SCARABAEINAE Latreille, 1802
True Dung Beetles
Only poorly represented in the UK, of the 9 species on the UK list at least 3 no longer occur here. All species are associated with decaying organic material, especially dung.
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Introduction
Because most species develop exclusively in dung, members of this subfamily are often referred to as True Dung Beetles. The subfamily is divided into about a dozen tribes but this may change as the phylogeny is worked out. Some smaller tribes e.g. Gymnopleurini, Eurysterini and Sisyphini are distinctive and undoubtedly monophyletic while others e.g. Dichotomiini and Canthonini may be polyphyletic and the limits are almost certainly going to change, following the classification can be very difficult as species and genera have frequently been reassigned and many differing versions can be found and continue to appear. For an insight into the problems of scarabaeine classification click HERE. This subfamily is by far most diverse in tropical regions where they are the dominant larger dung beetle fauna. The world fauna is estimated to include about 7000 described species, half of which are included in 2 tribes, Onthophagini and Oniticellini, Africa has the largest diversity with more than 2000 species in around 110 genera and, as variously classified, up to a dozen tribes. Many more species, up to 1000, await description from stored material and the ultimate size of the subfamily is likely to be much larger. Most feed on and develop among the dung of herbivores and omnivores but many also feed on decaying vegetation, plants and fungi. Many are known as ‘rollers’ as they form dung into spheres and roll it to excavated brooding chambers. Others are exclusively tunnellers; they bury the dung where they find it. A third group are ‘dwellers’ and these simply live within the dung in situ. Dwellers tend to be small and elongate types, along the lines of Aphodius. Most members of the subfamily are dull brown or black but many species are brightly coloured and metallic and this may be the main reason for their popularity with collectors. Most have stout and flattened bodies and tunnellers have robust and toothed legs adapted for burying and rolling. In many species the front tarsi are vestigial or missing in one or both sexes. Desert living species have spinose or hairy legs suited for moving sand. All have soft mouthparts adapted to feeding within dung and most do not feed on anything else as this medium provides all the necessary nutrients. In general the larvae feed on undigested plant material within the dung while adults rarely consume solids but squeeze the material and consume the nutrient rich liquid. Most locate food using a strong sense of smell while some may attach themselves to animals or follow them waiting for the dung
to appear. Once dung has been found it is dealt with immediately as competition may be fierce. Rollers form balls and roll them away in more or less straight lines in an attempt to prevent them being stolen, when suitable ground has been found they will bury the balls and use them either for food storage or for brood development in chambers or tunnels. Males usually roll the balls while females follow or attach themselves to the ball. Sometimes tunnels are previously prepared, otherwise the ball is buried in the first soft ground they find. After burying the ball beetles will mate underground and the female will lay an egg or several eggs among the host material. Some species will remain to guard the ball and even the developing offspring while others leave the tunnel to begin the process again. Tunnels may be used more than once, ending up with a stack of balls each containing a larva or larvae, and in such cases the resulting adults will eclose together or else those at the top of the tunnel will emerge first. Several dung-rollers occur in Europe but none extend to the UK.
Tribes
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CANTHONINI Peringuey, 1900 (=Deltochilini Lacordaire, 1856) is a large tribe of around 1000 species in about 120 genera. They are small to medium sized beetles, 2-33mm, and round or oval in shape with only minimal sexual dimorphism; males lack horns to the pronotum or head. The antennae are 9 segmented. Most species are ball rollers; carrion or dung is shaped and rolled away from the food source and buried. The group is widely distributed in tropical and sub tropical regions with many species in North America and the dry areas of South American rain forests. There are around 340 New World species in 27 genera. A few genera occur in Southeast Asia, Australia and New Zealand but the greatest diversity is in Old World tropical regions, there are many island endemics and Madagascar is particularly rich in endemic genera and species
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COPRINI Kolbe, 1805 is a medium-sized tribe, often listed as a distinct subfamily, with around 20 genera and more than 550 species worldwide. The near-cosmopolitan genus Copris Geoffroy, 1762 includes about 250 species of which 105 are Afrotropical and around 30 occur in the Americas. The New World fauna otherwise includes more than 220 species of 4 genera with the majority occurring in Central and South America. The group is otherwise diverse in Southeast Asia and, particularly, Africa. Heliocopris Hope, 1837 is a widespread Old World genus, about 45 occur in Africa and 4 in Asia while one is common to both regions, it includes the largest members of the subfamily, up to 65mm in length and is only approached in size by a few African and South American species, it includes many iconic species and is generally prized by collectors. Species of Coprini are generally medium sized beetles, 8-25mm, elongate and very convex and robust. Most are black. Sexual dimorphism is usually strong with males having horns or tubercles to the head and/or the pronotum. The antennae are 9 segmented. The mid and hind tibiae are usually strongly dilated, an adaptation to the dung rolling way of life. The European fauna includes 4 species of Copris.
