Camponotus: A Sugary High

I think I may have said before that Australia is the land of ants. When travelling in Australia's arid regions (i.e. most of the continent), ants are often the most visible animals about. Perhaps the most visible of all Australia's ants are the meat ants (Iridomyrmex), but not too far behind them are the sugar ants of the genus Camponotus.

Workers and emerging queens of banded sugar ants Camponotus consobrinus around the nest opening, copyright Steve Shattuck.

Camponotus is a genus of the ant subfamily Formicinae found pretty much everywhere around the world that ants are to be found. It is massively diverse: well over 1000 species have been assigned to this genus over the years, with probably more to be described. They are correspondingly diverse in habits and appearance. Some are among the giants of the ant world, others are much smaller. Some form massive colonies that are difficult to miss and forage during the day, others are more retiring and emerge only at night. Some construct their nests in holes under the grounds, others hollow out wood or use the holes left by other wood-boring insects. Most (but not all) Camponotus species exhibit some form of worker polymorphism: rather than having just a single worker caste, a colony will often include large major workers and much smaller minor workers, with the two forms superficially looking quite different. Sometimes the distinction between majors and minors will be quite clear, other times there will also be workers of intermediate sizes. In some Australian species, known as honeypot ants, there are specialised workers called 'repletes' who spend their lives hanging in one spot inside the nest, being fed by the other active workers until their gasters swell into engorged round balls. These repletes serve the colony as a living larder, able to regurgitate their stored excess of food when needed by their nestmates. Despite all this diversity, most Camponotus species are readily recognisable as Camponotus: they usually lack spines on the mesosoma (the 'thorax'), the back end of which is narrow and often arched. This smoothness and slimness gives Camponotus a distinctive look that kind of puts me in mind of the ant version of a greyhound. The majority of Camponotus species also differ from other ants in lacking the metapleural gland, a gland producing an antibiotic chemical whose opening is usually visible near the rear of the mesosoma.

Camponotus aurocinctus, copyright Steve Shattuck.

Camponotus species have been referred to in Australia as 'sugar ants' in reference to their diet, which is commonly dominated by the sugary excretions of plant-sucking bugs that they attend. In other parts of the world, they have sometimes been referred to as 'carpenter ants' in reference to the wood-tunneling habits of their most notorious representatives. Bug-derived honeydew is high in sugar but low in other essential nutrients, so the ants also feed on things such as the scavenged bodies of the bugs themselves after death. They are also probably assisted in meeting their nutritive needs by Blochmannia, an endosymbiotic bacterium that infests specialised cells in the gut of Camponotus and closely related genera (Wernegreen et al. 2009). Genetic data from the endosymbiont indicates that it probably synthesises nutrients the ant does not otherwise ingest. It may also play some role in compensating for an absence of metapleural gland secretions. As well as the gut, Blochmannia infest the ovaries of reproductive females and are passed to the next generation via the developing oocytes. Phylogenetic analysis of Blochmannia indicates that it is closely related to other endosymbiotic bacteria found in mealybugs, and it is possible that the ancestors of Camponotus picked it up in the course of feeding on honeydew.

Honeypot ant Camponotus inflatus repletes hanging in the nest, copyright Mike Gillam.

The sheer size of Camponotus as a genus has been a challenge to understanding relationships within the genus. Over thirty subgenera have been proposed at one time or another, but many of these are poorly defined and many authors eschew using them in favour of informal species groups. It does not help matters that, since the early 20^th century, most reviews of Camponotus have been conducted at a local rather than a global level. Those studies that have touched on Camponotus phylogeny in recent years suggest the need for a large-scale revision, with few of the subgenera supported as monophyletic.

REFERENCES

Wernegreen, J. J., S. N. Kauppinen, S. G. Brady & P. S. Ward. 2009. One nutritional symbiosis begat another: phylogenetic evidence that the ant tribe Camponotini acquired Blochmannia by tending sap-feeding insects. BMC Evolutionary Biology 9: 292. doi:10.1186/1471-2148-9-292.

Delta Wasp

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Two views of the potter wasp Delta unguiculata, copyright Entomart.

Not so long ago, I found myself struggling with the challenge of identifying potter wasps. Potter wasps are close relatives of the social wasps, close enough that they are usually classified in the same family Vespidae, but they belong to a distinct lineage (the subfamily Eumeninae) of a more solitary bent, each female constructing its own individual nests in which to lay its eggs. The 'potter' part of their name refers to their preferred material for said nests which are sculpted from mud. Though they do not form the vexatious swarms that social wasps can, potter wasps still tend to be relatively large and impressive wasps, and like social wasps they are usually strikingly patterned in bold colours to give fair warning of their potentially painful stings.

