The Adrastini

Glyphonyx sp., copyright Mike Quinn.

For the subject of my next post, I drew the click beetle tribe Adrastini. Well, actually, I drew the tribe Synaptini but dibs on that name was originally called by a family of sea cucumbers so it seems that 'Adrastini' should be the tribe's proper name. I described click beetles, and the nature of their click, in an earlier post.

The Adrastini are one of those groups of animals for which there seems to be little known to discuss other than their general morphology. The more typical click beetles tend to be fairly uniform in their general appearance and are often not that easy to distinguish. Adrastins belong to the subfamily Elaterinae and resemble other elaterines in their deflexed mouthparts, arcuate prosternum, open mesocoxal cavities and tarsal claws without basal setae. They differ from other elaterines in having serrate tarsal claws according to Stibick (1979). Mind you, another related group, the Melanotini, are supposed to be distinguished by their pectinate claws and I'm not entirely sure what the difference between 'serrate' and 'pectinate' is supposed to be in this context.

The Adrastini are widespread though they seem to be absent from Australia. Several genera are recognised; one of these, Glyphonyx, is distinctly larger than the rest and includes about half the tribe's known species. As far as I know, the larva has never been described for any member of this group, so what they are doing ecologically remains a largely unknown quantity.

REFERENCE

Stibick, J. N. L. 1979. Classification of the Elateridae (Coleoptera). Relationships and classification of the subfamilies and tribes. Pacific Insects 20 (2–3): 145–186.

Blister Beetles

Zonitis sayi, copyright Carol Davis.

This is a blister beetle of the genus Zonitis. Blister beetles, the family Meloidae, get their name from their production of cantharidin, a defensive chemical that can burn the skin of would-be predators. Zonitis is a widespread genus of blister beetles with over 100 species described from around the world. However, it should be noted that its wide distribution may relate to the genus being poorly defined and future revisions may divide its members between other genera (as I believe has already happened for the Australasian 'Zonitis'). As it is, Zonitis species are characterised by fully developed elytra and functional wings, and cleft tarsal claws with two rows of teeth on the upper section (Enns 1956). Adult Zonitis are flower-feeders, visiting composite plants (i.e. daisies and similar plants), and some species have the mouthparts modified into a tube for sucking nectar.

Most blister beetles exhibit what is known as hypermetamorphism or hypermetaboly, where the larvae pass through morphologically differentiated stages before reaching pupation. Zonitis species develop as parasitoids or kleptoparasites of bees. Females lay large numbers of eggs (up to and exceeding 500 in a batch) on their host plant, most commonly on the flowers though sometimes on the undersides of leaves. The eggs hatch into active, long-legged larvae that attach to bees visiting the flowers and so get carried to the bee's nest. Once there, they moult into a less mobile stage and feed on the food stores laid aside for the bee's larva, and potentially on the larva itself. In the North American species Zonitis atripennis flavida, the beetle larva completes its development in a single cell but European species consume the contents of two bee cells before reaching maturity. Following the initial active instar, meloid larvae pass through four feeding instars before entering a quiescent, immobile stage called the hypnotheca or prepupa. The hypnotheca moults into another feeding instar before the larva finally enters the pupal stage (Bologna et al. 2008). What the point (if anything) of the hypnotheca is, I have no idea. However, it is worth noting that hypnothecae of another meloid species, Hornia boharti, have been recorded surviving for multiple years without feeding before moulting to the next instar.

Once adults emerge from the host cell, they of course disperse to conduct their own affairs. Natural history data is patchy but indications are that many species are picky in their choice of host plant. From an economic perspective, their damaging role as a parasite of pollinating bees may be partially counterbalanced by their potential role as pollinators in their own right, but who can say which way the scales lean?

REFERENCES

Bologna, M. A., M. Oliverio, M. Pitzalis & P. Mariottini. 2008. Phylogeny and evolutionary history of the blister beetles (Coleoptera, Meloidae). Molecular Phylogenetics and Evolution 48: 679–693.

Enns, W. R. 1956. A revision of the genera Nemognatha, Zonitis, and Pseudozonitis (Coleoptera, Meloidae) in America north of Mexico, with a proposed new genus. University of Kansas Science Bulletin 37 (2): 685–909.

Darklings, Tok Toks and Pie-dishes

False wireworm beetle Gonocephalum sp., copyright EBKauai.

It has been noted to the point of cliché that the Creator has an inordinate fondness of beetles. Even within the massive range of beetle diversity, though, certain families stand out as particularly diverse. One such family is the Tenebrionidae, with over twenty thousand known species worldwide. The family is sometimes referred to as the darkling beetles but no one vernacular name is really sufficient for this group. Not only are tenebrionids taxonomically diverse, they are morphologically diverse, varying from long-legged and elongate to hemi-spherical and robust, from smooth and shining to ornate and hairy, from dull-coloured and retiring to bright and striking. Habits vary from detritivorous to xylophagous (feeding on decaying wood) to herbivorous to mycetophagous, with even a few predators. Larvae of some species are of economic significance as pests: the false wireworms feed on the roots of crops or lawns, while mealworms and flour beetles attack stored products (mealworms are, of course, also used as pet food and occasionally even as human food). Several species live as inquilines of social insects such as ants or termites. The highest diversity of tenebrionids is in relatively arid regions; some species, such as the tok tok beetles of southern Africa and the pie-dish beetles of Australia, are familiar sights in such habitats.

Pie-dish beetle Helea sp., copyright Australian Museum.

With such high diversity, it is not easy to define this group without encountering exceptions, but generally tenebrionids have the antennae eleven-segmented and inserted below lateral expansions of the genae. The procoxal cavities are usually closed externally, and the legs of most species have a 5-5-4 tarsal formula. The first three sternites of the abdomen are fused (Kergoat et al. 2014). Several subfamilies are recognised, but they are commonly grouped into three clusters known as the lagrioid, pimelioid and tenebrionoid branches of the family (Matthews & Bouchard 2008). Many members of the lagrioid and tenebrionoid branches possess well-developed defensive glands in the abdomen. The rear sternites of the abdomen in these species are hinged on the sides rather than along the midline as in more primitive forms, allowing the abdomen to expand as the gland reservoirs fill with a repugnant fluid that can be expelled when required. Many larger tenebrionids have a tendency to walk with their rear ends tilted upwards, ready to unleash at a moment's notice.

Allecula rhenana, copyright Stanislav Krejčík.

Members of the pimelioid branch, including the subfamilies Pimeliinae and (possibly) Zolodininae, lack abdominal defensive glands. In many parts of the world, pimelioids are the dominant tenebrionids in dry habitats. The lagrioid branch includes the single subfamily Lagriinae, defined by features of the genitalia. Matthews & Bouchard (2008) also listed the small subfamily Phrenapatinae in this branch but a molecular phylogenetic analysis of the family by Kergoat et al. (2014) placed this latter subfamily in the tenebrionoid branch. The tenebrionoid branch also includes the Tenebrioninae, Diaperinae, Alleculinae and Stenochiinae, though monophyly of the Tenebrioninae and Diaperinae is uncertain (Kergoat et al. 2014). Diaperines include a number of shiny, sometimes strikingly coloured species; members of the tribe Leiochrinini look more like ladybeetles of the Coccinellidae than typical tenebrionids. The Tenebrioninae include such notable members as the false wireworms of the tribe Opatrini, the mealworms of the Tenebrionini and the flour beetles of the Triboliini. Finally, the Alleculinae are a distinctive group of often relatively soft-bodied tenebrionids readily distinguished from other members of the family by their pectinate claws; in some older classifications, alleculines were treated as a separate family of their own.

