MM359999

Hyadesiids are aquatic mites belonging to the Order Acariformes, Suborder Astigmata. They are algivorous and primarily inhabit marine and brackish waters; however, some species occur in fresh water (Krantz 1978). To our knowledge, freshwater hyadesiids have not yet been found in Australia, but as they are common in coastal areas it seems possible that they have also invaded inland waters.

Astigmatans of the families Acaridae, Algophagidae and Hyadesiidae are similar in appearance. Indeed, the Algophagidae was once included within the Hyadesiidae. However, acarids have tarsal claws that attach directly to the tarsi, whereas algophagids and hyadesiids have tarsal claws at the ends of flattened pulvilliform pretarsal stalks. In algophagids, the pretarsi of all legs are the same length, while in hyadesiids the pretarsi of legs I and II are much longer.

References:

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.