Nevertheless, despite being the sort of thing that would be likely to attract interest, identifying potter wasps can be a definite challenge. For a large part of the twentieth century, eumenine genera were mostly divided very finely, with the features separating related genera often difficult to distinguish. Here in Australia, I found an approachable identification guide for most eumenines to be nigh on nonexistent. One potter wasp genus that I did successfully pull out, however, was Delta.

Female Delta campaniforme constructing a nest, from Brisbane Insects.

Delta is a genus of about fifty species of potter wasp found in warm regions of the Old World. At least one member of the genus, D. campaniforme rendalli, has become established in Florida after being introduced there from southern Africa (Menke & Stange 1986). Delta belongs to the Eumenes group of genera, in which the first segment of the metasoma (the petiole) is very long and slender. Distinctive features of Delta within this group include the second segment of the metasoma being relatively short with the associated tergum bell-shaped, and the males having the last segment of the antenna bent backwards to form a hook (Nguyen 2015). Females build their mud nests, which they stock with moth caterpillars, cemented to flattened surfaces such as the sides of buildings or along branches. The species introduced to North America possibly arrived in the form of a nest glued to some easily transportable substrate such as a shipment of lumber.

The names of Delta and many other Eumenes-group genera derive from the work of Henri de Saussure, who recognised a single genus Eumenes corresponding to this group but divided it into a number of sections that he labelled Alpha, Beta and so forth. Later authors raised these sections to the status of separate genera though some expressed the objection that Saussure may have never intended these alphabetical designations to be formal names at all. The validity of Saussure's 'genus-group names' was eventually settled by a decision of the International Commission on Zoological Nomenclature but authors such as Menke & Stange (1986) have continued to criticise the recognition of these difficult segregate genera, especially as, whereas the Eumenes group as a whole is probably monophyletic, many of its component genera may not be. Future classifications may yet see Eumenes gathering its prodigals back into the fold.

REFERENCES

Menke, A. S., & L. A. Stange. 1986. Delta campaniforme rendalli (Bingham) and Zeta argillaceum (Linnaeus) established in southern Florida, and comments on generic discretion in Eumenes s. l. (Hymenoptera: Vespidae: Eumeninae). Florida Entomologist 69 (4): 697–702.

Nguyen, L. T. P. 2015. Taxonomic notes on the genus Delta de Saussure (Hymenoptera: Vespidae: Eumeninae) from Vietnam. Animal Systematics, Evolution and Diversity 31 (2): 95–100.

These Ants Must Be Crazy

Black or longhorn crazy ant Paratrechina longicornis, copyright Efram Goldberg.

I have to admit that my ant-identifying skills are fairly rudimentary. I can recognise some of the more distinctive and/or common varieties—meat ants, bull ants, strobe ants, maybe even green-headed ants—but that's about as far as it goes. One ant species that I would have a decent chance of recognising right off the bat, however, is the black crazy ant Paratrechina longicornis.

Black crazy ants are an excellent example of what ant experts refer to as 'tramp species'—generalist species that have spread over a wide range in association with humans. Indeed, the black crazy ant is believed to be the most widespread of all ant species (Wetterer 2008): in tropical regions, it is nigh-on ubiquitous, and in cooler regions it lives within buildings and other warm structures built by humans. So widespread is it, and so readily does it spread, that we can't say for absolute certain where it originally came from: most likely it originated somewhere in south-east Asia, but other possibilities have been considered over the years.

Black crazy ants belong to the ant subfamily Formicinae; as such, they lack the sting carried by ants of other subfamilies and instead have a nozzle-like pore in its place that they use to spray formic acid at perceived threats. They are distinguished from other ants by their slender appearance, with numerous upright bristles on the body, and long legs and antennae. The antennae are most distinctive, with a particularly long scape (the first antennal segment, before the sharp 'elbow'). Paratrechina longicornis are known as 'crazy' ants because of their erratic mode of foraging, wandering about seemingly aimlessly and not following clear trails. Other ants with similar modes of behaviour have also been dubbed crazy ants, such as the yellow crazy ant Anoplolepis gracilipes, but they are not close relatives.

Effectiveness in numbers: black crazy ants bring down a Florida carpenter ant Camponotus floridanus, from AntWeb.

Black crazy ants may form large or small colonies as circumstances allow; part of the secret of their success is that these colonies can be found in man-made marginal habitats such as on ships at sea. Crazy ant colonies may reach plague proportions; this website relates an account of students at a Florida primary school being so beset by crazy ants that food and other possessions had to be kept in sealed bags on tables at all times with the table legs set in bowls of water to prevent the ants crawling up them. Black crazy ants produced winged reproductives like other ants, but the new queens remove their wings before they expand and emerge from the nest already wingless. While at first glance this seems counter-productive, I can see this behaviour being another factor in their success as a tramp. Colonies living in isolated habitatssuch as the aforementioned ships and buildings in cold climates will tend to persist in that location, rather than losing all their reproductive potential in fruitless exploratory nuptial flights.

