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 25 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.
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.
The Boridae are a small family of beetles with no vernacular common name, though recent authors have coined the name conifer bark beetles.Callirhipidae
Callirhipidae is a family of beetles in the superfamily Byrrhoidea. It was described by Emden in 1924.Chalcodryidae
The Chalcodryidae are a family of beetles in the large suborder Polyphaga.Chelonariidae
Chelonariidae or turtle beetles is a family of beetles in the superfamily Byrrhoidea. It was described by Blanchard in 1845.Cucujoidea
Cucujoidea is a superfamily of beetles. They include many fungus beetles, as well as lady beetles ("ladybugs" or "ladybirds"). Also included are a diversity of lineages of "bark beetles" unrelated to the "true" bark beetles (Scolytinae), which are weevils (superfamily Curculionoidea).Cucujus
Cucujus is a genus of beetles in the family Cucujidae, the flat bark beetles. It contains 15 currently recognized species and subspecies.Cucujus cinnaberinus
Cucujus cinnaberinus is a species of beetles in the family Cucujidae, the flat bark beetles. It is native to Europe, being most common in Central Europe and rare in much of Southern and Western Europe.This beetle lives under tree bark. It is associated with oaks (Quercus spp.), maples (Acer spp.), and poplars (Populus spp.). It can be found in various habitat types, including forests and urban areas. It is a saproxylic species, often feeding on decomposing wood. It has also been observed eating maggots and the larvae of other beetles.This beetle is on the IUCN Red List as a near-threatened species. It is on many national lists of threatened species in Europe. Forest management practices include the removal of dead wood and dying trees, reducing available habitat and food sources for the beetle.Histeroidea
Histeroidea is a superfamily of beetles in the infraorder Staphyliniformia.Laemophloeidae
Laemophloeidae, "lined flat bark beetles," is a family in the superfamily Cucujoidea characterized by predominantly dorso-ventrally compressed bodies, head and pronotal discs bordered by ridges or grooves, and inverted male genitalia. Size range of adults is 1–5 mm (0.04–0.2 in) in length. Currently, it contains 40 genera and about 450 species, and is represented on all continents except Antarctica; species richness is greatest in the tropics.
Historically, Laemophloeidae was treated as a subfamily of Cucujidae, but starting in the middle of the 20th century, most of what had been treated as subfamilies of the Cucujidae were considered to be families.
Most laemophloeids, adults and larvae, are found under bark of dead trees, where they apparently are primarily fungivores, although some genera with adults having subcylindrical bodies (e.g., Leptophloeus, Dysmerus) occur in the galleries of bark beetles (Curculionidae: Scolytinae), upon which they may feed. A few genera, but most particularly Cryptolestes, contain some species that are pests of stored grain products. The most important of these are C. ferrugineus (Stephens), C. pusillus (Schönherr), and C. turcicus (Grouvelle).Several genera exhibit unusual modifications to male antennae (especially Cryptolestes, Dysmerus, and Microbrontes), with the scape expanded into hook-like or blade-like structures Several other genera (Rhinomalus, Rhinophloeus, and Metaxyphloeus) related to Laemophloeus are atypical in that the adults are rostrate to varying degrees Photographs of most world genera are available at, and most North American species are pictured at,Michael C. Thomas
Michael C. Thomas (born 1948) is an American entomologist who is co-author of the book series American Beetles.
Born in Miami, Florida, Thomas graduated from the University of South Florida in 1970 with a Bachelor of Arts degree in fine arts, followed by a Master of Science degree in Entomology from the University of Florida in 1981. Thomas has also received his Ph.D. from the University of Florida.
From 1986 to 1988, Thomas worked as a Taxonomic Entomologist for the West Virginia Department of Agriculture.
