Great Basin Naturalist


Galls induced by tephritid flies (Diptera: Tephritidae) on Chrysothamnus nauseosus ssp. albicaulis, consimilis, graveolens, and salicifolius are useful in taxonomic identification of these subspecies in Utah. In this study, "callus" galls were found almost exclusively on ssp. albicaulis. "Cotton" galls were more frequent on ssp. consimilis and graveolens. "Mace" galls occurred on all four subspecies but were the only gall found on naturally occurring populations of ssp. salicifolius. Gall form specificity is not as well correlated with C. nauseosus subspecies in peripheral areas of the species range as in Utah. This decrease in specificity may be due to decreased competition for the host plant in outlying areas.