The Running of the Termites

I don't know how many people would profess to have a favourite genus of termites. Which is a shame, because there are some real stand-out examples. Snapping termites, magnetic termites, glue-spraying termites... For my own part, though, I have a particular fondness for the Australian harvester termites of the genus Drepanotermes.

Soldiers and workers of Drepanotermes perniger, copyright Jean Hort.

Nearly two dozen species of Drepanotermes are found on the Australian continent to which they are unique (Watson & Perry 1981). They are arid-environment specialists, being most diverse in the northern part of Australia. My reasons for being so fond of them are, I'll admit, decidedly prosaic. The worker caste of most termite species is very difficult if not impossible to identify taxonomically; one termite worker usually looks very much like another. Drepanotermes workers, however, are different. The name Drepanotermes can be translated as "running termite" and, as befits their name, Drepanotermes of all castes stand out for their distinctly long legs. Soldiers of Drepanotermes also have distinctively shaped mandibles which are sickle-shaped and have a single projecting tooth on the inner margin. They are similar to soldiers of the related genus Amitermes (of which Drepanotermes may represent a derived subclade) but the mandibles of Amitermes tend to be straighter and more robust.

The long legs of Drepanotermes reflect their active harvester lifestyles. Workers will emerge from the nest at night in search of food to carry back home. In the red centre of Australia they will primarily collect spinifex; they will also take fallen leaves, tree bark and the like. Soldiers keep guard while the workers forage. I've found them clustered around a nest entrance of an evening, just their heads poking out to snap at passers-by. Workers may wander up to about half a metre from the nest entrance as they forage. The concentrations of vegetable matter produced by Drepanotermes storing food sources in their nest may form a significant factor in the nutrient profile of areas where they are found.

Alate and soldiers of Drepanotermes rubriceps, copyright Jean Hort.

Depending on species and circumstance, the nests of Drepanotermes may be mounds or entirely subterranean with the latter being the majority option. They prefer compact soils such as clay though they may burrow through looser soils where there is a denser subsoil. Drepanotermes may construct their own nest or move into nests constructed by other termites. One aptly named species, D. invasor, seems to take over pre-existing nests more often than not. Subterranean nests are arranged as a series of chambers about five to ten centimetres in diameter connected by tunnels. These chambers may be arranged vertically, one below another, or they may form a rambling transverse network. Above ground, subterranean nests may be visible as an open circle devoid of vegetation. The ground in these circles is hard as concrete and may remain clear for decades after the actual nest has gone. Walsh et al. (2016) refer to the remains of nests protruding above ground along vehicle tracks after the soil around them has worn down. Local people have a long history of taking advantage of the open space offered by termite nests, such as to move more easily through scrub or as resting or working places.

The alate castes of Drepanotermes tend to be poorly known. Indications are that mature reproductives spend little time in the parent nest before leaving to breed. For most species, breeding flights take place in late summer. Alates may emerge either by day or night. The time of emergence seems to depend on the species; night-flying alates have distinctly larger eyes than day-fliers. Unfortunately, because alates have rarely been collected in association with a nest, we are largely still unable to tell which alates belong to which species.

REFERENCES

Walsh, F. J., A. D. Sparrow, P. Kendrick & J. Schofield. 2016. Fairy circles or ghosts of termitaria? Pavement termites as alternative causes of circular patterns in vegetation of desert Australia. Proceedings of the National Academy of Sciences of the USA 113 (37): E5365–E5367.

Watson, J. A. L., & D. H. Perry. 1981. The Australian harvester termites of the genus Drepanotermes (Isoptera: Termitinae). Australian Journal of Zoology, Supplementary Series 78: 1–153.

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.

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.

The Terrestrial Fauna of Barrow Island

Nihara R. Gunawardene, Jonathan D. Majer, Christopher K. Taylor & Mark S. Harvey (eds) 2013. The Terrestrial Invertebrate Fauna of Barrow Island, Western Australia. Records of the Western Australian Museum, Supplement 83. 406 pp.

For several years now, my colleagues and I have been monitoring terrestrial invertebrates on Barrow Island here in Western Australia. Some of you will have already heard of Barrow Island; for anyone that hasn't, Barrow is the second-largest island off the coast of WA (it's about 25 km long and 12 km wide). It has two main claims to fame: (a) it has been a recognised nature reserve for over 100 years, with thriving populations of a number of animals that are rare or extinct elsewhere, and (b) for the last 50 years, it has also been a working oil field, most recently managed by the oil company Chevron. It also lies close to large offshore natural gas deposits, and in 2003 Chevron and its associates were given permission to build a processing plant on Barrow Island for extraction of the gas. This permit, however, carried strong caveats: development of the plant is not to compromise the value of Barrow as a nature reserve. That's where we come in: on a regular basis, we travel to the island to look for any undesirables that may have managed to slip through the stringent quarantine requirements that have been placed on transport to Barrow (nothing so far, touch wood). Before plant development was begun, a large-scale survey was also conducted to identify the pre-existing invertebrate fauna of Barrow Island: before you can say whether something isn't there, you need to be able to say what is.

Over the course of these surveys, a sizeable collection of material has been accumulated from an area that had previously been only sporadically sampled. Over two dozen taxonomic experts were consulted in the process of identifying this material, a lot of which represented species potentially new to science. And so, some time in 2012, we asked the people who had been involved with the project if they would like to contribute to a collection of papers on Barrow Island invertebrates. The response was mostly positive, and The Terrestrial Invertebrate Fauna of Barrow Island, Western Australia was released to the world a couple of weeks ago.

We're very pleased with how it turned out. Some of the contributors provided overviews of their taxon of interest; others provided descriptions of new species. Authors came from both the academic and private sectors, and we're grateful to everyone who put time and effort into answering our calls. In the end, we had 22 chapters on hand, including material on animals from arachnids to isopods to ants, and 25 new species: one snail, two spiders, a silverfish and 21 flies. Not all of these new species were from Barrow Island alone: the chapter on Dolichopodidae (long-legged flies) by Dan Bickel represents a review of the fauna of the entire Pilbara region.

The book is available for purchase from the Western Australian Museum, but I've noticed that their site doesn't provide an article listing. Therefore, I'm including one below, with the abstracts for each article. Contact details for the corresponding authors have been included as hyperlinks, if you want to ask them about their articles. And again, thank you to everyone involved.

