Atholus duodecimstriatus (Schrank, 1781)
Suborder:
Superfamily:
Family:
Subfamily:
Genus:
POLYPHAGA Emery, 1886
HYDROPHILOIDEA Latreille, 1802
HISTERINAE Gyllenhal, 1808
Atholus Thomson, C.G., 1859
This species occurs through most of the Palaearctic region, from Portugal to the far east of Russia and Japan, and extends south to Taiwan and Korea; it is present throughout Europe and North Africa and occurs on the Mediterranean islands, Azores and Madeira. The nominate subspecies is more western; occurring throughout Europe and extending east through Russia and Asia Minor to Afghanistan and Central Asia while ssp. quatuordecimstriatus (Gyllenhal, 1808) is distributed from central and northern Europe to China, Japan, Taiwan and Korea. In the UK the species is generally common across England and Wales including IOW and Anglesey but not Man, and more local and scarce further north to the Scottish Highlands and in Ireland. Adults are active year-round, they become common during April and remain so until the autumn, and population peaks occur during May and September. Habitats include dung and compost in just about any situation, including domestic gardens, but they have also been recorded from a wide range of situations including decaying fungi, haystacks, carrion and old bird and mammal nests, and they occasionally occur under stones on grassland and in wooded areas. During the summer large numbers of adults may be found in horse and cattle dung and, especially, in mixed straw and dung piles, old compost heaps are likely to host the species, especially where they largely comprise grass cuttings and are still producing heat. Both adults and larvae are predatory, feeding on diptera larvae etc., breeding occurs during spring and summer and development is rapid, as is typical of species in such habitats. Adults are both diurnal and nocturnal and while they are rarely seen away from their usual habitats they disperse by flight and during the summer may occasionally be swept from low vegetation. Baited carrion and dung traps are likely to produce the species in numbers and searching typical habitats through the winter is often productive.
4.0-5.5 mm. Elongate, broadly-oval and continuous in outline, glabrous, body shiny black, appendages dark brown. Head transverse with small, almost flat eyes that are often partially hidden within the thorax, anterior margin straight behind a small and almost semi-circular labrum, mandibles produced forward, robust and with a strong internal tooth. Vertex almost flat and without structure, bordered by an impressed line that runs across the anterior margin and recurves laterally to the base. Pronotum transverse, broadest across acute posterior angles and smoothly narrowed to projecting anterior angles, apical and basal margins almost straight. Surface smoothly convex and very finely punctured except for a row of stronger puncture-like impressions along the basal margin. Lateral and apical margins with a complete impression that does not extend to the base, inside this there is sometimes a partial impression but only towards the base, otherwise without impressions or fovea. Scutellum small, triangular and sharply-pointed. Elytra evenly curved from sharp and slightly obtuse shoulders to separately-rounded apical margins, each with six almost complete striae, the innermost often interrupted on the disc, the subhumeral stria absent or only suggested near the middle (in ssp. quatuordecimstriatus there is always a distinct subhumeral stria). Pygidium very finely punctured throughout. All tibiae broadly expanded from the base, middle and hind tibiae with long external spines, front tibiae with three external teeth, and all tibiae with a strong terminal spur. Tarsi 5-segmented in both sexes.