New data on the mite genus Chaetodactylus (Acariformes: Chaetodactylidae) from Russia, with the description of a new species

Mites of the genus Chaetodactylus (Acari: Chaetodactylidae) are specialized cleptoparasites or commensals of solitary bees, primarily of the family Megachilidae. Three species (Chaetodactylus birulai, Ch. dementjevi, and Ch. osmiae) have previously been recorded in Russia, but their morphological characteristics and host associations remained poorly studied. Based on a new material collected in European Russia, a comprehensive redescription of the phoretic deutonymphs of Ch. dementjevi Zachvatkin, 1941 is provided and its host associations with Megachile bees is confirmed. The study also clarifies key diagnostic features of the phoretic and inert deutonymphs of Ch. osmiae (Dufour, 1839) widely distributed in the Palearctic region. A new species Ch. pesenkoi sp. nov. is described from the phoretic deutonymphs found on Lithurgus cornutus (Megachilidae). The new species differs from Ch. dementjevi by the larger body size and significantly lesser setal length ratio se:si. This finding is the first record of a Chaetodactylus species from bees of the genus Lithurgus in the Palearctic region.