In recent times, P. longicornis has been recognised as one of a number of species in the genus Paratrechina (of which it is the effective type). However, a phylogenetic study by LaPolla et al. (2010) of the group of genera to which Paratrechina belongs has found that the genus as then recognised was polyphyletic. Rather than being directly related to other 'Paratrechnina', P. longicornis was most closely related to two south-east Asian genera Euprenolepis and Pseudolasius. This lead to the resurrection of two older generic names, Nylanderia and the cringe-inducingly named Paraparatrechina, into which all Paratrechina species other than P. longicornis were transferred.

REFERENCES

LaPolla, J. S., S. G. Brady & S. O. Shattuck. 2010. Phylogeny and taxonomy of the Prenolepis genus-group of ants (Hymenoptera: Formicidae). Systematic Entomology 35: 118–131.

Wetterer, J. K. 2008. Worldwide spread of the longhorn crazy ant, Paratrechina longicornis (Hymenoptera: Formicidae). Myrmecological News 11: 137–149.

More on Spider-Hawks

A couple of years ago, I presented a bit of an abortive post on wasps of the family Pompilidae, the spider-hawks. Despite their striking appearance and relatively high visibility, I noted, it was nigh on impossible to find reliable taxonomic information on them.

Diagram of the forewings of Cryptocheilus australis (above) vs Heterodontonyx bicolor (below) from Wahis (2008), showing the differences in the shape of the marginal cell (the large cell along the top margin of the wing).

This question came back to the fore for me recently when I had to attempt to identify a number of spider-hawks for work. With no recent key available for Australian pompilids, I had to try and piece together clues. As it turns out, a large part of the difficulty in identifying spider-hawks is that they are, overall, a conservative bunch. Though coming in a range of sizes and colours, they tend to be structurally uniform. This makes it difficult to find reliably key-able characters, and means that evolutionarily quite distinct species can look superficially quite similar. Take, for example, one of the most 'familiar' of the Australian pompilids, the black-and-orange Cryptocheilus bicolor. Recently, Wahis (2008) established that this was not a true species of Cryptocheilus, but belonged to a distinct (albeit related) genus as Heterodontonyx bicolor. The two genera can be distinguished by the shape of the marginal cell in the forewing, which is distally pointed in Heterodontonyx but rounded in Cryptocheilus. The thing is, many of the photos one may find online labelled as 'Cryptocheilus bicolor' are true Cryptocheilus, not Heterodontonyx. Those on Wikipedia may be correctly identified, but these here are not. Not every large orange-and-black spider-hawk in Australia is Heterodontonyx bicolor.

Specimen of Telostegus inermis, copyright Josef Dvořák.

So what of Telostegus, the genus that I was complaining about being unable to find the diagnostic characters for in my earlier post? Evans (1972) describes it as having bifid tarsal claws, and a vena spuria in the forewing. A vena spuria ('spurious vein') is a fold in the wing that might be mistaken at first glance for a wing vein. In the images above, it can be seen as a dark line along the middle of the wing in the dorsal view. Evans (1972) separated two genera of spider-hawks, Telostegus and Elaphrosyron, on the basis of the number of submarginal cells in the forewing (two in Telostegus, three in Elaphrosyron) but more recent authors have not regarded this distinction as valid.

REFERENCES

Evans, H. E. 1972. A review of the Australian species of Elaphrosyron and Telostegus, with notes on other genera (Hymenoptera: Pompilidae). Breviora 386: 1–18.

Wahis, R. 2008. Contribution à la connaissance des Pompilides d’Australie (Hymenoptera : Pompilidae). 2. Sur quelques spécimens récoltés par G. Else (Natural History Museum, London) avec descriptions de deux espèces nouvelles des genres Auplopus et Ctenostegus. Faunistic Entomology 61 (1–2): 23–31.

The Phaeogenini: Widdle Icky Newmans

Female Diadromus collaris on a pupa of a diamondback moth Plutella xylostella, from here.

The ichneumons are perhaps the best-known family of parasitic wasps. Most people will have come across a description of the classic ichneumon lifestyle at at least some point: a female lays an egg in the larva of another insect, which then hatches into a wasp larva that eats out its hosts insides before emerging at maturity, leaving an empty husk behind. It is easy to see why ichneumons have become the poster children for parasitoid wasps everywhere: not only are they one of the most diverse wasp families, they can often be dramatic in appearance, growing to remarkable sizes. However, not all ichneumons are giants.

Female Eparces quadriceps, copyright Tom Murray.

