Sand fleas

Code OP089999

One of three Australian families in the superfamily Crangonyctoidea, which are the dominant amphipods of cold, running freshwaters in Australia. Crangonycoidea can be distinguished from other Australian aquatic Amphipoda by a combination of features: (1) the antennules are the same length as or longer than the antennae; (2) the accessory flagellum of the antennule is conspicuous with 2 or more articles, although it is short; (3) all three uropods are well-developed; (4) the third uropod carries a 1-2 segmented outer ramus of which segment 2 may be well developed or very short, and almost always an inner ramus which often is shorter than the outer ramus; (5) the telson is cleft or notched (except in one species of Paramelitidae); (6) the mandible has a palp.

Perthidae comprises a single genus ( Perthia ) of two species from south west WA. The antennules are not significantly longer than the antennae (they sometimes are so in other families of this superfamily). The accessory flagellum of the antennule is 2-segmented. Thoracic segments carry dendritic (branching) sternal gills. The gnathopods are large and not rugose. Pereopod 6 is longer than pereopod 7. In one species the inner ramus of uropod 3 is 1/4 the length of the outer ramus, in the other it is approximately 2/3 as long as the outer ramus.

References:

Bradbury, J. H., and W. D. Williams. (1999) Key to and checklist of the inland aquatic amphipods of Australia . Technical reports of the Australian Museum, number 14.

Horwitz, P., Knott, B. and Williams, W.D. (1995) A Preliminary Key to the Malacostracan Families (Crustacea) found in Australian Inland Waters . Co-operative Research Centre for Freshwater Ecology Identification Guide No. 4., Albury, NSW.

Williams, W. D. (1980) Australian Freshwater Life . Macmillan.