The Stilt Bug Neides tipularius

Image copyright Janet Graham.

This is Neides tipularius, a widespread bug in the western part of the Palaearctic region. It feeds on a wide range of plants: I've seen references to it on grasses, on composites, or on chickweeds. It prefers drier regions such as coastal dunes or heaths.

Neides tipularius is a fairly typical member of the stilt bug family Berytidae. Berytids are more or less slender bugs in general but Neides is one of the more slender and long-legged ones. There are few other bugs with which a berytid could be confused; not only is there the wispy legginess to mark them, but berytids have distinctive long antennae with a short, spindle-shaped terminal segment forming a dark bobble at the end. Latreille (1802) did place N. tipularius in the genus Ploiaria, but that is now used for a group of small, long-legged assassin bugs with raptorial forelegs for catching prey.

Image copyright Sanja565658.

As with many other bugs, Neides tipularius exhibits polymorphism in wing development with flightless brachypters having narrower wings that only just reach the tip of the abdomen. Whether a given individual grows into a flying or flightless adult appears to be connected to the conditions under which they develop. Hot springs and summers have been noted to lead to increased numbers of macropterous adults.

REFERENCE

Latreille, P. A. 1802. Histoire Naturelle, générale et particulière des crustacés et des insectes vol. 3. Familles naturelles des genres. F. Dufart: Paris.

Cicadomorpha

Textbooks will tell you that the term 'bug' should be restricted to insects of the order Hemiptera though, as I've noted before, I don't know if I've ever met anyone who actually used the word that way. For many people, one of the groups of actual bugs that they are most likely to be aware of are members of the Cicadomorpha.

Tasmanian hairy cicada Tettigarcta tomentosa, copyright Simon Grove.

Cicadomorphs include the cicadas (Cicadoidea), leafhoppers (Membracoidea) and spittlebugs (Cercopoidea). As a group, they are distinguished by an enlarged postclypeus (the upper part of the front of the head below the antennae), simple antennae with a whip-like flagellum, and small and narrowly placed mid-coxae (Dietrich 2005). The enlarged postclypeus is associated with adaptations for feeding on xylem, deeper in the plant stem than many other plant-sucking bugs prefer, though derived subgroups of the leafhoppers have changed back to phloem or parenchyma. Well over 30,000 species of cicadomorph are known from around the world. Cicadas can be readily distinguished from other cicadomorphs by their possession of three ocelli in a triangle on the top of the head whereas leafhoppers and spittlebugs have only two or no ocelli.

Male bladder cicada Cystosoma saundersii, one of the world's more ridiculous animals, from Brisbane Insects.

Cicadas are best known, of course, for their singing. The songs are produced by a pair of membranous 'drums', the tymbals, at the base of the abdomen; muscular vibration of the membranes produces the sound. In most cicadas, only the male possesses these tymbals. However, both sexes possess tymbals in the hairy cicadas Tettigarcta, two species found in alpine regions in south-eastern Australia. Hairy cicadas also differ from the remaining cicadas in other ways, most notably in lacking the well-developed tympana on the underside of the abdomen that typical cicadas hear with (hairy cicadas have simpler hearing organs in their place). As a result, Tettigarcta is placed in its own distinct family, sister group to the remaining cicadas in the Cicadidae. Though now restricted to Australia, fossil species from the Mesozoic and Palaeogene of other parts of the world have also been placed in the Tettigarctidae (Shcherbakov 2008); however, they are mostly so placed on the basis of shared primitive rather than derived features and may well represent stem taxa for Cicadoidea as a whole. Other derived features of the cicadas proper in the Cicadidae include gas-filled chambers in the abdomen that resonate the calls produced by the tymbals. In males of another Australian species, the bladder cicada Cystosoma saundersii, these resonating chambers reach a remarkable size and the entire abdomen looks to have been blown up like a beach ball.

Froghopper Cercopis vulnerata, copyright Richard Bartz.

The spittlebugs or froghoppers of the Cercopoidea are smaller cicadomorphs, distinguished from species of the Membracoidea by their short and cylindrical (rather than long and quadrate) hind tibiae. The name 'spittlebug' refers to the nymphs of these bugs living covered with a protective covering of foam. In one family, the Machaerotidae, the nymph produces a calcareous tube around itself that it fills with fluid. The foam or fluid used for protection by cercopoids is primarily composed of the nymph's own excrement: the xylem fluids that they feed on are mostly water, after all, so they produce a large quantity of watery excreta.

Mango leafhopper Idioscopus nagpurensis, one of the world's many, many species of Cicadellidae, copyright Arian Suresh.

The third main subgroup of the cicadomorphs, the Membracoidea, is by far the most diverse, particularly the largest family Cicadellidae (leafhoppers). My own impression from my experience of collecting insects in various locations is that cicadellids are just everywhere. Over 20,000 species of this family have been described to date, and it has been estimated that the true number may be much higher. For instance, at one location in North America close to 100 species of a single genus Erythroneura have been recorded from a single plant (Dietrich 2002). Just how such a high diversity of closely related species can live in such close proximity remains a largely unanswered question, though some studies have apparently suggested the possibility of very fine micro-habitat partitions (making sense of the great mass of cicadellid diversity is not helped by many species exhibiting dimorphism between flying and flightless forms, similar to that I recently described for delphacids). Another notable feature of cicadellids is the protection of brochosomes, tiny, hollow, soccerball-like granules constructed of protein nets with which the leafhopper coats itself after moulting. The hydrophobic brochosomes help to keep the hopper free of water droplets and its own wet, sticky excreta. They may also serve other protective functions: females will coat newly laid eggs with a layer of brochosomes that may serve to prevent egg parasitoids such as micro-wasps from attacking the eggs.

Membracid leafhopper Cladonota benitzei, copyright P. Lahmann.

The membracoids also include the Membracidae, renowned for the remarkable appearance of the pronotal shield (the top and front of the thorax) in many species. In more humble membracids, the pronotum may form a high mound or pillar, but in others it may extend into bizarre arrangements of globules and branched spines hanging above the leafhopper like a baroque chandelier. Again, just what the purpose of this extravagant morphology is remains unknown but many authors have proposed some sort of protective function. It has been suggested that pronotal projections may help membracids mimic part of their host plant, or potential predators such as parasitic wasps. Alternatively, they mean that potential predators such as birds find the hopper just too hard to swallow.

REFERENCES

Dietrich, C. H. 2002. Evolution of Cicadomorpha (Insecta, Hemiptera). Denisia, Neue Folge 4 (176): 155–170.

Dietrich, C. H. 2005. Keys to the families of Cicadomorpha and subfamilies and tribes of Cicadellidae (Hemiptera: Auchenorrhyncha). Florida Entomologist 88 (4): 502–517.

Shcherbakov, D. E. 2008. Review of the fossil and extant genera of the cicada family Tettigarctidae (Hemiptera: Cicadoidea). Russian Entomological Journal 17 (4): 343–348.

Hoppers

The world is home to a wide variety of leafhoppers, both in terms of number of species and range of morphological disparity. One of the more diverse leafhopper families is the Delphacidae, including over two thousand species from around the globe. Delphacids are relatively small leafhoppers that are easily distinguished from other families by the possession of a large movable spur at the end of the tibia of the hind leg. I can't say as I know what the function of this spur is, but similar structures in other insect groups may be used for grooming.

Brown leafhoppers Nilaparvata lugens, from ICAR. The individual on the right is a long-winged disperser, the one on the left is a flightless brachypter.

