Silphium herb gall wasps: Cryptic species or unworked?

The Antistrophus rufus species complex (Hymenoptera: Cynipidae: Aulacideini) comprises three described cryptic species that induce cryptic galls on Silphium plants. Taxonomic work on North American herb gall wasps has been incredibly sparse, and minimal diagnostic characters are known for the rufus complex. To determine whether this complex was truly cryptic or simply the result of the taxonomic impediment, we designed a morphological survey of 50 characters and examined them for each member of the rufus complex, including the three described species as well as an undescribed species galling Silphium integrifolium. 13 morphological characters showed utility for the diagnosis of at least one species of the rufus complex. This data will be used to publish a revision of the rufus complex including a key to species and the description of the new species.