Size: 1.1 mm (body)
Det. H.C. Proctor 2011: "A beautiful and graceful Unionicola sp. (Hygrobatoidea: Unionicolidae). Most prey on microcrustaceans, particularly cladocerans, in their post-larval stages and parasitize dipterans and trichopterans as larvae. However, many species of Unionicola are parasites of bivalves in their post-larval stages."
Image at BugGuide.net
iNaturalist observation