Pseudotyrannochthonius giganteus is a species of pseudoscorpion in the Pseudotyrannochthoniidae family. It is endemic to Australia. It was described in 1971 by Austrian arachnologist Max Beier.
The body length of the female holotype is 3 mm; that of the paratype males is 2.2âÂÂ2.5 mm.
The species occurs in south-west Western Australia. The type locality is Calgardup Cave, near Augusta in the Leeuwin-Naturaliste National Park. The type specimens were collected from the final chamber on roots hanging from the cave ceiling.
The pseudoscorpions are cave-dwelling, terrestrial predators.