Cis bidentatus (Olivier, 1790)
This species is locally common from lowlands to sub-alpine altitudes throughout Europe from the Pyrenees to Italy and Ukraine in the south, and to the UK and northernmost parts of Fennoscandia in the north, it is absent from most of the Balkan countries and Greece, and the eastern extent of its distribution appears to be western parts of Russia. In the UK it is generally common throughout England, Wales and Northern Ireland; it is widespread in the Scottish Highlands but only very rarely recorded from Southern Ireland. Adults are present year-round; they occur small numbers in old fungal fruiting bodies through the winter and become common from March or April until September, peaking in abundance from June until August. Typical habitats are deciduous woodland and wooded parkland where they are associated with a wide range of fungi; in the UK they are most frequently recorded from Piptoporus betulinus (Bull. Ex Fr.) on birch (Betula pendula Roth,) and so will be found wherever the host occurs e.g. on individual trees or groups of trees growing on heaths and moorland or even in domestic gardens. More generally they may be found on a wide range of broadleaved trees and, in higher European latitudes, they are often common in sporophores of Fomitopsis pinicola (Sw,) P. Karst. on pine. Larvae have been recorded during the summer in sporophores of Piptoporus betulinus, Rigidiporus ulmarius (Sow. Ex Fr.) Imazeki, Trametes gibbosa (Pers.) Fr. (1836) and Laetiporus sulphureus (Bull.) Murrill (1920), and adults have been recorded from the following fungi: Cerioporus squamosus (Huds.) Quélet (1886), Mensularia radiata (Sowerby0 Lázaro Ibiza, Trametes versicolor (L.) Lloyd (1920), Heterobasidion annosum (Fr.) Bref., Gleophyllum odoratum (Wulf.:Fr.) Imazeki, Cerioporus varius (Pers.) Zmitr. & Kovalenko as well as various oyster mushrooms, Pleurotus (Fr.) P. Kumm. Adults are easily sampled by tapping sporophores over a net, they occur in fungi in all stages of decay and are often common in old and very dry samples, they are active nocturnally and may be observed on the surface, and they sometimes occur among bark and decayed wood samples taken from trees infected with fungi.
Cis bidentatus 1
© Lech Borowiec
2.0-2.8 mm. Long-oval and very convex, entirely dark to pale brown, sometimes almost black, elytra with very fine scales which need to be looked for carefully and may only become obvious by manipulating specimens under low-angled light. Head transverse from above, with convex, protruding eyes and converging temples, evenly convex and finely punctured, anterior clypeal margin straight in the female, produced into a sharp tooth at the lateral angles in the male. Antennae pale brown throughout; 10-segmented with a loose 3-segmented club. Pronotum transverse, widest about the middle and curved to obtuse posterior angles and, viewed from directly above, conspicuous anterior angles, surface evenly convex, smooth and finely punctured, anterior margin produced into two conspicuous raised teeth in the male. Elytra about twice as long as the pronotum, with angled shoulders and a continuously-rounded apical margin that covers the abdomen, surface smoothly convex, without striae and evenly punctured throughout, the punctures about as strong as those on the pronotum and each bearing a tiny scale. Front tibiae produced into a sharp tooth at the outer apical angle. Tarsi 4-segmented; basal segments short and lobed, apical segment long and curved.