The tribe Phaeogenini includes some of the smallest ichneumons, with some species being only a few millimetres long (Rousse et al. 2013). They belong the the subfamily Ichneumoninae, within which they are distinguished from most other tribes by their possession of round rather than elongate spiracles on the petiole. They are otherwise quite diverse in appearance, and Gauld (1984) suggested that they may be a polyphyletic assemblage of species that had convergently evolved their common features as a result of their small size. However, molecular phylogenetic analyses have largely supported the monophyly of the Phaeogenini (e.g. Quicke et al. 2009). One genus, Lusius, tends to be placed elsewhere among the ichneumons, but this is probably due to its having an anomalous 28S rDNA sequence with a number of deletions; Quicke et al. (2009) implied that they thought it more likely to still be a true phaeogenin. Some authors have suggested a relationship between phaeogenins and another unsual small ichneumon genus Alomya (in which case, due to the vagaries of priority, the name of this tribe becomes the Alomyini), but molecular analysis does not support this association.

Dirophanes fulvitarsis encounters a smaller wasp (perhaps a figitid?). Copyright J. K. Lindsey.

Like other members of the Ichneumoninae, the Phaeogenini are parasitoids of Lepidoptera: specifically, in accord with their small size, micro-lepidoptera. However, identification of the hosts of phaeogenins can be difficult, as they tend not to attack them until after the host has formed a cocoon (Diller & Shaw 2014). Where hosts are known, they are often borers in plant stems or leaves. The phaeogenin Diadromus collaris attacks the diamondback moth Plutella xylostella, a significant pest on brassicas and related plants. As such, it has been widely introduced around the world to help in the control of this pest.

REFERENCES

Diller, E., & M. R. Shaw. 2014. Western Palaearctic Oedicephalini and Phaeogenini (Hymenoptera: Ichneumonidae, Ichneumoninae) in the National Museums of Scotland, with distributional data including 28 species new to Britain, rearing records, and descriptions of two new species of Aethecerus Wesmael and one of Diadromus Wesmael. Entomologist's Gazette 65: 109–129.

Gauld, I. D. 1984. An Introduction to the Ichneumonidae of Australia. British Museum (Natural History).

Quicke, D. L. J., N. M. Laurenne, M. G. Fitton & G. R. Broad. 2009. A thousand and one wasps: a 28S rDNA and morphological phylogeny of the Ichneumonidae (Insecta: Hymenoptera) with an investigation into alignment parameter space and elision. Journal of Natural History 43 (23–24): 1305–1421.

Rousse, P., S. van Noort & E. Diller. 2013. Revision of the Afrotropical Phaeogenini (Ichneumonidae, Ichneumoninae), with description of a new genus and twelve new species. ZooKeys 354: 1–85.

Ant-like Ichneumons

Female Gelis, copyright Krister Hall.

The ichneumons are one of the best-known groups of parasitoid wasps. The most familiar ichneumons are relatively large for parasitoid wasps, and sometimes even for wasps in general. This can make them somewhat intimidating in appearance, especially considering the likelihood of the long ovipositor of a female being mistaken for a sting by those not in the know. However, not all ichneumons are giants. The photo above shows a tiny ichneumon of the genus Gelis, females of which are wingless and bear a distinct superficial resemblance to ants. This resemblance is likely to afford them some protection from potential predators, and at least one Gelis species, G. agilis, has been shown to release a chemical when threatened very similar to the alarm pheromones of the black garden ant Lasius niger (Malcicka et al. 2015). On the other hand, one might be tempted to wonder if this mimicry may sometimes serve a more nefarious purpose: another species, G. apterus, has been recorded as a parasitoid of the ant-eating spider Zodarion styliferum (Korenko et al. 2013). However, G. apterus has not been recorded to use its ant appearance to lure its host; instead, the female ichneumon uses its ovipositor to pierce the igloo-like silken retreat that the spider occupies during the day. Other species of Gelis are known to be parasitoids of moth cocoons rather than spiders (Gauld 1984), so Gelis' status as an ant-mimic and its choice of host may be simple coincidence.

Phygadeuon exiguus, copyright James K. Lindsey.

Gelis belongs to a world-wide tribe of ichneumons known as the Phygadeuontini (sometimes referred to in older sources as the Gelini), a diverse group including well over 100 genera. Most, but not all, phygadeuontins are also among the smaller ichneumons. The range of hosts attacked by the group is equally diverse, including (among others) moths and lacewing pupae, and spider egg sacs, while some are hyperparasitoids on the pupae of other parasitoid wasps (Gauld 1984). Species of the genus Phygadeuon include parasitoids of wood-burrowing beetles that use the enlarged ends of their antennae to tap at wood in search of hollow burrows within. Some phygadeuontins are external parasitoids, while others are endoparasitoids. The larvae of Gelis apterus can even be regarded as true predators, as they attack not the eggs of their host but its newly-hatched spiderlings (Korenko et al. 2013). A common theme between these diverse hosts, though, is the production by most of them of silken cocoons or other protective structures that the female phygadeuontin is able to pierce with her ovipositor.