REFERENCES

Kergoat, G. J., L. Soldati, A.-L. Clamens, H. Jourdan, R. Jabbour-Zahab, G. Genson, P. Bouchard & F. L. Condamine. 2014. Higher level molecular phylogeny of darkling beetles (Coleoptera: Tenebrionidae). Systematic Entomology 39: 486–499.

Matthews, E. G., & P. Bouchard. 2008. Tenebrionid Beetles of Australia. Australian Biological Resources Study.

Powder-post Beetles: Got Wood?

Jesuit beetle Bostrychopsis jesuita, from PaDIL.

Back when I was collecting insects in the Australian arid zone, one of the more easily recognisable animals that we would regularly come across was the jesuit beetle Bostrychopsis jesuita. I have no idea what gives them the name 'jesuit beetle', but these relatively large black beetles with their spiny pronotum with its two 'horns' coming off the front is not likely to be confused with much else. (Actually, now I think about it, could it be the horns that make them Jesuits? In which case, ouch.)

Bostrychopsis jesuita is one of the larger beetles belonging to the Bostrichidae, a family commonly going by the vernacular names of auger beetles or powder-post beetles. Both these vernacular names refer to the fact that many species in the family, particularly as larvae, are wood-borers (not fortune-tellers—that would make them augur beetles), with the ability to turn sapwood into a powdery frass. As a result, a number of species are notable timber pests. Other species, particularly the larger grain borer Prostephanus truncatus and the lesser grain borer Rhyzopertha dominica, are seed-feeders and pests in stored grain. A single genus, Endecatomus, is mycophagous, feeding on polypore fungi growing on dead hardwood trees (Liu & Schönitzer 2011). Bostrichids belong to a larger group of beetles, the Bostrichoidea, that are superbly adapted to feeding on dry foodstuffs (other members of the Bostrichoidea include the spider beetles of the Ptinidae and the carpet beetles of the Dermestidae). Modifications of the gut in most bostrichoids allow them to efficiently resorb water from the gut contents, and they can obtain pretty much all the moisture they need direct from the air.

Lesser grain borers Rhyzopertha dominica, from the US Department of Agriculture.

The bostrichids are divided between a number of subfamilies, members of which appear quite distinct from one another. Members of the Bostrichinae (to which Bostrychopsis belongs) and Dinoderinae are cylindrical and robust, with short sturdy legs. In some species, the rear of the body appears sharply cut off by a flat declivity in the rear of the elytra; this declivity can be by males to block the entrance to holes in the wood while the female is laying eggs deeper within (Lawrence & Britton 1991). Superficially, Bostrichinae can bear a close resemblance to another, unrelated group of wood-boring beetles, the bark beetles of the Scolytinae (I have to confess to confusing them myself when sorting specimens). The two groups can most readily be distinguished by their antennae, which are geniculate (elbowed) with a compact club in scolytines but non-geniculate with a loose clube in bostrichines.

A lyctine Trogoxylon impressum, copyright Udo Schmidt.

Members of other bostrichid subfamilies are not adapted to boring in wood as adults as well as as larvae, and as such are more elongate and less compact. The Lyctinae are more or less flattened, rectangular beetles that have been treated as a separate family in the past due to their distinct appearance. One group of lyctines, the Cephalotomini, are even more flattened than others, and are specialised for living as inquilines in the tunnels made by other bostrichids, feeding on their frass; their flattened bodies allow them to press themselves against the side of the tunnel and allow their host beetles to walk over them. Rather than boring deep into wood like bostrichines to lay eggs, females of species with non-boring adults use a long, flexible ovipositor to reach into cracks and other breaches in the tree's bark (Liu & Schönitzer 2011).

REFERENCES

Lawrence, J. F., & E. B. Britton. 1991. Coleoptera (beetles). In: CSIRO. The Insects of Australia 2^nd ed. vol. 2 pp. 543–683. Melbourne University Press.

Liu, L. Y., & K. Schönitzer. 2011. Phylogenetic analysis of the family Bostrichidae auct. at suprageneric levels (Coleoptera: Bostrichidae). Mitt. Münch. Ent. Ges. 101: 99–132.

Jewels among Beetles

There are many contenders for the title of most stunning-looking insect but there is no question that the jewel beetles have a place among the line-up. Some of these brilliantly coloured insects look as if they could have been sculpted from gleaming metal:

Buprestis niponica, copyright Kohichiro Yoshida.

Buprestis is a genus of jewel beetles found in the Holarctic region, with the greater diversity around the Mediterranean and North America. Somewhere between forty and eighty species are recognised, depending on whether the closely related genera Cypriacis and Yamina are regarded as distinct or not. Species of Buprestis come in a variety of colours, with green, blue or black backgrounds often patterned with yellow or red.

Female Buprestis octoguttata ovipositing, copyright Christian Fischer.

Despite their attractive appearance, jewel beetles are not always welcome. They spend the larval part of their life cycle burrowing into wood so some are known for damaging timbers. The preferred hosts of most Buprestis species, where known, appear to be conifers such as pine, spruce and larch. They primarily attack dead and dying wood, and females of some species are known for searching the trunks of trees following fires to find where protective bark has cracked open (some jewel beetle species in other genera are commonly known as 'fire beetles' in reference to this habit). Buprestis larvae have been claimed to live for extraordinarily long periods. Mature beetles have been observed emerging from furniture and the like multiple decades after the original tree was felled, leading to claims of larval life spans of up to 51 years! It almost goes without saying that such inferences have attracted their share of scepticism, with detractors suggesting the possibility of eggs being laid after the wood was already worked. It is true that the low nutritious value of dry wood might be expected to lead to slow development, but how slow are you willing to believe?

Magnificent Eurhins

Eurhinus festivus(?), copyright Andreas Kay.

Weevils are one of the most incredibly diverse of beetle groups, coming in an incredible array of shapes and structures, but they are not usually renowned for their bright colours. Nevertheless, in a group of this size, there is always scope for surprise: witness the image above. Eurhinus is a genus of absolutely stunning metallic-coloured weevils native to Central and South America; one species, E. magnificus, was first recorded in Florida in 2002 and has since become established there. The photo above was identified on Flickr as E. magnificus but looking over the descriptions in Casey (1922) I suspect it is more likely to be the closely related E. festivus. Eurhinus magnificus differs in having patches of red on the pronotum and elytral humeri (the 'shoulders'); see photos here, for instance.

