A Little Bit on Lesser Dung Flies

Copromyza stercoraria, photographed by Blaauw7.

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

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

Podiomitra sp., photographed by Inna Strazhnik.

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

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

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

REFERENCES

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

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

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

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

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

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.

Beetle Flies

Unidentified celyphid, photographed by Giovzaid85.

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

Another celyphid, photographed by Melvyn Yeo.

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

Photo by Meng Foo Choo.

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

Celyphus koannanius, from here.

REFERENCE

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

Freak of the Week: Wingless, Legless Flies

I found this while looking up identification info for phorid flies, of which we currently seem to be receiving something of an influx in our samples.


Photoes from here.

Most of what you see in the lower of the two photoes above are larvae of army ants of the genus Aenictus. The odd one out is the whiter 'larva' in the centre—which is not a larva at all, but a fully adult female of the phorid fly Vestigipoda longiseta! (The upper photo shows the same animal in close-up.) This bizarre animal makes its living by imitating its host larvae and being fed by the larvae's deluded carers. Five species of Vestigipoda have been described to date from Malaysia (Disney et al., 1998; Murayama et al., 2008).


Close-up of head of Vestigipoda maschwitzi, from Disney et al. (1998).

Cases of neoteny, where insects develop full sexual maturity while still 'larvae', are not unknown among holometabolous insects (I earlier described a case involving the beetle Micromalthus). However, Vestigipoda cannot be regarded as neotenous because the female has a fully developed adult head.

So far, Vestigipoda seems to only be known from females. It is possible that males, when found, may turn out to be much more normal phorid flies. The challenge would be recognising them as related to their bizarre females.

REFERENCES

Disney, R. H. L., A. Weissflog & U. Maschwitz. 1998. A second species of legless scuttle fly (Diptera: Phoridae) associated with ants (Hymenoptera: Formicidae). Journal of Zoology 246 (3): 269-274.

Maruyama, M., R. H. L. Disney & R. Hashim. 2008. Three new species of legless, wingless scuttle flies (Diptera: Phoridae) associated with army ants (Hymenoptera: Formicidae) in Malaysia. Sociobiology 52 (3): 485-496.

More than Just Sophophora (Taxon of the Week: Drosophilidae)

The variety of drosophilids, from here. In the classification used in this post, the species illustrated would be Sophophora simulans and Idiomyia conspicura.

Today's Taxon of the Week is a group of which one particular species has already occupied a reasonable chunk of screen time at this site. The recent taxonomic controversy over Sophophora melanogaster* has been covered here, here and here, and I'm sure that by now we're all well and truly sick of the horrid little beast. The Drosophilidae is a family of some 3500 species of which S. melanogaster is but one. Surely it's time some of the other drosophilids were given their dues?

*As noted in earlier posts, there is really no justification for including the Sophophora species in the genus Drosophila. Even if you subscribe to a classificatory theory that forgives paraphyly, there are simply too many non-Drosophila genera separating Sophophora from Drosophila sensu stricto to make including the latter in one genus reasonable (see Linde et al., 2010, and various other references mentioned therein). It's like the entomological version of West and East Pakistan. [facetious snark] So now the decision about appropriate naming has been officially made, can we please all get over it and deal with the consequences? [/facetious snark]

Drosophilids are treated as part of a large grouping of flies known as the acalyptrates. Acalyptrates possess short antennae with a horseshoe-shaped fissure between the antennae and the upper part of the face but lack a calypter, a lower lobe at the base of the wing found in houseflies and blowflies. Distinguishing the various acalyptrate families from each other can be an absolute nightmare (I speak from painful experience) but the features of Drosophilidae include an incomplete subcostal vein in the wing, three (occasionally two) pairs of bristles on the face with the front pair pointing forwards and the remainder pointing backwards, and usually no bristles on the anepisternum (one of the side plates on the thorax) (Grimaldi, 1990).


Pair of Drosophila endobranchia courting on the carapace of the land crab Gecarcinus ruricola whose mouthparts will become home to their commensal larvae. From Stensmyr et al., 2008.

