Causing small to large (several centimeters in extent when swollen) orange-brown[*] galls on leaflets, midribs, and petioles of Dryopteris arguta (Kaulf.) Wats. The galls are fleshy and gelatinous, becoming small, wrinkled, and hard when dry; much swollen when wet.

• Mix amended this in a later article, describing the galls as green in May-June when they first appear