Eurhinus species feed on vines of the Vitaceae, the grape family. Eggs are inserted into young stems where the larvae cause distinct galls as they develop. It does not look like they are known to cause significant damage to economically important species though studies on whether it can successfully attack grapes are inconclusive.

REFERENCE

Casey, T. L. 1922. Studies in the rhynchophorous subfamily Barinae of the Brazilian fauna. Memoirs on the Coleoptera 10: 1-520.

Spotless Ladybirds

Ladybirds are one of the first types of insect most children learn to recognise. Most people recognise these beetles straight away with their bright, contrasting colour patterns and shiny elytra. Many people are also aware of the beneficial role they may play in gardens and horticulture, feeding as both adults and larvae on plant-sucking insects such as aphids. However, ladybirds are a lot more diverse than many people realise. The great majority of species in the ladybird family Coccinellidae are not brightly coloured, and many of them do not feed on aphids.

Rhyzobius cf. chrysomeloides, a typical member of the Coccidulini, copyright Mick Talbot.

The ladybirds of the cosmopolitan tribe Coccidulini are mostly small species; many are dully coloured, though some are more distinctly patterned. As recognised by Ślipiński (2007) in his revision of the Australian Coccinellidae, the group is a diverse one and difficult to define; common features of its members include pubescent rather than shiny elytra, and certain features of the genitalia. A phylogenetic analysis of coccinellids by Seago et al. (2011) did not resolve the Coccidulini as a monophyletic clade, suggesting the possibility that they may represent a basal grade of unspecialised taxa, but no reclassification of the group appears to have been proposed as yet.

Stethorus punctillum, copyright Gilles San Martin.

The most familiar ladybirds are more or less hemispherical, but coccidulin species may vary in shape from rounded to oblong, with the body convex to flattened. The Tasmanian species Nat vandenbergae* particularly stands out in this regard, being oval and flattened with relatively long legs and antennae, and at first glance might be mistaken for a chrysomelid leaf beetle rather than a coccinellid. The rounded species of the genera Stethorus and Parastethorus include some of the smallest of all ladybirds, some being only a millimetre or so in length.

*Yes, the genus name for this species is Nat. Other coccidulin genera named by Ślipiński (2007) include Roger and Robert.

A mealybug destroyer Cryptolaemus montrouzieri engaged in destroying a mealybug, copyright Cynthia Bingham Keiser.

Being so small and easily overlooked, the life habits of many coccidulins remain poorly known. Many feed on aphids or scale insects in the usual ladybird manner. The orange-and-black Cryptolaemus montrouzieri was one of the first ladybirds to be deliberately used for biological control of pests; originally native to eastern Australia, it has been introduced to other parts of the world such as the United States to help control mealybugs. The tiny Stethorus and Parastethorus species feed on spider mites (Tetranychidae), species of which may similarly cause damage to crops. But other coccidulins have more unexpected diets. The larva of another Australian species, Bucolus fourneti, is a specialised predator of ants, lying in wait under the bark of Eucalyptus trees to ambush its prey as it passes by.

REFERENCES

Seago, A. E., J. A. Giorgi, J. Li & A. Ślipiński. 2011. Phylogeny, classification and evolution of ladybird beetles (Coleoptera: Coccinellidae) based on simultaneous analysis of molecular and morphological data. Molecular Phylogenetics and Evolution 60: 137–151.

Ślipiński, A. 2007. Australian Ladybird Beetles (Coleoptera: Coccinellidae): Their biology and classification. Australian Biological Resources Study: Canberra.

Philonthus: Too Many Staphylinids

Philonthus marginatus, copyright James K. Lindsey.

Working with staphylinids, it has to be said, can be horrible. They are treated as one of the most diverse of the beetle families—perhaps the most diverse of all—but compared to other diverse families they attract relatively little study. The majority of staphylinids are usually either very small or soft-bodied, not uncommonly both together, making them difficult to prepare and maintain as dry specimens. For the soft-bodied species, with their reduced elytra, many of the easily visible features that can be so useful for other beetle groups are obscure or unavailable. They also tend to be drab in coloration, without much in the way of striking patterning. As a result, it is often impossible to identify staphylinid species without examining minute features of the appendages or the genitalia. Something to keep in mind as you read the following.

Species of the genus Philonthus are relatively large as staphylinids go, often about half a centimetre in length, but they are certainly not free of the problems affecting other members of the family taxonomy-wise. The genus is massively diverse—over 1200 species have been described from around the world. Attempts have been made to break them down into more manageable chunks, such as through the recognition of subgenera, but these have mostly failed to gain much traction. Most recent authors have only recognised informal species groups within the greater mass.

Philonthus carbonarius, copyright James K. Lindsey.

In general, species of Philonthus are smooth, without excessive hairs, and have labial palps with the last segment fusiform and about as wide as the penultimate segment (Tottenham 1955; Stan 2012). Males have the aedeagus (the intromittent organ of the genitalia) rotated in the abdomen so its paramere (off-branch) is located on the left side rather than ventrally as in other genera (Tottenham 1955). Some species may have a metallic sheen to their coloration; others are a plainer black or reddish. Species may also differ in the number and arrangement of setae on the pronotum.

Where their lifestyles are known, most Philonthus are associated with decomposing organic matter such as animal dung, compost or leaf litter. Some are predators of other insects and insect larvae found in such habitats (such as fly larvae); these species have highly developed senses to locate decaying matter, and are strong fliers to disperse to suitable habitats (Majka et al. 2009). Some species of Philonthus may act as predators of other pest insects, helping to keep their numbers down.

REFERENCES

Majka, C. G., J.-P. Michaud, G. Moreau & A. Smetana. 2009. Philonthus hepaticus (Coleoptera, Staphylinidae) in eastern Canada: are distribution gaps distinctive features or collecting artifacts? ZooKeys 22: 347–354.

Stan, M. 2012. On the species of Philonthus Stephens (Coleoptera: Staphylinidae: Staphylininae: Staphylinini: Philonthina) in the collections of Romanian natural history museums. Travaux du Muséum National d'Histoire Naturelle "Grigore Antipa" 55 (2): 233–276.

Tottenham, C. E. 1955. Studies in the genus Philonthus Stephens (Coleoptera: Staphylinidae). Parts II, III, and IV. Transactions of the Royal Entomology Society of London 106 (3): 153–195.

Sunorfa

The Queensland pselaphine Sunorfa nigripes, from Chandler (2001).

When I began researching the taxon that was to be the subject of this post, I was surprised to discover that it had weaseled its way onto this site once before. Back in the day, I used an example of the beetle genus Sunorfa to illustrate a post about a closely related genus for which I had been unable to find an image (before a reader pointed me in the direction of one). Sunorfa is a member of that wonderful group of miniature gargoyles, the Pselaphinae (I had the pleasure/pain of sorting a handful of pselaphines at work just the other week; their minute size [usually only a millimetre or two long] makes them a real challenge to work with but their bizarre morphologies make it impossible to resent them). Most species of Sunorfa are found in tropical rainforest litter in southern Asia and Australasia from Sri Lanka to Fiji with the highest diversity of species in New Guinea. In addition, a handful of species are found in the Seychelles. I haven't come across any direct indication of what Sunorfa are doing in all these places but presumably, like other pselaphines, they are predators of even smaller arthropods.

