Acanthogethes Reitter, 1871
POLYPHAGA Emery, 1886
CUCUJOIDEA Latreille, 1802
MELIGETHINAE Thomson, C.G., 1859
A. brevis Sturm, 1845
A. solidus (Kugelann, 1794)
Acanthogethes solidus (Kugelann, 1794)
A very widespread European species distributed from Spain east to the Caucasus and from Turkey to southern Scandinavia. In the U.K. the species occurs in south and east England north to south Yorkshire and Lancashire and there are records from coastal limestone and heathland on the north and south Welsh coast. A generally local species of calcareous dry grassland, meadows, hillsides and cliffs. Adults occur from April to September or a little later according to the season. The larvae develop within the unopened buds of common rock-rose, Helianthemum nummularium (L.)* Adults may be found in unopened buds or among the flowers and generally occur in numbers, being easy to see among the bright yellow petals etc. They have also been recorded from field bindweed, (Convolvulus arvensis L.).
Among the British species of Meligethinae only two have a well-marked tooth at the base of the claws and this feature, along with the surface structure of the pronotum and elytra, will identify A. solidus. In fresh, well formed specimens the form of the front tibiae is enough to identify the species. 1.6-2.8mm Form short and convex. Dorsal surface dull black; pronotum and elytra strongly punctured and microscopically reticulate, especially around the lateral and basal margins of the pronotum. In addition to this combination of characters the pro tibiae are quite unlike those of any other British species; there are four very large and blunt teeth externally towards the apex.
*In the southeast common rock-rose is confined to calcareous soils on chalk and limestone but on more increasingly acid soil further north; in Scotland it has been recorded among heather on soils of pH 3.8.
Acanthogethes solidus 1
© Lech Borowiec http://www.cassidae.uni.wroc.pl/Colpolon/index.htm
Acanthogethes solidus 2
Acanthogethes brevis Sturm, 1845
This species has a mostly southern and western distribution in Europe, it is locally common in the south and west but tends to be very local and generally scarce in the north, it extends from Portugal to the Black sea and parts of south-western Russia and is present on most of the Mediterranean islands but absent from North Africa, and to the north it extends to the UK and the Baltic coast of Germany and Poland. In the UK it is very rare and mostly confined to a few coastal sites in North Wales and Yorkshire where it occurs on calcareous grassland and limestone cliffs and outcrops. Adults are active from May until August and may be abundant where they occur, they frequent a range of flowers but more especially those of various Helianthemum Mill., in Europe and North Wales on Hoary rock-rose (H. canum (L.), which is sometimes referred to as H. oelandicum var. canum Rouy & Foucaud, 1895) while more generally on Common rock-rose (H. nummularium (l.) Mill.) and probably other members of the genus. Females oviposit in unopened flower buds where the larvae will feed on developing seeds and flower parts. Larvae develop quickly and are fully grown within two weeks; they probably pass through two instars (which is typical of the subfamily) and then drop to the ground where they pupate in a subterranean cell. New generation adults appear in early summer, they fly to flowers where they feed on pollen and nectar but they will not reproduce until they have overwintered.
1.2-2.6 mm. Broadly-oval, discontinuous in outline and rather flattened dorsally, body entirely shiny black or, in var mutabilis Rosenhauer, 1856, with the elytral disc reddish, appendages reddish-brown but often with the femora and antennal clubs darker. Head narrowed and produced in front of large convex eyes, vertex and frons finely punctured and almost flat. Pronotum widely transverse, broadest slightly behind the middle and narrowed to rounded posterior angles and obtuse anterior angles, apical margin weakly curved and basal margin sinuate, lateral margins evenly explanate and curved, moderately strongly and densely punctured, the cuticle between smooth and not reticulate. Elytra broadest behind acutely-angled shoulders narrowed to oblique, almost truncate, apical margins, surface smooth and without striae, punctured as the pronotum or a little finer and more densely so, explanate margins distinctly bordered and much narrower than those of the pronotum. Middle and hind tibiae broadly expanded, front tibiae with strong, sharply acute teeth from the basal quarter or third, those towards the apex usually larger. All claws with a strong basal tooth, this will distinguish brevis from all other UK members of the subfamily except for solidus, from which it may be distinguished by the sharp teeth on the front tibiae and lack of reticulate microsculpture between the pronotal and elytral punctures.