Contribution to the life history and morphology of the water mite Panisellus thienemanni (Acari, Hydrachnidia: Hydryphantidae)

Abstract

The crenobiontic water mite Panisellus thienemanni (K. Viets, 1920) is a rare species confined to Europe, occurring in predominantly shaded helocrenes. Larvae of this species are known to utilize two species of springtails (Collembola) within the family Tomoceridae as a host. With only sparse published data available of P. thienemanni, this paper provides an up-to-date status of its distribution in the Netherlands, and presents new data on the morphology, life cycle, and host-parasite relationship. We report the first record of the species using a host within the family Isotomuridae (Collembola), i.e. Isotomurus fucicola Schött, 1893. The finding was part of a survey in a shaded helocrene spring in the eastern part of the Netherlands, carried out in 2011 and 2012. We particularly looked at the host species being used by larvae of P. thienemanni at the site, the number of larvae attached to an individual springtail, and the attachment site of the host. Furthermore, we compared some morphological characteristics of adult males and females with descriptions in literature. We briefly discuss the not yet fully understood life cycle of P. thienemanni based on existing data, and our own observations.