Most drosophilids are small flies (the largest belong to the genus Idiomyia and have wingspans of up to two centimetres). The majority of species feed as larvae on yeasts and the like growing on decaying plant matter but a number are more outré in their dietary habits (Ashburner, 1981). Scaptomyza larvae mine leaves while larvae of Lissocephala powelli, Drosophila carcinophila and D. endobranchia live as commensals on the mouthparts of land crabs, feeding on the bacteria growing there. Several species of various genera are predatory, mainly on small plant-sucking bugs such as scales and whiteflies though other targets are known (including two unrelated species feeding on frog eggs and at least one record of larvae of a generalist species taken from a secondarily infected wound of a surgery patient). The Drosophila simulivora group includes four West African species whose larvae are aquatic predators of midge and sandfly larvae. Perhaps the most incredible carnivorous drosophilid is the European Cacoxenus indigator which lays its eggs in the brood cells of the mason bee Osmia coerulescens. The mason bee arranges its cells in single file in a long tube and the female Cacoxenus will insert a single egg into each cell except the last. The fly larva feeds on the food stores left for the bee larva and eventually on the bee larva itself (though it is unclear whether the fly actually attacks the bee while it is alive or simply scavenges it after it dies from strarvation, as it has been known for the bee and fly to both emerge alive from a single cell). The reason the female Cacoxenus does not lay in the terminal cell is that, once her own larvae pupate into adult flies, they are unable to break free of the brood cell themselves and are dependent on the one surviving bee to release them as it frees itself from the nest.


Two males of the hammer-head fly Idiomyia heteroneura performing competitive displays. This is an endangered species with a restricted range on the island of Hawai'i. Photo from here.

The highest concentration of drosophilid diversity is found in the Hawaiian islands which are home to perhaps more than 1000 species (O'Grady et al., 2003) divided between the genera Scaptomyza and Idiomyia (the latter referred to by many authors as "Hawaiian Drosophila"). Many of these species, it should be noted, are exceedingly rare and localised and many remain undescribed. Molecular analysis indicates that the Hawaiian drosophilids form a single clade, indicating a single colonisation of the island (O'Grady & DeSalle, 2008). However, Scaptomyza also includes a number of continental species that appear to be derived from a Hawaiian ancestor.

REFERENCES

Ashburner, M. 1981. Entomophagous and other bizarre Drosophilidae. In The Genetics and Biology of Drosophila vol. 3A (M. Ashburner, H. L. Carson & J. N. Thompson, eds) pp. 395-429. Academic Press: London.

Grimaldi, D. A. 1990. A phylogenetic, revised classification of genera in the Drosophilidae (Diptera). Bulletin of the American Museum of Natural History 197: 1-139.

Linde, K. van der, D. Houle, G. S. Spicer & S. J. Steppan. 2010. A supermatrix-based molecular phylogeny of the family Drosophilidae. Genetics Research 92: 25-38.

O'Grady, P., J. Bonacum, R. DeSalle & F. Do Val. 2003. The placement of Engiscaptomyza, Grimshawomyia, and Titanochaeta, three clades of endemic Hawaiian Drosophilidae (Diptera). Zootaxa 159: 1-16.

O'Grady, P., & R. DeSalle. 2008. Out of Hawaii: the origin and biogeography of the genus Scaptomyza (Diptera: Drosophilidae). Biology Letters 4: 195-199.

In Which, Despite Not Being The Crowd Favourite, Drosophila funebris Holds D. melanogaster Down and Kicks It Repeatedly in the Teeth

The original and still reigning champion, Drosophila funebris. Fear it, I say! Photo by Nicolas Gompel.

It's been two years in the making, but the ICZN decision on Drosophila has finally been announced (ICZN, 2010). You may recall that an application had been submitted (Linde et al., 2008) to make Drosophila melanogaster, the subject of countless genetic studies, the type species of the genus instead of the current holder of that title, D. funebris. See previous posts here and here for background details.

And the verdict: by a surprisingly large margin (23 to 4, with one absence), the Commission has turned the proposal down. Drosophila funebris remains the valid type species of the genus; D. melanogaster retains the potential for reclassification. Those of you with a particular interest in the workings of nomenclature* would do well to get hold of a copy of the decision. In light of the higher than usual public interest in this case, the unusual step has been taken of publishing individual comments from each of the commissioners on the reasoning behind their decisions. As well as the insight provided into this particular case (and it's worth noting that some of the commissioners on both sides of the floor ended up voting against their own initial sympathies), some of the comments provide interesting talking points about the role of nomenclature in general.

*Yes, we do exist. I'm afraid the doctors say that there's nothing they can do.

Some of the reasons given for voting against the proposal were reasonable, others less so. A. small number of commissioners voiced the complaint that the proposal was asking the ICZN to endorse a particular taxonomic method; as I argued in one of the previous posts, it did no such thing and I am rather disappointed that this issue was raised. Some commissioners also turned down the proposal on the grounds that it was premature (Miguel Alonso-Zarazaga stated that he "felt that the authors of the case had not allowed the community to have a healthy discussion of their proposals, since the ‘detailed phylogenetic studies’ mentioned in the case were still largely unpublished, and were thus hypothetical"). However, while the proposal may have been precipitated by an as-yet unpublished study, the results of that study are hardly novel. As pointed out by László Papp in his comments on his supporting vote, the issue that any subdivision of Drosophila would require the removal from that genus of D. melanogaster has been under discussion for at least 35 years (a time when, I should note, purely phylogenetic considerations were often considered less significant).

