Tiny ant-like web denizen - Tennesseellum formica

Moved

Moved from Spiders.

… Joe Lapp, 27 June, 2012 - 11:24am

Yes, Tennessellum formica

This specimen has a cheliceral stridulatory file, placing it in Linyphiidae. Keying through Linyphiidae easily lands me at Tennesseellum. Only one known species east of California puts this at Tennesseellum formica. It'll take an expert at working with such a tiny epigynum to determine whether this is actually an undescribed species.

I'm getting better at the scope images too. I added a bunch. The most important trick was to drop the alcohol level so that it just barely covers the specimen. Alcohol greatly distorts the image.

The specimen also matches the habitus description for Tennesseellum very well. The original description indicated that the abdomen was white with dark bands. Notice that only the very posterior is white in the original specimen, but that the alcohol has whitened the remainder of the red on the abdomen. Also notice that the alcohol solution has fleshed out the abdomen a bit to give it more of its original shape -- ant-like with a mid-abdominal depression. The epigynum, as far as I can make it out (only slightly better than the photo here) matches the drawing in SONA as well. This thing reads Tennesseellum all over.

… Joe Lapp, 27 June, 2012 - 11:23am

Voucher images

Very nice.

… Lynette Elliott, 27 June, 2012 - 5:30pm

Tennesseellum?

I betcha this is Tennesseellum formica. I now have a specimen to compare it to. I don't think I looked for a cheliceral stridulatory file. I assume the females have one too? I'll have a look.

… Joe Lapp, 20 June, 2012 - 7:43pm

Added image of sternum

I'm having trouble getting this to family. I'm not sure if it is an adult. There is a large lump where the epigynum should be and possibly copulatory openings, but the thing is way too tiny for me to be sure.

The critter has three claws and no scopulae. Check out the image I just posted of the sternum. There are triangular projections from the sternum *between* the coxae. These are not the precoxal triangles of Castianeira, which are behind the coxae and point *to* the coxae. Seems to me like this interesting character could be diagnostic.

… Joe Lapp, 10 February, 2012 - 1:34pm

Linyphiidae

Are you comfortable moving these to Linyphiidae?

… Lynette Elliott, 10 February, 2012 - 9:56am

I'm on my way to the lab right now. I'll bring this one along to have a closer look. Should be easy to ID at least to family under a good scope.

… Joe Lapp, 10 February, 2012 - 10:19am

Hi Joe, Do that. My own po

Hi Joe,

Do that. My own poorly considered hunch is theridiid, but as you all know my hunches sometimes go... "wide of mark". :-)

See if you can get a shot of that epigynum (if that's what is there).

… Kevin Pfeiffer, 11 February, 2012 - 2:30am

No comb

I looked carefully at tarsus IV and saw no comb. Setae appeared uniform across tarsus IV and metatarsus IV. Check out the new pictures I posted.

… Joe Lapp, 11 February, 2012 - 9:32am

The banded appearance of the abdomen is throwing me -- don't think I've ever seen anything like that.

… Kevin Pfeiffer, 11 February, 2012 - 11:24am

no comb

So sheetweb or dwarf spider?

… Lynette Elliott, 11 February, 2012 - 10:22am

No clue

I have no clue what it is, but I can send it to someone to find out.

… Joe Lapp, 11 February, 2012 - 2:16pm

Could you see under the micro

Could you see under the microscope whether it has a mature epigynum?

… Kevin Pfeiffer, 11 February, 2012 - 2:24pm

I couldn't be sure. There is a large structureless lump, which could just be an effect of the spider having been dehydrated. At probably 200x magnification I saw what may have been something very tiny with a little bit of structure where the epigynum would have been. You'd probably need 400x magnification to make sense of it.

… Joe Lapp, 11 February, 2012 - 2:33pm

Could be a plug, which sugges

Could be a plug, which suggests that it is mature.

… Kevin Pfeiffer, 11 February, 2012 - 2:44pm

My guess is something in Linyphiidae

I can't say for sure from looking at these photos, but that bulging sclerotized region you mentioned sure does look like an epigyne in the making. She's pretty dehydrated, so I wonder if that has a small part in making the area appear bulged out more than normal. Linyphiid epigyna are pretty straightforward in the adult stage so it should be easily recognizable after another molt. I know that some linyphiids do actually have a scape, but I'm not familiar enough with the family yet to know which species do or do not have them (the family is HUGE). I wonder what she'll look like after a couple springtails or fruitflies and some water? Water would be more important than food in this case. She'll need adequate hydration in order to complete her next molt. She won't eat if she's about to molt anyways.

She does also resemble a corinnid, though, but I don't know of any corinnds in your area that are this small (since she looks penultimate). Corinnids are only 2-clawed, whereas the linyphiids are 3... so because the scope didn't reveal a 3rd claw makes me wonder if this is indeed a corinnid? Sometimes the 3rd claws can be sort of hidden, sometimes by hairs and sometimes just by the angle they are being viewed from... and with such a tiny leg to maneuver, finding the 3rd one might be tough(?)

… Mandy Howe, 24 July, 2010 - 12:16am

Unfortunately, I've already b

Unfortunately, I've already bottled her. I couldn't see a third claw because my scope isn't powerful enough. I now have access to the scopes at UT, so I could take her there. I was guessing 3-clawed because she seemed much more at home in a web. After tonight's disastrous attempt to key a 2.5mm male one of these just to genus, I don't even think I'll try a smaller size.

… Joe Lapp, 24 July, 2010 - 1:05am

It looks awfully hairy for a linyphiid, and kind of reminds me of a corinnid - the posture, the abdomen. But I'll look again Monday when I'm at the museum. You'll prob have it solved by then

… Nina Sandlin, 11 February, 2012 - 8:39pm

Yeah, that thought resonates with me, too (hi, Nina -- except for the size). As has happened (to me) before, the dehydrated condition of the specimen doesn't help -- it can really throw off the visual appearance.

Joe, unless someone else steps up (is quite okay), you're welcome to send the specimen to me. Easier, though to send it to my sister in SD, where it would have to wait, though, until I am there in July. So if you want a faster resolution (assuming a resolution is possible), then someone else will have to volunteer.

… Kevin Pfeiffer, 12 February, 2012 - 1:19am

I might do that Kevin. Thanks

I might do that Kevin. Thanks! I also have a batch pending for Hank Guarisco, and I might just put it in there.

… Joe Lapp, 12 February, 2012 - 2:22am

Moved

Moved from ID Request.

… Lynette Elliott, 22 July, 2010 - 4:09pm