Synsphyronus hadronennus is a species of pseudoscorpion in the Garypidae family.

It was described in 1987 by Australian arachnologist Mark Harvey.

The specific epithet hadronennus comes from the Greek hadros ('stout' or 'well-developed') and nennos ('uncle'), referring to the species’ apparently close relationship with its smaller relatives, S. paradoxus and S. heptatrichus.

[1] The species occurs in the Top End of the Northern Territory.

The type locality is 6 km west of South Alligator, where the holotype was found beneath the bark of a eucalypt.