Bembex nigrifrons Provancher, 1888:415 - As Microbembex nigrifrons: - 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); Amarante, 2002Amarante, S.T.P. 2002. A synonymic catalog of the neotropical Crabronidae and Sphecidae (Hymenoptera: Apoidea). Arquivos de Zoologia (São Paulo) 37:1-139. (distribution).
Microbembex monodonta neomexicana Johnson & Rohwer, 1908:375, sex not indicated.Las Cruces New Mexico, August 30th. - 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.:1707 ( listed as synonym of Microbembex nigrifrons (Provancher, 1888)); Amarante, 2002Amarante, S.T.P. 2002. A synonymic catalog of the neotropical Crabronidae and Sphecidae (Hymenoptera: Apoidea). Arquivos de Zoologia (São Paulo) 37:1-139.:10 ( listed as synonym of Microbembex nigrifrons (Provancher, 1888)).
Microbembex monodonta deltaensis Johnson & Rohwer, 1908:375, ♂. ♂♂, Delta. Colo., July 29, 1898. - 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.:1707 ( listed as synonym of Microbembex nigrifrons (Provancher, 1888)); Amarante, 2002Amarante, S.T.P. 2002. A synonymic catalog of the neotropical Crabronidae and Sphecidae (Hymenoptera: Apoidea). Arquivos de Zoologia (São Paulo) 37:1-139.:10 ( listed as synonym of Microbembex nigrifrons (Provancher, 1888)).