Mesostenus audax Cresson, 1878:207, ♀.Georgia (leg. Ridings); Townes & Townes, 1962Townes, H.K. & M. Townes 1962. Ichneumon-flies of America north of Mexico: 3. Subfamily Gelinae, tribe Mesostenini. Bulletin of the United States National Museum 216 (3):1-602.:28, Type ♀ (Philadelphia). - 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). - As Baryceros audax: - Townes & Townes, 1962Townes, H.K. & M. Townes 1962. Ichneumon-flies of America north of Mexico: 3. Subfamily Gelinae, tribe Mesostenini. Bulletin of the United States National Museum 216 (3):1-602.:27 (comb. nov.); Porter, 1975Porter, C.C. 1975. A new floridian Polycyrtidea with comments on Zoogeography of Florida Mesostenini (Hymenoptera: Ichneumonidae). The Florida Entomologist 58 (4):247-255. (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 Baryceros audax audax: - Townes & Townes, 1962Townes, H.K. & M. Townes 1962. Ichneumon-flies of America north of Mexico: 3. Subfamily Gelinae, tribe Mesostenini. Bulletin of the United States National Museum 216 (3):1-602. (distribution). - As Crypturopsis audax: - Cushman, 1929Cushman, R.A. 1929. A revision of the North American Ichneumon-flies of the genus Mesostenus and related genera. Proceedings of the United States National Museum 74 (art. 16):1-58. (distribution), 25 (comb. nov.).
Mesostenus exaptus Cresson, 1878:208, ♀.Massachusetts (leg. Ridings); Townes & Townes, 1962Townes, H.K. & M. Townes 1962. Ichneumon-flies of America north of Mexico: 3. Subfamily Gelinae, tribe Mesostenini. Bulletin of the United States National Museum 216 (3):1-602.:28, Type ♀ (Philadelphia). - 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); Townes & Townes, 1962Townes, H.K. & M. Townes 1962. Ichneumon-flies of America north of Mexico: 3. Subfamily Gelinae, tribe Mesostenini. Bulletin of the United States National Museum 216 (3):1-602.:28 ( listed as synonym of Baryceros audax audax (Cresson, 1878)); 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.:468 ( listed as synonym of Baryceros audax (Cresson, 1878)).
Mesostenus Saundersi Cresson, 1878:208, ♀.Canada West (leg. Wm. Saunders); Townes & Townes, 1962Townes, H.K. & M. Townes 1962. Ichneumon-flies of America north of Mexico: 3. Subfamily Gelinae, tribe Mesostenini. Bulletin of the United States National Museum 216 (3):1-602.:29, Type ♀ (Philadelphia). Synonymized with Baryceros audax (Cresson, 1878) 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.:468. - As Baryceros audax saundersi: - Townes & Townes, 1962Townes, H.K. & M. Townes 1962. Ichneumon-flies of America north of Mexico: 3. Subfamily Gelinae, tribe Mesostenini. Bulletin of the United States National Museum 216 (3):1-602. (distribution), 29 (comb. nov. & stat. nov.). - As Mesostenus saundersii: - 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).
Mesostenus armatus Provancher, 1886:76, Townes & Townes, 1962Townes, H.K. & M. Townes 1962. Ichneumon-flies of America north of Mexico: 3. Subfamily Gelinae, tribe Mesostenini. Bulletin of the United States National Museum 216 (3):1-602.:29, Type ♀ (Ottawa). Synonymized with Baryceros audax (Cresson, 1878) 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.:468. - Townes & Townes, 1962Townes, H.K. & M. Townes 1962. Ichneumon-flies of America north of Mexico: 3. Subfamily Gelinae, tribe Mesostenini. Bulletin of the United States National Museum 216 (3):1-602.:29 ( listed as synonym of Baryceros audax saundersi (Cresson, 1878)).