COLEOPTERA > POLYPHAGA > CUCUJOIDEA > Silvanidae

Also known as Flat Grain Beetles, the Silvanidae family is represented in Britain by 12 species in ten genera, separated into two subfamilies, Brontinae and Silvaninae.

In the Silvaninae there are two rather similar Silvanus saproxylic species in the UK, Silvanus bidentatus and Silvanus unidentatus, both with very scattered, primarily south-eastern distribution. The more common species is Silvanus unidentatus although, to put that into perspective, at the time of writing (March 23) the NBN Atlas only showed 365 records. Silvanus bidentatus had just 68, with only two very old local records, both from the New Forest. I can only surmise that the very small size and lifestyle of these species means that they are generally overlooked and, that any that are seen, are probably not photographed and/or certainly not recorded.

Silvanus bidentatus is the larger of the two by a fraction at 2.8-3.4mm. The head is supposed to have distinctly larger temples than Silvanus unidentatus, but that particular feature and the size are of little use unless you're directly comparing the species. Fortunately, there are two further characters that help to distinguish Silvanus bidentatus. Firstly, the fact that the head, pronotum and elytra are equally dull, whereas in Silvanus unidentatus the head and elytra are shiny and only the pronotum is dull. Secondly, the pronotum has a continuous longitudinal depression, which is actually rather difficult to make out, but is coupled with strongly acute anterior angles that can be seen quite clearly in some shots.     

Typically found under damp, close-fitting, rather than loose, bark on both standing and fallen timber, particularly oak and beech. Adults may be found year-round, but are known to be most common in early spring and late autumn.

Updated, Jan.24 (v.2)