REFERENCES

Gauld, I. D. 1984. An Introduction to the Ichneumonidae of Australia. British Museum (Natural History).

Korenko, S., S. Schmidt, M. Schwarz, G. A. P. Gibson, & S. Pekár. 2013. Hymenopteran parasitoids of the ant-eating spider Zodarion styliferum (Simon) (Araneae, Zodariidae). Zookeys 262: 1–15.

Malcicka, M., T. M. Bezemer, B. Visser, M. Bloemberg, C. J. P. Snart, I. C. W. Hardy & J. A. Harvey. 2015. Multi-trait mimicry of ants by a parasitoid wasp. Scientific Reports 5: 8043. doi:10.1038/srep08043.

Wasps in the Sand

Sand wasp Bembix oculata with prey (a bombyliid, I think), copyright Carlos Enrique Hermosilla.

The sand wasps of the tribe Bembicini are a diverse group of about 500 species of wasp that get their name because, obviously, of their habit of constructing burrows in sand-banks. Like other members of the wasp family Crabronidae, sand wasps provision these burrows with food for their larvae in the form of other insects. The adults themselves feed on nectar. Some of the Bembicini are among the larger members of the Crabronidae, and most of them are strikingly marked in black and yellow, white or red. Other characteristics of the group include an elongate labrum above the mouth, and the reduction of the ocelli, often to simple scars.

Bembicins are divided between a reasonable number of genera (Bohart & Menke, 1976, listed fifteen, but subsequent authors have recognised more) but the greater number of species are included in just one of these, the cosmopolitan Bembix with over 300 species (some older sources spell this name 'Bembex', but Bembix seems to be correct). Bembix is also the only genus found outside the Americas. Bohart & Menke (1976) suggested three main lineages within the Bembicini: one containing the relatively plesiomorphic genera Microbembex and Bicyrtes, a group of four genera including Stictiella and Glenostictia in which the ocelli are sunken into pits, and a large group containing genera related to Bembix with a raised welt at the front of the scutum on the thorax.

Sand Wasp - Bembix americana from Dick Walton on Vimeo.

While other wasps will lay their egg(s) on a paralysed insect in a brood chamber and then fly off never to return, many bembicins continue to bring fresh food items to the burrow throughout their larvae's development (take a look at the video above, by Dick Walton). The majority of bembecins provide their larvae with flies as food, which they paralyse with their sting and then carry back to the burrow between their mid-legs. Only a small number of genera regularly use other prey, though notably these genera include both Bicyrtes and Microbembex (so predation on flies is possibly ancestral for a clade excluding these two genera rather than for the tribe as a whole). Bicyrtes species stock their burrows with bugs (Heteroptera), most commonly nymphs. Microbembex species are the gourmands of the tribe, taking prey ranging from mayflies to midges. They are also somewhat unusual in that they stock their burrows with dead as well as paralysed insects (because they are providing food continuously, freshness over an extended period is less important than it is for other wasps). Females may compete for dead insects: in the words of J. Parker (as quoted by Bohart & Menke, 1976): "The struggles at the mouth of the burrow for the possession of a dead insect are frequent and furious, the contestants grappling and rolling over and over on the sand. Frequently it happens that the prey is dropped in the struggle, and while the pair of contestants are rolling on the sand a third wasp comes along and settles the quarrel by quietly carrying off the coveted treasure". Of the other bembecin genera, species of the genera Stictiella and Editha are predators of Lepidoptera. Editha species are found in southern South America, and include the largest of the bembecins. Xerostictia longilabris, a member of the Stictiella-group from southern North America that gets its own genus, has been recorded stocking its burrow with ant-lions and flatid bugs (Evans 2002). Members of other genera may also stock their burrows with prey other than flies, though in the majority of cases they do not do so exclusively (Evans 2002).

Sand wasp, possibly Microbembex monodonta, burying the entrance to her burrow. Copyright Tim Lethbridge.

Many bembecins (most notably in the genera Microbembex and Bembix) nest gregariously, and may form sizable colonies. Species of Bembix will maintain the same colony from year to year. In some species, such as B. pallidipicta, the females may dig accessory burrows near the main burrow without laying eggs in them; these have been presumed to act as decoys to discourage parasitoids or kleptoparasites. Males perform prolonged 'sun dances' above the colony in which they fly in circles or figures-of-eight, looking out for attractive females (O'Neill 2001). Males of many species have a serrated mid-femur that they use to hold down the female's wings while mating; in species without these leg serrations, mating may involve more of a struggle (Bohart & Menke 1976). The male produces a loud chirping during mating, presumably just to add atmosphere.