Less trivial are the concerns that the proposal introduced a higher overall nomenclatural instability than the current status quo and that it may have set an uncomfortable precedent. The commission was being asked to choose between maintaining Drosophila for a smaller number (about 300) of species including some very well-known taxa, or a potentially much larger number (up to about 1100) of mostly less familiar species. Should "celebrity names" carry that much greater weight? Also, while the combination Sophophora melanogaster may be unfamiliar, there is no actual ambiguity about to what it refers.

Some commissioners, as well as many of the ICZN's press statements, raised the argument that "drosophila" could still be used as an informal name for Sophophora melanogaster. True, as far as it goes, and not unprecedented: names such as "azalea" and "cosmos" continue to be used despite the genera of those names being stricken from the technical literature long ago. Nevertheless, this is not anywhere near a satisfactory solution. As a corollary example, a number of recent authors have proposed restricting "Aves" to the crown group of birds on not unreasonable grounds. The supposed divide between technical and vernacular names has done nothing to dissuade people from objecting to the idea that creatures such as Archaeopteryx and Ichthyornis may no longer be "birds".

My thanks go to Kim van der Linde (first author of the proposal) and Elinor Michel (secretary of the ICZN) for sending me copies of the decision. Kim's own reaction to the ruling can be read here.

REFERENCES

Linde, K. van der, G. Bächli, M. J. Toda, W.-X. Zhang, Y.-G. Hu & G. S. Spicer. 2007. Case 3407: Drosophila Fallén, 1832 (Insecta, Diptera): proposed conservation of usage. Bulletin of Zoological Nomenclature 64 (4).

More in the Bloodsucking Vein (Taxon of the Week: Simulium)

Female Simulium feeding. Photo by maz_nat.

Blackflies of the genus Simulium (including several hundred species - see Adler & Crosskey, 2008, for a listing if you're really keen) are found around the world and familiar to most people for their blood-sucking habits. Like other members of the fly clade Culicomorpha, such as mosquitoes and chironomid midges, the larvae of blackflies are aquatic filter-feeders while only the females feed on blood as adults. In fact, blackflies (like other culicomorphs) are primarily nectar- rather than blood-feeders. Both males and females feed on nectar as adults and the females may require only a single blood meal to complete development of their eggs (Cupp & Collins, 1979).


Simulium larvae in a stream. The close-up photo is of the head of a filter-feeding larva. Photo from here.

Which is not to say that the role of blackflies as parasites is negligible. Askew (1971) refers to a plague of Simulium columbaschense in 1923 causing the deaths of nearly 20,000 head of livestock along the banks of the Danube. The most notorious blackflies are members of the Simulium damnosum complex of Africa (with one species, S. rasyani, in Yemen) which carry the human-parasitic worm Onchocerca volvulus. As well as the debilitating skin disease infection with Onchocerca causes in the majority of cases, approximately 250,000 people are rendered blind by Onchocerca infections every year. The various species of the Simulium damnosum complex are largely indistinguishable externally and require examination of their chromosome arrangements to be identified; however, different species differ significantly in their potential as Onchocerca vectors. Some 55 'species' have been identified in the complex, making it one of the largest known assemblages of cryptic species (Post et al., 2007).

REFERENCES

Adler, P. H., & R. W. Crosskey. 2008. World blackflies (Diptera: Simuliidae): a fully revised edition of the taxonomic and geographical inventory. http://blackflies.info/sites/blackflies.info/files/u13/blackflyinventory_2008_Adler___Crosskey_1.pdf. Accessed 23 March 2010.

Askew, R. R. 1971. Parasitic Insects. Heinemann Educational Books: London.

Cupp, E. W., & R. C. Collins. 1979. The gonotrophic cycle in Simulium ochraceum. American Journal of Tropical Medicine and Hygiene 28 (2): 422-426.

Post, R. J., M. Mustapha & A. Krueger. 2007. Taxonomy and inventory of the cytospecies and cytotypes of the Simulium damnosum complex (Diptera: Simuliidae) in relation to onchocerciasis. Tropical Medicine and International Health 12 (11): 1342-1353.

Name the Bug: Boreus

Boreus sp. Photo by A. Staudt.

