Archive for July, 2010

Weekly Bits & Pieces: Oribatulid Leg-well Ornaments

July 23, 2010

A Dystopian Future Earth or on what a Zygoribatula rests its leg?

Although my postings have been infrequent, I think I’ve more or less reached my original goal of filling the mitey void left by the demise of the late UQ Mite Image Gallery with a set of false-coloured mite SEMs of equal or better quality and exceeded the original gallery in terms of scientific content (not to mention navel-gazing). Some day I will figure our how to use WordPress properly and have all of the images easily available for perusal without having to backtrack through all the omphaloskepsis, but until then I think I need to pay attention to Kaitlin’s point and try to post more frequently.

Since full-mite coloured SEMs take an extraordinary amount of time to compose, and I am flat-out fulfilling all of my other commitments, I’ve decided to start posting a few interesting bits & pieces of mites. I’m not sure that I even need to or should spend any time trying to tart these up with colour, because I find them extremely interesting just as they are. Well, I will let you all judge for yourselves:

Cerotegument in leg I well of Zygoribatula sp. 2

These images were grabbed at 18,000 magnifications and represent ‘ornamentation’ of what is called the cerotegument: a secretion alleged to be composed of waxes and proteins that coats the outer cuticle of oribatid mites. I thought that this ornamentation might be a useful taxonomic character in a messy genus, Zygoribatula, but other genera (Oribatula, Dometorina) in the family (Oribatulidae) have similar ornamentation.

Oh well, it is still interesting, but what is its function? The rest of the surface of these mites is covered with a more or less smooth and thin coating of cerotegument – presumably keeping water in the mite and other things out . But why these pedestals in the grooves where legs I are retracted when the mites are annoyed? (NB – much of the surface structure of oribatid mites can be explained as protection from predators grabbing hold of limbs.)

When I first saw this pattern, it reminded me of pictures in magazines of the pulp era showing cities of the future with interconnecting anti-gravity roadways: better yet, cities on some hive-planet of insectoid aliens (I prefer to think of our future in a more low density, back to nature, gardens in the sky kind of way). However, I am open to more realistic suggestions. I assume the flattened tops (maximum diameter about one half of a millionth of a millimeter) support the withdrawn leg and form an air chamber under the leg, but why?


And the answer is: Austromesocypris

July 20, 2010

Looks like peteryeeles from ptygmatics takes honours for this 2nd Electron Raster Challenge, or at least I agree with the first half of his rather broad hypothesis: Austromesocypris. Also, Koen Martens took a break during his most recent field trip to Australia to view the image and agrees (but points out dissection would be needed to determine the species). If you want to learn more about these fascinating terrestrial ostracods, then I highly recommend the 2004 paper by Martens and his colleagues, a wonderful combination of taxonomy, phylogenetic analysis, and zoogeography:

Koen Martens, Patrick De Deckker, Giampaolo Rossetti. 2004. On a new terrestrial genus and species of Scottiinae (Crustacea, Ostracoda) from Australia, with a discussion on the phylogeny and the zoogeography of the subfamily. Zoologischer Anzeiger 243: 21–36.

As for the blobs that have everyone stumped, you will have to take my word for it – rotifers – or at least that is what a few that I slided from a companion Austromesocypris turned out to be. The preparation for SEM was not very kind to them, but I thought they would make a nice link to the first Challenge and its spiny-headed rotifer gone monster. During the rainy season the forest floor is as wet as my garden in this torrential Alberta summer, which is extremely wet, so the rotifers may be commensals taking advantage of a mobile feeding platform. However, since this ostracod crawled out of a sample drying on a Berlese funnel, perhaps rotifers also engage in phoresy.

I know I have a few more Greyscale images of Austromesocypris somewhere on a cd, but since I can’t find them, I’ll just have to end this post with a tiny mite first described by the great A.D. Michael 125 years ago:

A mite found wandering the Meanook Biological Research Station in Alberta

Macromite’s Second Electron Challenge

July 4, 2010

Rainforest Electron Raster Mystery with Blobs

I spent my lunch break one day this week talking ant mites and looking over the amazingly diverse collection of laelapid mites that formed a significant subset of the 200 mite species that a graduate student has found on Ohio ants over the last few years. The conversation drifted to bug blogs and the usual adulation that one hears for Alex Wild from the ant-infatuated. Of course, I asked why would an mymecoacarophile mention Myrmecos before macromite? After the usual gushing about all the wonderful things on Myrmecos, this student pointed out that ‘Well, you don’t post very often you know.’

Point taken and given that I’ve been stuck in this bloody airport for the last 8 hours and it may be as long again before I’m home, might as well do some of that not very often blogging.

Here’s the second macromite challenge: what is it and what are those blobs on the outside? As a few clues to get you started I’ll tell you that the larger animal is terrestrial and not uncommon in soil and litter on the floor of subtropical rainforest in southeastern Queensland. The first time I saw one of these crawling across the floor of a live extraction container I was flummoxed and then amazed. But amazement and the Australian fauna are never too far apart.