BIPHYLLIDAE LeConte, 1861
False Skin Beetles
Biphyllus lunatus occurs commonly throughout England and Wales among coal fungus on ash, while Diplocoelus fagi is a very local species restricted to the south.
POLYPHAGA Emery, 1886
CUCUJOIDEA Latreille, 1802
Biphyllus Dejean, 1821
Diplocoelus Guérin-Méneville, 1844
A relatively small family of about 190 species included in 7 genera. They have a worldwide distribution with the largest diversity (66 spp.) in the Neotropics. In the Northern Hemisphere diversity falls rapidly with latitude; in the United States there are 2 genera and 3 species. They are generally woodland insects with the adults and larvae occurring together and although the early stages of most species are poorly understood it is very likely that most are mycetophagous, feeding upon and living within dendrophilous fungi. Two genera are represented in the U.K; Biphyllus Dejean, 1821 and Diplocoelus Guérin-Méneville, 1844, each by a single species.
Byphillids are small, <5mm, and rather drab species; most are brown or grey with pale or orange markings. The habitus is typified by the U.K. species; elongate-oval with a relatively large head, prominent eyes that often have large facets, and the entire dorsal surface with short pubescence. The pubescence is generally erect, short and curved so that it is visible in outline along the pronotal and elytral margins. The antennae are 11-segmented with a distinct 2 or 3-segmented club and inserted under the front margin of the head. The terminal segment of the maxillary palps is cylindrical, that of the labial palps are dilated and transverse. The pronotum is transverse and bearing one or two lateral longitudinal ridges parallel to the side margin. Scutellum distinct. Elytra with regular striae, including a scutellary stria, consisting of strong punctures. Elytral epipleurs distinct. Tarsi 5-5-5 without any obviously lobed segments. Last segment very long. Claws simple. The larvae are almost cylindrical with distinctly pigmented tergites and small conical urogomphi.
Both our U.K. species were formerly included in the Erotylidae but are easily distinguished by the pronotal ridges and the lack of obviously bilobed tarsal segments. Both are keyed out in Joy’s handbook; Biphyllus (as Diphyllus) in the Nitidulidae, and Diplocoelus in the Cryptophagidae. Biphyllus can be identified by the elytral marking while Diplocoelus is rather drab brown but the pronotal sculpture, strongly punctured elytra and simple tarsi will serve to identify both species.
Dark brown to black, each elytron with a transverse, angled patch of pale pubescens near the middle and often a sub-apical patch. Pubescence more evenly recumbent throughout. Antennal club 2-segmented. [Some specimens have small patches of pale pubescence to the pronotum and a pale humeral mark.]
(Chevrolat in Guérin-Méneville, 1837)
Dark to pale brown, elytral disk often darker. Pubescence on pronotum and elytra uniformly pale; both recumbent and semi-erect hairs present on the elytra. Antennal club 3-segmented.