Anommatus Wesmael, 1835
POLYPHAGA Emery, 1886
CUCUJOIDEA Latreille, 1802
ANOMMATINAE Ganglbauer, 1899
A. diecki Reitter, 1875
A. duodecimstriatus (Müller, P.W.J., 1821)
This large genus includes more than 80 species and is most diverse in the western Palaearctic region, especially around the Mediterranean; 82 species are listed as European in the Fauna Europea but diversity decreases rapidly with latitude, the German fauna includes 8 species of which only 2 extend north into the UK. They are all small, 1.2-2.0mm, elongate species with the head and pronotum quadrate to slightly transverse or elongate, and the elytra elongate with the apex continuously rounded or acuminate. Most species are pale orange to deep reddish brown and rather shiny and apart from tiny sensory setae located in punctures on the head, pronotum and elytra they are glabrous. A characteristic feature is the lack of eyes but otherwise the head is large and well-developed although often largely hidden within the pronotum, the antennae are 11-segmented but appear to be 10-segmented due to the tenth being fused with the terminal segment to form a broad club; the 2 basal segments are large and swollen, the third elongate and 4-9 small, quadrate or transverse and the terminal segments expanded and flattened so forming a circular or, in some species, truncate club. The vertex and frons are variously punctured but often sparsely though relatively strongly so and the frontoclypeal suture, labrum and mandibles are well-developed. The pronotum and elytra are generally convex and narrowly explanate; the pronotum strongly though not densely punctured and finely margined, the lateral margin smoothly curved or almost straight and sometimes very finely crenulate. In some species the pronotum is broadest behind the anterior angles and narrowed to the base. The elytral base is as wide as or a little wider than the pronotal base and is sometimes weakly produced into a blunt angle, the basal margin sometimes weakly raised. All species have 6 or 7 rows of wide and shallow punctures forming striae which continue to the apex or merge just before. The legs are short and robust; femora broad and without teeth etc, tibiae broadly expanded to a truncate apex, each with 2 tiny spurs on the inner angle and 1-3 larger teeth externally before the apex. Tarsi 3-segmented with the terminal segment much longer than the others which are often obscure and always difficult to count, claws relatively large, curved and simple or with a weak basal tooth.
They are mostly subterranean, feeding upon roots and tubers or organic matter, and sometimes occur among extraction samples but in the warmer months may also occur under logs or among decaying wood etc. Some continental species are associated with wetlands and occur in winter flood-refuse while others e.g. A. contractus (Geoffroy, 1785), a northern species which extends into Fennoscandia but not the UK, is associated with decaying timber. When discovered among roots or root vegetables some may occur in large numbers. All species are flightless and most are of very local distribution and scarce, or at least under-recorded, and there are Mediterranean and Atlantic island endemics, but conversely some have become widespread globally having been transported among plant material and gravel etc. Some are considered to be threatened by habitat destruction or modification e.g. A. reitteri Ganglbauer, 1899 is Red List 2 classified-highly endangered-in Germany. Adults may be found by extracting likely samples or by sieving damp litter etc. taken near the ground surface.
Anommatus duodecimstriatus (Müller, P.J.W., 1821) is a widespread European native; it is common around the Mediterranean, extending east to the Caucasus and Turkey and including much of North Africa, but becoming less so further north e.g. it is very rare in Poland, and extending to Fennoscandia and the UK. They are slow-moving and flightless subterranean beetles but have become widely established throughout the world, no doubt through trade, e.g. in South Africa, Tasmania, Chile, and New Zealand and, since its discovery in the 1970s among imported plants, North America. In the UK there are scattered records mostly from southeast England, the midlands and eastern Wales but given its lifestyle the species is likely to be under-recorded. The species is thought to reproduce parthenogenetically as male specimens have not been found, adults occur mostly through the summer and autumn among organic-rich soil to a depth of 20cm but might occur in a range of situations e.g. among harvested potatoes, root-crops and flower bulbs or corms or under damp logs that have been lying for some time. Adults have been recorded from under stones and fungi and among moss in wooded areas, under mouldy straw and accumulated decaying litter in agricultural situations, under plant pots and decaying wood and among compost in gardens and, on the continent, among decaying plant remains and wood in cellars. They may occur in any situation and need to be searched for very carefully e.g. an adult was found among a suction sample from a road verge in Dorset (Hunnisett, J. 2011, Coleopterist 20(1) p.30) and we have recorded them from extraction samples taken from a local woodland on New Year’s Day. Little is known of their biology but adults are believed to be predators of insect early-stages.
Anommatus diecki Reitter, 1875 is a recent addition to the UK list and is so far known from only a few specimens collected in during May, July, October and November, 1985 around Liverpool. The continental range is mostly southern; France, Switzerland, Italy and Corsica and it is absent from many central and northern countries but it does occur very rarely in Sweden where, as with the UK populations, it may have been imported with nursery stock. Adults occur in much the same situations as the previous species and in Sweden they are often found together.
Our UK species may be determined by the following key:
Basal margin of the pronotum smooth but for some tiny crenulations caused by a single row of fine punctures. Basal margin of the elytra with several deep fovea. - A. duodecimstriatus
Basal margin of the pronotum obviously and usually deeply emarginate close to the posterior angle, inside these the margin is broken up by a series of about 10 large punctures. Basal elytral margin without basal fovea. - A. diecki