Boreus is the main genus in the family Boreidae, a holometabolous insect family found in the northern parts of Eurasia and North America. Boreids are active during winter, when they are found among patches of moss on which they lay their eggs or on snow drifts between mossy rocks. Their apparent affinity for snow (the main source of moisture in the cold but dry habitats they prefer) together with their jumping movement gives them the common name of "snow fleas". Boreids also resemble fleas in effectively lacking wings - females lack them entirely, while males have the wings highly modified into a pair of large stiff hooks over the back (the individual in the photo above is a male). These hooks are, of course, useless for flying, but are used by the male in mating. As described by Cooper (1974): "An ardent male, when within some millimeters range, springs at the female, ensnaring her with his tong-like wings while seizing whatever he can of her extremities with one or both of his genital claspers". After the male's grip on the female has been secured (not always a simple process - see Cooper, 1974, for fuller details) and their genitalia have been conjoined, he may carry her about on his back in the mating position for several hours (the hook-wings are not actually used to hold the female while mating, only in the initial grab).

Most authors have included the Boreidae in the order Mecoptera, the scorpionflies. However, both molecular and morphological data have indicated that the Mecoptera as traditionally recognised are paraphyletic - from a phylogenetic perspective, the Siphonaptera (fleas) definitely and the Diptera (flies) possibly can be regarded as mecopterans. As a result, some authors have proposed restricting Mecoptera to a monophyletic core (the panorpoid families) and removing the families Boreidae and Nannochorista (a Gondwanan genus whose larvae are aquatic predators in streams of chironomid fly larvae) each to a separate monofamilial order. Both molecular and morphological data agree that the boreids are the sister group to the fleas (Grimaldi & Engel, 2005), making the name "snow flea" rather prescient. An alternative suggestion by Novokshonov (2002) that boreids are derived from the Palaeozoic family Permochoristidae is, as pointed out by Grimaldi & Engel (2005), rather weakened by the point that permochoristids are known only from isolated wings, making it somewhat difficult to understand how they could be compared to boreids and a relationship suggested in the first place.

REFERENCES

Cooper, K. W. 1974. Sexual biology, chromosomes, development, life history and parasites of Boreus, especially of B. notoperates, a southern Californian Boreus. II. (Mecoptera, Boreidae). Psyche 81: 84-120.

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

Novokshonov, V. G. 2002. Order Panorpida Latreille, 1802. The scorpionflies (=Mecaptera Packard, 1886, =Mecoptera Comstock et Comstock, 1895, +Neomecoptera Hinton, 1958, +Paratrichoptera Tillyard, 1919, +Paramecoptera Tillyard, 1919). In History of Insects (A. P. Rasnitsyn & D. L. J. Quicke, eds.) pp. 194-199. Kluwer Academic Publishers: Dordrecht.

"Electronic Publication of Nomenclatural Acts is Inevitable"

The Jurassic mecopteran Lichnomesopsyche gloriae, one of six new fossil species not published today. The black line is highlighting the long proboscis; the scale bar represents 10 mm. Image from Ren et al. (2009).

So sayeth Mike Taylor (for my own confused ramblings through the quagmire of electronic publication, read my earlier posts on the subject). And this day presents us with a spectacular demonstration of that point.

In a paper in today's issue of Science, Ren et al. (2009) have presented an analysis of Jurassic to early Cretaceous long-proboscid scorpionflies and their role as probable pollinators of nectar-producing gymnosperms (as has also been suggested for kalligrammatid lacewings). As part of this study, Ren et al. present descriptions of six new species and two new genera of fossil scorpionflies. Nothing out of the ordinary here, except that (Science being Science, with its notorious restrictions on article length) the species descriptions are published in the Supporting Online Material.

From the point of view of the ICZN, Science is a perfectly valid forum for publication - thousands of copies are printed every week. But these printed editions don't include the online supplements, so the online-only component of the journal is currently not a valid publication. Technically speaking, the new species of Ren et al. (which are referred to and illustrated but not described in the print version) are nomina nuda. They are not valid names. But these online-only names have not appeared in some far-flung unfrequented corner of the internet, they have appeared in one of the world's most prominent science journals (like it says on the label). Their validity is going to be pretty much taken for granted.

REFERENCES

Ren, D., C. C. Labandeira, J. A. Santiago-Blay, A. Rasnitsyn, C.-K. Shih, A. Bashkuev, M. A. V. Logan, C. L. Hotton & D. Dilcher. 2009. A probable pollination mode before angiosperms: Eurasian, long-proboscid scorpionflies. Science 326: 840-847.