REFERENCES

Bohart, R. M., & A. S. Menke. 1976. Sphecid Wasps of the World: a generic revision. University of California Press.

Evans, H. E. 2002. A review of prey choice in bembicine sand wasps (Hymenoptera: Sphecidae). Neotropical Entomology 31 (1): 1-11.

O'Neill, K. M. 2001. Solitary Wasps: behavior and natural history. Cornell University Press.

Psenulus: Silk-Weaving Wasps

Female Psenulus pallipes carrying an aphid back to her nest. Copyright Jeremy Early.

Because I am an obsessive-compulsive weirdo, I spend a good chunk of my spare time at home sorting through biology publications and pulling out names (you can seen some of the results of this at my other site, The Variety of Life). Back on July 1, I tweeted: "And from tonight, I delve into sphecoids. To species level. This could take even longer than the oribatids." Never, as it turns out, were truer words spoken, as we have now very nearly reached the end of July, and I am still only a relatively small part of the way through this diverse group of wasps (to be more specific, I've been taking stuff out of Bohart & Menke's [1976] Sphecid Wasps of the World, and I've only gotten as far as p. 179 of what is a 695-page book: there are over 7500 species listed in that book, a depressing high proportion of which appear to have originally been placed in the genus Sphex). And seeing as so much of my time recently has been spent on sphecoids, it is only appropriate that my semi-random selection for this week's post has been one: the pemphredonine Psenulus trisulcus.

The sphecoids are a group of solitary wasps including such beasts as the digger wasps and sand wasps. Bohart & Menke (1976) placed them all in a single family Sphecidae, but this does not represent a monophyletic group, as some 'sphecoids' are more closely related to bees than to other sphecoids. As a result, most recent authors have divided the sphecoids between three families: the Ampulicidae (cockroach wasps), Sphecidae (digger wasps, etc.) and Crabronidae (sand wasps, etc.) The Pemphredoninae are a group of mostly quite small wasps in the last of these families. Psenulus is a genus of about 120 species of pemphredonines found on most continents except South America; P. trisulcus is one of only a small number of Psenulus species found in North America (the genus is most diverse in the Oriental region). Like other sphecoids, females of Psenulus species provision their nests with paralysed prey insects for their larvae to feed on after hatching. While more familiar sphecoids such as digger or sand wasps may dig tunnels in which to construct their nest cells, Psenulus species use hollows such as beetle borings in plant stems. Krombein (1979) listed P. trisulcus as nesting in elder stems; another Psenulus species has been recorded constructing cells in hollow grass stems floating on water (Bohart & Menke 1976). I have not been able to find a record of the preferred prey of P. trisulcus itself, but closely related species such as P. pallipes, a Holarctic species shown in the photo at the top of this post, attack aphids. In the case of P. pallipes, a single nest cell may be packed with as many as 27 aphids, providing plenty of food for an emerging larva. Other Psenulus species may collect other Hemiptera, such as psyllids (plant-lice) or leafhoppers. Psenulus trisulcus resembles P. pallipes in its overall black coloration, and the characters distinguishing the two would not be visible without a close microscopic examination: in P. trisulcus, the ridge running between the antennae is marked by longitudinal grooves that are not present in P. pallipes, and the petiole of P. trisulcus has a ridge along its underside (Malloch 1933*).

*As corrected by Pate (1944), who noted that Malloch's "trisulcus" was actually a different species that he named "parenosas" (subsequently regarded as a subspecies of pallipes), and that the true trisulcus was actually Malloch's "sulcatus".

Pinned specimen of Psenulus trisulcus, copyright York University.

The nests of Psenulus trisulcus and P. pallipes are also unusual in being lined with silk, with silk also being used to construct the partitions between cells. While many insects produce silk as larvae, it is more uncommon for them to continue doing so as adults (and only the females do so in the case of Psenulus). The source of Psenulus' silk was long uncertain (with one researcher suggesting that it was extruded from the labial palps), until Melo (1997) established that it was secreted from bristle-like spinnerets that form fringes on the hind margins of the fourth and fifth sternites of the gaster. However, not all Psenulus species have such fringes: Melo (1997) examined three spinneret-less species and found that their silk glands opened directly on the underside of the gaster (with long erect setae possibly assisting in the spreading of silk in these species). This makes for an interesting comparison with spiders, in which the fossil Attercopus suggests the evolution of spinnerets from previously disassociated silk glands. Unfortunately, we don't yet really know what the relationships are within Psenulus, and whether the spinneret-less model is truly ancestral.

REFERENCES

Bohart, R. M., & A. S. Menke. 1976. Sphecid Wasps of the World: a generic revision. University of California Press.

