Bradybaenids: The Little Freaks

Just a quick one this week, as I'm busy preparing for the International Conference of Arachnology in Taipei next week. The wonderful assembly in the photograph above (by B. Frank) is a congregation of the Asian tramp snail Bradybaena similaris. The Bradybaenidae are a family of small snails, closely related to the garden snails of the Helicidae, that are mostly native to eastern Asia. However, a few species such as B. similaris have become widespread around the world as a result of human transportation. Not deliberate transportation of the snails themselves, of course, but transportation of plants and plant matter that have had the snails clinging to them. Also, recent phylogenetic studies have indicated that the Australasian snails hitherto included in the Camaenidae are in fact not close relatives of the North American representatives of that family, but should be placed close to or even within the Bradybaenidae (Wade et al. 2007).

Euhadra grata gratoides, from here.

You may already be familiar with the production by some species of snail of 'love darts', small calcareous spears that a mating snail fires into its partner. The function of the love dart is still not entirely understood, though it does seem to improve sperm uptake by the snail being darted: whether by lowering its ability to resist insemination, or because snails are mini-masochists that get off on being stabbed, I couldn't say. Most textbooks describing the use of love darts will (at least effectively) base their description on the common garden snail Cornu aspersum (or Cantareus aspersus, or whatever the heck we're supposed to be calling it these days), which leaves its love dart embedded in its partner's skin. Bradybaenids whose mating behaviour has been studied, however, do things a bit differently. Instead of abandoning its dart after a single firing, bradybaenids withdraw the dart and use it to stab their partner repeatedly, making it more of a love shiv than a love dart. And when I say repeatedly, I mean repeatedly: mating pairs of Euhadra subnimbosa would, on average, stab each other with the dart over 3300 times (Koene & Chiba 2006). So vigorous is the stabbing, in fact, that the dart pierces straight through the recipient and emerges through its foot! For those with JSTOR access, a video of the process can be seen at http://www.jstor.org/stable/10.1086/508028. And trust you to go rushing to watch a film of gastropod SM.

REFERENCES

Koene, J. M., & S. Chiba. 2006. The way of the samurai snail. American Naturalist 168 (4): 553-555.

Wade, C. M., C. Hudelot, A. Davision, F. Naggs & P. B. Mordan. 2007. Molecular phylogeny of the helicoid land snails (Pulmonata: Stylommatophora: Helicoidea), with special emphasis on the Camaenidae. Journal of Molluscan Studies 73: 411-415.

All About Buris ensipes

Sunorfa, from here.

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

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

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

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

REFERENCES

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

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

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

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

Holometabolous When?

A few days ago, I asked you to guess the problem with this T-shirt (from here):

'Holometaboly' refers to the life-cycle found in insects belonging to the clade Holometabola (i.e. flies, moths, wasps, beetles, etc.), where the larval stage is significantly different in appearance to the adult stage, and the body undergoes significant reconstruction during an intervening, quiescent pupal stage. Some of you may be aware that thrips are not members of the clade Holometabola, being instead more closely related to the Hemiptera, the sucking bugs. Nevertheless, thrips can indeed be described as holometabolous, as they have evolved a pupal stage in their life cycle independently of the holometabolans. So my problem with the slogan 'Holometabolous before it was cool' is not with the use of the word 'holometabolous'.

It's with the word 'before'. The earliest known crown-group thrips, and thus the earliest known thrips that we can be reasonably certain was holometabolous (absent actual fossilised thrips pupae) is Liassothrips crassipes from the Late Jurassic (Shmakov 2008). In contrast, the earliest known crown-group holometabolans are stem-beetles and stem-neuropterans from the Early Permian, a good hundred million years or so before (Grimaldi & Engel 2005). Even if we open the gates to potential stem-group thrips (which may or may not have been holometabolous), that doesn't take us back any further than a potential tie with the Holometabola.

Liassothrips crassipes, from Schmakov (2008). Scale bar equals 1 mm.

So while thrips may be holometabolous, the possibility that they were so 'before it was cool' is fairly remote. Thrips are much more likely to have been late-comers to the holometaboly game.

REFERENCES

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

Shmakov, A. S. 2008. The Jurassic thrips Liassothrips crassipes (Martynov, 1927) and its taxonomic position in the order Thysanoptera (Insecta). Paleontological Journal 42 (1): 47-52.

