Metacolus conicus Provancher, 1887:200 - As Sympiesis conica: - 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).
Coccophagus compressicornis Provancher, 1887:206 - Dalla Torre, 1898Dalla Torre, C.G. 1898. Catalogus Hymenopterorum hucusque descriptorum systematicus et synonymicus, V. Chalcididae et Proctotrupidae. Sumptibus Guilelmi Engelmann, VII + 598. (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.:970 ( listed as synonym of Sympiesis conica (Provancher, 1887)).
Sympiesis nigripes Ashmead, 1888:VII - 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.:970 ( listed as synonym of Sympiesis conica (Provancher, 1887)).
Sympiesis massasoit Crawford, 1913:258, ♂♀. Holotype, Auburndale, Massachusetts (U.S.N.M., No. 15096). - 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.:970 ( listed as synonym of Sympiesis conica (Provancher, 1887)).