Distinctive features of Sunorfa compared to other pselaphines include a strong transverse sulcus (groove) across the rear part of the pronotum, and a cylindrical abdomen in which the upper tergites and lower sternites are fused into single continuous rings. They also have characteristic foveae (deep depressions) on the top of the head, the base of the elytra including on each side at the 'shoulders', and in the middle of the metasternum (the rear underside section of the thorax) (Chandler 2001). Similar foveae are found in one form or another, in one place or another, on most pselaphines. They have received a lot of attention in taxonomic studies (their appearance and distribution is one of the most reliable features in distinguishing pselaphine taxa) but their function is less well known. Chandler (2001) expressed the opinion that foveae in different parts of the body serve different purposes. Those on the thorax have solitary, sensilla-like setae at their centres and probably represent sensory structures of some kind. Conversely, foveae on the head and abdomen lack such setae and commonly connect to one another internally to form solid tubes. These tubes may function as struts, providing the body with rigidity and strength as the animal is reduced down in size.

REFERENCE

Chandler, D. S. 2001. Biology, morphology, and systematics of the ant-like litter beetle genera of Australia (Coleoptera: Staphylinidae: Pselaphinae). Memoirs on Entomology, International 15: 1–560.

Click! Goes the Beetle

The click beetle Athous haemorrhoidalis, copyright André Karwath.

There have been occasions when I've found myself complaining of the difficulty of recognising particular beetle families. It almost goes without saying, however, that this difficulty does not apply across the board. Whereas some beetle families may indeed be generically small and brown, there are others that are almost instantly recognisable. One such family, for the most part, is the click beetles of the Elateridae.

Click beetles are a cosmopolitan family with well over 900 known species. The majority of click beetles adhere to a consistent basic form: they have elongate, slender bodies, often with distinct longitudinal grooves running down the elytra. The front part of the body (the prothorax) is relatively large, and more or less acutely pointed at the back corners. Between the prothorax and the next part of the body (the mesothorax), the body is strongly constricted top to bottom so that the beetle can be flexibly bent. This distinguishes the Elateridae from most other beetle families (except for a few close relatives), and this is where the 'click' comes in. If the beetle finds itself lying on its back (or wishes to escape from a threat), it is able to arch itself so that the thoracic junction is lifted upwards. On the rear margin of the underside of the prothorax is a notched peg that sits against the front of the mesothorax, holding the two sections apart like the stick in a cartoon crocodile's jaws. This builds up a lot of potential energy that the beetle is able to hold in place until it suddenly releases the peg, which then slams back into a ventral groove at the front of the mesothorax with an audible 'click'. The effect of this sudden release of energy, followed by an equally sudden stop, is to cause the beetle to rapidly bend forwards, much in the manner of a person folding over as they receive a powerful punch to the gut. This self-inflicted gut punch results in the beetle being flung in the air, somersaulting to a hopeful landing on its feet. Evans (1972) conducted an analysis of the click-jumping of the elaterid Athous haemorrhoidalis, which is about a centimetre-and-a-half in length, and found that it could be lifted over a foot above the ground, tumbling several times over the course of a single jump. He calculated that during the jump it could be subjected to an acceleration of up to 3800 ms^-2, equivalent to a force of 380 G, one of the highest acceleration forces known in the animal kingdom (a human subjected to a similar force would soon end up like a satchel of instant pudding). Ribak & Weihs (2011) subsequently found, however, that the beetle has no actual control over its movements once flung and is just as likely to end up flat on its back again as the right way up, requiring it to attempt a second jump.

Fire beetle Pyrophorus sp., copyright Andreas Kay.

Adult click-beetles feed on the juices from plants but larvae may be more diverse in habits, including phytophagous, saprophagous or predaceous forms. Some burrowing phytophagous larvae, known as wireworms, can be notable pests, feeding on the roots and buried seeds of crop plants. Predatory forms, on the other hand, can be quite beneficial: the eyed elater Alaus oculatus of North America, for instance, has larvae that feed on the larvae of other beetles burrowing in wood. The Elateridae also include the fire beetles of South and southern North America, belonging to the tribe Pyrophorini. These beetles have a pair of large bioluminescent spots on their back at the rear of the prothorax. The larvae and even the eggs of fire beetles are similarly bioluminescent, and my guess is that the bioluminescence provides some sort of defense against predation.

Larva of Drilus on a snail, copyright Cécile Bassaglia.

Not all elaterids match the family's standard morphology, however. An analysis of elaterid phylogeny by Kundrata & Bocak (2011) found that a few groups that had previously been classified as separate families were in fact derived subgroups of the Elateridae. The 'Cebrionidae' (possibly a polyphyletic assemblage in the elaterid subfamily Elaterinae) are softer-bodied than other elaterids and lack the ability to click (presumably because their cuticle does not provide the resistance for a clicking mechanism to work). Female cebrionids may be flightless, with reduced wings and/or elytra. Even more dramatically altered are the females of the tribe Drilini (previously recognised as the Drilidae), the false firely beetles, which are larviform in appearance with only the head metamorphosing to an adult appearance. The larvae of Drilini feed on snails, and have a lifestyle that straddles the boundary between predator and parasite. Rather than killing and eating the prey snail immediately, they crawl into its shell and feed on it slowly; it may take several days for the larva's victim to actually meet its demise.

REFERENCES

Evans, M. E. G. 1972. The jump of the click beetle (Coleoptera, Elateridae)—a preliminary study. Journal of Zoology 167: 319–336.

Kundrata, R., & L. Bocak. 2011. The phylogeny and limits of Elateridae (Insecta, Coleoptera): is there a common tendency of click beetles to soft-bodiedness and neoteny? Zoologica Scripta 40: 364–378.

Ribak, G., & D. Weihs. 2011. Jumping without using legs: the jump of the click-beetles (Elateridae) is morphologically constrained. PLoS ONE 6 (6): e20871. doi:10.1371/journal.pone.0020871.

Omorgus: A Beetle with a Taste for Hair

A group of Omorgus clambering over what looks like a scat, copyright Stephen Cresswell.

I still remember my first Omorgus. Pretty much as soon as I saw it in the pitfall trap, I knew that this was a different type of beetle from any I'd seen before. Large, knobbly, robust... it looked a picture of glorious ugliness. Which only made it all the more frustrating that, somewhere in the process of making it into the trap, this particular specimen appeared to have somehow lost its head. Without the ability to look it in the face, I might never know what I'd found.

It wasn't until later in the lab that I discovered my mistake: my beetle wasn't headless at all! Instead, the head was retracted back, hidden beneath the expanse of the pronotum (the dorsal shield of the first thoracic segment). And so I became acquainted with my first keratin beetle.

A similar Omorgus to the one I found, O. bachorum, to give some idea how I missed the head. Copyright Clare McLellan.