Delphacids feed on the phloem of their host plants; the greater number of species are associated with monocots such as grasses. A number of species are significant economic pests; perhaps the most infamous are the brown leafhopper Nilaparvata lugens and white-backed leafhopper Sogatella furcifera which attack rice. They feed at the base of rice plants, causing the formation of round, yellow patches that soon dry up and turn brown, a condition known as 'hopper burn'. Death of the entire plant will often follow. As well as the direct damage from feeding, these leafhopper species also transmit viruses that further impact yields. Historically, numerous famines have been blamed on leafhopper outbreaks, such as the Kyoho famine of 1732 that saw rice production reduced to only 10% of its previous level. Estimates of the number of people affected by the famine seem to vary widely—according to Wikipedia, the official death toll was a bit more than twelve thousand people, but estimates of the actual number of fatalities range well in excess of 150,000. In more recent years, leafhopper outbreaks may be exacerbated by indiscriminate fertiliser and pesticide use, with the latter reducing competition for the hoppers from other insects or predators.

Delphacids (and many other leafhoppers) commonly exhibit polymorphism in wing development with both flying macropterous and flightless brachypterous forms occuring in a single population. The question of macroptery vs brachyptery is an environmental one. If a developing delphacid receives sufficient nitrogen then it will develop into a flightless adult, remaining in the place of its birth to continue to benefit from the good feeding conditions there. But if feeding conditions become degraded and the developing nymph is deprived of nitrogen then it will develop into a fully-winged adult that can leave its home in search of more favourable conditions elsewhere. Because of their small size, migrating delphacids may be carried long distances by the winds. In the case of pest species, this phenomenon of migration further exacerbates the problem of control as hopper populations from different countries are regularly mixed, increasing genetic diversity and resistance to varying control methods.

REFERENCE

Urban, J. M., C. R. Bartlett & J. R. Cryan. 2010. Evolution of Delphacidae (Hemiptera: Fulgoroidea): combined-evidence phylogenetics reveals importance of grass host shifts. Systematic Entomology 35: 678–691.

Edible Stinkbugs

In recent years, there has been some discussion in certain circles about whether people in western cultures should become more accepting of the practice of entomophagy: that is, eating bugs. For the most part, insects do not play a big part in diets in the English-speaking world except indirectly. In other parts of the world, however, certain insects may be eaten with relish. One such insect is the edible stinkbug Encosternum delegorguei of southern Africa.

Edible stinkbug Encosternum delegorguei, from Dzerefos et al. (2013).

The edible stinkbug is a member of the family Tessaratomidae, one of a number of families in the stinkbug superfamily Pentatomoidea. Tessaratomids are mostly relatively large, flat-bodied stinkbugs, often with shining metallic coloration, found in warmer parts of the world. They are all plant-suckers; one species, the lychee stinkbug Tessaratoma javanica, is a significant pest of lychee crops while the bronze orange bug Musgraveia sulciventris is a pest of citrus trees in Australia. The edible stinkbug feeds on a range of tree species, belonging to a number of different flowering plant families such as Combretaceae, Fabaceae and Ebenaceae. Though widespread in southern Africa, their distribution seems to be patchy; only certain ethnicities have a tradition of stinkbug harvesting (Dzerefos et al. 2013).

Harvester collecting stinkbugs, copyright Cathy Dzerefos.

Edible stinkbugs are collected during winter (the dry season) when they aggregate in large protective clusters (up to football-sized) on particular trees. Like other stinkbugs, Encosternum delegorguei produce a foul-smelling defensive chemical from glands on the thorax. As well as smelling bad, this chemical can stain skin and may cause temporary blindness if it gets into eyes. Dzerefos et al. (2013) note that stinkbug harvesters informed them that exposure to the defensive chemical over several years could cause fingernail loss and wart growth. The chemical needs to be removed from the bugs before they are cooked for consumption because, as one harvester explained, "if you eat the unprepared one it will kill taste for a month".

Clusters of stinkbugs are collected live into bags which are then shaken to encourage the bugs to discharge their chemicals. Further processing could be done by two methods. Perhaps the more common method is to pinch off the head of each bug then squeeze out the contents of the thorax, after which the bugs are cooked immediately. However, the Bolobedu people (who collect stinkbugs more for commercial sale than for their own consumption) place the bugs into a bucket with a perforated base, then pour hot water over them and stir vigorously. The bugs discharge their glands into the water as the heat kills them. They are then rinsed off in cold water, then returned to hot water for about eight minutes, then spread out on bags on the ground to dry. Any bugs that had not fully discharged their glands before dying can be recognised by dark marks on the thorax and are discarded. Though slightly more involved than the waterless method, this process of preparation has the advantage that bugs can be stored for some time rather than having to be cooked immediately. Stinkbugs are usually cooked by braising in a frying pan with salt; they are supposed to have a spicy taste, like chili.

Basket of prepared stinkbugs, from here.

According to Dzerefos et al. (2013), many of the stinkbug harvesters they spoke to reported a decline in populations of the bugs in recent years. Potential reasons for the decline included drought and/or the felling of trees that would otherwise be used by the bugs as roosts. Could edible stinkbugs be more widely used commercially? Perhaps, but it should be noted that while some groups relish the bugs, their neighbours disdain the delicacy. Mind you, Bolobedu people apparently didn't eat the bugs themselves before the 1980s, only taking up harvesting them when co-workers in tea plantations taught them what a resource they had on their hands!

REFERENCE

Dzerefos, C. M., E. T. F. Witkowski & R. Toms. 2013. Comparative ethnoentomology of edible stinkbugs in southern Africa and sustainable management considerations. Journal of Ethnobiology and Ethnomedicine 9: 20.

Hairy-Winged Barklice

Forewing and fore tibia of Siniamphipsocus fusconervosus, from Mockford (2003). Scale bar for the femur = 0.1 mm.

For my next semi-random post, I drew Siniamphipsocus, a genus of more than twenty species of barklice known from eastern Asia. Most of these species were described by China by the almost ludicrously prolific psocopterologist Li Fasheng who over the course of his career has described close to 1000 psocopteran species—nearly a fifth of the world's barklouse fauna. It should be noted, though, that this productivity has not entirely come without criticism: for instance, in the case of the Siniamphipsocus species, most if not all are known from a single sex with some described from males and others from females (Li 2002).

Siniamphipsocus is a genus of the Amphipsocidae, a family of barklice most easily recognised by their wings which have a double row of setae along each of the veins. Amphipsocids can be relatively large as barklice go: the largest Siniamphipsocus species, S. aureus, has a body length of four millimetres, with the forewings being up to 6.75 millimetres long. Features distinguishing Siniamphipsocus from other amphipsocids include the absence of the brush of hairs present at the base of the hind wing in many other species, the absence of a spur vein in the rear of the forewing pterostigma, and the presence of a row of minute spines along the fore femur (Li 2002). Distinguishing the individual species of the genus requires fine attention to details such the patterns of markings on the face, the proportions of the wing veins, and details of the genitalia.

REFERENCES

Li F. 2002. Psocoptera of China (2 vols). Science Press: Beijing.

Mockford, E. L. 2003. New species and records of Psocoptera from the Kuril Islands. Deutsche Entomologische Zeitschrift 50 (2): 191–230.

Two New Insect Orders?

