Ontogeny of morphological traits in Eupelops variatus (Mihelcic, 1957), with remarks on juveniles of Phenopelopidae (Acari: Oribatida)

Juvenile instars of oribatid mites of the family Phenopelopidae are well known compared to most other families, however, information on the morphological ontogeny of the majority of species is still insufficient or unknown. Comparative characteristics of immatures of species of Phenopelopidae are given based on our own data and available literature sources. The major characteristics of immature instars of 11 species are presented, and the morphological ontogeny of Eupelops variatus (Mihelcic, 1957) is investigated based on material from southern Europe. From these studies, it can be generalized that the juvenile morphologies of phenopelopid genera are quite similar and uniform. The juveniles have plicate integument, marginally flattened opisthonotum, and short gastronotic setae c(1), c(3) and of the d-series. The juveniles of the phenopelopid species differ from one another in morphological characters such as body size, development of the prodorsal ridges, lamellar, interlamellar as well as gastronotic setae of c(2), lp and h-series either in larva or nymphs, and all these characters have species-specific value.