Omorgus is one of the handful of genera of keratin beetles, a group of relatives of the scarabs known as the Trogidae or Troginae (there has been some inconsistency as to whether trogids are treated as their own family or as a subfamily of the main scarab family Scarabaeidae). They have robust forelegs with large femora, and striate elytra that are often covered with tubercles and/or setae. Trogids vary in size from about half a centimetre in length up to three centimetres. They get their name of 'keratin beetles' from their unique diet: both as adults and larvae, trogids feed primarily on keratin such as animal hair. They are most commonly scavengers, feeding at animal carcasses (often arriving late in the process, taking the parts of the animal rejected as indigestible by other scavengers). However, they also feed on other animal foods such as insect larvae, eggs or guano, and some appear to be specialist associates of bird nests or animal burrows (Scholtz 1986). An Australian flightless species Omorgus rotundulus was found to have a gut full of other arthropods, particularly ants and termites, in quantities that lead to the suggestion that it might be an active predator rather than a scavenger (Houston et al. 2010).

An Omorgus chowing down on a dead lizard, copyright William Archer.

Earlier authors commonly treated all trogids as belonging to a single genus Trox, but more recent authors have recognised four or five genera in the family. Omorgus includes about 150 species (Strümpher et al. 2014) found mostly in arid regions. The most obvious feature separating Omorgus species from other trogids is that the pedicel (the second segment of the antennae) is attached to the scape (the first segment) subapically rather than apically. In all species but one, the scutellum (the little thoracic shield visible between the bases of the elytra) is hastate (shaped a bit like a spear-head, with a constricted base broadening out further down) rather than a more simple oval as in other trogids. The exception, T. batesi, is a South American species that is placed in its own subgenus Haroldomorgus. The remaining species are divided between two subgenera Omorgus sensu stricto and Afromorgus, distinguished by features of the male genitalia (Scholtz 1986). Afromorgus is found in Africa and Asia whereas the type subgenus contains the Australian and other American species.

Most trogids are fully capable of flight (many are attracted to lights at night) but, as alluded to above, a handful of species are flightless. In flightless species, the elytra become fused together into a sold carapace. The impression I get from scanning the literature is that flightlessness in trogids may not be so much a matter of conserving energy as it is of conserving water. For animals living on a dry diet in a dry habitat, such adaptations are only to be expected.

REFERENCES

Houston, T. F., J. Zhang & B. P. Hanich. 2010. Diet of the flightless trogid beetle Omorgus rotundulus (Haaf) (Coleoptera: Trogidae) in the Little Sandy Desert of Western Australia. Australian Entomologist 36 (4): 207–212.

Scholtz, C. H. 1986. Phylogeny and systematics of the Trogidae (Coleoptera: Scarabaeoidea). Systematic Entomology 11: 355–363.

Strümpher, W. P., C. L. Sole, M. H. Villet & C. H. Scholtz. 2014. Phylogeny of the family Trogidae (Coleoptera: Scarabaeoidea) inferred from mitochondrial and nuclear ribosomal DNA sequence data. Systematic Entomology 39: 548–562.

Small Carrion Beetles: A Bunch of SBBs

A fairly typical small carrion beetle, Catops tristis, copyright Trevor and Dilys Pendleton.

Anyone who takes on the task of beetle identification will soon discover that (to agree with Haldane) their sheer diversity can be overwhelming. Bird-watchers often complain about the challenges of identifying what they refer to as LBJs, Little Brown Jobs, but entomologists may have as much if not more to complain about when faced with the prospect of SBBs: Small Brown Beetles. The features marking a particular SBB as one family or another are often (at least to a novice) difficult to distinguish; members of unrelated families may look remarkably similar, whereas close allies may look surprisingly different.

The Leiodidae are, for the most part, firmly in the ranks of SBBs. This taxonomically small but morphologically diverse family is hard to come up with a coherent description for: though modern coleopterists have little doubt that they form a coherent clade, certain subgroups have become notably divergent. At least one leiodid, the beaver parasite Platypsyllus castoris, barely even looks like a beetle at all and was classified for a brief period in the 1800s as a distinct order of insects. Nevertheless, most leiodids are recognised by the structure of their antennae: the five-segmented club at its end has a distinct constriction as the eight antennal segment is smaller than the seventh and ninth segments on either side. Many leiodids are scavengers of plant or animal matter, but some are fungivores and a few (as already indicated) are parasites of mammals.

Small carrion beetles of the genus Sciodrepoides feeding on a deer carcass; copyright Stephen Cresswell.

Among the various subgroups of the Leiodidae are the Cholevini, commonly known as small carrion beetles. As their name indicates, these mostly feed on the remains of dead animals, though at least some are not above scavenging on other decaying matter. Some species are found in subterranean habitats, such as caves or the burrows of rodents, feeding on guano or other refuse. The Cholevini are one of the tribes in the leiodid subfamily Cholevinae, which has sometimes been treated in the past as a separate family Cholevidae or Catopidae. The Cholevinae differ from most other leiodids in the presence of an occipital carina or crest on the back of the head; such a carina is also present in the parasitic Leptininae, which Peck (1990) speculated to be derived from the cholevines. Members of the tribe Cholevini differ from other Cholevinae in having the setae on the elytra irregularly arranged (vs arranged in rows), giving the elytra a granular rather than a striate appearance.

Members of the Cholevini are mostly found in the Holarctic region, with only a few species in the Oriental region and none further south (Peck & Cook 2002). The greatest diversity in the group is found in Eurasia; only four of the 24 genera are found in North America, and only one of these (the monotypic Catoptrichus frankenhauseri) is unique to that continent. For the most part, cholevins do not vary much in appearance, and species are difficult to distinguish without examining the genitalia (these are true SBBs). Catoptrichus frankenhauseri has distinctive antennae, with lateral projections on either side of each segment(C. frankenhauseri is also noteworthy for the manner of its initial discovery, with the type specimen being collected from a human cadaver [Peck & Cook 2002]). Some of the subterranean species of cholevins have reduced eyes or wings, and a handful of species are entirely flightless.

REFERENCES

Peck, S. B. 1990. Insecta: Coleoptera Silphidae and the associated families Agyrtidae and Leiodidae. In: Dindal, D. L. (ed.) Soil Biology Guide pp. 1113–1136. John Wiley & Sons.

Peck, S. B., & J. Cook. 2002. Systematics, distributions, and bionomics of the small carrion beetles (Coleoptera: Leiodidae: Cholevinae: Cholevini) of North America. Canadian Entomologist 134: 723–787.

To Make a Willow Weep

Pair of spotted willow leaf beetles Chrysomela vigintipunctata, copyright P. V. Romantsov.

As noted in an earlier post, the leaf beetles of the Chrysomelidae include some very attractive representatives. The two individuals in the photo above belong to the widespread genus Chrysomela, many species of which feed on leaves of members of the tree genera Salix, the willows, and Populus, the poplars. Some species can become numerous enough on their hosts to cause extensive defoliation, and the cottonwood leaf beetle Chrysomela scripta is regarded as a serious pest of trees such as the cottonwood Populus deltoides.

Mating pair of Chrysomela populi, copyright Beentree.

