Rhysothorax rufus (Fabricius, 1792)
A widespread though sporadic and generally rare species of central and northern Europe, it inhabits sparsely vegetated sandy coasts from northern France to the Baltic countries and southern Fennoscandia, inland it occurs very rarely on sandy margins of inland reservoirs and lakes etc., extending east into Russia and Kazakhstan. Following introductions from Europe is now established in northeast America and southwest Canada where it occurs in similar habitats, this north-western population is generally acknowledged to be from introductions but the species may be native as well as there are remote and distant populations in e.g. Nebraska, Kansas and Colorado. In the UK it is known from only two areas; the northeast coast of England above Liverpool and the coast of Glamorganshire in South Wales but the species has been in long-term decline, there are no recent records and it is classed as endangered. Adults occur from April until October with most records from May and June, they typically inhabit open dunes with little or no vegetation, often where the sand has been disturbed or recently deposited by wind, and more rarely on vegetated dune slacks. Adults are very difficult to find and populations may occur sporadically over the years, presumably due to local conditions such as substrate disturbance, and have been variously quoted as nocturnal or diurnal although they are known to fly well and have been recorded swarming in bright sunshine. The life history and biology remain largely unknown but adults are known to feed on detritus among sand.
Very distinctive among our fauna; entirely reddish-brown with the basal margin of the pronotum raised and the longer spur at the apex of the hind tibiae broad and rounded at the apex. 3.6-5.5mm. Body elongate-oval and discontinuous in outline, moderately convex and widest in the apical half of the elytra. Head granulate, the clypeus densely so, and sparsely pubescent, with gena produced over the antennal insertions. Pronotum broadest towards the base and narrowed to produced anterior angles, surface shiny, weakly rugose and extremely finely punctured, the base evenly and weakly curved; not sinuate. Elytra with well-impressed and punctured striae complete to the apex, interstices flat or very weakly convex, rather dull and lacking punctures. Anterior tibiae with two large external teeth in the apical half and a smaller tooth about the middle, middle and hind tibiae expanded towards truncate apices, without transverse ridges but with several conspicuous tubercles. Front tibial spur short and slender, mid-tibial spurs slender and unequal, the larger a little longer than the first two tarsomeres, hind tibial spurs short, broad and flattened.