More on Drosophila and Sophophora

Before I start this post, a public service announcement. This month, a group of bloggers have joined together to present an initiative called Silence is the Enemy. The aim of this initiative is to raise awareness about the epidemic of sexual assualt faced by women in war-torn parts of Africa, and also to raise awareness about the issues of sexual assault in general. As part of this campaign, all those websites connected to it will be donating their proceeds from the month of June to Médecins Sans Frontières, which is working as we speak to bring aid and comfort to women affected by sexual assault (as well as bringing aid in countless other ways to people around the world who would otherwise be unable to obtain proper medical treatment). Contributing sites include The Intersection, On Becoming a Domestic and Laboratory Goddess, Bioephemera, Adventures in Ethics and Science, Aetiology, Neurotopia, The Questionable Authority and Drugmonkey. Every time you visit one of those sites in the coming month, you help to raise revenue for an extremely important cause. So visit early, visit often.

Now, on to today's post:

Some of you may remember this post from over a year ago, when the proposal was put before the ICZN to make Drosophila melanogaster the type species of the genus Drosophila. For this post, I'm going to take that other post as read. At the present point in time, the ICZN has not yet voted on that application. But this does not mean that things have been sitting unremarked - quite to the contrary.

As well as publishing applications to the ICZN and their results, the Bulletin of Zoological Nomenclature also publishes comments from the general taxonomic public on cases being considered, allowing other workers to put forward their arguments for whether the commission should accept or deny an application. To be quite honest, this is usually the dullest part of the Bulletin. The majority of applications are fairly straightforward, and it is fairly uncommon for comments to say anything much more extensive than either "sounds good to me!" or "No sir, I don't like it"*. The Drosophila case, however, has inspired a barrage of commentary in the pages of the Bulletin to a level that has probably never been seen there before. The June 2008 issue of the Bulletin included nearly fourteen pages of commentary on the application. Some of these "comments" bordered on being full articles - Prigent (in the June 2008 issue), for instance, filled up three full pages ("no sir, I don't like it"), while McEvey et al. (also June) put their names on two and a half pages ("no sir, I don't like it, but it should probably happen anyway"). [Disclaimer: I haven't yet seen the March 2009 issue of the Bulletin, but apparently it's got even more comments to read.] So what have been the main points raised for and against the proposal?

*This is not to say that the comments are completely pointless - for a start, they're probably the primary means for the commissioners to gauge the popularity or otherwise of an application. Still, the vast majority of them are not particularly likely to become citation classics.

A common complaint has been that supporting the decision would be to support a particular classification or method of classification (or, to put it another way, "Oh noes! They be taking my paraphylum!") As stated by Thompson et al. (June 2008):

The proposal declares that the current concept of Drosophila is 'paraphyletic' and thus 'violates modern systematic practice'. That practice is cladistics or Hennigian systematics. For followers of 'evolutionary' systematics or phenetics, paraphyletic taxa are acceptable. Then there are the issues of the utility of large and small taxa (i.e. lumping vs splitting). We feel strongly that the Commission should not be endorsing one classification paradigm over another.

Some of you may have been struck by the gratuitous conflations of phylogenetic and taxonomic methodologies in the second and third sentences there*, but let's ignore those for now and move on, shall we? It would indeed be a strong violation of the ICZN's principles to judge between paradigms (though I've previously questioned the possibility of a truly paradigm-free nomenclatorial system). In this case, however, the Commission is being asked to do no such thing. Those authors who wished to retain Drosophila melanogaster and D. funebris (the current type species) within a single genus, whether paraphyletic or not, would still be perfectly free to do so - from their perspective, the case is largely irrelevant. Even if an author wised to divide up Drosophila by non-cladistic means, then odds are that they would still end up wanting to place D. melanogaster and D. funebris, because the two species are about as different from each other as any taxa within Drosophila could be - that's why they've been placed in separate subgenera in the first place - and then we'd be facing the exact same question. Indeed, it could be argued (whether validly or not) that the current situation is the one impeding taxonomic freedom, because no-one has been willing to take the step of removing D. melanogaster from Drosophila. So overall, the "no paradigm endorsement" argument is dead in the water from the outset.

*I'm not sure that a phenetically-derived classification really can be said to "permit" paraphyly - it's more that for phenetics, questions of monophyly vs. paraphyly vs. polyphyly become irrelevant.