When a new species of insect is described as being distinct enough to represent a new order, it's kind of a big deal. So it certainly caught my attention over the past year when, not one, but two species from Cretaceous Burmese amber were considered worthy of the honour. Now, I'm going to be up front here and say that, while both are very interesting specimens, in both cases I think that the 'new order' label may be a trifle overblown. What's interesting to me is that my reasons for thinking so are different for both. Let's take a look, shall we?

Lateral and dorsal views of holotype of Alienopterus brachyelytrus, from Bai et al. (2016). Pink scale bar = 1 mm.

The first was published in March of last year by Bai et al. (2016) under the name of Alienopterus brachyelytrus. In overall appearance, Alienopterus resembled a long-legged cockroach, but with the head clearly visible instead of hidden by the pronotum in the cockroach manner. The head would have been mobile and capable of being turned in the manner of a modern cockroach or mantis. The forewings were hardened and reduced to small pads covering only the base of the hind wings, which retained their full length. The femora of the front legs bore a pair of dense rows of setae on their underside, and Bai et al. suggested that Alienopterus may have used these setae to help it grab prey.

A phylogenetic analysis of Alienopterus placed it together with the modern cockroaches and mantids, specifically as the sister group to the latter. Because Alienopterus lacked the primary distinguishing features of a mantis (such as the spined raptorial forelegs), and because of its distinctive wing morphology, Bai et al. made it the type and only species of a new order, the Alienoptera. But there are a number of reasons why I find this designation problematic. It is generally agreed these days that cockroaches and mantids (and termites) together form a clade known as the Dictyoptera. Many people have an idea that cockroaches are one of the oldest living groups of insects, having supposedly been around for hundreds of millions of years. But modern cockroaches and mantids only diverged sometime during the Jurassic and Cretaceous; earlier members of the Dictyoptera were cockroach-like, certainly, but they were just as close to mantids as to cockroaches, and also had features very distinct from either. If we are to recognise a distinct 'order' for Alienopterus purely on phylogenetic grounds, then we would also have accept several separate 'orders' for each of the various lineages of stem-dictyopterans. And as distinctive as Alienopterus is morphologically, it is not the only (or even the most) unusual member of the Dictyoptera. This is, after all, the lineage that has given the termites with their wood-chomping biology and baroque caste system, beetle-like taxa with full-on elytra, and active leapers like the Jurassic Skok svaba or the modern Saltoblattella montistabularis.

There is a definite paradox at play here. On the one hand, the question of which lineages get designated 'orders' is completely arbitrary because there is no formal definition for an 'order' except that it is a taxon that is somehow more significant than a 'family' (itself a completely arbitrary level). From that perspective, there is no inherent reason why the Dictyoptera should not get divided between any number of orders. But on the other hand, the concept of 'order' has a certain cultural cachet. 'Orders' are kind of the base units of entomology: the first thing that any student of entomology is likely to do is learn to distinguish between the various insect orders. Labelling a particular taxon an 'order' is a statement of value; it says that that taxon is somehow fundamentally important in a way that other taxa are not. And while, again, Alienopterus is a very interesting animal in terms of what it can potentially tell us about cockroach-mantis relationships, it is hard to see how it can be called 'fundamental'. There have been extinct 'orders' recognised from the fossil record, such as the Palaeodictyoptera, but such taxa represent notable radiations. With only a single known species, referring to Bai et al.'s taxon as 'Alienoptera' tells us little more than calling it an unplaced species within the Dictyoptera.

Various views of Aethiocarenus burmanicus from Poinar & Brown (2016).

The other new 'order' made its appearance in December, when Poinar & Brown (2017) published Aethiocarenus burmanicus (if you're confused about the date, it reflects the difference between the online and print publication). This was a very odd little insect: a flattened and wingless yet long-legged animal with long antennae. The most distinctive feature of Aethiocarenus is its head, which is globular with great bulging eyes and placed on a narrow neck. Poinar & Brown suggest that it may have made its living hunting in confined spaces, such as crevices in bark or among epiphytes. Because of its highly distinctive appearance from any other known insect, Poinar & Brown placed it in its own new order, the Aethiocarenodea.

In this case, my issue with the establishment of a new 'order' is that it is essentially a statement of ignorance. As distinctive as Aethiocarenus is, there are many equally unusual-looking insects that are not placed in their own 'order'—particularly among wingless forms that can get up to all sorts of freakiness. The overall 'jizz' of Aethiocarenus, particularly the distinct cerci, suggest that its affinities probably lie somewhere within the Polyneoptera, the group of insects including such forms as cockroaches, grasshoppers and stoneflies. Within other polyneopteran orders, a novice entomologist would be hard-pressed to recognise a sandgroper as a grasshopper, or the Javan cave-dweller Arixenia esau as an earwig. Similarly, without a formal analysis it is difficult to exclude the possibility that Aethiocarenus represents a kooky member of some already recognised order. And again, with only one known species, recognition of an 'order' Aethiocarenodea tells us little more than recognition of an unplaced Aethiocarenus.

REFERENCES

Bai, M., R. G. Beutel, K.-D. Klass, W. Zhang, X. Yang & B. Wipfler. 2016. Alienoptera—a new insect order in the roach-mantodean twilight zone. Gondwana Research 39: 317–326.

Poinar, G., Jr & A. E. Brown. 2017. An exotic insect Aethiocarenus burmanicus gen. et sp. nov. (Aethiocarenodea ord. nov., Aethiocarenidae fam. nov.) from mid-Cretaceous Myanmar amber. Cretaceous Research 72: 100–104.

A Question of Taste

The Hawaiian Islands have provided us with a number of impressive examples of species radiations. Some of these, such as the Hawaiian honeycreepers, are well known to the general public. Others, such as the subject of today's post, may not be so famous but are no less noteworthy nonetheless.

Individual of a Laupala species, copyright K. Shaw.

Laupala is a genus of crickets distributed between all of the main islands of the Hawaiian chain. For a long time, they were all believed to belong to a single species referred to as Paratrigonidium pacificum. However, in the late 1960s, two entomologists, Richard Alexander and David Otte, started taking recordings of the songs of Hawaiian crickets. They began to realise that individuals of 'Paratrigonidium pacificum' from different localities had noticeably distinct songs. Most of these songs consisted of a fairly basic series of regular pulses of sound, but the frequency of the pulses could vary from only one every three seconds to four every second. Some of the song types were extremely localised; Otte (1994) referred to an occasion when he lost his car keys while out collecting at night, and was able to relocate the area he had been in and find his keys by following which crickets were singing. There might be one song pattern to be heard on the windward side of a ridge and an entirely different pattern on the leeward side (admittedly, in the precipitous landscape of many parts of the Hawaiian Islands, a 'ridge' an amount to a pretty serious geological barrier) Eventually, Otte (1994) would recognise the earlier 'Paratrigonidium pacificum' as including over thirty species of Laupala, plus a couple of species distinctive enough to be placed in a related genus, Prolaupala. Some of these species can be distinguished by their external appearance, albeit by relatively minor variations in coloration and patterning that would not be easily picked up, or by features of the male genitalia. Many cannot and can only be distinguished by the songs of the males.

