Ichneumon lunator Fabricius, 1781:430,America boreali (Mus. Dom. Yeats); Merrill, 1815Merrill, J.H. 1815. On some genera of the pimpline ichneumonidae. Transactions of the American Entomological Society 91:109-154.:133, There seems to be no record of the present location of the type; 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.:430, Type ♀ (lost). - 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 macrurus macrurus (Linnaeus, 1771)). - As Megarhyssa lunator: - Merrill, 1815Merrill, J.H. 1815. On some genera of the pimpline ichneumonidae. Transactions of the American Entomological Society 91:109-154.:133 (listed). - As Megarhyssa macrurus lunator: - 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). - As Thalessa lunator: - Cresson, 1872Cresson, E.T. 1872. Hymenoptera Texana. Transactions of the American Entomological Society 4:153-292. (distribution); Morley, 1913Morley, C. 1913. A revision of the Ichneumonidae based on the collection in the British Museum (Natural History) with descriptions of new genera and species. Part II: Tribes Rhyssides, Echtrhomorphides, Anomalides and Paniscides. British Museum, London, England. 1-140. (distribution).
Thalessa histrio Kriechbaumer, 1890:487, 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.:430, Type ♂ (Vienna). - 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.:430 ( listed as synonym of Megarhyssa macrurus lunator (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.:355 ( listed as synonym of Megarhyssa macrurus macrurus (Linnaeus, 1771)); 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.:143 ( listed as synonym of Megarhyssa macrurus lunator (Fabricius, 1781)); Khalaim et al., 2021Khalaim, A.I., E. Ruíz-Cancino & J.M. Coronado-Blanco 2021. Darwin wasps of Mexico (Hymenoptera: Ichneumonidae): the subfamily Rhyssinae. Russian Entomological Journal 30 (3):305-313.:311 ( listed as synonym of Megarhyssa macrurus (Linnaeus, 1771)).