Differentiation of body form of Protoplophoroidea (Acari: Oribatida) in the light of ontogeny of three species

Abstract

The differentiation of body form of Protoplophoroidea in the light of ontogeny of Cosmochthonius ponticus Gordeeva, 1980, Sphaerochthonius splendidus (Berlese, 1904) and Haplochthonius simplex Willmann, 1930 is investigated. These species have primitive characters, like dorsal transverse scissures on the hysterosoma, four pairs of adanal and anal setae, and two pairs of exobothridial setae. However, in C. ponticus three dorsal scissures occur during ontogeny, in S. splendidus three scissures are present in the juveniles, and one scissure in the adult, while in H. simplex three scissures occur only in the adult. These species also differ by expansion of new segments in the anal region during ontogeny; in S. splendidus this expansion is the smallest, while in H. simplex is the largest. Cosmochthonius ponticus has hypertrophied, erectile setae of the e- and f-series, S. splendidus has armour-like, dorsal, pleural and ventral plates, while H. simplex has thin cuticle and short dorsal setae.

Keywords:

• Cosmochthonius ponticus
• Sphaerochthonius splendidus
• Haplochthonius simplex
• juveniles
• setation
• ontogeny

Acknowledgements

We express our gratitude to Prof. Dr RA Norton, State University of New York, Syracuse, USA, for thorough review of this manuscript and many valuable suggestions, and Prof. Dr S Kaczmarek, Department of Zoology, Kazimierz Wielki University, Bydgoszcz, for collecting specimens of C. ponticus.