All indications are that the Laupala have undergone rapid evolution to reach their current diversity. The oldest of the islands that Laupala species have been found on to date, Kauai, is about five millions years old. The big island of Hawai'i is less than a million years in age. Nor, of course, is there any reason to assume that the crickets have stopped diversifying. Laupala cerasina, a species found over a large part of the island of Hawai'i, is highly variable in both song pattern and morphological features; indeed, variation between populations of L. cerasina is such that they could easily be regarded as separate species were it not for the failure (to date) to identify clear separation between the variants. A comparison between phylogeny of the genus and island age suggests that Laupala species have been diverging at a rate of up to more than four speciation events per million years (Mendelson & Shaw 2005). This is one of the fastest recorded rates of speciation in the animal kingdom; only African cichlids have been calculated to be diversifying faster. It is perhaps not surprising that both of these cases of rapid speciation appear to be driven by features related to sexual selection; it has been suggested that the power of sexual selection is such that what amount to questions of taste can cause wholesale change in populations within a matter of generations. Patterns of variation observed within different species of Laupala are also consistent with the predictions of sexual selection: on the island of Oahu, the species L. pacifica has a song that is noticeably faster in localities where it co-exists with the slower-singing L. spissa than in localities where it is the only species.

Results of phylogenetic analyses from Shaw (2002), showing disagreements between nuclear and mitochondrial genetic analyses.

The Laupala radiation also resembles that of the cichlids in that it gets more complicated the closer one looks. In his original description of the radiation, Otte (1994) recognised three species groups, separated on the basis of morphological features. One of these, the L. kauaiensis group, contains those species found on the island on Kauai. As befits Kauai's position as the oldest and most isolated of the islands involved, phylogenetic studies agree that this species group is well separated from the other two. The other two, more diverse, groups, the L. cerasina and L. pacifica groups, are each dispersed over the islands of Oahu, Maui and Hawai'i (the L. cerasina group also includes two species on the island of Molokai). Analyses of nuclear genetic data support these species groups, implying multiple dispersals between islands. The phylogeny presented by Mendelson & Shaw (2005) on the basis of AFLP (amplified fragment length polymorphism) data is consistent with divergence of the two groups on Oahu followed by sequential dispersal of each of the two groups down the line of newly emerging islands; an earlier phylogeny presented by Shaw (2002) on the basis of nuclear sequence analysis is perhaps a bit less tidy but still fits the same overall framework. However, an analysis of mitochondrial genetic data that was also presented by Shaw (2002) presents a quite different picture. With the exception of the Kauai group, Otte's species groups were not supported by the mitochondrial data. Instead, two species from a single island that might be placed in separate groups by the morphological and nuclear data would be placed close together by the mitochondrial data.

How can this discrepancy between the data sources be explained? The most likely explanation is that the nuclear and mitochondrial data reflect different genetic histories. Because mitochondria are inherited only in the maternal line, interbreeding between individuals of different species can result in progeny containing nuclear and mitochondrial genes with entirely distinct heritages. The implication is that the boundaries between Laupala species have not been impervious, that there has been a certain degree of hybridisation in the past. Again, there are reasons for finding this credible. Studies of mating behaviour in Laupala have found that, as a species isolating device, song patterns are only effective at a long range. Females will only actively seek out males producing the right song patterns, but they will not refuse males singing differently whom they happen to encounter on the way. Song patterns are not the only reasons a female may have for refusal; for instance, Mullen et al. (2007) identified a distinct separation between species by cuticular chemistry, implying that individuals of different species smell or taste as well as smell different. Nevertheless, species of this genus diverged recently enough that it is quite credible that they could remain interfertile when the occasion arose.

REFERENCES

Mendelson, T. C., & K. L. Shaw. 2005. Rapid speciation in an arthropod. Nature 433: 375–376.

Mullen, S. P., T. C. Mendelson, C. Schal & K. L. Shaw. 2007. Rapid evolution of cuticular hydrocarbons in a species radiation of acoustically diverse Hawaiian crickets (Gryllidae: Trigonidiinae: Laupala). Evolution 61 (1): 223–231.

Otte, D. 1994. The Crickets of Hawaii: Origin, Systematics and Evolution. Orthopterists' Society, Academy of Natural Sciences of Philadelphia.

Shaw, K. L. 2002. Conflict between nuclear and mitochondrial DNA phylogenies of a recent species radiation: what mtDNA reveals and conceals about modes of speciation in Hawaiian crickets. Proceedings of the National Academy of Sciences of the USA 99 (25): 16122–16127.

ID for Heather?

The deadine for my crowdfunding drive has been extended. Thanks to your support, I am over 40% of the way towards success! But I'm still going to need everyone's help if I'm to be succesful. Please visit my page at Experiment.com and consider offering your support!

I was recently contacted by Heather Adamson who wanted to know if I could identify the animal in the above picture. She photographed it on an old post in the region of West Coolup, south of Mandurah here in Western Australia. I can tell her that it is some form of Lepidoptera larva (in other words, a caterpillar) and it looks like it may be beginning to weave itself a cocoon. Beyond that, I couldn't say. Do any of my readers have a better idea of what it is than I do?

Update: I shared this post to the Western Australian Insects group on Facebook, and Daniel Heald has suggested that Heather's photo may show the pupa of a lymantriid moth Teia athlophora. This species constructs itself a loose, cage-like cocoon from its own irritant hairs. The male, when he emerges, is a fairly standard looking brown moth, but the female is fat and flightless with only tiny stubs of wings. She will continue to live in and around her pupal cocoon, awaiting visits from courting males.

All that is Silver is not Fish

Common silverfish Lepisma saccharina, copyright Christian Fischer.

The insects are deservedly recognised as one of the most successful groups of organisms on the planet. Thanks in no small part to their unlocking the ability of flight, insects can be seen today in almost every part of the planet above sea level. But not all insects, of course, are flighted; many remain firmly on the ground. A large proportion of these are the descendents of flighted ancestors that returned to a terrestrial existence but there are also some whose ancestors never took to the skies. For most people, the most familiar of these original land-huggers are likely to be the silverfish of the family Lepismatidae.

Silverfish are long-bodied insects with a covering of reflective scales—hence the 'silver' part of their name. The 'fish' part probably refers to the manner of their movement; speaking from my own experience collecting them, these buggers move fast, slipping along the ground like a silver minnow. There are over 250 known species of Lepismatidae (Mendes 2002); probably many more remain to be described. They comprise over half the known species of the insect order Zygentoma (sometimes referred to as the Thysanura though most current entomologists tend to avoid that name due to its previous history referring to a now-obsolete grouping of the Zygentoma with the superficially similar Archaeognatha); the other families in the order are commonly subterranean and less commonly encountered by the average person. The highest diversity of silverfish occurs in tropical and subtropical parts of the world, particularly in arid or semi-arid regions. Adaptations of the rectal epithelium allow silverfish to absorb moisture straight from the atmosphere (or, to put it another way, they drink through their butt), making them ideally suited to tolerating the dryness of deserts. They are also suited to tolerating the relatively dry habitats offered by the interiors of human houses and several species have become our associates (in cooler parts of the world, these synathropic species are often the only lepismatids around). These include the common silverfish Lepisma saccharina and the giant silverfish Ctenolepisma longicaudata. The firebrat Thermobia domestica is a colourfully patterned human associate that likes it particularly warm; it is usually restricted to places like the backs of stoves or alongside hot-water cylinders where it can find the heat it craves. Being detritivores (that is, they feed on dust), human-associated silverfish are usually quite innocuous though they may cause problems if their numbers get too high or if they get into stored foodstuffs.

Firebrat Thermobia domestica, copyright David R. Madison.

