Lagynochthonius polydentatus is a species of pseudoscorpion in the Chthoniidae family. It is endemic to Australia. It was described in 2008 by Australian arachnologists Karen Edward and Mark Harvey.[1]
The species occurs in the Murchison bioregion of Western Australia. The type locality is a borehole on Sturt Meadows Station, some 40 km north-west of Leonora.[1]
The arachnids are cave-dwelling, terrestrial predators.