Heliocopris sp. (Kenya)
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ATEUCHINI Montreuil, 1998. A very diverse tribe of around 750 species included in 40 or so genera, the majority occur in the New World but Africa is also diverse and several occur in southern Asia and Australia. Many are attractively coloured; glossy chestnut brown and red, and many show pronounced sexual dimorphism. Most are coprophagous; dung rollers and tunnellers, but a few are saprophagous, notably the South American Bdelyrus and Bdelyropsis, some of which are found in Bromeliads. Uroxys (60 species) and Trichillum (5 species) are widely distributed in South America and contain some small, specialized species which are phoretic on Sloths, other species occur in North American forests and open grassland.
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EUCRANIINI Brullé, 1834 is a small tribe of 4 genera and about 20 species of small to medium (up to 20mm) sized dung rollers and tunnellers. Many show a spectacular degree of sexual dimorphism. All occur in the New World and most in the arid regions of Argentina, Bolivia and Ecuador.
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EURYSTERNINI Volcano, Martinez and Pereira, 1960 includes about 30 species of the single genus Eurysternus Dalman, 1824, they occur from Mexico to warmer parts of South America and are unusual among the subfamily in that they are unable to roll brood-balls. Females form balls of dung which are kept together and covered with soil etc, a single egg is laid in each and either both sexes or, more usually, the female guards the nest while the larvae develop. This is also the only genus in which members occasionally commit infanticide by consuming the brood balls, this has also been observed in some Heliocopris but only when there is no other food source for caring females, in the present genus infanticide occurs even when alternative food is available. Members are atypical of the subfamily in being less compact, more elongate and parallel-sided than is usual and most have very long legs with strongly toothed tibiae. Sexual dimorphism is generally only weakly developed.
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GYMNOPLEURINI Lacordaire, 1856. This is an Old World tribe of 4 genera and more than 100 species, most occur in Southeast Asia and Africa although 4 species of the widespread genus Gymnopleurus Illiger, 1803 (sometimes included within the Scarabaeini) extend into Europe.
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ONTHOPHAGINI Lacordaire, 1856. This large tribe is dominated by the large genus Onthophagus Latreille, 1802 which contains more than 2000 species (although some estimates place this at 2500), of which more than 800 occur in Africa. Members of the tribe occur worldwide but the largest diversity is seen in Africa; of a total of more than 2200 species in around 35 genera more than 1100 of 32 genera are African. Towards more temperate regions this diversity declines rapidly e.g. the European fauna includes 53 species of 3 genera, including 47 Onthophagus, while in France there are 23 species in 3 genera, of which 20 are Onthophagus. As with many groups of the Scarabaeidae the present tribe, and especially the genus Onthophagus, is undergoing constant revision. They are small to medium sized beetles, 2-14mm, oval and convex or dorsally flattened, and generally drab coloured in temperate regions but often brightly coloured and metallic in the tropics. Good, if rather random, examples worth searching on line for are O.nigricornis Fairmair, 1887, a spectacular bright metallic green and bronze species from Kenya which reaches 13mm and displays extreme sexual dimorphism and O. gazella (Fabricius, 1787) a widespread African species which is now established in Australia following introduction. Sexual dimorphism is a general feature of the tribe; in males the head or pronotum or both have developed horns or carinae which are often exaggerated. The elytra sometimes bear longitudinal raised carinae or the pro-tibiae may be elongate, compared to the female, and have a long ‘brush’ or ‘comb’ of setae at the apex. The females generally bear carinae or tubercles to the head or pronotum rather than horns. The scutellum is always hidden and the elytra bear 7 discal striae. All legs have well developed tarsi and claws. The mid and hind tibiae are broadly dilated in both sexes. The pygidium is exposed and the abdomen has 6 visible fused sternites. The clypeus is expanded, covering the mouthparts.
