Morphological and ecological differentiation of Eupelops and Propelops (Acari, Oribatida, Phenopelopidae)

Abstract

In this study, the morphological and ecological differentiation of Eupelops Ewing, 1917 and Propelops Jacot, 1937 were investigated in the light of Eupelops strenzkei and Propelops canadensis. The juveniles of these species have plicate integument and a dorsoventrally flattened hysterosoma, with short and thin setae c₁, c₃ and of d-series on the gastronotum, whereas the shape of marginal gastronotal setae differs in these species. The juveniles of P. canadensis have all these setae short and thin, except for setae lp and of h-series in the tritonymph, which are usually longer and thicker than other setae, whereas those of E. strenzkei have most marginal setae on the gastronotum longer and thicker than other setae, especially lp and h₁ in the larva and h₃ in the nymphs. Moreover, P. canadensis has short seta h₃ in the larva, whereas in E. strenzkei only a vestige of this seta remains, as in other Eupelops species, and this morphological character has generic value. The deutonymph, tritonymph and adult of P. canadensis have solenidion φ on tibia IV, but lack seta d, whereas those of E. strenzkei have thick seta d on this segment, but lack solenidion φ, as in other Eupelops species, which have also generic value. The adults of both species have 10 pairs of notogastral setae, including c₂, but in P. canadensis setae lp and h₃ are inserted close to each other, with porose area A1 between them, as in some species of Eupelops, whereas in E. strenzkei these setae are separated, with porose area A1 adjacent to seta lp, as in other species of Eupelops. The adults of both species have ventrodistal apophysis on genu I, as in other species of Eupelops and Propelops. All instars of E. strenzkei have secondarily anarthric subcapitulum, as other Eupelops species, which are used to remove dead parenchymous tissue, whereas those of P. canadensis have diarthric subcapitulum and normal chelicerae, which crumble the litter.

Keywords:

• Oribatid mites
• Eupelops strenzkei
• Propelops canadensis
• morphology
• juveniles
• ontogeny
• phylogeny
• leg setation
• ecology

Acknowledgements

The third author would like to thank Dr Sergey Chalov (Lomonosov Moscow State University, Russia) for his kind invitation to participate in an international scientific expedition to Kamchatka (Russia) under the EU FP - 7 IRSES Project (Flumen Grant Agreement No 318969). We also thank the anonymous reviewers for thorough review of this manuscript and all professional suggestions that considerably improved the scientific value of this paper.