The single extant species of Protonephrocerus is known only from Chile and Argentina. One undescribed species also occurs in this region but it appears that there are unlikely to be any other extant species of Protonephrocerus discovered. The hosts of Protonephrocerus are unknown.

Protonephrocerus look superficially like some Pipunculinae. However, the hind margin of the eye is excised medially as in Nephrocerus. The wing has a pterostigma (absent in Nephrocerus).

• Protonephrocerus
  • Protonephrocerus florissantius †
  • Protonephrocerus chiloensis

This is the most enigmatic genus of Pipunculidae from a classification perspective. They resemble Nephrocerus in some ways and Pipunculinae in other respects. They are currently considered to be the sister group to Nephrocerus, but we are collecting molecular evidence to test this hypothesis. I suspect that more data will show that they are actually the sister group to the Pipunculinae.