The camaenid snail Rhagada barrowensis. The identity of Barrow Island's common Rhagada species has been subject to a bit of confusion over the years; Johnson et al. describe it as a new species in this book.

Dorian Moro and Russell Lagdon, pp. 1-8.
History and environment of Barrow Island

Barrow Island represents a unique island ecosystem off north-western Australia. It has ecological affinities to the Cape Range region of the Australian mainland, and it also supports an oil and gas resource industry. The island hosts a long-unburnt vegetation complex, and a diverse community of vertebrate and invertebrate fauna occupy the disturbed and undisturbed habitats of the island. In the absence of non-indigenous predators or herbivores, without extensive land clearing, and with an instituted level of island quarantine, these environmental values have persisted to make Barrow Island an important environmental asset for Australia, and an example where island ecology functions in the presence of resource extraction. To date, almost 2,800 species of terrestrial and subterranean species have been consistently recorded from Barrow Island. These include 378 native plant species, 13 mammal species (including two species of bats), at least 119 species of terrestrial and migratory birds, 43 species of terrestrial reptiles, one species of frog, three subterranean vertebrates, at least 34 species of subterranean invertebrates, and the most speciose of all, over 2,200 terrestrial invertebrates.

Russell Lagdon and Dorian Moro, pp. 9-11.
The Gorgon gas development and its environmental commitments

Chevron has made an important contribution to our knowledge and understanding of the Barrow Island flora and fauna, and to the Australian economy. This knowledge has been primarily founded from the investigations and commitments of joint venture partners associated with the environmental impact assessment for the Gorgon Gas Development. The Gorgon Gas Development is one of the world’s largest natural gas projects and the largest single natural gas project in Australia’s history. Development has been balanced between energy needs and environmental management. Through plans, procedures, programs and research, Chevron Australia and its joint venture participants have established a benchmark for environmental management of this important island reserve. Furthermore, the Gorgon Joint Ventures have contributed to one of the largest biodiversity offset and Net Conservation Benefit programs in Western Australia.

Jonathan D. Majer, Shae K. Callan, Karl Edwards, Nihara R. Gunawardene and Christopher K. Taylor, pp. 13-112.
Baseline survey of the terrestrial invertebrate fauna of Barrow Island

Barrow Island is Western Australia’s second largest offshore island and its flora and fauna have been able to evolve without major human disturbances. Chevron Australia Pty Ltd and its Joint Venture Participants made an application to construct a plant to liquefy natural gas on the island in 2001. One of the conditions under which approval was granted was the implementation of a rigorous biosecurity effort to ensure that no non-indigenous species (NIS) are introduced or allowed to establish on the island. To fulfil this condition it was first necessary to characterise what was already present on the island. A series of surveys have been performed using a purpose-designed sampling protocol in order to provide baseline data on the existing terrestrial invertebrates on Barrow Island. A total of 1,873 morphospecies were sampled but subsequent surveys and taxonomic developments have increased the count to 2,397. This compares with an estimated species richness of 2,481 terrestrial invertebrate species on the island. Composition of the fauna varied considerably between the wet and dry seasons and between years, even when samples were taken during the same month. Composition also varied with distance from the coast, which may be associated with soil type and vegetation association. Twenty five non-indigenous species and seven putative non-indigenous species have been found, all of which are believed to have been present prior to commencement of the Gorgon Gas Development project.

Peter Whittle, Frith Jarrad and Kerrie Mengersen, pp. 113-130.
Design of the quarantine surveillance for non-indigenous species of invertebrates on Barrow Island

The Ministerial conditions for regulatory approval for the Gorgon gas project on Barrow Island included a quarantine surveillance program having detection power of 0.8 for non-indigenous species of terrestrial invertebrates, vertebrates and plants. No method was available for design of such a program, so we developed a new method and designed surveillance systems that were implemented successfully in 2010−11 for the first of four years over the construction period. Here we describe the method and outline the invertebrate surveillance system, after the experience of the first year. We discuss a set of issues that characterised the design problem, which we consider typical of many surveillance applications. We suggest that the method is broadly applicable for objective design of surveillance, for biosecurity and other settings.

Ken Walker, pp. 131-134.
Providing web based diagnostics for the Barrow Island baseline survey

During the years of 2005 to 2007, an extensive baseline study of the Barrow Island invertebrate fauna was conducted. This survey included more than 50 sample sites across the island and multiple collecting techniques were used at each site. Over 14,000 specimens were collected during this survey. Taxonomic specialist who examined this material nominated over 2,000 morphospecies of which about 300 could be placed to species rank. Having done all of this collecting and identification, the question then was how best to access and use this valuable resource. All of the specimens were stored in two institutions in Perth – several thousand kilometres south of Barrow Island. Manual access to these specimens was slow which hindered the decision making processes needed when a suspected non-indigenous species was found on the island. The decision was made to digitise the diagnostic characters for representative of each morphospecies. These images were to be made available through a website called PaDIL (Pests and Diseases Image Library). Each species was to have its own webpage containing at least 4 diagnostic images of each species and all of the species collection points to be displayed on an interactive Google Map. Species, as well as higher ranks, could be queried alone or against sample localities or against Indigenous or Non-Indigenous status. Individual species pages could be opened and comparative images tables could be pre-defined and presented or users could build their own comparative image tables in real time. The development of the Barrow Island PaDIL website made the results of the entire Baseline Study accessible to anyone with a web browser from anywhere with an internet connection. The Barrow Island PaDIL website is a major part of the Quarantine efforts of Chevron on Barrow Island.

Christopher K. Taylor, pp. 135-144.
Annotated bibliography for Barrow Island terrestrial invertebrates

A bibliography is provided of publications treating terrestrial invertebrates on Barrow Island. A brief overview is also given of natural history and invertebrate collections on Barrow Island.

Garth Humphreys, Jason Alexander, Mark S. Harvey and William F. Humphreys, pp. 145-158.
The subterranean fauna of Barrow Island, north-western Australia: 10 years on

Barrow Island, situated off the north-west Australian coast, is well recognised for its subterranean fauna values. Sampling for both stygobitic and troglobitic fauna has taken place on the island since 1991, and Humphreys (2001) summarised the then current state of knowledge of the island’s subterranean fauna. Sampling for impact assessment purposes on the island over the past decade has substantially increased the recorded species richness of Barrow Island. The number of documented stygal taxa has more than doubled since 2001, from 25 to 63 species now known. Troglobitic diversity has also substantially increased, with six species known in 2001 and 19 troglobitic taxa known today. The total recorded subterranean species richness for Barrow Island at this time stands at 82 species. It is likely that considerably more species remain to be recorded, as even the additional surveys of the past decade leave many areas of the island unsampled.
The distributions and minimum area of occupancy for many species known from Barrow Island in 2001 have also been significantly expanded by the sampling efforts of the last decade. This includes specially protected species listed under State and Commonwealth Government legislation. The available data suggest the fauna of the island may number in the hundreds of species, many of which are endemic, confirming its status as internationally significant for subterranean biota.