The second major argument is that changing the type species increases the amount of taxonomic instability rather than decreasing it. Unlike the first argument, this one actually has some legs. As I mentioned in the earlier post, the current subgenus Drosophila is considerably larger than the subgenus Sophophora to which D. melanogaster belongs. Therefore, making D. melanogaster the type species of Drosophila potentially means that more individual species will end up undergoing name changes than if the type species remained D. funebris. Also, while D. melanogaster is the most commonly used Drosophila species in research, it is not the only species used in research. A significant number of other species have also come under the microscope, and some of these other model species (such as D. virilis and D. mojavensis) belong to subgenus Drosophila rather than Sophophora. On the other hand, many more model species (such as D. simulans and D. yakuba) are also members of Sophophora, so changing the type species preserves their names in their current combinations as well.

From a purely taxonomic viewpoint (as many commenters have stated), the answer is a simple one - the current situation is clearly valid under the rules, nomenclatural changes are a perfectly valid part of an developing taxonomic system, there ain't nothing wrong with Sophophora melanogaster, whaddya complaining about? Unfortunately, the reason why this case was proposed in the first place was that such a change does not only affect taxonomists. The case is most elegantly summarised, I think, by McEvey et al.:

The binomen Sophophora melanogaster would continue to convey a precise meaning, and in this sense there would be no confusion. [However] With respect to nomenclatural instability, there may be considerable reluctance to adopt the unfamiliar binomen Sophophora melanogaster and many would, no doubt, continue using Drosophila melanogaster, Drosophila or just melanogaster. And this would be confusing. Information retrieval would be hampered.

Thompson et al. claim that such fears of confusion are overblown, and specifically cite the case of the mosquito Aedes aegypti, widely studied as a major disease vector, which has been renamed and almost universally accepted as Stegomyia aegypti in recent taxonomic revisions. This was perhaps the most comic moment in the affair to date, because as pointed out by van der Linde et al. in the December 2008 Bulletin, Aedes-errr-Stegomyia aegypti provides a very strong argument in favour of the application. Taxonomists have mostly accepted the name Stegomyia aegypti, but almost everyone else working on the beast - ecologists, parasitologists, epidemiologists - has rejected it, and continues to use the name Aedes aegypti. A wide rift has developed between the two sides, making communication between disciplines increasingly difficult. One should never underestimate the holding power a name can have if it somehow catches the public's imagination. After all, we still witness the occasional trotting out of Brontosaurus, a name that was in proper use for less than twenty-five years and was sunk into synonymy more than a hundred years ago.

So ultimately the question is whether preserving the names of a smaller number of economically significant taxa is more important than preserving those of a much larger number of taxa of less direct significance to humans. And I have to admit, I'm glad I'm not one of the people having to make an actual decision on this one.

REFERENCES

Linde, K. van der, G. Bächli, M. J. Toda, W.-X. Zhang, T. Katoh, Y.-G. Hu & G. S. Spicer. 2008. Comment on the proposed conservation of usage of Drosophila Fallén, 1823 (Insecta, Diptera). Bulletin of Zoological Nomenclature 65 (4): 304-307.

McEvey, S. F., M. Schiffer, J.-L. Da Lage, J. R. David, F. Lemeunier, D. Joly, P. Capy & M.-L. Cariou. 2008. Comment on the proposed conservation of usage of Drosophila Fallén, 1823 (Insecta, Diptera). Bulletin of Zoological Nomenclature 65 (2): 147-150.

Prigent, S. R. 2008. Comment on the proposed conservation of usage of Drosophila Fallén, 1823 (Insecta, Diptera). Bulletin of Zoological Nomenclature 65 (2): 137-140.

Thompson, F. C., N. L. Evenhuis, T. Pape & A. C. Pont. 2008. Comment on the proposed conservation of usage of Drosophila Fallén, 1823 (Insecta, Diptera). Bulletin of Zoological Nomenclature 65 (2): 140-141.

Drosophila forever?

As I've commented before on this blog, taxonomy holds an unusual position in the biological sciences in that it fills two equally significant roles. On the one hand, it is a science in its own right, investigating the best way to describe and express the relationships between organisms. On the other hand, it supplies the means for communication between biologists in all fields. For the most part, these two aims compliment each other, but sometimes they can clash. The first aim implies continual change, as our understanding of the relationships between organisms changes and (hopefully) improves. Wheeler (2007) commented in a recent editorial that "Doing taxonomy as an independent science advances simultaneously both the aims
of taxonomy and its users", a sentiment that I agree with fully (be warned, though, that the general tone of Wheeler's editorial is fairly incendiary). To fulfil the second aim, however, a certain amount of stability is usually desired, as researchers who are not working in taxonomy may have trouble keeping up with the changes (or, for that matter, appreciating their necessity).

