Systematic position of Umbellozetes Krivolutskiy, 1969 (Acari: Oribatida) in light of the ontogeny of Umbellozetes slaveki n. sp.

On the basis of adult morphology the oribatid mite genus Umbellozetes has been included in the family Tegoribatidae (Achipterioidea) since its original description. Juveniles of this family and other Achipterioidea have plicate cuticle and lack a humeral organ, but the ontogeny of Umbellozetes has been unknown. Herein, we use specimens of all instars to propose and describe Umbellozetes slaveki n. sp. from Central Mongolia. Juveniles of U. slaveki have smooth cuticle, a humeral organ in nymphs, and a dark pigmented macrosclerite around the opisthonotal gland opening, all of which are typical traits of Ceratozetidae, rather than Tegoribatidae. The adult of U. slaveki lack also a posterior notogastral tectum and has long and thin solenidia on legs that is typical for Ceratozetidae. Based on these and other morphological characters, we propose and support the transfer of Umbellozetes to trichoribatinae Ceratozetidae.