Michael S. Johnson, Sean Stankowski, Corey S. Whisson, Roy J. Teale and Zoë R. Hamilton, pp. 159-171.
Camaenid land snails on Barrow Island: distributions, molecular phylogenetics and taxonomic revision

Three species of camaenid land snails occur on Barrow Island: Quistrachia barrowensis and two previously unassigned species of Rhagada. Based on morphological re-evaluation and analysis of sequences of the mitochondrial gene COI, we have revised the taxonomy of these species, providing a clearer understanding of their geographic distributions and origins. The supposed Barrow Island endemic Q. barrowensis is synonymous with Q. montebelloensis from the Montebello and Lowendal Islands. The small species of Rhagada, confined to the northern tip of Barrow Island, is conspecific with R. plicata, whose distribution also includes the Montebellos and the Lowendals. The large species of Rhagada is described here as R. barrowensis sp. nov., known only from Barrow Island and adjacent Pascoe Island. The three camaenids represent deeply divergent lineages with different geographic origins, indicating that the local diversity on Barrow Island has come about through a complex history. With maximum geographic spans of only 22 to 70 km, the short-range endemism of these species highlights the conservation significance of Barrow Island.

Volker W. Framenau and Anna E. Leung, pp. 173-184.
Costacosa, a new genus of wolf spider (Araneae, Lycosidae) from coastal north-west Western Australia

A new genus of wolf spider (family Lycosidae Sundevall, 1833), Costacosa gen. nov. is described from north-west Western Australia to include C. torbjorni sp. nov. (type species) and C. dondalei sp. nov. The genus belongs to the subfamily Lycosinae Sundevall, 1833 and differs from all other Australian genera in this subfamily with similar somatic morphology, in particular Venator Hogg, 1900 and Knoelle Framenau, 2006, mainly in genitalic characters. The tegular apophysis of the male pedipalp has a pronounced ventral spur, a distinct ventral edge of species-specific shape and serrations along its apical edge. The female epigyne has an elongated triangular atrium and the medium septum is longer than the posterior transverse part. Costacosa are medium-sized wolf spiders of overall brown colouration and with broad light median and sublateral bands on the carapace and a black patch in the frontal two-thirds of the venter. Costacosa torbjorni is the most commonly recorded wolf spider on Barrow Island, from where currently seven species of Lycosidae are known.

Simon Judd and Giulia Perina, pp. 185-207.
An illustrated key to the morphospecies of terrestrial isopods (Crustacea: Oniscidea) of Barrow Island, Western Australia

This paper presents an illustrated key to eighteen morphospecies of terrestrial isopods from Barrow Island with a brief summary regarding their currently known distribution and potential endemicity to the island. Six described species are recorded, Ligia exotica (family Ligiidae), Alloniscus pallidulus (Alloniscidae), Laevophiloscia yalgooensis (Philosciidae), Porcellionides pruinosus (Porcellionidae), Barrowdillo pseudopyrgoniscus, Buddelundia hirsuta (both Armadillidae), but the identifications of most need to be confirmed following genus-level revisions and examination of type- or topotypical material. The key includes twelve undescribed species and at least two undescribed genera from the family Armadillidae, one of which is apparently restricted to Barrow Island. Although there is still considerable taxonomic work required to evaluate distributions, it appears that at least six of the eighteen species are potential short-range endemics (SRE).

Catherine A. Car, Megan Short, Cuong Huynh and Mark S. Harvey, pp. 209-219.
The millipedes of Barrow Island, Western Australia (Diplopoda)

Six species of millipedes are recorded from Barrow Island, including three species of pin-cushion millipedes of the order Polyxenida, Lophoturus madecassus (Marquet and Condé, 1950) (Lophoproctidae), Unixenus mjoebergi (Verhoeff, 1924) (Polyxenidae) and Phryssonotus novaehollandiae (Silvestri, 1923) (Synxenidae), a single species of the order Spirobolida, Speleostrophus nesiotes Hoffman, 1994 (Trigoniulidae), and two species of the order Polydesmida, Boreohesperus dubitalis Car and Harvey, 2013 (Paradoxosomatidae) and one species of the family Haplodesmidae (genus and species indet.). Lophoturus madecassus is circum-tropical in distribution, Unixenus mjoebergi and Phryssonotus novaehollandiae are found also on mainland Australia, but the other three species are endemic to the island. Speleostrophus nesiotes is a highly modified troglobiotic species, currently listed as threatened by the Western Australian government. It is unclear at present whether the haplodesmid specimen is a troglobite.

Penelope Greenslade, pp. 221-228.
Composition of Barrow Island collembolan fauna: analysis of genera

Collembola have been collected from Barrow Island for the first time; a maximum of seventy one species were detected, of which a high proportion are undescribed. Only four non-indigenous species (NIS) species have been collected, three in very small numbers but one was a large population introduced to the island in lengths of timber which were subsequently sent off the island. Despite few of the species being described, most have been collected before and endemism is low. One new genus record for Australia, Calx, was found. The presence of a species of Temeritas is unusual in that the males showed strong sexual dimorphism, and a species of Acanthocyrtus that lacked any pigment was collected in reasonable numbers. Collections from bore holes were rich in species. Five species were recorded only from bore holes and may be island endemics. The intertidal fauna was also rich in species with 14 found, all restricted to this habitat. Soil fauna density of Collembola was found to be high, with a mean average potential density of nearly 47,000/m². A proportion of the terrestrial Collembola fauna is active under all weather conditions but other species are only active after rain. In general, the terrestrial fauna shows a dominance of the families Isotomidae and Bourletiellidae, which is typical for the wet/dry tropics where trees are absent.

Graeme Smith, pp. 229-240.
A new species of Heterolepisma from Barrow Island (Zygentoma: Lepismatidae)

The silverfish fauna of Barrow Island is discussed and Heterolepisma parva sp.nov. is described from extensive material collected mostly in pitfall traps or Winkler sac leaf litter samples.

