Lamachus contortionis Davis, 1897:284, ♀. Holotype ♀, District of Columbia (Amer. Ent. Soc.). - 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); Khalaim et al., 2019Khalaim, A.I., E. Ruíz-Cancino, J.M. Coronado-Blanco & Á. Castañeda-Vildózola 2019. First record of the genus Lamachus Förster, 1869 (Hymenoptera: Ctenopelmatinae) from Mexico, with description of two new species. Russian Entomological Journal 28 (2):169-179. (distribution).
Lagarotis diprioni Rohwer, 1915:217 - 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.:596 ( listed as synonym of Lamachus contortionis Davis, 1897).