Rugilus angustatus (Geoffroy, 1785)

Locally common throughout the Palaearctic region including the Near East but not North Africa and now widespread in eastern North America, no doubt from European adventives, this is among the most widespread species of the genus. In Europe it occurs from Spain to Greece in the south and extends north into the UK and Denmark and to the Arctic Circle in Sweden and Finland although it appears to be absent from Norway; it is generally common in southern and central regions but otherwise local and scarce. Here it locally common in Norfolk and parts of Suffolk but otherwise scarce and very local in Southern England and South Wales. The species is typical of permanently damp habitats; in the UK mostly among moss or vegetation in fens and marshes or in decaying hay and straw in arable situations but on the continent also in open grassland, all types of damp woodland and often in disturbed areas, in North America often among bark or logs in wooded areas as well as wetlands generally, including among debris in a Beaver dam, and specimens were found on shed windowpanes in central New York. In Northern Europe adults occur year-round, they are active in all but the coldest winter spells and peak in abundance during March and April and again in September, suggesting spring breeding. They may be sampled by sieving moss and litter etc., especially moss that has accumulated on fallen branches or logs, they often occur among flood refuse and, at least in North America, they have been swept in flight on warm evenings.

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6.0-6.5 mm. Body black but for the red pronotum and yellowish elytral apices, antennae dark, usually with the base of most segments narrowly yellow and the apical segments substantially pale, palps brown, usually with the apex of most segments pale, legs brown but often with the middle and hind femora and tibiae darker. Dorsal surface finely pubescent throughout. Head elongate, broadest across eyes that occupy less than half the lateral margin and with rounded temples converging to a very narrow neck, surface without depressions or structure, evenly and densely punctured throughout. Labrum smoothly curved and with a small tooth either side of the middle, mandibles long and curved; the right with four internal teeth and the left with three. Antennae inserted laterally in front of the eyes and outside the base of the mandibles, 11-segmented and filiform with the basal segment distinctly longer than the third segment. Pronotum elongate and narrower than the head and elytra, broadest about the middle and converging to a narrow apical margin and a much broader basal margin, surface punctured throughout, less densely so than the head, except for a smooth and narrowly depressed median strip. Lateral pronotal margins reflexed and not visible from above. Elytra elongate, almost parallel-sided from rounded shoulders to incurved apical margins and evenly punctured throughout, sutural margin depressed, otherwise without depressions or striae. Abdomen relatively short, dilated about the middle, four basal tergites strongly bordered, fifth tergite longer than 1-4 and only finely bordered, all tergites finely and densely punctured except for the base of the first and second with much stronger punctures. In males the eighth sternite is depressed medially and strongly excised apically. Legs long and slender, tibiae without a distinct apical spur and all tarsal segments elongate and narrow.