In areas where they are native, silverfish may be quite diverse. Watson & Irish (1998) conducted a study of an area of the Namib Desert that was home to eight different species of silverfish. They found a tendency for the species to differ in their preferred microhabitat within the area: some were restricted to the upper parts of the sand dunes dominating the region, others were restricted to the rocky hollows separating the dunes. Those found in rocky lower zones resembled the familiar human-associated species (indeed, they included members of the same genus as the giant silverfish, Ctenolepisma) in being elongate and slender. In contrast, those species found higher in the dunes themselves were shorter and more flattened with well-developed spines covering the legs. These features allowed the dune silverfish to effectively 'swim' through the sand, using the spines on the legs to dig about and their flattened form to slip between grains.

REFERENCES
Mendes, L. F. 2002. Taxonomy of Zygentoma and Microcoryphia: historical overview, present status and goals for the new millennium. Pedobiologia 46: 225–233.

Watson, R. T., & J. Irish. 1998. An introduction to the Lepismatidae (Thysanura: Insecta) of the Namib Desert sand dunes. Madoqua 15 (4): 285–293.

Ami-, Ami-termes

Soldier of Amitermes, copyright Alexander Yelich.

I've referred before to my enthusiasm for termites, those wonderfully weird sociable scions of the cockroach clan. For today's post, I'm looking at one of the larger and most widespread termite genera, Amitermes.

There are over 100 species of Amitermes found in tropical regions around the world, though they are most diverse in Africa and Australia. They are members of the so-called 'higher termites' of the Termitidae, those termites with a gut microbiota dominated by bacteria rather than protozoa. Soldiers of Amitermes have long sickle-shaped mandibles with a more-or-less well-developed tooth on each mandible; these mandibles are used to slash at perceived threats, the effect of this direct attack being presumably exacerbated by offensive chemicals that seep from the fontanelle, a pore on the front of the head capsule. Members of the genus are diverse in habits: some build sizable mounds above ground whereas others live in small colonies in underground tunnels. Some show a distinct preference for living in the nests of other termites, either moving into abandoned mounds after the original owners have perished or squatting in some overlooked corner of an active nest. Nests may be built directly around a food supply, or workers may go out to forage for food to bring home. In the latter case, the workers may construct a covered tunnel for themselves as they go; these trails may commonly be seen running along the ground in areas where such termites are abundant. Many Amitermes species feed on wood but they may also take other vegetable matter such as grass. A number of species feed on the dung of herbivorous mammals such as cattle or horses (Gay 1968), digesting parts of the consumed plant matter that the original feeder could not. One West African species, A. evuncifer, is a significant pest of crops, attacking root vegetables or the roots of young trees. Hill (1942) noted that mound-building Amitermes could present difficulties beyond just their feeding habits, explaining that "The frequent destruction of nest of [this genus] is perhaps the most important task of those employed in the maintenance of certain northern aircraft landing grounds, for the removal of the original nest almost invariably is followed the erection of another of a size and consistency that contributed a potentially dangerous obstacle to landing or rising aircraft".

Magnetic termite mounds, copyright David King.

Perhaps the most famous members of this genus are the 'magnetic termites' of northern Australia. These are three species that build mounds that, instead of being conical or globular like the mounds of other species, are long and narrow, almost blade-like. Even more strikingly, they are lined up almost exactly along a North-South axis, with at most a 10° deviation. Experimental alterations of such mounds indicate that the termites are indeed sensitive to the direction of magnetic fields though other factors such as local climatic conditions may also play a part. The shape of magnetic mounds is usually interpreted as an adaptation for temperature regulation: at the cooler ends of the day, the mound is receiving the full effects of the sun but during the hot midday only the thin upper edge is in the line of the light. However elegant an explanation this may seem, however, it overlooks the detail that a more standard globular mound is actually better for heat regulation overall. Round mounds have a much lower surface area-volume ratio and hence a lower rate of heat diffusion. Blade-shaped mounds may absorb heat quickly in the morning but they also lose heat quickly at night. An alternative explanation for the mounds' shape may lie in where magnetic mounds are found. It is worth noting that only one of the Amitermes species concerned, A. meridionalis, is an obligate constructor of blade-shaped mounds; the other two species, A. laurensis and A. vitiosus, may build either conical or blade mounds depending on local conditions. Magnetic mounds are constructed on flat flood plains, so the termites living inside them build up stores of grass to provide food when flood-waters prevent them from foraging outside the nest. By allowing better air flow within the nest than a conical mound, the blade-shaped mounds allow food stores to remain edible for longer, reducing the risk of them expiring before flood-waters recede (Korb 2011). Temperature regulation is still the best explanation for the regular orientation, of course, but is probably not the primary cause for the mound form overall.

Drepanotermes rubriceps soldiers around a nest entrance, copyright Lochman Transparencies.

Phylogenetic analysis of the termites by Inward et al. (2007) indicated that the genus Amitermes as currently recognised is probably not monophyletic, being paraphyletic to at least the Australian genus Drepanotermes. Members of this latter genus are grass-feeders, particularly on the hard Triodia (spinifex) grasses that dominate large parts of arid Australia (and which few animals without the super-charged termite digestive system can eat). In my experience, Drepanotermes are one of the few termite genera that can be reasonably easily recognised from the workers alone, which are noticeably longer in the legs than other termites. I've often seen Drepanotermes workers out foraging at night; the entrance to the underground nest (a simple hole) can usually be found nearby. The soldiers do not usually emerge from the nest, but a group of them will sit in the entrance hole with their heads poking out to provide defence. When collecting specimens, I've found that the challenge is to move fast enough to grab a soldier before it zips back into the tunnel, escaping your grasp.

REFERENCES

Gay, F. J. 1968. A contribution to the systematics of the genus Amitermes (Isoptera: Termitidae) in Australia. Australian Journal of Zoology 16: 405–457.

Inward, D. J. G., A. P. Vogler & P. Eggleton. 2007. A comprehensive phylogenetic analysis of termites (Isoptera) illuminates key aspects of their evolutionary biology. Molecular Phylogenetics and Evolution 44: 953–967.

Korb, J. 2011. Termite mound architecture, from function to construction. In: Bignell, D. E., et al. (eds) Biology of Termites: A Modern Synthesis pp. 349–373. Springer.

When Mayflies Last for Millions of Years

Mayfly Paraleptophlebia prisca preserved in amber, from Penney & Jepsen (2014).

Of all the media available for the preservation of fossils, none approaches perfection anywhere near as close as amber. There is little structural that amber does not preserve: external apperance, soft tissues, even cellular structure may potentially be examined. Amber offers us a window into the past unlike any other. The first amber deposits to go on the record (going back as far as the ancient Greeks), and the largest deposit yet discovered, was the Baltic amber of northern Europe, formed in the Eocene or Oligocene epoch* from the sap of a relative of the modern pines.

*Calculating the age of amber deposits is not easy. The amber itself cannot be dated directly (it is too old to be carbon-dated, of course, and it usually contains no mineral sediments that can be dated by other means) so aging it depends on indirect methods such as comparison of enclosed fossils with other aged samples, or dating of the deposits in which the amber is buried. Fossil comparisons suffer from the fact that the types of organisms that tend to be found preserved in amber are usually different from those preserved by other means (so we may know that two amber deposits are of similar age as each other, but we may still not know what that age actually is). Dating of surrounding deposits may be more straightforward, but is complicated by the fact that amber's relative buoyancy makes it prone to reworking (when a geological specimen becomes eroded out of its original formation and reburied in a younger one, thus making it appear younger than it is). Of course, if an amber deposit was produced over a long period of time, it may be impossible to tell if a particular piece comes from early or late in that period. Current consensus seems to indicate an Eocene age for the Baltic amber, but older references may refer to it as Oligocene or even Miocene.

