Wolf Spider problems - clypeus - grrrr

[MattPrince]

Hello,

having just got my first stereo microscope I was looking forward to getting to grips with lycosidae - wolf spiders - a group I've always struggled with previously.

So I bagged a female wolf spider as she was wandering around leaf litter in a damp section of old forest in Devon, and ignoring the fact that she wasn't mature (or at least the epigyne was obscured) took her home to have a look at under the scope.

here she is...


Now obviously identifying a live specimen is problematic, as I discovered when I ran into trouble trying to split out pardosa from non pardosa in the Roberts key - this uses the height of the clypeus - difficult to see from above.

With a bit of coaxing, I got a good view down onto the front of the spiders head ... and I'm still not sure about this clypeus measure.

Is it a lot easier to measure the clypeus height on a dead animal? Only it was very difficult to see where the clypeus stops and the mandibles start!

Or is there another way for splitting these groups without using this feature?

Initially this specimens Clypeus appeared quite deep, but most of this was actually moving mandible - so in the end her clypeus height would seem quite shallow which indicates non pardosa, but which didn't lead me to anything conclusive as per a family.

uggh!

Matt

[No.9 Spider]

The most reliable method for positive i.d. is obviously via palps/epigyne for most species. Although straight forward for some species there are still many species that are difficult even under the microscope, Tegenaria and some of the Lycosidae, and plenty of Linyphiidae for example.
Some of these look easy at first glance, either the epigyne of the specimen appears obviously distinct until you look at the rest of the drawings for the group. Differences are usually very subtle so you need to look very carefully for distinguishing features in the drawings and compare to that area on your specimen.
Most vitally, the actual position and viewing angle of the specimen is paramount. The genitalia of a specimen can look nothing like the depiction you are using (Roberts or Locket and Millidge) but the slightest movement of your specimen and you will see it, and I'm talking thousandths of a degree probably.
Unfortunately for the more difficult species, then dead is the only option. The specimen can be positioned and manipulated at will in the glass beads in your watch glass whilst immersed in the IMS (Industrial Methylated Spirit).
You have to remember that all the diagnostic diagrams by whichever author are drawn from specimens immersed in preservative and it does make a difference in the look of the epigyne/palp.

[MattPrince]

Here's a view of the underside, I wasn't sure if she was mature or not, it could be that the epigyne is obscured here by hair - in which case I take your point, a vodka bath may well have shown up enough structure to id to species, but in this case I just wanted to try and get her to family via the key, rather than clinch a solid identification.



So my problem was with the splitting of pardosa in the keys by ascertainig the clypeus height (my gut feel on the markings is that this is a pardosa) and I was frustrated by how difficult I found this character on a living animal, and not certain how easy it is on a dead one as the lower edge of the clypeus is not obvious, and I'm suffering from the usual beginners problem of how deep is deep if you know what I mean.

I've been given a little glass container to view specimens in by Mr Smithers no less (some lucky lot will be at a course of his tomorrow - muggins hear forgot to book ) all I need now is the glass beads and I'll revisit the clypeus issue.

Thanks,
Matt

[No.9 Spider]

Hi Matt, I'd seriously consider getting a copy of Locket and Millidge 1 & 2. Roberts is superb, but sometimes personally a little too detailed. You'll also need the large format of Roberts as the field guide version covers few of the Linyphiidae.

[Jason Green]

I can't help with the determination, but...

Originally Posted by MattPrince

...and I'm suffering from the usual beginners problem of how deep is deep if you know what I mean.

Certainly do, that's in the same series as 'Punctation dense' and 'Punctation not so dense', isn't it? Having just identified a good few of my sphecids in the last few days I sing the praises of 'comparative material'., without which I doubt I'd have been able to proceed with confidence. Take a series of Pardosa specimens that you plan to work on, then place them in a position where they are all in-line (in watch-glasses/vials, or whatever) on a strip of cork and showing the part you need, then slide them from left-right under the microscope. Once you become familiar with them perhaps after several views, divide them into two sets - one with comparatively-deep clypei, and the other shallower - and you'll have your answer.

Of course, if No. 9's suggestion of the further literature is the more reliable option then go with that, but my technique there may help if not superceded.

[MattPrince]

Thanks guys - all good stuff.

No 9 - I was looking at the large format Roberts the other day, wondering if I aught to buy it. I hesitated, but I'll no doubt get it at some point, needed or not its a seminal work and the full size illustrations are superb. I'm not familiar with the other book you mention so I'll investigate that.

I know what you mean about the almost OTT level of detail with Roberts, but to give his illustration their due - sometimes, perhaps due to the angle thing you mention - it just clicks - like last night when a leptyphantes palp lined up just right for zimmermanni - very satisfying.

I've just downloaded the BAS liny keys - haven't looked at them yet - I'll have a crack at a minimalist liny in due course

Geoff - agree comparative material is important, though with arachnids we have the added difficulty of mainly dealing with wet material, so not so easy to line up.

I also find the photo's on euro spiders (hopefully I can mention that here - its not a competitor to WAB after all) useful for comparison.

In the end - as with all things no substitute for a bit of everything - multiple guides - comparative material - well classified photo reference material - and last but not least - help from others.

I'll try Geoffs comparison suggestion in some form, once I've racked up a few lycosids (probably wait till next season) and see how it pans out.

Cheers,
Matt