Catalogue of Organisms on Twitter

Ok, so I've finally opened an account on Twitter, about five years after it was a Thing. For those looking, I can be found at @CatOfOrg.

Book Review: The World's Rarest Birds, by Erik Hirschfeld, Andy Swash and Robert Still

The World's Rarest Birds is a fairly self-explanatorily named new book from Princeton University Press, a copy of which was recently forwarded to me to review. Published under the auspices of the conservation group BirdLife International, this book aims to provide information on every one of the world's 650 (or so) endangered bird species. To gather material for this, we are told, an international photography competition was held, and the book features mostly new photographs of nearly 600 bird species. Only 76 of the species covered could not be illustrated by photographs, and all of these have been represented with paintings by the artist Tomaz Cofta. And the results are...well, just take a look at this:

This is an incredibly handsome book. Every page just absolutely pops with colour, a veritable kaleidoscope of flight and feathers. Hours could be spent contemplating the images presented. A mass of red-breasted geese take flight on page 51, a pair of Bali starlings imitate gossiping suburban housewives on page 10, a Laysan duck strides amongst a flurry of flies on page 186, and a gloriously draggy bare-necked umbrellabird sneers at the camera on page 247. The images are crisp and clear, and accompanied by authoritative text. Nor does the book drop the ball any with the individual species accounts:

Every species receives a representative illustration and a quick rundown of status, estimated population, primary threats (represented by codes explained in the introduction to the book) and distribution map, though in the case of population estimates the choice of model can make some seem a little spuriously precise (such as the estimated 2090 Uvea parakeets). A red or green arrowhead against each species allows the reader to see at a glance whether a species' population has been declining or recovering (sadly, all the examples in the spread above are declining). A brief blurb provides specific information, most commonly a further rundown of the primary threats. Each species also has a barcode that is supposed to take the reader directly to that species' page on the BirdLife International website where more extensive information is available (not having the necessary features on my phone, I wasn't able to test this myself). The book and species accounts are divided into sections by continental mass; where a migratory and/or wide-ranging species can be regularly found in more than one continent, it is represented in multiple sections.

The real highlights of the book, in my opinion, are a number of sections covering more overarching topics: particular geographic regions (as in the example above), or particular groups of conservation interest such as bustards, vultures, or migratory birds. These provide a more synthetic view of the challenges, pressures, and occasionally conflicting interests affecting conservation around the world. However, it is also with these sections that one wonders how well the book is achieving its stated goal of advocacy. There are few images in the book other than those of birds, and I personally feel that the summary sections would have been a suitable place for some pictures more directly conveying the threats involved. A few well-placed photos of land clearance, grazing damage, or hunting snares may have sharpened this book's impact.

My other complaints are fairly minor. Some of the photos chosen to illustrate species accounts may have benefited from captions clarifying details such a whether the individual(s) shown is male or female, or where the photo was taken. The text's practice of consistently capitalising terms referring to formal conservation categories such as 'Endangered', 'Critically Endangered' or 'Extinct in the Wild' together with vernacular names, and of insistently providing the conservation status of each species when mentioned (never just 'the White-backed Vulture', but 'the Endangered White-backed Vulture'), can feel a bit heavy-handed at times. It can be hard not to read certain sentences as if Punctuated. For. Emphasis.

There is also the question of price. In an ideal world, one would not quibble at paying for quality, but sadly this world is not ideal. And so, having seen how much this book is awash with colour, how much effort has evidently gone into compiling it, it is with trepidation that we ask: how much?

And as it turns out, the list price is just $45 US. So if nothing else, the price of admission alone makes this worth it.

Quick Quiz

Recently, this has been seen doing the rounds on the interweb:

My first thought: clever. My second thought: hang on, there's something wrong here. Anyone care to guess what it was?

The Stone Mantis

Lithomantis carbonarius, as illustrated by Woodward (1876).

In 1876, Henry Woodward published the description of a large fossil insect found in a Scottish clay-ironstone nodule. This insect, when alive, would have had a wingspan of well over ten centimetres: Woodward measured the longest preserved wing at two and a quarter inches long, and a sizeable piece of the end was still missing. Believing it to be an ancient relative of the modern mantids, he named it Lithomantis carbonarius, the 'stone mantis from a coal measure'. Woodward's interpretation of his new fossil was to prove incorrect: it was not a mantis, but a member of those spectacular wonders of the Palaeozoic, the palaeodictyopteroids. More specifically, Lithomantis has been placed in a group of palaeodictyopteroids distinguished by Sinitshenkova (2002) as the Eugereonoidea.