David T. Jones, pp. 241-244.
The termites of Barrow Island, Western Australia

Forty years ago D. H. Perry, the renowned termite expert, published a checklist of 18 species that he had collected on Barrow Island. That checklist is now updated with the results of a recent invertebrate survey of the island, and a literature search for additional records. The updated list now runs to 27 species, all of which appear to be indigenous to the island.

Christopher K. Taylor, pp. 245-252.
The genus Lithoseopsis (Psocodea: Amphientomidae) in the Western Australian fauna, with description of the male of Lithoseopsis humphreysi from Barrow Island

The Australian Amphientomidae species Seopsis incisa Smithers, 1989 and S. humphreysi New, 1994 are transferred to the genus Lithoseopsis Mockford, 1993 as L. incisa new combination and L. humphreysi new combination, as a result of the discovery of speciens of L. humphreysi from Barrow Island, Western Australia. The male of L. humphreysi is described for the first time, and both macropterous and brachypterous individuals are described. The genus Lithoseopsis was previously known from North America only, and the addition of the Western Australian species significantly increases its range. A key is provided to the genera of Amphientomidae.

David Gopurenko, Murray Fletcher, Holger Löcker and Andrew Mitchell, pp. 253-285.
Morphological and DNA barcode species identifications of leafhoppers, planthoppers and treehoppers (Hemiptera: Auchenorrhyncha) at Barrow Island

The hemipteran suborder Auchenorrhyncha comprises a rich assemblage of plant feeding species, many of which are widespread in distribution and act as vectors of viral and fungal diseases affecting plants. Species level identifications in this group generally are possible only by examination of male specimens; prior DNA barcode analyses of a limited range of Auchenorrhyncha indicate that this approach may provide an expedient means to identify species within this diverse group. In this study we explored the utility of DNA barcoding for identification of a wider range of Auchenorrhyncha species than has been examined previously. Diverse fulgoroid (planthopper) and membracoid (leafhopper and allies) Auchenorrhyncha were sampled from Barrow Island, Western Australia, and identified to the least inclusive taxonomic units using morphology. DNA barcodes from 546 adult specimens were obtained and analysed using a General mixed Yule – Coalescent (GMYC) modelling approach to genetically delimit putative species, as a comparison to the morphospecies identifications. Additional DNA barcodes (N = 106) were obtained from nymphs and these were compared to adult DNA barcodes to identify species present among immature specimens.
Among adult specimens, 73 species were congruently delimited by morphology and genetic analyses when modelled using a single threshold GMYC. Congruence between morphological and molecular species assignments was greatly reduced when the Yule – Coalescent transition was allowed to vary across genetic lineages. In a separate DNA barcode analysis of all specimens using neighbour joining distance metrics, nymphs and physically degraded specimens were in most cases genetically linked to adult conspecifics. Ten genetic clades detected among the nymphs were not observed among adults and did not match pre-existing sequence accessions in GenBank or DNA barcode records in BOLD.
Of the 73 adult Auchenorrhyncha species congruently identified by DNA barcoding and morphology, most were Cicadellidae (N = 53 morphospecies), the remaining 20 morphospecies were sparsely representative of ten other families. Formal identifications to species level were available for only 36% of these 73 morphospecies, owing mainly to an absence of diagnostic male specimens within many of the delimited species. Indeterminate species detected among adults and nymphs are designated with interim species codes.
The work presented here demonstrates that DNA barcoding is likely to be a powerful investigative tool for identifying and understanding species limits in the Auchenorrhyncha, particularly if it is used within an integrative taxonomic framework.

Laurence A. Mound, pp. 287-290.
Thysanoptera (Insecta) of Barrow Island, Western Australia

Almost 50 species of the insect order Thysanoptera are here listed from Barrow Island, Western Australia, of which several are known only from this island. This cannot be interpreted as indicating that any species is endemic to the island, because almost nothing is known of the Thysanoptera fauna of the nearby mainland.

Daniel J. Bickel, pp. 291-348.
The family Dolichopodidae (Diptera) of the Pilbara region, Western Australia in its Australasian biogeographic context, with the description of 19 new species

The Dolichopodidae (Diptera) of the Pilbara Region (here also including Barrow Island and Cape Range), Western Australia are described, keyed and illustrated. The fauna comprises 41 species, including three with generic names only, being represented by females or badly damaged males. The following 19 species are newly described: Pseudoparentia canalicula sp. nov., Pseudoparentia niharae sp. nov., Paraclius manglar sp. nov., Medetera junensis sp. nov., Corindia gascoynensis sp. nov., Thinophilus eboricoxa sp. nov., Thinophilus yarraloola sp. nov., Chaetogonopteron capricorne sp. nov., Chaetogonopteron vexillum sp. nov., Sympycnus colliepa sp. nov., Sympycnus lacrimulus sp. nov., Sympycnus pistillus sp. nov., Sympycnus weano sp. nov., Sympycnus ephydroides sp. nov., Sympycnus hamulitarsus sp. nov., Diaphorus karijini sp. nov., Diaphorus garnetensis sp. nov., Chrysotus austrotropicus sp. nov. and Chrysotus pilbarensis sp. nov. Paraclius obtusus Hardy, 1939 is regarded as a new senior synonym of Paraclius albodivisus Parent, 1941, syn. nov. The Pilbara fauna is treated in the context of the wider Australian fauna, and many extralimital records are included. Many Pilbara species are found across tropical northern Australia, and sometimes into adjacent Melanesia. However, some species have a trans-continental distribution south of the monsoonal belt and also occur in central Northern Territory and subtropical interior Queensland suggesting a biogeographic track that now comprises favorable relictual habitats in a largely arid region. The Millstream site along the Fortescue River is particularly rich in species, and it is the only known locality of the isolated monotypic genus Pilbara Bickel.

David K. Yeates and Stefanie K. Oberprieler, pp. 349-354.
Two new species of the Australian bee fly genus Comptosia (Diptera: Bombyliidae) from Barrow Island, Western Australia

Two new species of the bee fly genus Comptosia Macquart from Western Australia, C. barrowensis and C. karijinii, are described.

