Ptilia crassula Cameron, 1884:484, ♀. ♀, Northern Sonora, Mexico (leg. Morrison). - Cameron, 1883-1888Cameron, P. 1883-1888. Biologia Centrali-Americana - Insecta. Hymenoptera. (Families Tenthredinidae-Chrysididae). Taylor and Francis, Red Lion Court, Fleet Street. 487 pp., 20 pl. (distribution), 468 (listed); Dalla Torre, 1894Dalla Torre, C.G. 1894. Catalogus Hymenopterorum. Vol. I: Tenthredinidae incl. Uroceridae (Phyllophaga & Xylophaga). G. Engelmann, 459. (distribution). - As Zynzus crassulus: - Smith, 1992Smith, D.R. 1992. A synopsis of the sawflies (Hymenoptera, Symphyta) of America south of the United States: Argidae. 39:1-201. (distribution), 185 (comb. nov.).
Ptilia nigerrima Cameron, 1884:485, ♂. ♂, Northern Sonora, Mexico (leg. Morrison). - Cameron, 1883-1888Cameron, P. 1883-1888. Biologia Centrali-Americana - Insecta. Hymenoptera. (Families Tenthredinidae-Chrysididae). Taylor and Francis, Red Lion Court, Fleet Street. 487 pp., 20 pl. (distribution), 469 (listed); Dalla Torre, 1894Dalla Torre, C.G. 1894. Catalogus Hymenopterorum. Vol. I: Tenthredinidae incl. Uroceridae (Phyllophaga & Xylophaga). G. Engelmann, 459. (distribution); Smith, 1992Smith, D.R. 1992. A synopsis of the sawflies (Hymenoptera, Symphyta) of America south of the United States: Argidae. 39:1-201.:185 ( listed as synonym of Zynzus crassulus (Cameron, 1884)).
Ptenus modestius Smith, 1970:88 - 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); Smith, 1992Smith, D.R. 1992. A synopsis of the sawflies (Hymenoptera, Symphyta) of America south of the United States: Argidae. 39:1-201.:185 ( listed as synonym of Zynzus crassulus (Cameron, 1884)).