Chrysomela beetles that feed on willows are able to sequester salicin from the willow's leave and use it to secrete a defensive compound of their own, salicylaldehyde. In one European species, Chrysomela lapponica, distinct populations have been identified that feed respectively on willow or birch leaves. Experimental studies have shown that the birch- and willow-feeding populations are largely reproductively isolated from each other: either their inter-fertility is reduced, or hybrid larvae that differ in feeding preference from their mother will be laid on the wrong host tree and be unable to survive. As such, the populations can be recognised as either in the process of diverging into separate species, or as already distinct cryptic species. As birch does not contain salicin, birch-feeding C. lapponica do not produce the salicylaldehyde found in willow-feeding populations, and birch-feeders fed on willow leaves are unable to utilise salicin (Kirsch et al. 2011).

Female Chrysomela lapponica ovipositing on birch leaf, copyright Juergen Gross. As well as the variation in host plant described above, members of this species also vary widely in coloration, from red and black as in the photo to entirely black in some individuals.

As willow is most likely the ancestral food type for C. lapponica, how did some populations make the change to feeding on birch despite losing a significant factor in their own defenses by doing so? One possibility that has been suggested is that the change happened not despite the loss of salicylaldehyde, but because of it (Gross et al. 2004). While the salicylaldehyde acts as an effective defense against generalist predators, some specialist predators and parasitoids of the beetles seem to be directly attracted to it, using it as a marker to track down their target. Pressure from this angle might favour the spread of a population that does not produce the alluring salicylaldehyde.

REFERENCES

Gross, J., N. E. Fatouros, S. Neuvonen & M. Hilker. 2004. The importance of specialist natural enemies for Chrysomela lapponica in pioneering a new host plant. Ecological Entomology 29: 584-593.

Kirsch, R., H. Vogel, A. Muck, K. Reichwald, J. M. Pasteels & W. Boland. 2011. Host plant shifts affect a major defense enzyme in Chrysomela lapponica. Proceedings of the National Academy of Sciences of the USA 108 (12): 4897-4901.

The Little Tike that is Tychus

Male (left) and female of Tychus niger, copyright Lech Borowiec.

Another brief beetle post for today. The species in the image above is the type species of Tychus, a genus of about 150 species of pselaphine beetles found in Eurasia and North America. Chandler (1988) regarded the North American species as a separate genus Hesperotychus but Kurbatov & Sabella (2008) felt that the differences between species from the two continents were not enough to warrant separation. There's probably still some work to be done here.

Like many other pselaphines, most of the work on Tychus has focused on the morphology of the various species, with relatively little having been said about its life habits. Heer (1841) described the habitat of T. niger as 'sub lapidibus et in graminosis' which I believe means 'under stones and among grass', and Kurbatov & Sabella (2008) recorded collecting a specimen of Atychodea pilicollis, a related species, in damp sand. The large, broad-ended palps (the appendages on the head behind the antennae) of Tychus species suggests that they are probably micropredators, like the pselaphine Bryaxis puncticollis whose hunting behaviour was described in an earlier post. Like most pselaphines, the small size of Tychus species means that they generally escape observation.

Tychus is the largest genus in the pselaphine tribe Tychini. Tychins are most diverse in the Holarctic region, with only a very few species found in southern and south-east Asia. Chandler (1988) characterised the Tychini by the shape of the third segment of the palp, which is invariably longer than wide, and by the antennae usually being inserted close together on a narrow rostrum, though this varies a lot in distinctiveness between species. Kurbatov & Sabella (2008) also identified a number of other features representing possible synapomorphies of the Tychini, and suggested that the Oriental genera Atychodea and Amorphodea represent the sister taxon of the remaining Holarctic genera. The genera of Tychini are all fairly similar in appearance; notable distinguishing features of Tychus include an asymmetrical aedeagus (the intromittent organ in the male genitalia) and the arrangement of foveae (hollows) on the elytra and sternites. Males of Tychus often have one of the antennal segments modified as in the male of T. niger shown above, with a median segment noticeably thicker and broader than those on either side. The purpose of this enlarged segment, as with so many other features of pselaphines, seems to be unknown.

REFERENCES

Chandler, D. S. 1988. A cladistic analysis of the world genera of Tychini (Coleoptera: Pselaphidae). Transactions of the American Entomological Society 114 (2): 147-165.

Heer, O. 1841. Fauna Coleopterorum Helvetica, pars 1. Impensis Orelii, Fuesslini et Sociorum: Turici.

Kurbatov, S. A., & G. Sabella. 2008. Revision of the genus Atychodea Reitter with a consideration of the relationships in the tribe Tychini (Coleoptera, Staphylinidae, Pselaphinae). Transactions of the American Entomological Society 134 (1-2): 23-68.

Sybra punctatostriata

Sybra punctatostriata, from here.

Just a very brief post today, because once again I've drawn a species that I haven't been able to find too much about. Sybra punctatostriata is a member of the Cerambycidae, the longicorn beetles, a diverse but (usually) fairly distinctive group of beetles whose larvae burrow into wood and plant stems. This species was first described by H. W. Bates in 1866 as part of a collection of beetles from Taiwan. Since then, it has been recorded over a wide area stretching from Japan in the north to Hainan in the south (though mostly in Japanese and Chinese sources that I don't have access to, and probably couldn't follow if I did). However, Samuelson (1965) indicated that S. punctatostriata was one of a number of very similar species in the genus Sybra, hinting that its range may require revision. Samuelson himself only identified a single specimen of S. punctatostriata from Okinawa in collections of beetles from the Ryukyus, which he described as showing some small differences from Taiwan specimens.

Another view of Sybra punctatostriata from the same site.

Sybra punctatostriata has been recorded feeding on Gossypium, the genus that includes cotton. However, other Sybra species are known to have wide host ranges. Sybra alternans, a species that has been recorded infesting bananas, has also been known to feed on fig trees, pineapple plants, passionfruit vines, beans... (Chen et al. 2001). It is possible that S. punctatostriata's host range may also be wider than recorded.

REFERENCES

Bates, H. W. 1866. On a collection of Coleoptera from Formosa, sent home by R. Swinhoe, Esq., H.B.M. Consul, Formosa. Proceedings of the Zoological Society of London 1866: 339-355.

Chen, H., A. Ota & G. E. Fonsah. 2001. Infestation of Sybra alternans (Cerambycidae: Coleoptera) in a Hawaii banana plantation. Proc. Hawaiian Entomol. Soc. 35: 119-122.

Samuelson, G. A. 1965. The Cerambycidae (Coleopt.) of the Ryukyu Archipelago II, Lamiinae. Pacific Insects 7 (1): 82-130.

Bark Beetles and their Hidden Harems

Galleries dug in a grand fir Abies grandis by fir bark beetles Pityophthorus pityographus, photographed by Louis-Michel Nageleisen.

For producers of commercial timber, the above picture would not be a pretty sight. Bark beetles are named after what they feed on: they chew galleries under the bark of trees. In some species that attack otherwise healthy trees, these borings may result in stunted growth or death. The beetles may spread fungal diseases as they move from one tree to another (Dutch elm disease is one example of a well-known disease spread by bark beetles). But on the other hand, many bark beetles play a vital row in nutrient recycling, feeding on already dead and dying trees and breaking down the wood.