Since 1988, Thomas has worked for the Florida Department of Agriculture and Consumer Services in Gainesville as a Taxonomic Entomologist, an Entomology Section Administrator, and a Curator of Coleoptera and Orthoptera. His research interests include the biology and systematics of Cucujidae, and the zoogeography of the Coleoptera of Florida.Pediacus
Pediacus is the largest genus in the family Cucujidae. It contains 31 currently recognized species. Pediacus adults are relatively small (2.7-7.0mm), flattened brownish beetles with no or very small temples, and short antennae with a distinct club. Male genitalia are inverted and possess a short flagellum.
The genus is Holarctic in distribution, but extends south as far as Guatemala in the Western Hemisphere, generally at high altitudes, and into Australia in the Eastern Hemisphere. Adults and larvae are found under dead bark; frequently that of conifers in North America. They are thought to be predaceous. Most of the world fauna of Pediacus has been revised recently and the genus is relatively well-known taxonomically. Included species are:
In addition to the extant species, a single fossil species, Pediacus periclitans Scudder, has been described from the Eocene deposits at Florissant, Colorado. Its assignment to Pediacus has been questioned.Pediacus andrewsi
Pediacus andrewsi is a species of flat bark beetle in the family Cucujidae. It is found in North America.Pediacus depressus
Pediacus depressus is a species of flat bark beetle in the family Cucujidae. It is found in Europe & Northern Asia (excluding China).Pediacus fuscus
Pediacus fuscus is a species of flat bark beetle in the family Cucujidae. It is found in Europe & Northern Asia (excluding China) and North America.Pediacus ommatodon
Pediacus ommatodon is a species of flat bark beetle in the family Cucujidae. It is found in North America.Pediacus stephani
Pediacus stephani is a species of flat bark beetle in the family Cucujidae. It is found in North America.Pediacus subglaber
Pediacus subglaber is a species of flat bark beetle in the family Cucujidae. It is found in North America.Rhinorhipidae
The Rhinorhipidae are a family of beetles, in the large suborder Polyphaga. It contains the single genus Rhinorhipus with a single species Rhinorhipus tamborinensisSilvanidae
Silvanidae, "silvan flat bark beetles", is a family of beetles in the superfamily Cucujoidea, consisting of 58 described genera and about 500 described species. The family is represented on all continents except Antarctica, and is most diverse at both the generic and species levels in the Old World tropics.Silvanids generally are small, brownish, flattened, pubescent and densely punctured beetles ranging from 1.2-15mm in length, and mostly with a 5-5-5 tarsal formula. They have short, strongly clubbed, to very elongate antennae, and frequently grooves or carinae on the head and/or pronotum. Many genera have the lateral margins of the pronotum dentate or denticulate. The family is divided unequally into two subfamilies: Brontinae and Silvaninae. The Brontinae, arranged in two tribes (Brontini and Telephanini) of 10 genera each, are larger, loosely jointed beetles with long antennae, an especially elongate scape, inverted male genitalia, and mandibular mycangia. Both brontine tribes have recently been reviewed at the genus level. The Silvaninae, which has not been divided into tribes, consists of 48 genera of mostly smaller beetles characterized by their closed procoxal cavities, mostly without mandibular mycangia, and non-inverted male genitalia.The largest genera are Telephanus (109 species), Psammoecus (81 species), and Cryptamorpha (27 species) (all Brontinae: Telephanini) and the Old World silvanine genus Airaphilus (35 species). There have been a number of major taxonomic studies in the Silvanidae in recent decades, including Halstead (1973), Sen Gupta and Pal (1996), Pal (1981, 1985), and Karner (1995, 2012).
Investigations into the phylogenetic relationships within the family and between the Silvanidae and other cucujoids are at the preliminary stages. A phylogenetic analysis of the "primitive" cucujoids using morphological characters of larvae and adults found a close relationship between the Silvanidae and Cucujidae. A molecular phylogenetic study primarily aimed at clarifying the status of the more "advanced" cucujoids nevertheless included exemplars of the basal taxa. It showed a close relationship between Passandridae and Silvanidae, and a more distant one with Cucujidae.
Extant Coleoptera families