Most of the insects we find preserved in Baltic amber are similar to those we find today (though differences in climate between now and then mean that the amber contains a number of groups that we would not expect to find so far north today). The specimen shown at the top of this post is assigned to a genus of mayfly (of the diverse family Leptophlebiidae) that remains widespread in Europe and North America today, of which it represents the earliest record. Like other members of the genus, it is a relatively small mayfly with a wingspan of less than 15 millimetres (I came across this fly-fishing website referring to the frustration of anglers trying to handle such small flies). Several specimens of this species are known from the Baltic amber, representing the subimaginal and imaginal stages of both sexes (mayflies are unique among living insects in that their wings become functional before they are fully mature; when a mayfly first emerges from the water it is as a near-mature subimago, subsequently moulting to a fully mature imago). Presumably, like modern mayflies, Paraleptophlebia prisca emerged as synchronised swarms, many individuals of which may have found themselves landing on an unwisely chosen tree-trunk and trapped within weeping sap.

This species was first described in 1856 by F. J. Pictet-Baraban along with other species of 'Neuroptera' from Baltic amber (at the time, the order Neuroptera included a wide range of insects with relatively unspecialised wings such as mayflies, dragonflies, bark-lice and lacewings). Pictet assigned it to the genus Potamanthus, another Recent mayfly genus albeit one in a different family Potamanthidae. He did express some uncertainty about this placement, an uncertainty that was later borne out by Demoulin (1968) who re-identified it as Paraleptophlebia on the basis of wing venation and male genital characters. Subsequent authors have agreed with Demoulin's assessment, regarding the mayflies of today as little different from those you might have found flying about over 50 million years ago.

REFERENCES

Demoulin, G. 1968. Deuxième contribution à la connaissance des Éphéméroptères de l’ambre oligocène de la Baltique. Deutsche Entomologische Zeitschrift, N. F. 15 (1–3): 233–276.

Penney, D., & J. E. Jepson. 2014. Fossil Insects: An introduction to palaeoentomology. Siri Scientific Press: Manchester.

Pictet-Baraban, F. J., & H. Hagen. 1856. Die im Bernstein befindlichen Neuropteren der Vorwelt. In: Berendt, G. C. Die im Bernstein befindlichen organischen Reste der Vorwelt vol. 2 pp. 41–126. Nicolaischen Buchhandlung: Berlin.

The Polyctenidae: Blood-sucking Bugs on Bats

Dorsal, ventral and lateral views of Eoctenes spasmae, from Marshall (1982).

If you ever feel inclined to scan through host records for ectoparasites (and really, why wouldn't you?), you may be struck by the impression that bats seem to be peculiarly lousy animals. There seems to be an unexpected number of groups of ectoparasites that have their highest number of species on bats. One possible reason for this is that, with over 900 potential host species, bat-parasite diversity is high simply because bat diversity is high. Nevertheless, there are other features peculiar to bats that make them excellent parasite hosts. The modification of their fore-legs into wings means that their ability to groom themselves is curtailed. Because many bat species roost in dense colonies, transmission of parasites from one bat to another may happen freely. And because most bats will consistently return to the same roost, speciation is promoted by each colony becoming like an isolated island.

At the same time, referring to bats as 'lousy' is misleading because one ectoparasite group that is curiously absent from bats is the true lice (why this should be I have no idea). Instead, bats are often host to a number of parasite groups all of their own. One such group is the Polyctenidae, flightless true bugs that are found only on bats in tropical and subtropical parts of the world. Polyctenids are closely related to the bed bugs of the Cimicidae and are not dissimilar in appearance. Noticeable differences are their relatively shorter antennae and absence of eyes. They also possess a number of bristle combs at various places on the body, roughly similar in appearance to those on fleas. Their front legs are short and have sucker-like structures on the tarsi instead of claws; the hind two pairs of legs are longer and clawed. The manner of movement of the legs is specialised for crawling among the hair of their host; if removed from the host, the bug is unable to move on a flat surface. Transmission of bugs from one host to another presumably happens only through direct physical contact. Polyctenids share with bed bugs the notorious practice of traumatic insemination with each male injecting sperm directly into the female's body cavity via sharpened genitalia. However, unlike bed bugs they are viviparous, producing live nymphs instead of eggs. The developing embryos are nourished by a 'pseudoplacenta' with a single female potentially containing several developing embryos in a conveyor arrangement at different stages of development. The most mature of these embryos protrudes from the female's genital opening for some time prior to birth and may be a third of its mother's size when born (Marshall 1982).

Type specimen of Hesperoctenes giganteus, from here.

Five genera of polyctenids are generally recognised, with four genera found in the Old World and only a single genus, Hesperoctenes, in the New World (Maa 1964; Ueshima 1972). A second New World genus, Parahesperoctenes, was described in 1947 from a single female, but as the features supposedly distinguishing it from Hesperoctenes related to the consistent duplication of combs, etc., it is thought likely that this was an ordinary individual of Hesperoctenes on the cusp of moulting from a nymph to an adult (so the features of the adult cuticle were visible through the translucent nymphal cuticle). Most of the polyctenid species have a restricted host range, being found on only a single bat species or a small number of closely related species. Some species of Hesperoctenes are more flexible, being found on a range of host species. Hesperoctenes and the Old World genus Hypoctenes are found on free-tailed bats of the Molossidae. Of the other Old World genera, Adroctenes is found on horseshoe bats and leaf-nosed bats of the Rhinolophidae and Hipposideridae, Polyctenes is found on ghost bats of the Megadermatidae, and Eoctenes is found on Megadermatidae, Nycterididae and Emballonuridae. Records of polyctenids from other bat families are currently regarded as suspicious, due to either mislabelling or cross-contamination. Ueshima (1972) suggested that records of Hesperoctenes fumarius from the bulldog bat Noctilio labialis might result from bugs being transferred while the bulldog bats were sharing a roost with their more usual molossid hosts.

Relationships between the genera were discussed by Maa (1964) who divided the family between two subfamilies on the basis of comparative features; a formal phylogenetic analysis of the family appears to still be wanting. On the basis of Hesperoctenes being the 'most specialised' genus and its shared host family with Adroctenes, Maa suggested an Old World origin for Polyctenidae. Eoctenes, with its broad host family range, was regarded as 'least specialised' and likely to be evolutionarily older than other genera. Many of the features distinguishing the polyctenid genera relate to the arrangement of combs: which combs are present where and how they are developed. Prior to Maa's revision, Hesperoctenes had been regarded as likely to be primitive within the Polyctenidae due to its relatively low number of combs. The mid- and hind legs of Adroctenes are fairly short compared to those of other genera.

REFERENCES

Maa, T. C. 1964. A review of the Old World Polyctenidae (Hemiptera: Cimicoidea). Pacific Insects 6 (3): 494–516.

Marshall, A. G. 1982. The ecology of the bat ectoparasite Eoctenes spasmae (Hemiptera: Polyctenidae) in Malaysia. Biotropica 14 (1): 50–55.

Ueshima, N. 1972. New World Polyctenidae (Hemiptera), with special reference to Venezuelan species. Brigham Young University Science Bulletin, Biological Series 17 (1): 13–21.

Thrips Wars!

Two males of Elaphrothrips tuberculatus fight it out on the left, while the object of their desire guards her egg-mass on the right. Figure from Crespi (1986).

