Bassus maculifrons Cresson, 1865:272, ♀. Holotype ♀, Colorado Territory, 1864 (leg. Mr. James Ridings). - Cresson, 1868Cresson, E.T. 1868. A list of Ichneumonidae of North America, with descriptions of new species. Part II. Transactions of the American Entomological Society 2:89-114. (distribution). - As Syrphoctonus maculifrons: - 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); 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); Ruíz-Cancino et al., 2002Ruíz-Cancino, E., D.R. Kasparyan & J.M. Coronado Blanco 2002. Ichneumonidae. In: Llorente Bousquets, J. & J.J. Morrone (Ed.). Biodiversidad, taxonomía y biogeografía de artrópodos de México: Hacia una síntesis de su conocimiento, volumen III. 631-646. (distribution).
Bassus semifasciatus Walsh, 1873:87, ♂. Holotype ♂. - 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.:717 ( listed as synonym of Syrphoctonus maculifrons (Cresson, 1865)).