Nicholas B. Stevens, Syngeon M. Rodman, Tamara C. O’Keeffe and David A. Jasper, pp. 355-374.
The use of the biodiverse parasitoid Hymenoptera (Insecta) to assess arthropod diversity associated with topsoil stockpiled for future rehabilitation purposes on Barrow Island, Western Australia

This paper examines the species richness and abundance of the Hymenoptera parasitoid assemblage and assesses their potential to provide an indication of the arthropod diversity present in topsoil stockpiles as part of the Topsoil Management Program for Chevron Australia Pty Ltd Barrow Island Gorgon Project. Fifty six emergence trap samples were collected over a two year period (2011 and 2012) from six topsoil stockpiles and neighbouring undisturbed reference sites. An additional reference site that was close to the original source of the topsoil on Barrow Island was also sampled. A total of 14,538 arthropod specimens, representing 22 orders, were collected. A rich and diverse hymenopteran parasitoid assemblage was collected with 579 individuals, representing 155 species from 22 families. The abundance and species richness of parasitoid wasps had a strong positive linear relationship with the abundance of potential host arthropod orders which were found to be higher in stockpile sites compared to their respective neighbouring reference site. The species richness and abundance of new parasitoid wasp species yielded from the relatively small sample area indicates that there are many species on Barrow Island that still remain to be discovered. This study has provided an initial assessment of whether the hymenoptera parasitoid assemblage can give an indication of arthropod diversity. However, further work would still be required to more robustly establish the use of the hymenoptera parasitoid assemblage as indicators of arthropod diversity.

B. E. Heterick, pp. 375-404.
A taxonomic overview and key to the ants of Barrow Island, Western Australia

This work characterises the ant (Hymenoptera: Formicidae) fauna of Barrow Island, Western Australia, and provides a key to the workers and several unique reproductives of the 117 species recorded from the island thus far. In all, 11 of the 13 subfamilies of Western Australian ants have been recorded from Barrow Island, but Myrmeciinae and Heteroponerinae are absent. At a generic level, the fauna of the island is less rich, holding 36 of the 71 genera currently known from Western Australia. The ant fauna is characteristic of the Eremaean Botanical Province of the Pilbara, rather than that of the Carnarvon Basin from which Barrow Island is geologically derived. Ninety-three ant species (79.5% of the total on Barrow Island) are shared with the ant fauna of the Pilbara region on the adjoining mainland, but only 52 species (44.4% of the total) are shared with the ant fauna of the Carnarvon Basin. The island is very rich in unspecialised and thermophilic ant species. Five such genera, i.e., Iridomyrmex (14 spp.), Monomorium (13 spp.), Polyrhachis (12 spp.), Melophorus (10 spp.), and Camponotus (nine spp.) make up almost 50% (i.e., 49.6%) of the island’s ant fauna. Very few ants appear to be endemic to Barrow Island. The relative proportions of the two major subfamilies (Formicinae and Myrmicinae, together comprising 61.5% of the total ant richness) are similar to the proportions found in the South-west Botanical Division for these two subfamilies (i.e., 65.9%), with Barrow Island having a slightly lower ratio of formicines to myrmicines than is found in the south-west of the state. An estimate of the total number of ant species likely to occur on Barrow Island, using the Estimate-S program (Colwell 2009), suggests that a maximum of fourteen additional species may be as yet unrecorded.

Jonathan D. Majer, Nihara R. Gunawardene, Christopher K. Taylor and Mark S. Harvey, pp. 405-406.
A last word

The work reported on in this volume is the culmination of nine years of data gathering stemming from the original baseline surveys on Barrow Island. Not surprisingly, this has resulted in one of the most comprehensive terrestrial invertebrate surveys ever performed on an offshore island on this continent. There are other substantial surveys, but these have generally focussed on specific taxonomic groups, rather than the whole spread reported here.

Snap! goes the Termite

The snapping termite Cavitermes tuberosus, from Wiki Termes.

For the subject of today's post, I drew the termite subfamily Termitinae. Termites are extraordinary animals: socially complex, ecologically vital, dietically remarkable. Personally, I'm rather found of these communal cockroaches.

Termites of the family Termitidae (commonly referred to as the 'higher termites') differ from other, 'lower' termites in the nature of their gut biota (without which they would not be able to digest their cellulose diets): instead of having flagellated protozoa in their gut, termitids carry symbiotic bacteria. This difference in symbionts is reflected by a difference in diet. Higher termites feed on more decayed wood or plant matter than lower termites; some higher termites feed directly on organic-rich soil that contains little or no plant material (Inward et al. 2007). Subfamilies within the Termitidae are also distinguished on the basis of their gut anatomy: members of the Termitinae have what is called a 'mixed segment' on the outer edge of their intestine (Lo & Eggleton 2011). In the mixed segment, instead of the division between the mesenteron (the middle section of the intestine) and the proctodaeum (the posterior section) being simple and straight across, the mesenteron wall extends backwards along one side of the gut only; it has been suggested that the mixed segment functions to pump alkaline fluids into the gut, maintaining appropriate pH and fluid levels for the symbiotic bacteria in the hindgut (Bignell et al. 1983).

Workers of Amitermes dentatus repairing a damaged nest, from here.

The Termitinae have also been distinguished on the basis of the morphology of their soldiers, with most genera having soldiers with elongate mandibles that have relatively few large teeth. These are used to bite and slash at threats to the colony. However, phylogenetic analyses have contradicted this distinction (Inward et al. 2007). The Termitinae are paraphyletic with regard to the Nasutitermitinae, who have developed a very different method of defense: the mandibles are reduced, and instead the front of the head is drawn out into an elongate 'nose'. At the end of the 'nose' is a glandular opening from which the soldiers squirt a sticky glue at their opponents. Also nested within the Termitinae are the Syntermitinae whose soldiers combine both methods of defense: they retain sickle-shaped mandibles that are used to pierce the cuticle of attackers while the protruded glandular opening is used to apply toxic secretions. Chemical defenses are also not unknown among more standard termitines: soldiers of Globitermes sulphureus were dubbed 'walking bombs' by E. O. Wilson due to their explosive (and often self-destructive) discharge of toxic chemicals from hypertrophied labial gland reservoirs in the abdomen. It should also be noted that a small number of termitines do not produce soldiers at all: they may live in association with other soldier-producing termites, like the Australian Invasitermes, or they may feed on low-nutrient soils (presumably making the maintenance of a soldier caste too nutritionally expensive), like the Indomalayan genera Protohamitermes and Orientotermes.