Reconstructed wings of Lycocercus goldenbergi from Kukalová (1969), showing the overlap between the fore and hind wings; note also the bold colour patterning (often preserved in insect wings).

The palaeodictyopteroids are a group long overdue a truly comprehensive revision, and many aspects of their higher classification remain debatable. Of the current default classification, that of Sinitshenkova (2002), Prokop & Nel (2004) somewhat snarkily commented that, "Sinitshenkova’s classification cannot be considered based on the cladistic method, even if it uses the cladistic terminology". Nevertheless, Sinitshenkova defined the Eugereonoidea by a number of wing characters: wings that were about 2.5 times as long as broad, a subcostal vein reaching the costal vein near the wing apex, medial and cubital veins with little-branched anterior forks but much-branched posterior forks, and a tendency for the archedictyon (the net-like array of veinlets running amongst the major wing veins in palaeodictyopteroids) to become simplified or replaced by direct cross-veins. Members of the Eugereonoidea are known from the Upper Carboniferous and Lower Permian (Sinitshenkova 2002; Prokop & Nel 2007) and, like other palaeodictyopteroids, would have inhabited tropical latitudes in life.

Wings of the eugereonid Peromaptera filholi, from Kukalová (1969).

Like other palaeodictyopteroids (and, indeed, many other Palaeozoic insect groups in general), Eugereonoidea are mostly known from fossils of the wings, but those that are more completely known are large-bodied insects with relatively long sucking beaks. One species, Eugereon boeckingi, had a beak over three centimetres long; that of Lithomantis was a bit more restrained at only just over one centimetre. They used these impressive weapons to attack the stems of the ferns and seed ferns of the time in search of sap. Other palaeodictyopteroids, including the eugereonoid Lycocercus goldenbergi (Kukalová 1969), had much shorter beaks, and would have probably fed from spores or seeds. Eugereonoids had fairly broad-based wings with the fore and hind pairs of wings originally little differing from each other. The pronotum bore well-developed paranotal lobes that have lead to descriptions of these insects as 'six-winged'; though the pronotal lobes could not actively flap in the manner of true wings, Wootton & Kukalová-Peck (2000) suggested that they were somewhat movable, and could have been used to stabilised pitch. In the family Lycocercidae, the two pairs of wings overlapped to a degree unknown in any living insects; in Notorhachis wolfforum, the forewings overlapped the hind wings almost entirely. As argued by Wootton & Kukalová-Peck (2000), these species would have flown quickly but with relatively little manouevrability, like insectoid turkeys. In contrast, members of the families Eugereonidae and Megaptilidae developed relatively long narrow forewings followed by shorter, broader hind wings. Like modern insects with comparable wing morphologies (such as bees and butterflies), members of these families probably beat the two pairs of wings in concert, and would have been more manoeuvrable compared to the lycocercids. However, with an estimated wingspan of over a foot, the eugereonoid Megaptilus blanchardi was by far the largest insect ever known to develop this mode of flying.

REFERENCES

Kukalová, J. 1969. Revisional study of the order Palaeodictyoptera in the Upper Carboniferous shales of Commentry, France part II. Psyche 76: 439-486.

Prokop, J., & A. Nel. 2004. A new genus and species of Homoiopteridae from the Upper Carboniferous of the Intra-Sudetic Basin, Czech Republic (Insecta: Palaeodictyoptera). European Journal of Entomology 101: 583-589.

Prokop, J., & A. Nel. 2007. New significant fossil insects from the Upper Carboniferous of Ningxia in northern China (Palaeodictyoptera, Archaeorthoptera). European Journal of Entomology 104: 267-275.

Sinitshenkova, N. D. 2002. Superorder Dictyoneuridea Handlirsch, 1906 (=Palaeodictyopteroidea). In History of Insects (A. P. Rasnitsyn & D. L. J. Quicke, eds) pp. 115-124. Kluwer Academic Publishers: Dordrecht.

Woodward, H. 1876. On a remarkable fossil orthopterous insect from the coal-measures of Scotland. Quarterly Journal of the Geological Society of London 32: 60-65.

Wootton, R. J., & J. Kukalová-Peck. 2000. Flight adaptations in Palaeozoic Palaeoptera (Insecta). Biol. Rev. 75: 129-167.