The Cucujidae, "flat bark beetles," are a

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

of distinctively flat

beetle Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...

s 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 70 species distributed in five genera. It was indicated Cucujus species are scavengers, only feeding on pupae and larvae of other insects and on other subcortical beetles such as their own. Since the Cucujidae prey on larvae of potentially tree damaging beetles that spread fungal diseases, they are considered to be beneficial to the health of living trees. PalaestesMontage

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; ''Platisus'' Erichson, 5 spp. in Australia and New Zealand, and ''Thesaurus'' known from South America. Platisus coloniarus habitus

Cucujidae have elongate parallel-side bodies ranging from 6 to 25 mm in length. Most are brown colored, while others are black, reddish or yellow. Heads are triangular in shape, with

filiform Filiform, thread or filament like, can refer to: * Filiform, a common term used in botany to describe a thread-like shape *Filiform, or filiform catheter In medicine, a catheter (/ˈkæθətər/) is a thin tubing (material), tube made from m ...

to moniliform antennae of 11 antennomeres, and large

mandibles In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

. The

pronotum The prothorax is the foremost of the three segments in the thorax of an insect, and bears the first pair of legs. Its principal sclerites (exoskeletal plates) are the pronotum ( dorsal), the prosternum (ventral), and the propleuron (lateral) on e ...

is narrower than the head. Pediacus subglaberMontage

Both larvae and adults live under bark, otherwise little is known of their habits.D. B. Smith and M. K. Sears. 1982. Mandibular structure and feeding habits of three morphologically similar coleopterous larvae: ''Cucujus clavipes'' (Cucujidae), ''Dendroides canadensis'' (Pyrochroidae), and ''Pytho depressus'' (Salpingidae). Canadian Entomologist 114: 173–175. Larvae and adults appear to be predacious. '' Cucujus cinnaberinus'' seems to be able to colonize isolated habitats from persisting local populations if there is a sufficient quantity of suitable deadwood in the habitat and it has the other requirements of saproxylic beetles. The family was formerly larger, with subfamilies Laemophloeinae, Silvaninae, and Passandrinae (and some tenebrionoid genera mixed in), but revisions have raised the subfamilies to family status. While there have been claimed fossil records going back to the Early Cretaceous (such as those from the

Crato Formation The Crato Formation is a geologic formation of Early Cretaceous (Aptian) age in northeastern Brazil's Araripe Basin. It is an important Lagerstätte (undisturbed fossil accumulation) for palaeontologists. The strata were laid down mostly during ...

of Brazil), the oldest unambiguous records are from the

Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...

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 ''Polypedilum vanderplanki'' or the sleeping chironomid, is a dipteran in the family Chironomidae (non-biting midges). It occurs in the semi-arid regions of the African continent (e.g. northern Nigeria and Uganda). Its larvae are found in small t ...

''. It uses a variety of anti-freeze proteins in contrast with the non-protein

xylomannan Xylomannan is an antifreeze molecule, found in the freeze-tolerant Alaskan beetle ''Upis ceramboides''. Unlike antifreeze proteins, xylomannan is not a protein. Instead, it is a combination of a sugar (saccharide) and a fatty acid that is found in ...

exploited by another arctic beetle ''

Upis ceramboides ''Upis ceramboides'' is a species of beetle, one of many wood-living insects that benefit from forest fires. It often occurs in quantities below the bark on the fire-damaged birches, but can sometimes be seen on other deciduous trees such as wil ...

''.

References

*HORAK, J., VAVROVA, E., & CHOBOT, K. (2010). Habitat preferences Influencing POPULATIONS, distribution and conservation of the Endangered Saproxylic beetle CUCUJUS cinnaberinus (coleoptera: Cucujidae) at the landscape level. ''European Journal of Entomology'', 107(1), 81-88. *Bonacci, T., Mazzei, A., Naccarato, A., Elliani, R., Tagarelli, A., & Brandmayr, P. (2018). Beetles “IN red”: Are the ENDANGERED FLAT bark beetles CUCUJUS Cinnaberinus and c. Haematodes Chemically protected? (coleoptera: Cucujidae). ''The European Zoological Journal'', 85(1), 128-136. {{Taxonbar, from=Q947515 Cucujoidea families