Krombein, K. V. 1979. Catalog of Hymenoptera in America North of Mexico vol. 2. Apocrita (Aculeata). Smithsonian Institution Press.

Malloch, J. R. 1933 Review of the wasps of the subfamily Pseninae of North America (Hymenoptera: Aculeata). Proceedings of The United States National Museum 82 (26): 1-60.

Melo, G. A. R. 1997. Silk glands in adult sphecid wasps (Hymenoptera, Sphecidae, Pemphredoninae). Journal of Hymenoptera Research 6: 1-9.

Pate, V. S. L. 1944. Synonymical notes on the psenine wasps (Hymenoptera, Sphecidae). Canadian Entomologist 76 (7): 133.

Wasps with Fangs on their Feet?

Theronia septentrionalis, photographed by Stephen Cresswell.

The ichneumons are one of the more familiar groups of parasitoid wasps for the general public. The species in the photo above is a member of the Theronia group of ichneumons, which attain a reasonable size by wasp standards (a number of species seem to be in the range of 1.5 centimetres long) and are often brightly coloured in yellow or green. The Theronia group is primarily tropical in distribution, though some species are found in more temperate regions. Authors have differed on whether they treat this group as a single genus or divide it between about half a dozen genera; either option is complicated by the fact that both the group as a whole and some of its constituent restricted genera are doubtfully monophyletic (Gauld et al. 2002). Where their larval hosts are known, many members of the Theronia group are endoparasitic in moth cocoons (including some economically significant pests such as the gypsy moth), though at least some species are not parasites of the moth itself but are hyperparasites of other ichneumon larvae attacking the moth. One (sub)genus, Nomosphecia, includes parasites of vespid wasp larvae (Gauld 1984).

Male Theronia atalantae, photographed by Phil Huntley-Franck.

Bright colours are often a sign of danger in the animal kingdom, and the Theronia group seem to follow that trend. One of the group's distinctive features is larged, curved claws with an associated spatulate bristle. As noted by Gauld (1984), "When caught they sink their large claws into their captor." This sounds uncomfortable enough in itself, especially as said claws have a tendency to break and leave their tips embedded in the skin if the wasp is not allowed to remove them in her own time. But there's more: the inside of the claw bears a fluid-filled cavity, and the act of embedding the claws releases the contents of this cavity into the wound. In other words, the claws seem to function in much the same way as the fangs of a venomous snake.

Or do they? We know that the fluid injected by Theronia into would-be attackers can cause irritation to vertebrate epithelium (Gauld et al. 2002), but we don't seem to know just what it contains or how it acts. As such, we don't know how confident we can be that the fluid is indeed effective defensively. Theronia may have poison claws that act like fangs. Or it may just have big sharp claws, and that may be enough.

REFERENCES

Gauld, I. D. 1984. An Introduction to the Ichneumonidae of Australia. British Museum (Natural History).

Gauld, I. D., D. B. Wahl & G. R. Broad. 2002. The suprageneric groups of the Pimplinae (Hymenoptera: Ichneumonidae): a cladistic re-evaluation and evolutionary biological study. Zoological Journal of the Linnean Society 136: 421-485.

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.

Sociable Spider-Hawks

The wasp in the photo above (taken by Henrik Gyurkovics) is Telostegus inermis, a member of the family Pompilidae. I've always known pompilids by the vernacular name of spider-hawks; other names I've heard include spider-hunters or tarantula hawks. They get these names because the females capture spiders that they paralyse with their sting. The helpless spider is then dragged into a burrow, where the spider-hawk lays an egg on it. When the egg hatches, the spider will become food for the developing larva.

Spider-hawks of the genus Telostegus are known from the greater part of the Old World. Normally, at this point, I would say something about their distinguishing characters, but I'm afraid that you've got me there. A morning spent trying to dig up descriptions has largely failed, with the necessary references being scattered and inaccessible to yours truly. Though spider-hawks are among the more visible of wasp families, they have not been that extensively studied. Indeed, one of the first things I came across in my search was this dis-heartening exchange discussing how there was (as of 2009) only one researcher in Europe with the experience to reliably identify pompilids, who is difficult to contact due to failing health. Sadly, this is a scenario all too familiar in the world of taxonomy.

The nesting behaviour of three Australian Telostegus species (one under the since-synonymised genus Elaphrosyron) was described by Evans & Matthews (1973). Each built nests in which a single entrance lead through branching tunnels to multiple cells, each containing a single spider. In at least one species, Telostegus socius, the soil from the burrow was piled in a mound in front of the entrance. Evans & Matthews also noted that another pompilid species, Ceropales ligea, would sometimes lay its own eggs on the Telostegus' spider as the female of the latter was in the process of transporting it, making C. ligea a cuckoo pompilid. The name of Telostegus socius refers to another characteristic of its nests: a large number of females would build their nests in close proximity. Such gregarious behaviour is also known from wasps in other families (such as the sand wasps of the crabronid genus Bembix). It does not represent true social behaviour like that of ants or vespid wasps, as each female is still constructing and stocking her own nest. Nevertheless, any would-be predators may now be faced with a whole group of defending wasps instead of just one, and it is tempting to see such gregarious nesting as an early step towards true social behaviour.

