Anthonomus (Cnemocyllus) decipiens Dietz is designated as type species of Cnemocyllus Dietz. The twenty-three North American species assigned to the Anthonomus subgenus Cnemocyllus include ten previously placed in the subgenus: A. albus Hatch, A. decipiens LeConte, A. dorothyae Hatch, A. elongatus LeConte, A. jacobinus Dietz, A. juncturus Fall, A. ligatus Dietz, A. pictus Blatchley, A. quesnelensis Sleeper,
and A. tenuis Fall; three species formerly in Anthonomus but not in Cnemocyllus: A. stolatus Fall, A. inermis Boheman, and A. ornatulus Dietz; two species once in Epimechus Dietz but subsequently transferred to Anthonomus: A. arenicolor (Fall) and A. canoides (Fall); and eight new species: A. californiensis, new species (California and Baja California); A. bajaensis, new species (Baja California); A. intermedius, new species (Utah); A. extensus, new species (British Columbia, California, Idaho, Oregon, and Washington); A. deserticolus, new species (Arizona, Baja California, California, Guerrero, New Mexico, Sonora, and Texas); A. schuhi, new species (California and Oregon); A. latus, new species (California); and A. squamoerectus,
new species (California and Oregon). The species of Anthonomus in the subgenus Cnemocyllus are distinguished from other Anthonomini by the combination of having vestiture of more-or-less broad, dense scales, 6 or 7 antennal funicular articles, a slender endophallic transfer apparatus and, in most, the slightly to strongly curved metatibia of the male. The tarsal claws are variable, toothed or untoothed. The names Anthonomus cycliferus (Fall), A. malkini Hatch and A. summeri Hatch are placed in new synonymy under A. jacobinus Dietz; A. cretaceus (Champion) is placed in new synonymy under A. decipiens
LeConte; A. imbricus Hatch is placed in new synonymy under A. quesnelensis Sleeper; A. mannerheimi Dieckmann (A. brunnipennis Mannerheim, not Curtis) and A. subvittatus LeConte are placed in new synonymy under A. inermis (Boheman); A. minutus Hatch is placed in new synonymy under A. dorothyae Hatch. Adults of many of the species of the subgenus Cnemocyllus have been collected on plants in the family Asteraceae. The larvae of several of the species are known to develop on these plants.