Limnoxenus is a large hydrophilid beetle with adults 9mm in length (much larger than most NZ freshwater species). The underside of the thorax is keel-shaped. The adults have long swimming hairs on the tarsi (last leg segments). They have a 5-segmented abdomen and 9-segmented antennae. We don’t have a description of the larvae.
Limnoxenus are rarely found, but they are known from weedy ponds.
The larvae are likely to be predators, but as in other hydrophilids the adults may also scavenge on streambed detritus.
The presence of Limnoxenus is more likely to reflect pond-like habitat conditions rather than any particular water quality conditions. This genus has not been assigned tolerance values but the hydrophilids have family scores of 5 (hard bottom sites) and 8.0 (soft bottom sites).