REFERENCE

Evans, H. E., & R. W. Matthews. 1973. Behavioural observations on some Australian spider wasps (Hymenoptera: Pompilidae). Transactions of the Royal Entomological Society of London 125 (1): 45-55.

A Bunch of Apocrites

An unidentified male of Megalyridae, a family of 'evaniomorphs' parasitic on wood-boring beetles, from here.

During the late nineteenth century, many women attempted to achieve a 'wasp waist', using corsets to tighten their waist to as narrow a diameter as possible. The style was so-called, of course, because of its resemblance to the body of a wasp, with a sharp constriction dividing the body. However, this feature is not universal among wasps: rather, it characterises a distinct clade within the wasps, the Apocrita.

Basal members of the Hymenoptera possess a broad junction between thorax and abdomen like that seen in other insects. In apocritan wasps, the first segment of the abdomen became incorporated into the body of the thorax (where it is referred to as the propodeum) and the characteristic wasp waist developed at the front of the second abdominal segment. Because the major divisions of the body in Apocrita therefore do not correspond directly to the thorax and abdomen of other insects, workers on Apocrita instead refer to the mesosoma and metasoma (or 'altitrunk' and 'gaster'). So narrow is the connection between mesosoma and metasoma, in fact, that members of the Apocrita are incapable of taking solid food: only liquids can pass through the waist. This limitation is believed to have later been significant in the development of the social wasps and ants: because mature ants cannot themselves eat solids, they must feed any solid food they collect to their larvae. The larvae then regurgitate the semi-digested food in a liquid form that the adults can handle. This dependance on their larvae induced the formation of stable colonies. Mature wasps that do not form colonies feed on naturally-occurring liquids such as nectar.

An unidentified wasp of the Stephanidae ovipositing, from Singapore Nature.

Ancestrally, the Apocrita are a lineage of larval parasites, and the majority of species remain so today. The wide distribution of parasites of wood-boring beetles among basal apocritans, and in their sister group the Orussidae among the non-waisted wasps, suggests that this was probably the original lifestyle for the apocritans (Grimaldi & Engel 2005). Living Apocrita can be divided between five main groups: the Stephanidae, the Aculeata (stinging wasps, including all the social forms such as ants and bees), the Ichneumonoidea (ichneumons and braconids), the Proctotrupomorpha, and the Evaniomorpha (though the monophyly of the latter group is debatable). The Stephanidae are a family of long slender beetle parasites that are most diverse in tropical parts of the world.

An evaniid of the genus Hyptia, from Kurt Schaefer.

The evaniomorphs have been suggested to form a group on the basis of the form of the inner articulation of the coxa (the basal segment) of the middle pair of legs, but the polarity of this feature is debatable (Ronquist 1999). The type superfamily, the Evanioidea, includes a group of families characterised by having the articulation of the metasoma to the mesosoma positioned high up on the propodeum rather than low down as in most other wasps. The hatchet wasps of the Evaniidae have a particularly distinctive body form: the mesosoma is boxy, often almost square in side view; the first segment of the metasoma is developed into a long and narrow petiole; and the remainder of the metasoma is relatively small and hangs off the petiole like the head of the eponymous hatchet. Evaniids are parasites of cockroaches, laying their eggs on the cockroaches' egg cases.

Female trigonalyid of the genus Trigonalys, photographed by Simon van Noort. Note the hooked end to the metasoma; when ovipositing, the female will stand on one side of a leaf and hook her metasoma around to lay her eggs on the other side of the leaf.

Females of another evaniomorph family, the Trigonalyidae, lay large numbers of eggs inserted into incisions on a plant leaf. When a piece of leaf containing a trigonalyid egg is eaten by a caterpillar, the egg hatches out and the trigonalyid larva emerges, then burrows into the body of the caterpillar. However, the larva's target is not the caterpillar itself. Instead, the trigonalyid is looking for the parasitic larva of another wasp that may be inside the caterpillar: it is what is called a hyperparasite (that is, a parasite of a parasite). Trigonalyids are also known as parasites of the larvae of social wasps: when the social wasp feeds its larvae on a caterpillar containing a trigonalyid, the trigonalyid may infect the larva to which it is fed (Grimaldi & Engel 2005).

REFERENCES

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

Ronquist, F. 1999. Evolution of the Hymenoptera (Insecta): the state of the art. Zoologica Scripta 28: 3-11.