All of the codes of nomenclature have a central commission to regulate taxonomy - zoology has the International Commission on Zoological Nomenclature, botany has the International Association for Plant Taxonomy. One of the main roles of these commissions is to allow suspension of the usual rules in cases where their strict application would cause more trouble for communication than otherwise. In the case of zoology, applications for rulings on such cases that are submitted to the ICZN are published in the journal Bulletin on Zoological Nomenclature, allowing researchers the opportunity to comment on submissions before the Commission decides on them. One submission that appeared in the December 2007 issue of the BZN involves a case that could affect a large number of researchers in many fields - the impending revision of the fly genus Drosophila.

Drosophila is a very large genus, containing about 1500 species. However, phylogenetic studies (e. g. Robe et al., 2005) have found that Drosophila as currently defined is significantly paraphyletic with regard to a number of other genera in the family Drosophilidae. There are two options to resolve this situation. One is to sink all the smaller genera arising from Drosophila into the larger genus. However, this is not regarded as a suitable solution - not only would it leave Drosophila with over 2000 species, but it would result in over a hundred secondary homonyms (two or more species ending up with the same name as a result of change in genus assignment) that would require correction. The other option, that seems much more likely to be used, is to divide Drosophila into a number of smaller genera. The name Drosophila would then be restricted to a smaller group of species closely related to the type species.

All this would be fairly routine, except that one of the species affected happens to be one of the most widely used model organisms in genetics - the "fruit fly" Drosophila melanogaster (the inverted commas are because Drosophila isn't really a fruit fly proper, but a vinegar fly). So familiar is this species that many people simply refer to it as Drosophila without invoking the species name. One might be forgiven for expecting D. melanogaster to be the type species of Drosophila, but it's not. That honour goes to Drosophila funebris (shown at the top of the post in a photo from here). And as it happens, the two species are not that closely related. If Drosophila is divided up, the Drosophila melanogaster everyone knows and loves becomes a far less familiar Sophophora melanogaster. How will geneticists respond to the loss of their favourite organism?

To avert an apocalypse in evolutionary biology, van der Linde et al. (2007) have made a submission to the ICZN to redefine the type species of Drosophila. They suggest that that honour be given to D. melanogaster rather than D. funebris, meaning that D. melanogaster would remain forever more Drosophila. But if this is accepted, what will become of D. funebris and its close friends and relatives? Will the ICZN exalt D. melanogaster to the position of type species? Or will the geneticists just have to learn to refer to Sophophora, and like it?

REFERENCES

Linde, K. van der, G. Bächli, M. J. Toda, W.-X. Zhang, Y.-G. Hu & G. S. Spicer. 2007. Case 3407: Drosophila Fallén, 1832 (Insecta, Diptera): proposed conservation of usage. Bulletin of Zoological Nomenclature 64 (4).

Robe, L. J., V. L. S. Valente, M. Budnik & E. L. S. Loreto. 2005. Molecular phylogeny of the subgenus Drosophila (Diptera, Drosophilidae) with an emphasis on Neotropical species and groups: a nuclear versus mitochondrial gene approach. Molecular Phylogenetics and Evolution 36: 623-640.

Wheeler, Q. D. 2007. Invertebrate systematics or spineless taxonomy? Zootaxa 1668: 11-18.

A Queenage of Strepsiptera

Those of you wondering about the significance of the title to this post might want to check out the comments for last week's post on Embioptera. I noted there that a collective noun for Strepsiptera would arguably be one of the most useless concepts in the English language. In making that comment, I was referring to the fact that Strepsiptera, to the best of my knowledge, pretty never occur in noticeable groups. In fact, Strepsiptera are one of the rarest of all insect orders - so rare as to be almost mythical*. As such, their existence is not widely known by non-entomologists, and the discovery of a strepsipteran specimen is usually heralded by an unsuspecting research assistant looking down a microscope at a dish of unsorted survey specimens suddenly exclaiming, "What the f*** is that?"

*If you want a more concrete example, an ecological survey being conducted by colleagues of mine has so far collected tens of thousands of specimens - including about three strepsipterans.

Strepsiptera are endoparasites of other insects. The name means 'twisted wing', and you may also find them being called stylops*. Both sexes are parasitic as larvae, and after pupating the winged males leave the host in search of females (the picture above, from Tree of Life, shows a male Pseudoxenos leaving its wasp host. Ick). Mature males never feed, and may only survive for a few hours. The females, except for one primitive family, never leave the host, but remain in a larva-like form.

*By the way, 'stylops' is both the singular and the plural.



