Archive for April, 2015

An Empty Shell

April 25, 2015
Epicrius male gnatho

Under the business end of a male sejid mite

Macromite has been more than a bit of a slacker this last year or so, both scientifically (only one paper published – a record low) and in social media. I blame the latter on Facebook which has eaten all my social media impulses and regurgitated them into several-weekly postings on the fauna and flora accessible to my point-and-shoot camera. Alas, that does not include mites.

Epicroseius outside moult

The cast skin (exuviae – always plural, like clothes, so do not make the abomination of ‘exuvia’)

Also, I now live in the near outback: far from microscopes and internet access. My modem connection is both slow, expensive and unreliable and not conducive to rambling on about mites. That is a drag, but sometimes late at night the bandwidth is accessible and I am not asleep and that is true this post-ANZAC Day. Ergo, I would like to make a point about moulting in Mesostigmata that I don’t think  I have ever published: Mesostigmata moult forwards!

Epicroseius inside moult

Inside the glove: where the chelicerae and palps are extracted

Well, at least this species in the reasonably early derived (I would say ‘primitive’, but I know I would be stoned by the cladistically correct) Sejidae, or at least what I think is best attributed to an undescribed species of Epicroseius, moults this way. I know because I was able to culture it by feeding it nematodes (its’s progenitors came from a sample of wood mulch on the University of Queensland St Lucia campus). I think spiders moult the same way, but at least some members of the Acariformes go their own way. Possibly this may be phenological support for the lack of sister-group status between the two superorders of ‘mites’.

Epicroseius lateral

Epicroseius all grown up and undescribed

I do think that splitting the skin above the gnathosoma and other limbs is normal for Mesostigmata, but this hypothesis really needs to be tested against a variety of lineages. Meanwhile I will be wandering the back roads of Pie Creek, Qld, and learning to appreciate the larger charismatic microfauna including things like Clown Bugs – the habitat of Coreitarsonemus, the mites that eat the stink glands of leaf-footed bugs, or so it is asssumed!

Clown Bug Amorbus robustus 4th instar PieCk 2March15