Archive for May, 2010

Of Knots & Worms Not: Gordialycus

May 23, 2010

In the last posting I mentioned some long and lean mites, but not having any good images of them, I used an interesting near-insect to test the 500 pixel width effect. In a month or so, however, I will be teaching about some of these mites (at The Ohio State University Acarology Summer Program) and I’m taking advantage of a very dreary Long May Weekend to start getting my lectures in order. Since I’m borrowing an image from a paper for my Power Point anyway, I thought I’d tart it up and trial it here.

The mite is the extraordinary Gordialycus tuzetae Coineau, Fize & Delamare Deboutteville and the picture originally composed by my friends Roy Norton, Anibal Oliveira, and Gilberto de Moraes for their 2008 paper reporting this mite, or an indistinguishable relative, from Brazil for the first time. The original image was composed from 3 separate rather low-magnification light-microscope micrographs – that is what it took to capture the entire animal. I’ve simply masked the mite and tarted it up in Photoshop with a less elongate and more mite-looking Speleorchestes species for comparison. The red arrows point to the tiny legs III and IV (just posterior is the genital slit).

Speleorchestes in its full glory - almost a quarter millimetre long

Both Gordialycus and Speleorchestes belong to the enigmatic Endeostigmata – a perhaps paraphyletic basket that includes the most primitive-looking acariform mites. Endeostigmatans are found throughout the World, but are especially prominent in very dry habitats or dry microhabitats within more mesic ones. Both hot and cold deserts (e.g. see the Nanorchestes I’ve posted on before) have more than their share of endeostigmatans. Members of the Nematalycidae are the most worm-like of the group, and Gordialycus by far the longest stretch, but being relatively elongate is normal for the family and not uncommon in other families of Endeostigmata.

 Gordia– is probably from the Greek for twisted or knotted – as in the famous Gordian Knot and –lycus possibly from the Greek for wolf. Since the gut contents of this mite have no solids, and no Alexander has yet come along to cut this not, we have no idea whether or not it is a predator. Haupt & Coineau (1999), however, have a hypothesis about how this mite uses the annulations of minute plates that ring its body to row its way through the deep sands in which it occurs. This particular mite was taken on a beach in Brazil – and deep accumulations of unconsolidated sand are where you will find this mite and its shorter relatives. Since the upcoming International Congress of Acarology is in Recife this August, perhaps the beaches there will be filled with acarologists trying to collect more of these spectacular mites – and maybe a few trying to figure out what they are doing while they worm their way through the sand.

 Species of Speleorchestes can be found on beaches too – but they can be found in a variety of habitats pretty much anywhere – my front yard, for instance. Speleo– probably refers to a cave and –orchestes possibly to dancing. Species of Nanorchestes can jump – as close to dancing as one might expect in a mite – and are tiny (nano-). I can’t remember ever seeing a Speleorchestes jump, but I can’t remember seeing any feed either. Alas, members of the Nanorchestidae also feed on fluids and so their foods are mysterious, although there is one report of a species munching on algae.

References:

 Coineau Y, Fize A, & Delamare Deboutteville C. 1967. Découverte en France des Acariens Nematalycidae Strenzke l’occasion d’aménagement du Languedoc-Rousillon. C. R. Acad. Sci., Paris 265: 685-688.

 Haupt J & Coineau Y. 1999. Ultrastructure and functional morphology of a nematalycid mite (Acari: Actinotrichida: Endeostigmata: Nematalycidae): adaptations to mesopsammal life. Acta Zool., Stockholm 80: 97-111.

 Norton RA, Oliveira AR & de Moraes GJ. 2008. First Brazilian records of the acariform mite genera Adelphacarus and Gordialycus (Acari: Acariformes: Adelphacaridae and Nematalycidae) International Journal of Acarology 34: 91-94.

Inspired by Myrmecos: Parajapyx

May 4, 2010

Parajapyx - another long, lean, post-crustacean

This posting was inspired by Myrmecos, a general lack of inspiration, and just wondering what a 500 pixel wide microarthropod might look like. Although there are some long, lean mites that might be more appropriate, Prolixus forsteri comes to mind, or perhaps the unbeatable long lean acarine, Gordialycus tuzetae Coineau, Fize & Deboutteville 1967 – which looks more like a giant nematode than a worm (for a light micrograph see*), alas, I have no pictures of them.

Really, I’m just tired of shovelling snow (~20 cm today, and it is well into May) and ready to veg out in front of the most recent Circus of the Spineless, so here’s one of my larger contributions, a ~ 3 mm long Parajapyx species from Queensland (where snows are few and far between). Not much seems to be known about these mini-diplurans. The monstrous Heterojapyx (~ 20 mm) make better pets, especially if you enjoy watching them catching collembolans with their posterior pinchers, twisting around their abdomens, and then eating the RSPCAless springtails alive, but are far too large to contemplate for the SEM.

Heterojapyx sp. -one of the largest living dipluran

*Norton RA, Oliveira AR & de Moraes GJ. 2008. First brazilian records of the acariform mite genera Adelphacarus AND Gordialycus (Acari: Acariformes: Adelphacaridae and Nematalycidae) Internat. J. Acarol. 34: 91-94.