Key to the species groups of Helophilus (Pilinascia)

1. Scutellum with two medial tuberculate swellings .............................................................. cingulatus group

- Scutellum normal, without such tuberculate swellings...............................................................................2

2. Metafemur with a large distinct basoventral process; wing with a stigmatic crossvein .. seelandicus group

- Metafemur simple, without a process; wing without a stigmatic crossvein................................................3

3. Eye pilose ............................................................................................................................ campbelli group

- Eye bare.......................................................................................................................................................4

4. Lateral ocelli closer to each other than to eyes; oral margin strongly produced anteriorly or ventrally; smaller, more slender and elongate flies .............................................................................. montanus group

- Lateral ocelli closer to eyes than to each other; oral margin not strongly produced; larger and more robust flies ..................................................................................................................................... antipodus group