All around, little dramas are taking place every day, conflicts as intense as the plot of any daytime soap opera. And like most daytime soap operas, the main focus of these dramas often comes down to who is shagging whom. Most people only known thrips as small annoying insects that damage garden plants and crops, but some thrips may engage in remarkable behaviours.

Elaphrothrips is a genus of thrips found almost throughout the tropics (though it is absent from Australasia). They are found on dead leaves, where they feed on fungal spores. Well over a hundred species have been named in Elaphrothrips, though Mound & Palmer (1983) pointed out that many of these may be turn out to be synonymous as individual species can vary significantly in appearance. Males may have thick forelegs with strong tubercles on the femora, while the forelegs of females are usually slender and lack tubercles. Indeed, the sexes are different enough that at one point they have been mistaken for separate genera. The males themselves may vary significantly in size, with larger males having correspondingly larger legs and spines.

A lot of these differences are related to the Elaphrothrips' mating behaviour. The best-studied of the Elaphrothrips species is E. tuberculatus, a widespread species in eastern North America and the largest North American thrips species. Elaphrothrips tuberculatus prefer dead oak leaves that are still hanging in clusters from the tree, where females lay eggs in clusters on the leaves and then stand guard over them. The females are themselves guarded by males, but the males may be challenged by others who want to take the female for themselves. Battles between male Elaphrothrips most commonly take the form of the two males lining up alongside each other, as in the drawing at the top of this post, and then one or each begins batting at the other with his elongate abdomen. Alternatively, one male may attempt to reach under his opponent's abdomen with his own, and then try to flip his opponent over. Crespi (1986) noted that challenging males were more likely to try to flip their opponent than defending males, perhaps because the success rate of flipping attempts was very low, making this tactic more of a gamble. Flipping could also act as a defense against a third attack strategy, in which one male would climb up onto the back of his opponent and use the tubercles on his forelegs to stab at his opponent's thorax. Larger males were more likely to stab their opponents than smaller males, which of course have less developed leg spines. However, a smaller male may also get around larger male through sneaking behaviour, mating with the female before her guarding male realises he is there.

Whichever male mates with the female, one thing is certain: he will only have daughters. Thrips have a haplodiploid sex determination system like that of ants and bees, with males developing from unfertilised ova and females from fertilised ones. Elaphrothrips tuberculatus adds another wrinkle to the system that only females hatch from eggs. Male offspring, on the other hand, develop inside their mother and are born live (Crespi 1989). Nevertheless, an individual female may have both male and female offspring, as she may change her reproductive mode between broods to be a live-bearer or an egg-layer!

REFERENCES

Crespi, B. J. 1986. Size assessment and alternative fighting tactics in Elaphrothrips tuberculatus (Insecta: Thysanoptera). Animal Behaviour 34: 1324-1335.

Crespi, B. J. 1989. Facultative viviparity in a thrips. Nature 337: 357-358.

Mound, L. A., & J. M. Palmer. 1983. The generic and tribal classification of spore-feeding Thysanoptera (Phlaeothripidae: Idolothripinae). Bulletin of the British Museum (Natural History): Entomology 46 (1): 1-174.

A Little Bit on Lesser Dung Flies

Copromyza stercoraria, photographed by Blaauw7.

The fly in the picture above is a typical member of the Sphaeroceridae, a family of over 1300 species of small flies that include some of the most ubiquitous of all insects. Despite their abundance, however, they rarely attract much attention from humans due to their small size, usually only about a couple of millimetres in length. Sphaerocerids are distinguished from other flies by the structure of the tarsus (the 'foot') on the hind leg. In most other flies, all the legs have the tarsi divided into elongate segments, but in sphaerocerids the first segment of the last tarsus is noticeably short and broad.

Sphaerocerids are sometimes referred to as 'lesser dung flies', referring of course to their small size and the diet of their larvae. However, lesser dung flies are not only associated with dung, but also feed on almost any form of decaying organic matter. They may be found on carrion or decaying vegetation or fungi. Some species may feed on a wide range of foodstuffs, but others are much pickier. One species, seemingly as yet unidentified, has been found in the excretory glands of a land crab. The coast-dwelling genus Thoracochaeta feeds on seaweed (Marshall & Buck 2010).

Podiomitra sp., photographed by Inna Strazhnik.

Though diverse, the majority of sphaerocerids are fairly conservative in appearance, including the Copromyza at the top of this post. There are, of course, notable exceptions. The individual just above is a representative of the Homalomitrinae, a rarely-collected subfamily of six known species in three genera from tropical Central and South America. The homalomitrines have a number of unusual features: their heads lack ocelli, have reduced bristles, and are more or less elongate; their thoraxes are relatively small; and the tarsi of all legs are short and broad. Two of the three genera, Sphaeromitra and Podiomitra, have markedly reduced venation in the wings. They do not have the appearance of strong fliers (though specimens have been collected in Malaise traps, indicating that they fly at least on occasion), but their extreme rarity (so far as is known) means that their lifestyles are almost unknown. Two species of Homalomitra, H. ecitonis and H. albuquerquei have been collected in association with army ants (Roháček & Marshall 1998), and it has been suggested that homalomitrines might develop in army ant middens, travelling phoretically by clinging to the ants with their modified tarsi (Marshall & Roháček 2003). However, it should be noted that this is largely speculative: the holotype of H. ecitonis, when collected, was reported to be walking amongst the supposed host ants, but otherwise little has been recorded of the nature of the association. It should also be noted that Roháček & Marshall (1998) suggested that H. ecitonis and H. albuquerquei form a clade to the exclusion of the other homalomitrine species, which further weakens confidence in extending the habits of these species to others.

There are also a number of species of sphaerocerid in which the wings are reduced or absent. The development of the wings may vary within a single species, as rather dramatically demonstrated by the specimen of Pullimosina meijerei shown above in a figure from Roháček (2012). This male exhibited unequal wing development, with the left wing that of a brachypterous individual but the right wing that of a macropter.

Sphaerocerids have been suspected as potential disease vectors due to their association with waste and decay, but actual evidence of negative impact on humans is rare. There appears to be at least one recorded case of sphaerocerid-caused intestinal myiasis (Marshall & Richards 1987), and sphaerocerids may become numerous enough to be a nuisance in places with a concentration of potential food, such as abattoirs or mushroom farms. Whatever their negative impacts may be, they are almost certainly outweighed by the positive: the ubiquitous sphaerocerids are probably major players in the process of breaking down waste materials and returning nutrients to the environment. They're the little flies that save you from being knee-deep in shit.

REFERENCES

Marshall, S. A., & M. Buck. 2010. Sphaeroceridae (small dung flies). In: Brown, B. V., A. Borkent, J. M. Cumming, D. M. Wood, N. E. Woodley & M. A. Zumbado (eds) Manual of Central American Diptera, vol. 2, pp. 1165-1187. NRC Research Press: Ottawa.

Marshall, S. A., & O. W. Richards. 1987. Sphaeroceridae. In: McAlpine, J. F. (ed.) Manual of Nearctic Diptera, vol. 2, pp. 993-1006. Biosystematics Research Centre: Ottawa.

Marshall, S. A., & J. Roháček. 2003. Podiomitra, a new genus of Homalomitrinae (Diptera: Sphaeroceridae) from Costa Rica. Proceedings of the Entomological Society of Washington 105 (3): 708-714.

Roháček, J. 2012. Wing polymorphism in European species of Sphaeroceridae (Diptera). Acta Entomologica Musei Nationalis Pragae 52 (2): 535-558.

