Alternative combination: Protereisma directum
Full reference: F. M. Carpenter. 1979. Lower Permian insects from Oklahoma part 2. Orders Ephemeroptera and Palaeodictyoptera. Psyche 86:261-290
Type specimen: MCZ 5180ab, a forewing. Its type locality is Midco Locality 15, which is in an Artinskian lacustrine lime mudstone in the Wellington Formation of Oklahoma.
Average measurements (in mm): forewing 28.3 x 6.5, hindwing 27.0 x 6.0, prothorax 2.00 x 4.00