Isobrachium rufiventre Ashmead, 1893:36 (key), 38, ♂♀. Types (Coll. Ashmead, National Museum, and American Entomological Society); Evans, 1961Evans, H.E. 1961. A revision of the genus Pseudisobrachium in North and Central America (Hymenoptera, Bethylidae). Bull. Mus. Comp. Zool. 126 (2):211-318.:293, Holotype ♀ (USNM, No. 2186). - Ashmead, 1893Ashmead, W.H. 1893. A monograph of the North American Proctotrypidae. Bulletin of the United States National Museum 45:1-472. (distribution); Dalla Torre, 1898Dalla Torre, C.G. 1898. Catalogus Hymenopterorum hucusque descriptorum systematicus et synonymicus, V. Chalcididae et Proctotrupidae. Sumptibus Guilelmi Engelmann, VII + 598. (distribution); Cockerell, 1899Cockerell, T.D.A. 1899. A first list of the hymenopterous families Tenthredinidae, Siricidae, Chrysididae, Proctotrypidae, Cynipidae, Chalcididae and Braconidae collected in New Mexico. Transactions of the Kansas Academy of Sciences 16:212-216. (distribution). - As Isobrachium rufiventris: - Ashmead, 1894Ashmead, W.H. 1894. Some parasitic Hymenoptera from Lower California. Proceedings of the California Academy of Sciences 2 (4):122-129. (distribution). - As Pseudisobrachium rufiventre: - Evans, 1961Evans, H.E. 1961. A revision of the genus Pseudisobrachium in North and Central America (Hymenoptera, Bethylidae). Bull. Mus. Comp. Zool. 126 (2):211-318. (distribution); Krombein, 1963Krombein, K.V. 1963. Natural history of Plummers Island, Maryland. XVII. Annotated list of the wasps (Hymenoptera: Bethyloidea, Scolioidea, Vespoidea, Pompiloidea, Sphecoidea). Proceedings of the Biological Society of Washington 76:255-280. (distribution); Evans, 1964Evans, H.E. 1964. A synopsis of the american Bethylidae (Hymenoptera, Aculeata). Bulletin of the Museum of Comparative Zoology 132 (1):1-222. (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 2. Apocrita (Aculeata). Smithsonian Institution Press, Washington D.C. 1199-2209. (distribution); Lanes et al., 2004Lanes, G.O., F.T. Gobbi & C.O. Azevedo 2004. Report on a collection of Bethylidae (Hymenoptera) from central Florida, USA, with description of a new species of LepidosternopsisA Ogloblin. Journal of Hymenoptera Research 13 (1):57-63. (distribution).
Pseudisobrachium flavicoxis Fouts, 1928:122, ♀. Holotype ♀, Baldwin, Kansas (Coll. Fouts); Evans, 1961Evans, H.E. 1961. A revision of the genus Pseudisobrachium in North and Central America (Hymenoptera, Bethylidae). Bull. Mus. Comp. Zool. 126 (2):211-318.:293, Holotype ♀ (USNM, No. 62548). Synonymized with Pseudisobrachium rufiventre (Ashmead, 1893) by Evans, 1961Evans, H.E. 1961. A revision of the genus Pseudisobrachium in North and Central America (Hymenoptera, Bethylidae). Bull. Mus. Comp. Zool. 126 (2):211-318.:293. - Evans, 1964Evans, H.E. 1964. A synopsis of the american Bethylidae (Hymenoptera, Aculeata). Bulletin of the Museum of Comparative Zoology 132 (1):1-222.:68 ( listed as synonym of Pseudisobrachium rufiventre (Ashmead, 1893)); 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 2. Apocrita (Aculeata). Smithsonian Institution Press, Washington D.C. 1199-2209.:1219 ( listed as synonym of Pseudisobrachium rufiventre (Ashmead, 1893)).
Pseudisobrachium puncticeps Fouts, 1928:123, ♂. Holotype ♂, Glen Echo, Maryland, VIII-19-1916; Evans, 1961Evans, H.E. 1961. A revision of the genus Pseudisobrachium in North and Central America (Hymenoptera, Bethylidae). Bull. Mus. Comp. Zool. 126 (2):211-318.:293, Holotype ♂ (USNM, No. 62550). Synonymized with Pseudisobrachium rufiventre (Ashmead, 1893) by Evans, 1961Evans, H.E. 1961. A revision of the genus Pseudisobrachium in North and Central America (Hymenoptera, Bethylidae). Bull. Mus. Comp. Zool. 126 (2):211-318.:293. - Evans, 1964Evans, H.E. 1964. A synopsis of the american Bethylidae (Hymenoptera, Aculeata). Bulletin of the Museum of Comparative Zoology 132 (1):1-222.:68 ( listed as synonym of Pseudisobrachium rufiventre (Ashmead, 1893)); 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 2. Apocrita (Aculeata). Smithsonian Institution Press, Washington D.C. 1199-2209.:1219 ( listed as synonym of Pseudisobrachium rufiventre (Ashmead, 1893)).