Descriptions and figures of adults and all immature instars are given for a new species of mite belonging to the genus Pleuronectocelaeno associated with bark beetles of the genera lps and Dendroctonus. The genus is defined, and a key to its species and subspecies is included. Pleuronectocelaeno austriaca barbara Athias-Henriot is recognized as a species distinct from P. austriaca Vitzthum, and includes two subspecies: P. barbara barbara and P. b. borealis nomen novum for P. austriaca sensu Sellnick (1951).