MM309999

Hydrozetids are a family of mites from the Suborder Oribatida in the Order Acariformes. The entire family is composed of freshwater species. Hydrozetids prefer standing water but occasionally inhabit slow-moving streams (pers. obs., HCP). The cosmopolitan Hydrozetes is found in Australia.

Adult Hydrozetes are brown or blackish teardrop-shaped mites that are completely sclerotised. In contrast, larval and nymphal Hydrozetes are soft-skinned and pale, and sport numerous long, wiry, black setae. Hydrozetesare often associated with duckweed (Lemnaceae) on which they feed, sometimes burrowing within the tissues of the little floating plants (Krantz 1978).

Care must be taken when identifying oribatids from aquatic samples as terrestrial oribatids often fall into the water where they may be mistaken for aquatic species. One clue that you may have a terrestrial oribatid is that no aquatic species is known to have pteromorphs, the wing-like flaps above the leg bases of many terrestrial species.

References:

Colloff, M.J. and R.B. Halliday. 1998. Oribatid Mites: a Catalogue of Australian Genera and Species. Monographs on Invertebrate Taxonomy 6. CSIRO Publishing, Collingwood.

Krantz, G.W. 1978. A Manual of Acarology. 2nd edition. Oregon State University Book Stores, Corvallis, Oregon.

Walter, D.E. and H.C. Proctor. 1999. Mites: Ecology, Evolution and Behaviour. University of New South Wales Press, Sydney, New South Wales.