The fir bark beetle Pityophthorus pityographus itself, from PaDIL.

The bark beetles belong to a group called the Scolytinae. The scolytines include over 6000 species worldwide (only a relatively small percentage of which, it should be noted, are recognised as significant pests). Oddly enough, they are actually a kind of weevil. The most characteristic feature of most weevils is their elongate snouts, but in scolytines these snouts have been lost (they would probably not be ideal for burrowing through wood). The fir bark beetle belongs to a subgroup of the scolytines called the Corthylini, distinguished from other scolytines by their elytra, which lock down so that a panel on the side of the body called the metepisternum is hidden when the elytra is closed (in other scolytines, it remains at least partially visible), and by the flattened round clubs on their antennae (Wood 1986). The Corthylini are themselves divided into two subgroups, the Corthylina and the Pityophthorina. The two groups are not that easily separated by their morphological appearance, but they are very different in their ecology. The Corthylina don't live directly under the bark, but deeper in the tree amongst the xylem (the central water-conducting tissue). Corthylinans and ecologically similar beetles, known as ambrosia beetles, live in association with a fungus that grows on the xylem. The beetles, which cannot directly digest the xylem themselves, feed instead on the fungus.

The Pityophthorina, on the other hand, are true bark beetles, with most species feeding directly on the tree's phloem (the sugar-conducting tissue around the outer part of the tree). Other species in this group burrow in the tree's seeds, or feed on the pith inside slender stems. The main diversity of Pityophthorina (and of Corthylini in general) is in the Americas, particularly in cooler temperate or tropical highland environments, with over 500 known species in North and South America. Two species, Pityodendron madagascarensis and Sauroptilius sauropterus, are found in Madagascar, while the genus Mimiocurus includes ten species found in Africa and Asia. The largest genus in the Pityophthorina, Pityophthorus, includes about sixty species in Africa and Eurasia in addition to over 300 in the Americas. Wood (1986) suggested that the Eurasian species of Pityopthorus were probably descended from relatively recent migrations from North America, but African and Madagascan species of Pityophthorina may represent more basal lineages.

Female Dendroterus decipiens, photographed by T. H. Atkinson.

As well as their economic and ecological significance, scolytines have attracted attention for the range of breeding behaviours they exhibit (Kirkendall 1983). Bark beetle galleries are not just feeding structures, they are also breeding structures. Females mate and lay their eggs within the galleries, and their larvae hatch and continue to feed there. The Pityophthorina are described as including both monogynous and polygynous species, but these terms refer to the number of females in a gallery, not necessarily the mating habits of the males. In monogynous species, a gallery will be home to only a single female. Construction of this gallery may have been started by the female herself, or it may have been started by a male who was then joined by the female. In most monogynous Pityophthorina, the latter is the case (and the mating system is monogamous as well as monogynous), but the female is the one to start the gallery in the genus Conophthorus (Conophthorus species feed in pine cones, and may be restricted to monogyny by the small spaces available for gallery construction). Conopthorus males that mate with the female may not remain in the gallery, but may leave directly after mating. Males that don't stay in the gallery can mate with more females, of course, but males who do stay will be able to prevent their mate from mating with another male herself before laying her eggs. Also, by helping to maintain the gallery (or by constructing the gallery himself to begin with), the male may encourage the female to oviposit faster, or improve conditions for the larvae when they hatch.

In polygynous species, such as most Pityophthorus species, a single gallery will be home to multiple females. In most polygynous Pityophthorina, a single male will co-habit with a harem of females. A few pityophthorinans of the genus Araptus are inbreeding polygynes: males do not leave their parent gallery, but instead mate with their sisters before the latter leave the gallery. Inbreeding species seem to show remarkable control over sex ratios in the population, with many more female larvae produced than males. Interestingly, monogynous and polygynous galleries tend to differ in physical structure: monogynous galleries tend to be simple and direct, with only one or two arms extending along or across the host plant from the central nuptial chamber. Polygynous galleries, on the other hand, may have several arms radiating from the nuptial chamber, with each arm probably being built by a separate female.

REFERENCES

Kirkendall, L. R. 1983. The evolution of mating systems in bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae). Zoological Journal of the Linnean Society 77: 293-352.

Wood, S. L. 1986. A reclassification of the genera of Scolytidae (Coleoptera). Great Basin Naturalist Memoirs 10: 1-126.

All About Buris ensipes

Sunorfa, from here.

The beetle pictured just above is not the intended subject of today's post. It is a related beetle found in Thailand, but I've used its photo instead of one of today's subject because, as far as I have been able to find, today's subject has never been illustrated. It was described as Dalmodes ensipes from San Esteban in Venezuela by Raffray in 1891, before it became de rigeur to illustrate any new species described (Raffray did illustrate a number of other species described in the same paper, but not this one). It has since been recorded from Antigua and Trinidad in the West Indies by Park et al. (1976), who also indicated that it should be placed in the genus Buris instead of Dalmodes, but did not illustrate it. Park (1942) had previously placed it in the genus Bythinophysis, but did not illustrate it then either. I have not been able to find any illustration of another species of Buris. Nor have I been able to find illustrations for any other species of Dalmodes, nor of Bythinophysis. Sadly, this is not an uncommon state of affairs for insect species. I did briefly consider the idea of composing an illustration of a potential Buris ensipes on the basis of Raffray's (1891) verbal description, but then I remembered that I was a rubbish drawer.

Buris ensipes is a member of the beetle group known as the Pselaphinae, of which another genus, Bryaxis, has previously been featured on this site. Like Bryaxis, Buris ensipes would probably be found in leaf litter, or possibly within rotting wood (specific collection details for Buris ensipes have not been recorded, but Park [1942] described pselaphines as found in both habitats). Also like Bryaxis, it is probably a micropredator, though again no record of its life habits has yet been made. Buris ensipes probably looks roughly similar to the photo of Sunorfa above, but Raffrays' (1891) description indicates that it would have shorter antennae (the first segment is described as subquadrate, and the end as obtusely pointed). A curved, transverse fovea (depression) is described as present in the rear half of the pronotum, and the elytra bear a pair of subhumeral foveae (i.e. just near the 'shoulders'). The fourth abdominal segment is toothed on either side. Also distinctive is the shape of the hind tibia, which is bisinuate with a median tooth. Overall, it is just over one and a half millimetres in length.

And that, as it stands, is just about all about Buris ensipes. Like all too many organisms, we have a morphological description, a few localities, and not a heck of a lot else. Buris ensipes just needs a little more love.

Update: A big thank you to Stephen Thorpe, who managed to do what I couldn't and locate an illustration of a Buris species, B. brevicollis, in Sharp (1887). I've reproduced the figure below; it also tallies reasonably closely with Raffray's description of B. ensipes. Potential differences between the species are that Sharp makes no mention in B. brevicollis of a toothed fourth abdominal segment like that of B. ensipes (though one should always be extremely cautious of assuming a given feature to be absent simply because a given author didn't mention it), and that Raffray referred to the tibial spine of B. ensipes as 'minute' whereas that of B. brevicollis looks quite sizable.

