 (2):1-676.:427 ( listed as synonym of Megarhyssa atrata atrata (Fabricius, 1781)); Krombein et al., 1979Krombein, K.V., P.D. Hurd, D.R. Smith & B.D. Burks 1979. Catalog of Hymenoptera in America North of Mexico. Volume 1. Symphyta and Apocrita (Parasitica). Smithsonian Institution Press, Washington D.C. 1-1198.:354 ( listed as synonym of Megarhyssa atrata (Fabricius, 1781)); Pook et al., 2016Pook, V.G., M.J. Sharkey & D.B. Wahl 2016. Key to the species of Megarhyssa (Hymenoptera, Ichneumonidae, Rhyssinae) in America, north of Mexico. Deutsche entomologische Zeitschrift 63 (1):137-148.:140 ( listed as synonym of Megarhyssa atrata (Fabricius, 1781)).
Rhyssa laevigata Brullé, 1846:78, ♂. Holotype ♂, Amérique septentrionale (M. Serville, leg. Bastard), Lectotype ♂ (Paris), designated by Townes & Townes, 1960Townes, H.K. & M. Townes 1960. Ichneumon-flies of America North of Mexico: 2. Subfamilies Ephialtinae, Xoridinae, Acaenitinae. Bulletin of the United States National Museum 216 (2):1-676.:427. - Townes & Townes, 1960Townes, H.K. & M. Townes 1960. Ichneumon-flies of America North of Mexico: 2. Subfamilies Ephialtinae, Xoridinae, Acaenitinae. Bulletin of the United States National Museum 216 (2):1-676.:427 ( listed as synonym of Megarhyssa atrata atrata (Fabricius, 1781)); Krombein et al., 1979Krombein, K.V., P.D. Hurd, D.R. Smith & B.D. Burks 1979. Catalog of Hymenoptera in America North of Mexico. Volume 1. Symphyta and Apocrita (Parasitica). Smithsonian Institution Press, Washington D.C. 1-1198.:354 ( listed as synonym of Megarhyssa atrata (Fabricius, 1781)); Pook et al., 2016Pook, V.G., M.J. Sharkey & D.B. Wahl 2016. Key to the species of Megarhyssa (Hymenoptera, Ichneumonidae, Rhyssinae) in America, north of Mexico. Deutsche entomologische Zeitschrift 63 (1):137-148.:140 ( listed as synonym of Megarhyssa atrata (Fabricius, 1781)).
Megarhyssa atrata lineata Porter, 1957:206, Townes & Townes, 1960Townes, H.K. & M. Townes 1960. Ichneumon-flies of America North of Mexico: 2. Subfamilies Ephialtinae, Xoridinae, Acaenitinae. Bulletin of the United States National Museum 216 (2):1-676.:426, Types 2 ♀♀ (New York). Synonymized with Megarhyssa atrata (Fabricius, 1781) by Krombein et al., 1979Krombein, K.V., P.D. Hurd, D.R. Smith & B.D. Burks 1979. Catalog of Hymenoptera in America North of Mexico. Volume 1. Symphyta and Apocrita (Parasitica). Smithsonian Institution Press, Washington D.C. 1-1198.:354. - Townes & Townes, 1960Townes, H.K. & M. Townes 1960. Ichneumon-flies of America North of Mexico: 2. Subfamilies Ephialtinae, Xoridinae, Acaenitinae. Bulletin of the United States National Museum 216 (2):1-676. (distribution); Pook et al., 2016Pook, V.G., M.J. Sharkey & D.B. Wahl 2016. Key to the species of Megarhyssa (Hymenoptera, Ichneumonidae, Rhyssinae) in America, north of Mexico. Deutsche entomologische Zeitschrift 63 (1):137-148.:140 ( listed as synonym of Megarhyssa atrata (Fabricius, 1781)).