The Cucujidae, "flat bark beetles," are a family of distinctively flat beetles found worldwide (except Africa and Antarctica) under the bark of dead trees. The family has received considerable taxonomic attention in recent years and now consists of 59 species distributed in four genera.
Included genera are: Cucujus Fabricius, with 14 species and subspecies distributed throughout the Holarctic; Palaestes Perty, 8 spp., Neotropical; Pediacus Shuckard, 31 spp., mostly Holarctic, but extending south into the Neotropics and to Australia; and Platisus Erichson, 5 spp. in Australia and New Zealand.
Cucujidae have elongate parallel-side bodies ranging from 6 to 25Â mm in length. Most are brown colored, while others are black, reddish or yellow. Heads are triangular in shape, with filiform to moniliform antennae of 11 antennomeres, and large mandibles. The pronotum is narrower than the head.
Both larvae and adults live under bark, otherwise little is known of their habits. Larvae appear to be predacious
The family was formerly larger, with subfamilies Laemophloeinae, Silvaninae, and Passandrinae (and some tenebrionoid genera mixed in), but recent revisions have raised the subfamilies to family status.
Species with extreme freezing tolerance
Cucujus clavipes puniceus (red flat bark beetle) found in arctic regions like Canada and Alaska desiccates to 30-40% body water in winter vs 4% body water in the chironomid fly, Polypedilum vanderplanki. It uses a variety of anti-freeze proteins in contrast with the non-protein xylomannan exploited by another arctic beetle Upis ceramboides.
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