The mushroom-like mound of Cubitermes, a major soil-feeding genus in Africa, photographed by Marco Schmidt.

Another mode of defense that is found only among the termitines (though phylogenetic analysis indicates that it has evolved multiple times) is the production of soldiers with elongate snapping mandibles. In these termites, soldiers store kinetic energy through muscular deformation of the mandibles, allowing them to be suddenly closed with great force (Prestwich 1984). So great is the force involved, in fact, that it seems to be not uncommon for the jaws to become completely crossed over as has happened to the individual at the top of this post. Snapping termites generally live in subterranean colonies, and even after the soldier has been 'spent' on the discharge of its mandibles, its body acts as a physical barrier in the confined tunnel. In some snapping termites, the mandibles are strongly asymmetrical, so the force of the closure is channelled through the left mandible only with doubled force. Asymmetrical snappers of the genus Neocapritermes, in fact, are able to knock out fairly large ants with a single blow. The video below shows a soldier of Planicapritermes attacking an ant: Or you can see Neocapritermes in action in this video. Keep a close eye on the screen around the 20-second mark...

REFERENCES

Bignell, D. E., H. Oskarsson, J. M. Anderson & P. Ineson. 1983. Structure, microbial associations and function of the so-called "mixed segment" of the gut in two soil-feeding termites, Procubitermes aburiensis and Cubitermes severus (Termitidae, Termitinae). Journal of Zoology 201: 445-480.

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.

Lo, N., & P. Eggleton. 2011. Termite phylogenetics and co-cladogenesis with symbionts. In: Bignell, D. E., et al. (eds) Biology of Termites: a modern synthesis pp. 27-50. Springer.

Prestwich, G. D. 1984. Defense mechanisms of termites. Annual Review of Entomology 29: 201-232.

The Stoneflies: Old or New?

Little snowfly Capnia nana, from here.

Despite being a working entomologist, I have to confess that there are some insect groups with which I am not entirely familiar. The stoneflies, Plecoptera, are one of those groups. I work in arid northern Australia, but stoneflies are associated with cool waters. The highest diversity live in temperate regions of the world; those whose ranges extend into lower latitudes are found higher in the mountains, away from the heat.

Stoneflies live in their favoured waterways as nymphs, emerging when they develop to adulthood (at least one species, Capnia lacustra of Lake Tahoe, appears to also be aquatic as an adult). The adults are large, long-bodied insects that are often better runners than they are fliers. Nymphs are primarily detritivores, but many species are carnivorous to a greater or lesser extent. Adults of some species do not feed; others feed on such things as encrusting algae or lichen or rotten wood. Depending on species, adult stoneflies may have full-sized wings, reduced wings or no wings at all; in some species, both flying and flightless morphs may be present. Two European species, Perla bipunctata and Perlodes microcephala, are solely brachypterous in Britain but may be either brachypterous or macropterous elsewhere in their range (Hynes 1976). Winged females of many species lay eggs while in flight, either dropping them into water or gliding to the water surface and letting the eggs be washed off from the end of the abdomen. Other species attach their eggs to stones underwater or insert them into crevices or rotting wood.

Tasmanian stonefly, Eusthenia sp., photographed by Nuytsia@Tas. More colourful than most other stoneflies, Eusthenia species raise their forewings when threatened to reveal brightly patterned hindwings.

Most recent authors have supported a division of the stoneflies between two lineages, the Antarctoperlaria and Arctoperlaria, that are both morphologically and geographically distinct (Zwick 2000). The Antarctoperlaria are found in South America, Australia and New Zealand. The Arctoperlaria, in contrast, are primarily found in the Northern Hemisphere (except for members of two families, the Perlidae and Notonemouridae). Many species of the Arctoperlaria signal to potential mates by drumming the abdomen on a substrate, a behaviour unknown in the Antarctoperlaria.

Nymph of Acroneuria abnormis, photographed by Michel Gauvin.

Stoneflies have often been regarded as one of the most primitive groups of winged insects, and their position remains contentious. The two main theories are that they are the sister group to all other neopteran insects (insects that are capable of folding the wings back flat over the body), or that they belong to the group known as Polyneoptera that also includes grasshoppers and cockroaches. Which of these is correct has been regarded as potentially significant in understanding how flight evolved in insects as a whole. As discussed in an earlier post, it has been suggested that insect wings are homologous with articulated gills in aquatic nymphs. As well as Plecoptera, the two living non-neopteran insect orders Odonata (dragonflies) and Ephemeroptera (mayflies) are aquatic as nymphs, and if Plecoptera are basal to other neopterans then it suggests that this life history may be ancestral for winged insects as a whole. However, differences in nymphal morphology between the three groups may indicate that the aquatic lifestyle has been independently acquired in all three from terrestrial ancestors, which would also be more likely if stoneflies are derived polyneopterans. Molecular studies have supported a polyneopteran relationship for stoneflies, but not with rock-solid support (e.g. Terry & Whiting 2005); morphological studies are equivocal and do not clearly point either way (Zwick 2009). The fossil record is also unclear: while a number of early insect groups have been connected to stoneflies, whether they are true stem-Plecoptera or closer to other polyneopteran lineages is debatable (Béthoux et al. 2011). It is also worth pointing out that while similarities between stonefly and mayfly gills have been cited in relation to their supposed homology with wings, different families of stoneflies have different gill types, and we still do not know whether and what kind of gills were ancestral for Plecoptera. Also, in those stoneflies with plate-like gills, the gills are not articulated like wings and incapable of independent movement (Zwick 2009).

REFERENCES

Béthoux, O., Y. Cui, B. Kondratieff, B. Stark & D. Ren. 2011. At last, a Pennsylvanian stem-stonefly (Plecoptera) discovered. BMC Evolutionary Biology 11: 248.

Hynes, H. B. N. 1976. Biology of Plecoptera. Annual Review of Entomology 21: 135-153.

Terry, M.D., & M. F. Whiting. 2005. Mantophasmatodea and phylogeny of the lower neopterous insects. Cladistics 21: 240–257.

Zwick, P. 2000. Phylogenetic system and zoogeography of the Plecoptera. Annual Review of Entomology 45: 709-746.

Zwick, P. 2009. The Plecoptera–who are they? The problematic placement of stoneflies in the phylogenetic system of insects. Aquatic Insects 31 (suppl. 1): 181-194.

