Yesterday I wrote this:
I've yet to find a centipede for the year, but I'm slowly working my way through the millipedes with this being the 6th species found so far. Nationally, there are many species of myriapod that I've yet to see, so it's definitely worth my while taking the time to key more of these through until I become more familiar with them.
Tonight I did my usual headtorch safari around part of the hotel garden and suddenly realised I'd never checked beneath the twenty or so boulders that are embedded in soil near the base of some trees. I heaved a few over, they really are quite well embedded, and spotted a small black staphylinid and a small white millipede. They both went into a pot and the first one to be checked was the millipede.
It was entirely white and around 6mm long. I noticed that the first abdominal segment failed to overlap the head and very almost bunged it away as being a juvenile Chordeuma (immature and hence not identifiable to species, but presumably C.proximum as per yesterday's examples). And then I noticed the complicated-looking gonopods with a couple of hooks on them. Hang on...so it must be a fully grown male millipede. A very small, all white male millipede at that. Blimey, and to think I almost discarded it! I opened up the millipede key and began. A closer look revealed rounded bumps or humps on the 'shoulders' of the body segments, I've never seen that before. Partway through the key to 'snake' millipedes, it dropped out as a 'flat-back' millipede. Oh right! I was very definitely in new territory with this individual.
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| This is the only meaningful image I took of the entire animal. Length is 6mm |
The ocelli were essentially invisible, though the key told me they were there. I adjusted the angle until finally I think I saw two, possibly three ocelli. Not at all easy. Initially I would have said it was a blind species, but the two choices given were a brownish animal with at least 10 ocelli arranged in a triangle and usually over 9mm in length, or a creamy white/amber coloured animal, less than 9mm and a single line of up to six ocelli.
The next part of the key asked if the ocelli were distinct and arranged in a line of 4-6, or were there up to 3 ocelli arranged in a line and very difficult to see. Er yeah, I'll go with the latter option! The key then advised that two difficult-to-key species drop out here and that novices should seek the help of an expert. So I messaged Mark Telfer, asking if he had any pics of the gonopods for the two species other than the illustrations shown in the key (I'd already looked and failed to find images online).
In the meantime I continued with the key. Essentially I had to dissect out the gonopods and align them in a certain position, allowing me to see if there were one or two pairs of projections at the front edge. The key went on to say that individuals of both species display variation in the form of the gonopods, and that even experts may find them difficult to distinguish from one another. Well I'd come this far, I wasn't being quailed by the wording in the final couplet of the key.
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| Probably the best of a bad bunch of images that I managed |
It is very difficult to reproduce in an image what your eyes see when you look down the barrel of a microscope. Partly because things resolve a lot easier using binocular vision, partly because you lose the 3D effect in an image and partly because the eye separates the various small parts as being individual pieces, whereas the camera just takes an image of whatever is in focus. It's frustrating, so you will just have to take my word that, at certain orientations, the various parts of the gonopods lined up and matched pretty closely the diagram for Brachychaeteuma bagnalli and didn't really resemble Brachychaetaeteuma bradeae very well at all, these being the two options given.
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| Penultimate stage of specimen preparation |
I successfully dissected out the gonopods (well, I basically destroyed the body segments all around them until all that remained were the gonopods and a fragment of the body segment housing them) and then orientated them until I could see them from directly in front as well as from above. The pair of large, hooked 'arms' were pretty obvious from most angles, but the pair of lateral extensions were surprisingly tricky to see until the orientation was just right. Then they were easy to see. I had the camera ready to take a picture, when a gust of wind came through the window and blew everything away. It's still gusting now, so much for the calm conditions of earlier. The gonopods, at a guess, measure about a third of a mm in diameter. I looked, trust me I looked, but I just couldn't find them.
Happy with my identification of Brachychaeteuma bagnalli, I checked BMIG and the Blower (1985) key, which had better illustrations than the key I was using, and then added the species to my PSL. It was only at that point that I realised that Steve Gregory, the myriapod god himself, is the only other lister to have recorded the species! Oh gosh, Mark Telfer hasn't seen it and there I was asking him for images of it. That's pretty shocking, I do hope I haven't offended him.
Anyway, that's seven species of millipede for the year so far. Still no centipedes, but they'll come soon enough I'm sure. My yearlist has crept up incrementally in the last 24 hours to 274 species (a noisy Barn Owl being the latest, about 20 minutes ago) compared to Ghostie's 115 species. My car is in the garage tomorrow, having the rear shockers replaced. Unbelievably, the rear box on the exhaust fell off today. I've notified the garage, but there's no way they'll have the part for tomorrow. Probably be another five week wait. Hopefully they can weld a collar on, or something, until a new one arrives and they can fit me in. I'm going to just wander the streets while I wait, see if I can't scrape up another 26 species to make it a nice round 300 in a week.