Chaetophora spinosa (Rossi, 1794)
This lowland species is widespread and locally common across southern and central Europe from Spain to Bosnia and Herzegovina, to the north it is much less common and extends sporadically to the UK, Denmark and the southern provinces of Fennoscandia, it is otherwise very widespread, extending through Asia Minor and Siberia to the far east of Russia, south into the Oriental region and following recent introductions is now established in eastern Canada and the United states. In the UK it is a very local across the southeast of England and East Anglia and there are a few scattered records from the West Country and the midlands although the species is tiny and not easy to find and so may be under-recorded. The species is eurytopic, in many areas of Europe it occurs on open sandy soils along riverbanks and wetland margins with plenty of moss and algae, it also occurs on sand dunes and salt marshes but more generally it inhabits open sites on sandy or chalky soils and may be common on disturbed damp sites such as quarries and reservoir margins, our only experience of the species was from a chalk hillside in the Buchinghamshire Chilterns, very remote from any water, when we saw hundreds of specimens active in bright sun on a chalk pathway, they were easy to observe but when alarmed vanished rapidly into crevices, adults fly and have been observed swarming on spring evenings and so may be quick to colonize new areas as on the continent it is often among the first species to establish among early succession mosses. Little is known of the biology but adults occur through the summer and peak in abundance during June and July, they are known to consume Cyanobacteria of the genus Nostoc Vaucher, 1888, ex Bornet & Flahaul. and have been associated with range of mosses; in Canada with Mnium hornum Hedw, (an abundant species throughout the UK), and in the United States with Pohlia atropurpurea (Wahlenberg) (which does not occur in the UK although several other members of the genus are present), Dicranella varia (Hedw.) Schimp. (abundant throughout the UK) and Aloina brevirostris (Hook. & Grev.) Kindb. which is a very local and scarce species with records across England and southern Scotland. Adults are not easy to find, especially as they can run remarkably quickly for such small beetles, they should be looked for carefully on the soil surface in warm open habitats exposed to the sun, pitfall trapping might be effective as they are active on the ground during the day and well-placed flight-interception traps might also be productive.
Chaetophora spinosa 1
Chaetophora spinosa 2
© Lech Borowiec
1.2-1.6 mm. Elongate and broadly-oval, convex above and below and entirely dark grey to black, legs dark brown with paler tarsi and antennae pale brown, upper surface with scattered erect pale truncate scale-like setae that more or less form longitudinal lines on the elytra. Head broadest across small eyes that form an obtuse angle between the temples and the clypeus, temples long, straight and slightly converging to the base (although they are usually substantially retracted into the thorax), lateral and anterior margins smoothly rounded and bordered throughout, surface with two deep oblique impressions that almost meet at the base, otherwise smoothly convex and finely granulate. Antennae characteristic; the two basal segments much broader than those following, the third distinctly shorter than the fourth and the last two segments form an abrupt asymmetric club, the apex of the tenth segment and the base of the terminal segments strongly oblique. Pronotum broadest across slightly obtuse posterior angles (from above) and unevenly narrowed to a curved anterior margin, surface evenly convex and densely punctured. Elytra broadest in front of the middle evenly curved laterally to a continuous apical margin and smoothly convex, surfaces finely punctured and roughly granulate, there are striae consisting of wide, shallow and often indistinct punctures but these vary and may be almost completely obliterated by the surface structure. Legs long and robust, tibiae broad and curved externally at the base and lined with a few truncate scale-like setae similar to those on the elytra but smaller, tarsi 4-segmented; the basal segments short and close-fitting and the last segment long and curved. Claws long and slender, weakly curved and without a basal tooth. In the UK only likely to be confused with species of Curimopsis Ganglbauer, 1902 but here the third antennomere is longer than the fourth and the head lacks oblique furrows.