We describe a new species of Paracarophenax Cross based on females found attached to the larvae of three Mycetophagus sp. (Coleoptera: Mycetophagidae) collected from the fungus Pleurotus ostreatus (Agaricales: Pleurotaceae) in Alberta, Canada. These mites exhibit a novel means of attachment: instead of grasping one of the host’s setae, adhesive pads are deposited on the host’s cuticle and gripped by the mite’s opposed tarsus I claw and uncinate seta uʺ. We hypothesize that the glue-like material is exuded from the mite’s mouth. The mite’s association with the larval beetle represents pre-parasitic (these mites are parasitoids of beetle eggs) and pre-phoretic (mites disperse on adult beetles) attendance of the host and is a rare record of phoretic (as opposed to feeding) attachment to a pre-adult stage in the Heterostigmatina. This mite is also the first record of the Acarophenacidae from the Mycetophagidae. We provide updated keys to the genera of Acarophenacidae and to species of Paracarophenax and move Paracarophenax dermestidarum to Aethiophenax, i.e. Aethiophenax dermestidarum (Rack 1959) comb. nov.
International Journal of Acarology / Vol. 43, No. 4, pp.329-335