New record of a parasitising species of Hydrachna (Acari, Hydrachnidia) on water beetles Eretesgriseus (Fabricius, 1781) (Coleoptera, Dytiscidae, Dytiscinae, Eretini).

The larvae of water mites of the genus Hydrachna parasitise water bugs and water beetles. Larvae of the genus Hydrachna attach to the thorax and abdomen sternites and tergites under the elytra. Up to now six species of Hydrachna were recorded from Iran, but there are no records on larvae parasitising on water beetles. There is some information about parasitising of Hydrachna on water beetles from the genus Eretes, which is very well adapted to dry climate. The aim of this paper is to describe the morphology of an unknown larva of the genus Hydrachna, found on Eretesgriseus.