Gymnopleurus geoffroyi (Fuessly, 1775) (Greece)
In temperate regions the species are univoltine with oviposition in late spring or summer. Development to adult generally takes between 7-10 weeks. Tunnels are excavated to between 20 and 250mm beneath dung and range from simple and unbranched to multibranched or complex systems with several openings to the surface. In many species the male excavates beneath the dung using the fore- legs, head and pronotum to dig. He then packs the tunnel with dung. Brood masses are formed by the female who will sometimes also help collect fresh dung. This is a continuing process and the nest will be expanded as the season progresses, new brood masses are often formed beneath existing ones so that eclosing adults do not disturb those above. Complete tunnels or systems may contain many brood masses, and nests are completed when the adults seal the shafts between masses and at the surface. Brood masses are usually small, weighing only a few grams, and spherical oval or elongate. Usually a single egg is deposited into each mass. Up to 14 brood masses have been recorded in a complex system in Spain. Females take up to 24 hours to construct a brood mass and so provisioning a nest may be a protracted process but the age of the masses does not correlate with adult emergence and more recently constructed masses may produce adults before older ones. Eggs hatch after a few days. There are three larval instars and most of the feeding is done by the first and second which pass rapidly within the mass. The third instar remains in its cocoon, forming the pupa. The pupal stage generally lasts for two or three weeks. New adults aestivate within the chamber without feeding and enter hibernation in the autumn, occasionally leaving the tunnel to feed. Outside of the temperate regions there is a tendency for the nests to become larger, with more brood masses and more generations, or even continuous breeding through the year. For much interesting information regarding the northern European fauna see HERE. While many species inhabit herbivore dung they may also have alternative food sourced such as decaying fungi or vegetation and some specialized tropical species feed on exclusively on fungi, fruit, carrion and even centipedes, a few highly specialized genera live within ant or termite nests, feeding on accumulated detritus.
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ONITINI Hope, 1837 includes 18 genera and about 200 species, it is essentially African although three genera, Bubas Mulsant, 1842, Onitis Fabricius, 1798 and Cheironitis van Lansberge, 1875 extend north into Europe, and several species of Onitis and Bubas have been introduced into Australia and the United States including Hawaii. The group is dominated by the large genus Onitis, which includes about 160 species and is the only genus to extend east into Asia and Southeast Asia. Species are typical of the family; short, convex and parallel-sided, they lack anterior tarsi and generally display only weak sexual dimorphism; in many the anterior tibiae of the male is extended into a curved hook-like process. Many species are brightly coloured and metallic. The life history of many is similar to that of geotrupids where burrows are excavated directly below the food source and provisioned with dung for the larvae, dung is formed into cylindrical masses and several eggs are laid into each. Most species are thermophilous and in warmer regions the life-cycle is rapid and several generations may be produced each year although in cooler temperate areas they are univoltine. Many species fly at dusk or dawn, often in large numbers and fresh dung is rapidly colonized and buried.
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ONITICELLINI d’Orbigny, 1916 includes about 150 species in 28 genera and 6 subtribes. It is essentially an Old World group with a single genus of 2 species endemic to Jamaica and one species of the large and mostly African and Asian genus Liatongus Reitter, 1893 is native to the United States. Several species have become established following introductions to Australia and North America. Africa is the most diverse region but the group is widespread in Asia and Southeast Asia and 4 species of 2 genera occur locally in southern Europe. The largest genus, Helictopleurus d’Orbigny, 1915, with about 55 species, is endemic to Madagascar. Members are mostly medium sized and very convex or dorsally flattened scarabs, many are drab but the group includes brightly coloured and metallic species and many display exaggerated sexual dimorphism with the males having head and/or pronotum modified, the legs are generally long and robust and anterior tarsi are present, Scaptodera rhadamistus (Fabricius, 1775) is a good example. Most species tunnel below herbivore dung but some construct brood cavities within the dung or in a depression excavated below the dung.
Onitis alexis Klug, 1835 (Morocco)
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PHANAEINI Macleay, 1819 is sometimes considered to be a subtribe of the Onitini. This tribe includes 12 genera and more than 150 species. They are small to medium species, 12-25mm, exclusive to the New World and mostly from tropical regions of South America. They are very robust species and many are brilliantly coloured and metallic. Many display extreme sexual dimorphism with well developed horns on the head and/or pronotum in the male. The antennae are 9 segmented with the basal segment of the club cup-shaped and encircling the two terminal segments. The anterior tarsi are absent in the males and either absent or present in the females. All tarsal claws are missing in both sexes. Many of the species are impressive and worth a look; all species of Phanaeus are impressive but in particular search for: P. amethystinus Harold, 1863, P. demon Laporte, 1840, P. difformis LeConte, 1847, and P. palaeno Blanchard, 1843. Also worth a look: Coprophanaeus jasius (Olivier, 1789), Sulcophanaeus balesi (Harold, 1868) and S. menelas (Castelnau, 1840).