Wigs and Wings and Other Things

Congratulations go to Adam Yates for successfully identifying this animal:


Arixenia esau, photographed in Deer Cave in Sarawak by Alan Cressler.

This "very interesting, though repulsive, insect" (to use the words of Hebard in 1927) is a member of today's Taxon of the Week, the Neodermaptera. Neodermaptera is the clade containing all living members of the Dermaptera, the earwigs, distinguished from various stem groups of the Dermaptera by features such as three-segmented tarsi and the lack of veins in the forewings (Engel 2003). Earwigs are one of the few groups of insects other than beetles to have the forewings hardened into elytriform cases, which in earwigs have also been greatly reduced in size (in earwigs, the hardened forewings are referred to as 'tegmina' rather than 'elytra', but these seem to be just different words for much the same sort of thing). The rarely-seen hindwings remain folded under the tegmina unless the earwig is flying (which they do not often do) and are simply bizarre. One of the characteristics of polyneopterans, the group of insects including crickets, cockroaches, earwigs and various others, is a tendency towards enlargement of the anal fan, the posterior part of the wing; in earwigs, the anal fan of the hindwing has become enlarged to the point that the wing is almost entirely anal fan with the anterior parts of the wing greatly reduced and crammed into a small toughened section towards the base. One of the stories floating about to supposedly explain the origin of the name 'earwig' claims that it is a corruption of 'ear-wing'. While the wings are indeed ear-shaped, the story rather loses credibility in face of the detail that the average person would probably never see them.


Earwig (probably a female Doru using the key in Engel 2003) with its wings spread, showing the semicircular shape and radiate anal veins. Photo by Sean McCann.

The other distinctive feature of most living earwigs is the development of the cerci at the end of the abdomen into a pair of large, hard forceps. The forceps are used for defense as well as capturing prey in those species that eat animal matter (most earwigs are omnivorous); they may also be used to help fold the wings under the tegmina. In most species, the males have heavier forceps than the females. The only earwigs to have filamentous cerci rather than forceps are the Arixeniidae and Hemimeridae, two families that live in association with mammalian hosts. Arixeniids (such as Arixenia in the top picture) are about 2 cm long and live on bats in south-east Asia; hemimerids are about half that size and live on African giant rats. Not are they distinctive among earwigs, they are the only known quasi-parasitic polyneopterans—I say 'quasi'-parasitic because they probably feed more on dead skin and host secretions than the actual living host itself. The arixeniids probably feed mostly on the rich deposits of bat poo in host roosting sites. Because of the lack of forceps and other features, these two families have often been placed in separate suborders from the remaining earwigs; at least one author argued that hemimerids should be removed from Dermaptera entirely and treated as a separate order. However, the current consensus is that the two families are probably derived from more normal earwigs, with their distinctive features being adaptations to their symbiotic lifestyles.


Forceps of the recently extinct Labidura herculeana of St Helena, the largest known earwig, alongside a 22 mm specimen of its more average close relative L. riparia. Photo by Philip Ashmole.

Another distinctive feature of the two mammal-associated families is that they are live-bearers. In all other families, the female lays a batch of eggs, usually in a burrow, that she watches over until the young hatch out. She continues to protect her young for their first one or two instars; after that they must fend for themselves. In fact, if the young do not move out quickly enough, their mother will eat them (Rentz & Kevan, 1991). Something, perhaps, to be kept in mind by all those parents who feel their adult offspring are taking too long to get their own place.

REFERENCES

Engel, M. S. 2003. The earwigs of Kansas, with a key to genera north of Mexico (Insecta: Dermaptera). Transactions of the Kansas Academy of Science 106 (3-4): 115-123.

Hebard, M. 1927. Studies in Sumatran Dermaptera. Proceedings of the Academy of Natural Sciences of Philadelphia 79: 23-48.

Rentz, D. C. F., & D. K. McE. Kevan. 1991. Dermaptera (earwigs). In: CSIRO. The Insects of Australia, 2nd ed., vol. 1, pp. 360-368. Melbourne University Press.

Name That Bug: Ponopterix axelrodi

Ponopterix axelrodi (from Bechly, 2007).

Obviously I'm going to have to refrain from using fossil insects as ID challenges in future, or at least confiscate Adam Yates' copy of Grimaldi & Engel (2005) before I do so to stop him from identifying them so quickly*.

*Unless, of course, I cruelly exploit Grimaldi & Engel's neglect of Palaeozoic polyneopterans.

Ponopterix axelrodi is a member of the Jurassic to Cretaceous insect family Umenocoleidae from the Lower Cretaceous Crato Formation of Brazil. Umenocoleids were originally described in 1973 as beetles, which they resemble in having the front pair of wings hardened into a pair of elytra (wing covers). However, while elytra are only found in two orders among the Recent insect fauna (beetles and earwigs), umenocoleids represent a third independent origin of elytra and are in fact related to dictyopterans (the clade that includes cockroaches, mantids and termites). The retention of a short ovipositor in Umenocoleidae (visible in the specimen above at the very end of the abdomen) places them just outside crown Dictyoptera, though a position closer to polyphagoid cockroaches has also been suggested (which would imply more than one loss of the ovipositor among dictyopterans).

As Adam pointed out, umenocoleids differ from beetles in that wing venation is still marginally visible on the elytra (among crown-group beetles, the original venation has been completely obliterated) and in the presence of cerci (two tail-like appendages at the end of the abdomen, one on either side of the ovipositor in females; cerci are absent in paraneopteran and holometabolous insects). The anterior light patch at the base of the elytron in the specimen above is also present in another specimen of the same species illustrated in Grimaldi & Engel (2005), so this was the original colour pattern of the animal when it was alive*.

*Don't let the poor reputation of cockroaches put you off - many roaches are very attractive insects, boldly patterned in contrasting colours**.

**Just be careful of the desert cockroaches that walk around with their backsides pointed into the air. If they feel that a potential threat is approaching too close, they can fire a stream of foul-smelling liquid towards it from a pair of abdominal glands. Not pleasant.

Umenocoleids also inspire the one detail in Grimaldi & Engel (2005) that causes me to scream with frustration. In the caption to their photo of Ponopterix axelrodi, G & E make the remark, "Umenocoleid roaches are known from the Late Jurassic to Cretaceous, though a putative living species exist". A living umenocoleid? Tell me more! Unfortunately, Grimaldi and Engel provide no citation for this statement, and I have been unable to find any reference to a living umenocoleid anywhere else. I'm still holding out hope, though.

