Protostephanus is an extinct genus of crown wasp in the Hymenoptera family Stephanidae known from an Eocene fossil found in the United States of America. The genus contains a single described species, Protostephanus ashmeadi placed in the stephanid subfamily Stephaninae.
Species taxanomy provided by GBIF Secretariat (2022). GBIF Backbone Taxonomy. Checklist dataset https://doi.org/10.15468/39omei accessed via GBIF.org on 2023-06-13; License: CC BY 4.0