In the extremely unlikely event of ever seeing a strepsipteran, you can rest assured that they cannot be easily mistaken for anything else. The picture above comes from here, and shows a generalised strepsipteran male. Strepsiptera have only one pair of functional wings, with the front pair reduced to balancing organs called halteres. The only other insect order to possess halteres are Diptera (flies), but in Diptera it is the hind pair that has been altered (more on that later). The antennae are branched and antler-like. The so-called 'raspberry eye' of Strepsiptera is actually unique in the insect world, with many disjoint ocelli. It can be seen better in the photo below of Caenocholax fenyesi (by Steve Taylor, from here).



The larvae are produced viviparously by the female, and emerge from the host in large numbers (so maybe there is a use for the collective noun, after all). The first instar larvae (known as triungulins) are surprisingly advanced, with well-developed eyes and legs in order to seek out a new host. Once they have found a host and burrowed in, however, all these mod-cons are jettisoned, leaving the larva legless and grub-like. The presence of such distinct larval stages is referred to as hypermetamorphosis. At least one strepsipteran family, the Myrmecolacidae, has particularly unusual host preferences - the males are parasites of ants, while the females favour grasshopppers and crickets (Kathrithamby et al., 2003). I have not been able to find whether the sex of the larva determines the host, or whether the host determines the sex.

Phylogenetically, the Strepsiptera are arguably the second most difficult insect order - probably, only the Zoraptera can claim to have caused more problems. Still, there are two main competitors for the position of nearest strepsipteran relative. For a long time, the Strepsiptera were associated with the beetles, to the extent that some authors even suggested reducing them to a subgroup of the Coleoptera. This was mainly predicated on similarities between the triungulin larvae of Strepsiptera and certain Coleoptera families, some of which shared the Strepsiptera's branched antennae and hypermetamorphosis. However, these features are also found in other unrelated insect groups, and the chance of convergence cannot be dismissed. Molecular analyses, on the other hand, suggested a relationship between Strepsiptera and Diptera, leading to the radical suggestion by Whiting & Wheeler (1994) that the strepsipteran halteres might actually be homologous to those of Diptera, and their difference in position might be due to a homoeotic reversal switching the identities of the wing pairs! At present, it is difficult to imagine how such a thing could have happened without fatally scrambling the rest of the insect's anatomy in that area, and even if they are sister groups, the Strepsiptera and Diptera may have still evolved their respective halteres independently.



Male Stylops pacificus mating with female parasitic on bee. Photo by Edward Ross, from Tree of Life.

And why should a collection of Strepsiptera be called a 'queenage'? It should be noted that parasitism by Strepsiptera (known as stylopisation), despite the inherent ickiness of having a grub-like parasite protruding from your abdomen, is rarely fatal, and males and larvae can emerge without harming the host. Indeed, stylopised hosts may live longer than they would normally. However, stylopisation can have other significant consequences. Gonad development is reduced, and stylopised hosts may often be sterile. Stylopisation may also have a dramatic effect on secondary sexual characteristics of the host - stylopised individuals may lose their expected secondary sexual features and develop features characteristic of the other sex (Salt, 1927). Hughes et al. (2004) discovered that stylopised individuals of one species of wasp did not work in the colony as normal, but abandoned the colony and formed loose aggregations elsewhere.

Parasite-induced castration is not uncommon in invertebrates, and it is believed that it is advantageous for the parasite to sterilise its host because then time and energy that the host would otherwise waste on finding and winning a mate and producing offspring can instead be focused on feeding the host and hence the parasite (think about the behavioural differences between a neutered and entire cat). Colony desertion by stylopised wasps is probably also induced by the parasite (stylopised individuals were not driven away from the colony by uninfected individuals) as the chance of successful male emergence and mating was greater in the aggregations than within the nest, where healthy wasps would destroy any male strepsipterans they spotted.

REFERENCES

Hughes, D. P., J. Kathirithamby, S. Turillazzi & L Beani. 2004. Social wasps desert the colony and aggregate outside if parasitized: parasite manipulation? Behavioral Ecology 15 (6): 1037-1043.

Kathirithamby, J., L. D. Ross & J. C. Johnston. 2003. Masquerading as self? Endoparasitic Strepsiptera (Insecta) enclose themselves in host-derived epidermal bag. Proceedings of the National Academy of Sciences of the USA 100 (13): 7655-7659.

Salt, G. 1927. The effects of stylopization on aculeate Hymenoptera. Journal of Experimental Zoology 48: 223-331.

Whiting, M. F., & W. C. Wheeler. 1994. Insect homeotic transformation. Nature 368: 696.