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SISYPHINI Mulsant, 1842 is a relatively small Old World group of about 75 species included in 3 genera. Nesosisyphus Vinson, 1946 includes 4 species and is endemic to Mauritius while both Neosisyphus Müller, 1942 and Sisyphus Latreille, 1807 are more widespread with most occurring in the African, Asian and Oriental regions and a few extending to Australia and Central America. Sisyphus is of interest to European coleopterists as a single widespread Palaearctic species, S. schaefferi (Linnaeus, 1758) is locally common in many areas. Sisyphus otherwise includes 28 Afrotropical species, 12 Oriental species and 2 from Central America. All are medium-sized scarabs, 3-10mm, characterized by a dorsally flattened body and very long intermediate and hind legs, most are smooth and drab coloured, mainly black, although some have strongly tuberculate elytra and pronotum, in most the head is widely explanate in front of the eyes and the elytra taper strongly from broad shoulders to narrow and rounded apex. All are dung-rollers; both sexes form a ball from recently deposited and moist dung and both roll it away from the pile, the male pushing with the middle and hind legs and the female pulling with her front legs. Both bury the ball or, if other beetles are nearby, the female will bury it while the male stands guard, and once underground the female will re-work the ball and lay a single egg into it, both sexes then abandon the tunnel and the single larva develops within. All species are diurnal although in tropical areas they also occur at light.
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SCARABAEINI Latreille, 1802. This is an Old World group of 8 genera and about 200 species, 3 genera are restricted to southern Africa and one occurs in Africa and Southeast Asia. The large genus Scarabaeus Linnaeus, 1758 includes about 150 species of mostly Afrotropical and Palaearctic origin but many are now more widespread due to introductions into other countries, especially Australia. Thirty one species included in 5 subgenera are Palaearctic of which 13 occur in Europe, generally up to around 48° north. Most European species also occur in Asia Minor and Africa. Species range in size from 18 to 36mm, they are broad and robust in build, entirely black or nearly so and both sexes (in common with some other Scarabaeinae genera) lack front tarsi; there is only a vestigial claw-like structure which might be used in forming and rolling brood balls. The middle and hind legs have well developed tarsi. Typically the clypeus is widely expanded and developed into broad teeth that align with those on the front tibiae, forming a semicircle when the beetle is rolled up. All species are dung rollers; they form balls from various kinds of dung, smaller ones for their own consumption and larger ones in which the larvae will develop-brood balls. Both types are buried to prevent desiccation. Adults excavate tunnels before going off to find dung for the brood balls. After burying the dung the female deposits an egg into the ball which will be consumed by the larva. Pupation occurs within the tunnel and, in temperate regions, the adults eclose in late summer or autumn, remaining in the tunnel until the following spring. Many European species of Scarabaeinae suffered a decline in the latter half of the 20th century due to changes in land use and the widespread application of agricultural and other chemicals, both of which they seem to be especially sensitive to. Typical of the genus, Scarabaeus variolosus Fabricius, 1787 is a local but widely distributed species found from France to Greece and Turkey including the Mediterranean islands, and North Africa. It inhabits regions with a Mediterranean climate i.e. low summer rainfall and mild winters, and generally occurs between 150 and 550m. Adults are active from July to October.
Sisyphus schaefferi (Linnaeus, 1758) (Morocco)
Scarabaeus variolosus Fabricius, 1787 (Greece)
UK Species
1.
Size large; 16-21mm
Size much smaller; <12mm
2.
Elytra entirely black.
Elytra pale with dark marks.
3.
Lateral margins of the pronotum sinuate behind the front angles. 6-11mm.
Lateral margins of the pronotum evenly rounded behind the front angles.
4.
Pronotum and elytra pubescent. 4-6mm.
Pronotum and elytra glabrous.
5.
Lateral margins of the pronotum sinuate behind the front angles.
Lateral margin of the pronotum rounded.
6.
Epipleura entirely yellow or brown. 6-8mm. Pronotum much more strongly metallic.
Epipleura black, or at least the longitudinal carina black. Pronotum less strongly metallic.
7.
Base of the horn in the male broad and angled. In the female the posterior transverse ridge on the head is as wide as the anterior ridge so that the fine lines connecting the ends of these are parallel.
Base of the horn narrow and not angled. In the female the posterior ridge is narrower so that the lines connecting the ends are angled towards the base of the head.
8.
Pronotum black. Fifth elytral interstice dark at base. 6-9mm.
Pronotum metallic green or black. Fifth interstice pale at base. 7-11mm.