Petiole miner etc. (cf. Diptera: Sciaridae) in Caltha

This tentative record is based on a leaf mine and associated damage to a petiole, found in a wetland in late May. The leaf mine was a grayish irregular blotch radiating from the point where the petiole attached to the leaf blade, similar to what is shown for Z. calthella in Eiseman et al. (2016) and Eiseman (2016). According to those references, larvae feed in the petiole as well as the leaf blade, and the petiole mine may appear brown in color. The petiole of the leaf I examined did show extensive brownish discoloration, but I was unable to locate a larva.