Limnoxenus niger (Gmelin, 1790)

This Western Palaearctic species is widespread across central and southern Europe from Portugal to Greece and north to the UK and the southern Baltic countries, it is also present on the larger Mediterranean islands, there are records from Turkey, Lebanon and Syria, and as far east as the Caspian sea. The first record from Algeria was recently confirmed (Incekara & Bouzid, 2007), the species having previously been thought to L. olmoi Hernando & Fresneda, 1994, a very local species of Portugal, Spain and North Africa, and the only other European member of the genus. L. niger is generally very local and scarce across Europe, and in some areas there are only very few modern records, in central regions mostly from lowland valleys. In the UK it is most frequent in coastal areas from Essex to Sussex, and from the Somerset Levels, but there are also scattered records from East Anglia and the east midlands, South Wales, and coastal Hampshire and Dorset, including IOW. Habitats include both fresh and brackish water, usually stagnant and densely vegetated pools and drainage ditches, and marshes. Adults have been recorded year-round; they are active over a long season from March or April and peak in abundance during spring and late summer. Dispersal by flight occurs in the spring. Breeding occurs in the spring, and females attach egg cases to vegetation just below the water surface; these were described by Van Berge Henegouwen (1975, available online), and are very distinctive; about 70 mm in length with about 20 mm rising protruding above the water. Larvae develop through the spring and pupation probably occurs among marginal substrate, new generation adults occur in the summer. Typical of the group, larvae are thought to be predacious, and adults probably feed on decaying vegetation although they may also be partly predaceous, but little is known of the biology.