This is the first reported study of corixid water bugs examining whether all species of a genus in one locality can be distinguished by their sounds. More extensive analysis than has been reported for any corixids revealed that, although some species are difficult to distinguish morphologically, inter-species sound differences are very clear.
The sounds of all nine species of Micronecta in the study area near Melbourne, Australia were recorded. Male sounds were recorded in the laboratory, over a minimum water temperature range of 15 to 25°C. Females do not produce sounds. Signals consisted of groups of pulse-trains, except for one species with signals of usually one pulse-train. Signals were species-specific; pulse-train rate alone was sufficient to distinguish between species. There were also species differences in other signal parameters. Males also produced clicks (single pulse-trains) and low-amplitude sounds; there were some species differences in the latter. Similar signals occurred between only one pair of species, which were from different habitats (ponds and rivers). Pulse periods and pulse-train periods were negatively correlated with temperature, with curves of best fit being quadratic. Five species were also recorded in ponds; the sounds and effect of temperature were compared with laboratory recordings.