Quill-Dwelling Cheyletid Mites in Birds of Prey: A New Genus from Haliaeetus albicilla and Evidence of Feather-Shaft Modification

A new genus and species, Aetocheyletia variata gen n., sp. n. (Cheyletoidea: Cheyletidae), is described from the White-Tailed Eagle Haliaeetus albicilla (Linnaeus) (Accipitriformes: Accipitridae) in Poland. This represents the first record of cheyletid mites of the tribe Metacheyletinii from birds of prey. The new genus is morphologically most similar to Metacheyletia Fain, 1972, but differs from it in the presence of subcapitular setae n and an additional minute ventral tooth on the palpal claw. We further document considerable variability in body chaetotaxy observed in nearly all examined females. The most frequent anomalies occur in the aggenital and genito-anal regions and include (i) duplication of setae arising from a single alveolus, (ii) supernumerary setae, and (iii) reduction. In addition, distinct oval, circular, and spiral deformations of the quill wall were observed exclusively in specimens infested by A. variata, occurring in six of these feathers. No comparable alterations were found among the remaining five, including those hosting other mite taxa. This distribution suggests an association within the examined material, although causality remains unresolved. The present study expands current knowledge of the diversity and host range of Metacheyletinii and provides new observations on morphological variability and potential interactions between quill-dwelling mites and feather structure.