Monotoma picipes Herbst, 1793
This generally common species has been recorded from various countries throughout the world and is now regarded as cosmopolitan; it is probably native to the Palaearctic region and spread by trade in agricultural products; arguably the commonest Eurasian species it occurs throughout Europe to the far north of Scandinavia and extends into the UK where it is among our most common members of the genus and, with the exception of the West Country, is widespread throughout England, Wales and southern Scotland. Adults occur year-round and are active from early spring until late autumn, they might be found among decaying plant material in just about any situation; compost and decaying grass cuttings, hay and straw, among moss and tussocks, in seaweed, among old and dry dung and occasionally under bark, among detritus in poultry houses or associated with ants. While not generally considered as a pest, there are records worldwide of their occurrence among various grains and cereals and also among stored traditional Chinese medicinal herbs. Little is known about the life-cycle but both adults and larvae are thought to be mould-feeders. We find them in numbers among grass cutting left to dry in the sun in our local park; pulling material apart over a sheet will expose them but they remain still or move very slowly and a little experience is needed before they become obvious, alternatively they are often found in numbers, and sometimes along with other Monotoma, among extraction samples from a wide range of habitats throughout the year.
Identification within this genus can be difficult and the characters are often subtle but the present species may be recognized by the form of the head and the deep impressions on the vertex and frons. 1.7-2.6mm. Head and pronotum very dark brown to black, elytra brown or reddish brown and usually paler than the forebody; humeral calli usually slightly paler. Head and pronotum coarsely punctured throughout. Head with convex and relatively large eyes, short temples, less than half the diameter of the eyes, which are produced laterally to an acute angle at the base, and a deep longitudinal impression either side, and diverging towards the base, from between the antennal insertions to the posterior margin of the eyes. Antennae inserted in a lateral cavity in front of the eyes, 11-segmented but appearing 10-segmented as the two terminal segments are fused and form an abrupt club. Pronotum quadrate or nearly so, broadest at or behind the middle with curved and toothed lateral margins, anterior angles with a forwardly-produced tubercle, posterior angles rounded and usually with a weakly protruding flat tubercle. Surface with a wide and shallow depression either side in the posterior half, this sometimes needs to be looked for very carefully with shallow lighting. Elytra elongate and curved laterally, with prominent shoulders which are slightly produced forward, rather abrupt, almost obliquely truncate, apical margins leaving the pygidium exposed. Striae strongly punctured; regular on the disc but confused towards the base and in the apical third, each puncture with a fine recumbent pale hair. Legs generally paler than the elytra, robust and relatively long, femora long and constricted ventrally before the apex, tibiae almost parallel-sided; in the male curved inwards near the apex. Tarsi 5-segmented although this is difficult to appreciate, the terminal segment longer than the others combined, claws smooth and weakly toothed at the base.
Monotoma picipes 1
© Lech Borowiec http://www.cassidae.uni.wroc.pl/Colpolon/index.ht
Monotoma picipes 2
© U.Schmidt https://www.kaefer-der-welt.de/index.htm