REFERENCES

Bechly, G. 2007. 'Blattaria': cockroaches and roachoids. In The Crato Fossil Beds of Brazil: window into an ancient world (D. M. Martill, G. Bechly & R. F. Loveridge, eds). Cambridge University Press.

Grimaldi, D., & M. S. Engel. 2005. Evolution of the Insects. Cambridge University Press. 755 pp.

All About Gerarus

There can be no doubting that the fossil record has provided us with knowledge of some extremely cool organisms. The funny thing is, not all of these extremely cool organisms are very well known. Most popular books on extinct animals tend to select from the same relatively small pool - dinosaurs, ammonites, maybe a trilobite or two. But there are other organisms that one would think would be the stuff of celebrity, but which get almost no screen-time at all. Take Gerarus, for instance - an animal so cool that I've used its name for my own e-mail address. Gerarus is one of the most abundant of Carboniferous insects - specimens have been recovered from almost all major terrestrial deposits of this time, including localities such as Mazon Creek in Illinois and Commentry in France (Béthoux & Briggs, 2008). It's a fairly large insect - some species had wingspans of over ten centimetres. But, beyond all this, the really awesome thing about this critter was that it looked like this:


Reconstruction of Gerarus danielsi from Burnham (1983).

Or in other words, like the unholy offspring of a mantis and a medieval mace. Gerarus was the proud owner of an inflated thorax, liberally studded with prominent don't-f***-with-me spines up to a millimetre in length. Wings of different individuals were notably variable in their venation patterns, suggesting relaxed selectional pressure, and this together with the shift in weight that would have resulted from the hypertrophied thorax suggest that Gerarus was probably not a very active flier (Béthoux & Nel, 2003). Instead, it would have clambered on vegetation like a stick insect, relying primarily on its spines to dissuade potential predators. If that wasn't enough, it could escape by jumping and using its wings as passive gliding planes.

The aforementioned variability of Gerarus and the other members of the family Geraridae led to earlier authors describing nearly every specimen as a separate species. Many of these were synonymised by Burnham (1983) in her review of the family, but it is quite possible that the group is still over-split. Initially, gerarids were included in the "Protorthoptera", an unabashedly paraphyletic or polyphyletic grouping of Palaeozoic polyneopteran-grade insects that was believed to be ancestral to such modern groups as cockroaches, crickets and stick insects, and possibly even to all other recent neopteran insects. When some more specific affinity was hypothesised, it was usually to the Orthoptera (crickets and grasshoppers). This hypothesis was challenged by Kukalová-Peck and Brauckmann (1992), who identified an expanded clypeus in Gerarus (the clypeus is the front part of an insect's head). This, together with certain features of the wing venation, lead them to position Gerarus closer to the Paraneoptera, the group including Psocoptera (booklice) and Hemiptera (bugs). Even more notably, they also identified exites on Gerarus' legs.


Figure of Gerarus danielsi specimen from Kukalová-Peck & Brauckmann (1992), as reproduced in Béthoux & Briggs (2008), showing exites attached to the legs.

Kukalová-Peck is best known for her theories on the origin of insect wings. Many fossil arthropods, and modern crustaceans, possess branched legs, and Kukalová-Peck holds that ancestral insects also possessed such legs, with the wings developed from side-branches (exites) that have become dissociated from the legs and moved closer to the top of the thorax. This contrasts with the earlier idea that insect wings were derived from dorsolateral lobes of the thorax itself. Kukalová-Peck's model has certainly got some points in its favour - it avoids the difficulty of a transition from a fixed lateral lobe to a mobile, articulated wing, and genetic studies have shown that similar genes are involved in the development of Drosophila wings as in that of crustacean gills (which are undoubtedly derived from exites). Kukalová-Peck also identified the presence of exites in a number of fossil insects as further support for her model (Kukalová-Peck, 1987).

However, there are a couple of stumbling blocks. Firstly, those fossil insects on which exites have been identified are phylogenetically nested among modern insects with unbranched legs, which would require the convergent loss of exites in a number of independent lineages (not impossible - exite loss seems to be directly connected to adaptation to life on land for arthropods). Secondly, and perhaps more damningly, some of Kukalová-Peck's reconstructions have been accused of (shall we say) a certain excess of imagination. Béthoux & Nel (2003) re-interpreted the wing venation of Gerarus, and found that it did not possess the features cited by Kukalová-Peck & Brauckmann (1992) as indicating paraneopteran relationships. That still left the expanded clypeus and the exites, but those little details were re-interpreted by Béthoux & Briggs (2008) as artefacts seemingly produced by over-enthusiastic preparation. The current indication is that Gerarus is a member of the Panorthoptera, the clade including Orthoptera plus the extinct orders Titanoptera and Caloneurodea. A close relationship between Geraridae and Titanoptera, enormous grasshopper-like insects, was popular for a while, but was rejected by Béthoux (2007)*. The exact affinities of Gerarus still await elucidation.

*Some day I may do a review of Béthoux (2007), a paper which may or may not constitute a glimpse into the fiery depths of hell. Right now, I haven't the strength.

REFERENCES

Béthoux, O. 2007. Cladotypic taxonomy applied: titanopterans are orthopterans. Arthropod Systematics and Phylogeny 65 (2): 135-156.

Béthoux, O., & D. E. G. Briggs. 2008. How Gerarus lost its head: stem-group Orthoptera and Paraneoptera revisited. Systematic Entomology 33 (3): 529-547.

Béthoux, O., & A. Nel. 2003. Wing venation morphology and variability of Gerarus fischeri (Brongniart, 1885) sensu Burnham (Panorthoptera; Upper Carboniferous, Commentry, France), with inferences on flight performance. Organisms Diversity & Evolution 3 (3): 173-183.

Burnham, L. 1983. Studies on Upper Carboniferous insects: I. The Geraridae (order Protorthoptera). Psyche 90 (1-2): 1-57.

Kukalová-Peck, J. 1987. New Carboniferous Diplura, Monura, and Thysanura, the hexapod ground plan, and the role of thoracic side lobes in the origin of wings (Insecta). Canadian Journal of Zoology 65: 2327-2345.

Kukalová-Peck, J., & C. Brauckmann. 1992. Most Paleozoic Protorthoptera are ancestral hemipteroids: major wing braces as clues to a new phylogeny of Neoptera (Insecta). Canadian Journal of Zoology 70: 2452–2473.