What Bug Is That? The guide to Australian insect families.

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The family contains a single genus with a wide distribution (Africa, Madagascar, Europe, southern Asia, the Philippines, Sunda Is, Sulawesi, New Guinea, Solomon Is and Australia). Adults are rarely collected because they fly before dawn for a short period only, and the taxonomy of the genus is based almost solely on the nymphs (Peters 1967). Nymphs inhabit large rivers or small streams with rubble or boulder substrata. Pearson and Penridge (1979) collected the north Qld nymphs in drift samples.


Nymphs from tropical rivers in far northern Qld (Pearson and Penridge 1979) represent an undescribed species of Prosopistoma . Prosopistomatid nymphs are unusual in having the mesonotum forming a carapace over the thorax and abdomen as far as segment 7 so that they superficially resemble notostracan Crustacea. Adults are morphologically unusual. The eyes of both sexes are small and widely separated. The fore wings have no cross-veins and the longitudinal veins in males are bordered by deep intercalaries; the venation of females is similar but there are no intercalaries. The fore legs of the male are barely longer than the mid and hind legs, while the legs of the female are vestigial. Females do not moult to the imaginal stage.