Morphological ontogeny, distribution of Hermannia scabra (Acari: Oribatida: Hermanniidae) in Svalbard and descriptive population parameters

Abstract

The morphological ontogeny and distribution of Hermannia scabra (L. Koch, 1879) in Arctic Svalbard and descriptive population parameters were investigated. All instars of H. scabra are stocky, as in other species of Hermannia Nicolet, 1855, and have the same gastronotal setal ontogeny (12 pairs in the larve and 16 pairs in the nymphs and adults). In this species, the prodorsal setae are similar to other species of Hermannia, except for the bothridial seta which is clavate, as in H. reticulata Thorell, 1871. In other species of Hermannia the bothridial seta is setiform. Most prodorsal and gastronotal setae of H. scabra are phylliform whereas in other Hermannia species they are thickened. The number of epimeral setae in the nymphs and adults and the ontogeny of leg setae are characteristic for H. scabra. This species has a holarctic distribution and in Svalbard is not as common as H. reticulata, but it achieves higher density than the latter species, mainly due to the abundance of juveniles. Hermannia scabra prefers moist and wet localities, and in Svalbard the highest density is achieved in vegetation class 8 (wet vegetated flats, beaches, slopes and river fans with some exposed Dryas vegetation and graminoids Luzula sp.).