Common name: Hister beetles, clown beetles
Number of species: 52
Size Range: 1-10mm
Tarsi: 5-5-5.
Description:
The 2012 British list has 52 species of Histeridae (1-10mm long), in seven subfamilies. The family have truncate elytra, leaving the final two abdominal segments exposed, and characteristic geniculate (elbowed) antennae with terminal clubs. Generally strong-flying, quadrate species, most are carnivorous and are often found on carrion, where they usually arrive late and feed on other scavenging species. When disturbed, they fold their appendages into grooves on the underside and play dead, often for a long time.
Subfamily Abraeinae contains nine small (1-3mm) species, mostly associated with wood in various states of decay. An exception is Halacritus punctum Aubé, which is only found under seaweed just above the high tide mark. Teretrius fabricii Mazur, a predator of Lyctus spp. (Bostrichidae), has not been recorded in Britain since 1936 and may well be extinct here.
Subfamily Saprininae contains 16 2-7mm species. Most of the Saprinus and Hypocaccus spp. are found in carrion and dung. Myrmetes paykulli Kanaar is widespread but scarce and found in association with the wood ant Formica rufa L., while Saprinus virescens (Paykull) is a predator, probably of Phaedon and Gastrophysa larvae (Chrysomelidae).
Subfamily Dendrophilinae has 7 British representatives. Several can be found beneath tree bark, but additionally one Dendrophilus species, D. punctatus (Herbst) is found in bird nests and occasionally in association with the wood ant F. rufa, where it can be joined by Dendrophilus pygmaeus (L.). Carcinops pumilio (Erichson) is another carrion species (although it is also found in other decaying organic matter, particularly bat droppings and vegetation), while Kissister minimus (Aubé) is usually found amongst grass roots in sandy areas. Dendrophilus xaveri Marsuel is of Japanese origin, and rarely, briefly established in grain and flour warehouses in port cities, particularly Bristol, London and Liverpool.
Subfamily Onthophilinae includes just two species, Onthophilus striatus (Forster) and O. punctatus (Muller), which can be separated from other Histeridae by the presence of longitudinal keels on the elytra. Onthophilus punctatus is very localised in England where it is associated with subterranean mammal nests and runs, but O. striatus is common and widespread in dung and leaf litter.
Subfamily Tribalinae has only one British representative, the black 2-3mm length beetle Epierus comptus, found only under beech (Fagus sylvatica L.) bark in Wiltshire and Hampshire.
Subfamily Histerinae includes 16 medium-sized (3-11mm) British species, mostly rounded, and shining black, rarely with red patterning. Many are common in dung, carrion and rotting fungi, but Hister quadrinotatus Scriba and H. illigeri Duftschmidt are thought to be extinct in Britain. Margarinotus marginatus (Erichson) is a specialist of mole nests and is thus likely to be under-recorded. Hister unicolor Linnaeus and Margarinotus ventralis (Marseul) are most likely to be encountered in dung on pasture, whereas Margarinotus brunneus (Fabricius) is most typically found in carrion and Margarinotus merdarius (Hoffmann) in garden grass and compost heaps or in birds’ nests in tree cavities. The rarely-encountered and usually strikingly red and black Hister quadrimaculatus Linnaeus, is restricted to the English coast in Hampshire and Kent.
Subfamily Haeterinae has only one British species, Haeterius ferrugineus (Olivier), a rare 1-2mm reddish beetle associated with ant nests, particularly those of Formica sanguinea Lat. in southern England.
Histeridae is a family of beetles commonly known as clown beetles or hister beetles. This very diverse group of beetles contains 3,900 species found worldwide. They can be easily identified by their shortened elytra that leaves two of the seven tergites exposed, and their geniculate (elbowed) antennae with clubbed ends. These predatory feeders are most active at night and will fake death if they feel threatened. This family of beetles will occupy almost any kind of niche throughout the world. Hister beetles have proved useful during forensic investigations to help in time of death estimation. Also, certain species are used in the control of livestock pests that infest dung and to control houseflies. Because they are predacious and will even eat other hister beetles, they must be isolated when collected.
Characteristics
The hister beetles are easily identified by their shiny elytra which is typically shiny black or metallic green. The two main shapes for this family are oval and flat. The elytra is shorter than the abdomen with typically two of the seven tergites exposed. Hister beetles have specialized heads that can retract into their prothorax and two geniculate (elbowed) antennae with clubbed ends. As predators, hister beetles commonly feed on the egg, larval, and adult stages of other insects. Certain species are also used to control livestock pests that infest dung or to control house flies. Histeridae are most active at night and they will play dead if they feel threatened.
Etymology
Histeridae was named by Leonard Gyllenhaal. Histeridae has two common names, the “clown” beetle and the “hister” beetle. There have been several theories explaining the origin of these common names. One theory for the “hister” nickname comes from the work of Juvenal, a Roman poet. Juvenal used the word “hister” to mean a dirty, lowly being. Another theory for the origin of this beetle’s name stems from the fact that in Latin, “hister” means actor.
Anatomy
The elytra and forewings are normally well developed in beetles, but in Histeridae the elytra are shortened and rectangular. The shortened elytra expose the final two of the seven tergites. The head has compound eyes, a mandible mouthpart, and shortened antennae. A distinctive characteristic is that the antennae are elbowed and contain three antennomeres that form a club at the end.
Clown beetles have an open circulatory system within its hemocoel, also known as a body cavity. They have a tube shaped heart that spans the length of the body, and use hemolymph as blood. This blood does not contain any oxygen, but carries nutrients throughout the body. Spiracles are located on the abdomen and are the tracheal system of the beetle. Oxygen is brought into the body by spiracles and tiny sacs exchange the oxygen like a mammal’s lung.
Habitat
Hister beetles are found throughout the world in various habitats. Histeridae have been located in North America, Central America, Europe, Asia, and Australia, but each hister beetle occupies certain niches. The beetles live in dung, carrion, dead vegetation, sandy areas, under tree bark, mammal burrows, and ant/termite colonies. Charactertistics of the hister beetle are dependent upon its habitat. For example, the flat hister beetles are found under bark, while the cylindrical beetles are not. The shape of the beetle will vary from species to species.
A remarkable ability of some hister beetles is their capacity to live in close proximity with ants (myrmecophiles) and termites (termitophiles). The hister beetles can live in harmony with the ants or prey on the ants, depending on the species.
Histeridae live in widespread habitats because they feed on other arthropods. As new food sources are introduced into an environment, the predators of that food source will soon follow. Histeridae live in areas where their prey feed. Some examples are mammalian nests where other arthropods scavenge for food or carrion where maggots will arrive.
