Antistrophus sp.
Skeletonplant spindle gall wasp

Host: Rush skeletonplant (Lygodesmia juncea).

Gall location: On the branches.

Description: Similar in appearance to galls of the skeletonplant pea gall wasp, but unlike that species, galls of the skeletonplant spindle gall wasp are directly integrated into the branch tissue. Overall, these galls are spindle-shaped swellings of the branches, often around 1 centimeter in length. Green and fleshy when fresh to brown and rough when dry and old.

Range: Thus far, this gall has only been located in several Midwestern states as well as southern Manitoba. However, as with the skeletonplant pea gall wasp, its range is probably far greater than currently known.

This gall is induced by an undescribed species of the genus Antistrophus. As with the skeletonplant collar gall wasp, this species was originally assumed to be a variant of the skeletonplant pea gall wasp, but preliminary results from an ongoing taxonomic study indicate that they are indeed different species.