REFERENCES

Park, O. 1942. A study in Neotropical Pselaphidae. Northwestern University Studies in the Biological Sciences and Medicine 1: i-x, 1-403, 21 pls.

Park, O., J. A. Wagner & M. W. Sanderson. 1976. Review of the pselaphid beetles of the West Indies (Coleopt., Pselaphidae). Fieldiana Zoology 68: 1-90.

Raffray, A. 1891. Voyage de M. E. Simon au Venezuela (Décembre 1887-Avril 1888). 10^e Mémoire. Psélaphides. Annales de la Société entomologique de France, ser. 6, 10: 297-330, pl. 6.

Sharp, D. 1887. Fam. Pselaphidae. In: Biologia Centrali-Americana. Insecta. Coleoptera, vol. 2, pt 1, pp. 1-46.

Dung Beetles

Flat-headed dung beetles Pachylomerus femoralis with a ball of the good stuff, photographed by Guido Coza.

The dung beetles of the Scarabaeini include 146 species found in Africa and Asia, classified by Forgie et al. (2006) into three genera: Pachysoma, Pachylomerus and Scarabaeus, with the last including the vast majority of species. The Scarabaeus species are perhaps the most famous of all dung beetles, renowned since ancient history when Egyptians saw a dung beetle rolling a ball of dung along the ground as a metaphor for the movement of the sun through the heavens*. Dung beetles collect their turd balls to use as food for themselves or for their larvae. Ball-rolling is not unique to the Scarabaeini as a method of transporting dung, however (it is also done by members of other dung beetle tribes), nor do all Scarabaeini species engage in ball-rolling.

*It probably does not say much for the standard of ancient Egyptian public sanitation that they were apparently so willing to believe that the ultimate source of all life on the planet was a giant mass of burning poop.

Flightless orange dung beetle Pachysoma denticolle, photographed by Alex Dreyer.

The flightless dung beetles of the genus Pachysoma, for instance, transport their food by dragging it along between their hind legs. Pachysoma species are also less choosy than other Scarabaeini, feeding not just on dung but all manner of organic detritus. They have specialisations allowing them to feed on drier food particles than other Scarabaeini, suitable for their arid habitats in southern Africa. In contrast, species of the subgenus Sceliages within Scarabaeus are the epicures of the scarabaein world: they feed entirely on dead millipedes, which they push along in front of themselves bulldozer-style (Forgie et al. 2005). Relatively few species of Scarabaeini feed by burrowing directly alongside piles of dung where they lay, but this may be done by Pachylomerus and Scarabaeus galenus (both of which may also transport food).

Individual of Sceliages transporting a millipede, photographed by Shaun Forgie.

Most Scarabaeini are active during the day, but a small number such as Scarabaeus satyrus are nocturnal in habit. In the phylogenetic analyses conducted by Forgie et al. (2005), these nocturnal species usually formed a single clade. Had the ancient Egyptians observed the nocturnal dung beetles as well, they could have presented us with a sky full of poo at all hours.

REFERENCES

Forgie, S. A., U. Kryger, P. Bloomer & C. H. Scholtz. 2006. Evolutionary relationships among the Scarabaeini (Coleoptera: Scarabaeidae) based on combined molecular and morphological data. Molecular Phylogenetics and Evolution 40: 662-678.

Forgie, S. A., T. K. Philips & C. H. Scholtz. 2005. Evolution of the Scarabaeini (Scarabaeidae: Scarabaeinae). Systematic Entomology 30: 60-96.

The Burlinius Head-hiders

Cryptocephalus (Burlinius) bilineatus, photographed by Josef Dvořák.

I may have to confess that, in direct opposition to the Deity, I am not overly fond of beetles. There are, quite simply, far too many of them, and even beetle families can be inordinately difficult to distinguish unless one is an expert (particularly the endless array of minute brown ones). Nevertheless, everything in beetles comes with an exception, and there are some groups that stand out: one of these is the leaf beetles of the Chrysomelidae. Chrysomelids are a highly diverse group, comparable to (though perhaps getting less press than) their close relatives the weevils and longicorns. They come in an enormous array of shapes and colours, and yet almost all (emphasis on almost) seem to carry an unmistakeable stamp saying, "I am a chrysomelid".

Cryptocephalus (Burlinius) pusillus, photographed by Amy.

The chrysomelid subgenus Burlinius of the genus Cryptocephalus includes over 120 species found across the Palaearctic region, with a single species known from the Simien Mountains of Ethiopia (Schöller 2002). The name Cryptocephalus means 'hidden head', and refers to how, when the beetle is viewed from above, the head is usually hidden underneath the pronotum. Species of Burlinius are relatively small with regular lines of punctures on the elytra, but are primarily distinguished from other Cryptocephalus species by the morphology of the male genitalia. The aedeagus (the intromittent organ) bears a dorsodistal appendage covering the dorsal opening, and two symmetrical ventral processes (Erber & Schöller 2006). The external appearance of many Burlinius species is known to be quite variable, and genital morphology is also the best way of distinguishing many species (Warchałowski 1999).

Figures from Warchałowski (1999) showing variation in elytral patterning between individuals of Cryptocephalus jocularius.

As you might have guessed from the vernacular name 'leaf beetles', chrysomelids are generally herbivorous. Host plant records for Burlinius species indicate that they are often polyphagous, feeding on a wide variety of hosts. Burlinius species have been recorded from legumes, composite-flowered plants, spurges, even pines (Erber & Schöller 2006). Cryptocephalus and related taxa belong to a subgroup of the chrysomelids called the Camptostomata, in which the females have an array of chitinous pads called the kotpresse in the rectum (Schöller 2008). The kotpresse is used to encase the eggs when they are laid in a covering made from faeces and other secretions; when the larvae hatches, it uses this covering for protection and adds to it itself as it grows.

Hazel pot beetle Cryptocephalus coryli larva in its protective case, photographed by Roger Key.

REFERENCES

Erber, D., & M. Schöller. 2006. Revision of the Cryptocephalus-species of the Canary Islands and Madeira (Insecta, Coleoptera, Chrysomelidae, Cryptocephalinae). Senckenbergiana Biologica 86 (1): 85-107.

Schöller, M. 2002. The first representative of Cryptocephalus subgen. Burlinius Lopatin from tropical Africa (Chrysomelidae: Cryptocephalinae). Genus 13 (1): 33-37.

Schöller, M. 2008. Comparative morphology of sclerites used by camptosomatan leaf beetles for formation of the extrachorion (Chrysomelidae: Cryptocephalinae, Lamprosomatinae). In: Jolivet, P., J. Santiago-Blay & M. Schmitt. Research on Chrysomelidae vol. 1, pp. 87-120. Brill: Leiden.

Warchałowski, A. 1999. Übersicht der westpaläarktischen Arten der Untergattung Burlinius Lopatin, 1965 (Coleoptera: Chrysomelidae: Cryptocephalus). Genus 10 (4): 529-627.