[ID] Woodlouse

[Action_Man]

I think this is Platyarthrus hoffmannseggi,is this correct ? ...

[Pudding4brains]

Originally Posted by Action_Man

I think this is Platyarthrus hoffmannseggi,is this correct ?

No, sorry, it most certainly isn't : P. hoffmannseggi is small but wide, blind (no eyes!) and has very robust antennae. Compare maybe here (shouldn't upload here as mine are not British).

This one could also maybe be mistaken for one of the other "small whities" in the Trichoniscidea (Trichoniscus, Trichoniscoides, Androniscus, Haplophthalmus) but the antenna alone already make very clear that it isn't as these all have a thin pointed flagellum of many indistinguishable articles.

Actually, this one has me baffled for the moment. Only thing I can come with is something amazingly unusual/bizarre like "young albino Oniscus asellus".

Because of the tubercles it looks a bit like a manca Porcellio scaber on first sight, but it isn't. A manca is the first stage just after "birth" (walking out of the broodpouch) that is usually small and white and only has 6 pereion (thorax) segments. But even on these the eyes are black!

This one has seven full grown pereionites so it has shedded at least 2-3 times already and should really have clearly visible beginning colour (and dark eyes).

The tubular antenna with three small segments in the flagellum rule out all Porcellionidae and really make for a young Oniscus asellus only I think (the shape of the antenna/flagellum is clearly juvenile). The tubercles are quite prominent, which is also still usual on youngsters of this species and sometimes leads to confusion with Porcellio.

But if it is indeed a young Oniscus asellus it must be an albino! I'll double check with my distribution data, just in case I've overlooked something though.

It would be good if you had a size estimate (I'm currently guessing 4-5mm?) and maybe some location and time of year data with it. And do you have more images (even bad ones, maybe through e-mail if they're not "upload-worthy"). Or - much better - do you still have the animal??!

Very interesting beastie!! Thanks for posting it
Arp

P.S. You seem to have a patent on strange critters - live near a nuclear plant?

[Action_Man]

I think i live downwind of Sellafield .

This particular specimen was photographed on 2006:09:28, i`ve had it for a while and only just noticed it, your estimation of the size is about right from memory, and the location was under a rock in my garden.

And again from memory, i think i have seen several of these, so albino maybe out of the question.

I think i will catalogue the ones i have here in my garden, and see if any match up ...

[Pudding4brains]

Originally Posted by Action_Man

I think i live downwind of Sellafield .

Well, as a matter of fact I checked with my literature and there is nothing else listed, even for all of Britain that comes remotely close ... so, yes it is Oniscus asellus

This particular specimen was photographed on 2006:09:28 ... your estimation of the size is about right from memory, and the location was under a rock in my garden.

That all fits nicely for O. asellus too.

And again from memory, i think i have seen several of these, so albino maybe out of the question.

Well, this one must be an albino. Even the eye has some reddish pigment.

I've made a little collage:


The top row kids are about 1 week old and only about 2 or 2,5 mm in size. These are still "white", but (on some of them) you can clearly make out the black eye.

The bottom row kids are about 2 month old and more in the range of your animal, but probably even a fair bit smaller still (!) These were 3,5mm (4 max) and are also still a bit "fatter"/"clumsier" than yours. The colouration however is clearly already happening (and has been for a while!)

I have never found an albino of any species myself yet, but I have little (if any!) doubt that this is one. Also, I'm not 100% sure about the "genetics" of albinism in woodlice - it could possibly be that an entire or partial brood comes out as albinos (which would explain your perception of seeing more of them), but I will have to read up on that.

I would be very, very interested in seeing more images of this critter or it's family (or even a specimen). It should be a little bigger by now and even easier to recognize as O. asellus (shape, morphology).

Also would be interested in using the image(s?) on the woodlouse website I'm preparing - credits and copyright notice provided of course... (??)

By all means, do check if you can find any again!
Thanks in advance
Arp

[Action_Man]

Perhaps my memory isent as good as i thought it was, maybe i only saw the one specimen .

You can use the image if you like, no problems. I only have one more image of the critter, but its very similar to the other one.

I have learned something valuable the last few days, if you find something interesting, capture it. The Springtail that i let escape really bugs me, i have looked through hundreds and havent seen anything similar at all, i`m just hoping if there was one there should be many, unlike the Woodlouse .

I will upload a better picture of the Woodlouse for you later ...