Demodex species (Acari:Demodecidae) parasitizing the brown rat, Rattus norvegicus (Rodentia): redescription of Demodex ratti and description of D. norvegicus sp. n. and D. ratticola sp. n.

Based on materials collected from wild populations of the brown rat. Rattus norvegicus in South Bohemia, Czech Republic, previously unknown male is described and female redescribed for Demodex ratti Hirst, 1917. All developmental stages are described for two new species, D. norvegicus sp. n. and D. ratticola sp. n. Also provided is a key to adults of four Demodex species presently known to parasitize Rattus norvegicus. Demodex ratti was recovered from the host's back, eyelids, and external auditory meatus, D. norvegicus from the anal and genital areas, and D. ratticola from vicinity of the mouth and the tip of muzzle.