Roháček, J., & S. A. Marshall. 1998. Revision of Homalomitrinae subfam. n. (Diptera: Sphaeroceridae), with the description of a new genus and three new species. European Journal of Entomology 95: 455-491.

Barrow's Scaly Bark-louse

Male of Lithoseopsis humphreysi, from Taylor (2013). As this specimen has been preserved in ethanol, most of the wings' scales have been washed off.

In yesterday's post, I told you about our project's new book on the terrestrial invertebrates of Barrow Island. In this post, I want to tell you about my own main contribution: a description of Barrow Island's resident species of Amphientomidae.

Amphientomidae is a family of the bark-lice, the Psocodea (or Psocoptera, perhaps). They differ from most other bark-lice in having the wings densely covered in scales, like the wings of a moth; someone on BugGuide once referred to an amphientomid as a "moth-hopper-louse-bug thingy". These scales are often arranged into striking patterns of contrasting colours (take a look at the individual below). When the late Courtenay Smithers initially identified our collections of bark-lice from Barrow Island (which we briefly reviewed last year, though most are still not identified to formal species), he highlighted the presence of an amphientomid in the collection as particularly interesting. Amphientomids are incredibly little known in Australia. Only three Australian species had previously been described, and all three were only known from a single specimen. The description in my paper is drawn from six specimens, so it represents a tripling of Australia's published tally!

A North American species of Lithoseopsis, L. hellmani, photographed by Diane Young.

With this in mind, a description of the Barrow Island amphientomid seemed in order. This, of course, required comparing it to the already-described Australian species, which had thankfully been given detailed descriptions (Smithers 1989; New 1994). Two of these were from Western Australia: one from the Kimberley region in the far north, the other from the Cape Range which is on the mainland close to Barrow Island. Both of these had been placed in the genus Seopsis, which is otherwise known from Africa and Asia. However, when I compared the Barrow Island specimens to descriptions of Seopsis and other Asian genera, things didn't quite add up. For instance, take a look at the face of the Barrow Island species:

In particular, note the position of the ocelli (the three simple eyespots) at the front of the face. In all the Australian species, these are widely spaced, and the two lateral ocelli are right alongside the compound eyes. In contrast, here is the face of a Japanese amphientomid:

The individual in this photo, from here, isn't identified but may belong to Paramphientomum yumyum (yes, really, that's its name). Note how in this species, all three ocelli form a close triangle in the centre of the face; Seopsis also has this arrangement of ocelli. Other features such as genital morphology were also inconsistent between the Western Australian species and Seopsis.

Instead, the Western Australian species are better placed in a genus called Lithoseopsis*. The Barrow Island specimens I assigned to the same species that had earlier been described from the Cape Range, Lithoseopsis humphreysi. There are some minor differences between the Barrow specimens and the Cape Range holotype, but with only one specimen available from the latter locality I couldn't really assess whether these were indicative of more than one species. The recognition of this species as Lithoseopsis is interesting, as this genus is otherwise known only from southern North America. How such an oddly disjunct distribution may have come about I have no idea; my first guess would be that it's somehow relictual. However, it's also worth pointing out that there are three other genera very similar to Lithoseopsis that share its broadly-spaced ocelli: the African genus Hemiseopsis and the circum-Mediterranean genera Marcenendius and Nephax. The relationship between these genera really deserves a proper study.

*And here's a bit of a cautionary tale for you all. When I initially submitted the manuscript of this paper for review, one of the reviewers pointed out that the Western Australian species shouldn't be placed in Lithoseopsis due to the absence of one of that genus' primary features, a sclerotised plate on the back of the abdomen. Therefore, the manuscript was revised and accepted to establish the WA species as a new genus. At this point, I should note, the only amphientomids that had been available from Barrow Island were males. However, shortly before the book was due to be published, I finally received a female specimen. This specimen possessed the sclerotised plate that had been absent in the males! The paper was quickly revised at the last minute to return the WA species to Lithoseopsis. The ability to examine a female from Barrow also lead me to change my mind about whether the Barrow species was distinct from the Cape Range species, represented only by a female holotype. Unfortunately, once the book had been published and I could see the final product, I found that I had missed correcting the genus and species name in the figure captions! Much wailing and gnashing of teeth immediately commenced, I can bloody well tell you. After the whole pureora/pureroa thing, 2013 has not made me look good as a proof-reader.

The Barrow Island specimens also tell us something interesting about intra-specific variation in amphientomids. A common feature of bark-lice is variation within species of wing development: individuals of a single species may have the wings fully developed, reduced or absent. In amphientomids, however, such variation has been rarely recorded. A couple of species are known in which males and females differed in wing development, but so far as was known all males and all females had wings the same size. In the Barrow Island specimens, however, some males had both pairs of wings large and fully developed, but others had the forewings slightly shortened and the hind wings reduced to minute flaps. As the reduced-wing specimens were otherwise little different from the fully-winged specimens, they seem unlikely to represent different species. Instead, Lithoseopsis humphreysi is the first recorded example for amphientomids of wing polymorphism within a single sex.

REFERENCES

New, T. R. 1994. A second species of Amphientomidae (Insecta: Psocoptera) from Western Australia. Proceedings of the Linnean Society of New South Wales 114 (4): 233–236.

Smithers, C. N. 1989. Two new species of Amphientomidae (Insecta: Psocoptera), the first record of the family for Australia. Proceedings of the Linnean Society of New South Wales 111 (1): 31–35.

Taylor, C. K. 2013. The genus Lithoseopsis (Psocodea: Amphientomidae) in the Western Australian fauna, with description of the male of Lithoseopsis humphreysi from Barrow Island. Records of the Western Australian Museum Supplement 83: 245-252.

Beetle Flies

Unidentified celyphid, photographed by Giovzaid85.

Those of you who follow me on Twitter (@CatofOrg) may have already seen these guys, but I thought it worth putting them up here as well. Because sometimes you come across an animal that just makes you stop, blink, and exclaim, "What the creeping jayzus is that!". Ladies and gentlemen, the Celyphidae.

Another celyphid, photographed by Melvyn Yeo.

Celyphids are flies that are doing their damnedest to look like a beetle (and are hence, unsurprisingly, commonly known as beetle flies). The scutellum, which in most flies is a relatively small lobe of the thorax sitting behind and between the wings, has become massively enlarged and overtops the abdomen. The wings (which are full-sized and fully functional) slip in underneath the scutellum when folded back. Just to add to the overall beetle-osity of the thing, celyphids can be very shiny and metallic (check out the blue-black item here). The function of this giant scutellum is unknown; protection is the first thing that comes to my mind, but I don't know if the scutellum is any more sclerotised than the rest of the animal. One suggestion that has apparently been made is that the scutellum may provide extra buoyancy in flight (Tenorio 1972), to which I ask, is it hollow or something?

Photo by Meng Foo Choo.

Celyphids are found in tropical Asia and Africa (all the photos on this page except the last were taken in Singapore). They are closely related to the more widespread family Lauxaniidae, and have been treated by at least some authors as a derived subgroup of the latter (some lauxaniids also show a degree of enlargement of the scutellum). The larvae of celyphids feed on rotting vegetation.

Celyphus koannanius, from here.

REFERENCE

Tenorio, J. M. 1972. A revision of the Celyphidae (Diptera) of the Oriental Region. Trans. R. Ent. Soc. Lond. 123 (4): 359-453.