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Tiny colorful theridiid - dorsal - Theridion llano - female

Tiny colorful theridiid - dorsal - Theridion llano - Female
Austin, Travis County, Texas, USA
August 8, 2014
Size: 1.5mm
Found on the dead flowerhead of Monarda (beebalm). I'm having trouble placing to genus. Some notes:

(1) Labium is triangular and not distally swollen, indicating Theridiidae.
(2) Fangs are long and thin, suggesting Euryopis or Dipoena, but seemingly not as long as shown in SONA figure 62.50.
(3) I do not see colulus or 2 replacement setae.

Images of this individual: tag all
Tiny colorful theridiid - dorsal - Theridion llano - female Tiny colorful theridiid - posterior - Theridion llano - female Tiny colorful theridiid - eyes - Theridion llano - female Tiny colorful theridiid - venter - Theridion llano - female Tiny colorful theridiid - side - Theridion llano - female Tiny colorful theridiid - ventral - Theridion llano - female

Moved from Spiders.

I don't know about ...
the finer details in keying it out to genus however the general appearance made me think Theridion and the epigynum and some of the other details are similar to what I see for Theridion llano. My resource isn't too recent though (H.W. Levi. 1957) so I don't know if I'm missing any other similar options.

TAMU collection
Okay Laura, Chad, I've heard from a few arachnologists about these photos, including Allen Dean at TAMU, who maintains the Texas checklist.

Allen says, "this appears to be Theridion llano," and is similar to the specimens that he has been labelling T. llano in the collection.

Others are suggesting that we not put so much weight on color pattern or eye sizing and spacing. There are a number of similarities, if not an exact match to the species description. Odds are that this specimen falls within the variability of the species, as both of you are suggesting. This is a difficult concept for software developer me to understand.

Thanks for all your help!

I like the give and take that goes along with identifying something that none of the debaters actually is familiar with. This was a great discussion and I'm happy that the result was a new species for BugGuide. Keep up the good work!

That's great that you were able ...
to get experienced outside opinions, I was wondering who the best person to contact would be. Definitely frustrating the way some descriptions are written. Pretty spider!

Thanks Laura. I have a copy of Levi's 1957 paper on Theridion. T. llano does seem to the best match of all the drawings, but this specimen doesn't satisfy the description he gives. In particular, he says that the carapace and legs are white, while the abdomen is "dusky" with an "indistinct median white band." He also says that the epigynum is a depression, whereas this one is a super-serious bulge. Thanks for checking the Theridion options, though!

Just weighing in...
First, I'll say I have no experience with this species and Texas is far away from my area of expertise (MN). I think you have the family right and would have to look at the spider in hand for keying it out; I'll trust your work with SONA.

When I look at this spider, it strikes me as Theridion. I looked through Levi's treatment of the genus and arrived at the same species as Laura: T. llano. Again, I have no experience with this species. It is simply the only one that has the broad, U-shaped scleritization on the epigynal plate. I think that Levi's drawings are very 2-dimensional and therefore it is difficult to determine depth; perhaps there is a bulge.

Here are the characteristics that seem good for a match: 1) Carapace is white(ish) with dusky median and marginal bands 2) Legs are white(ish) with reddish spots at the middle and ends of leg segments 3) there is a thin red line on the dorsal surface of the first pair of legs of your spider (may be a variable characteristic) 4)epigastric furrow has two white spots--one on each end 5) Eyes reddish and separated by the appropriate distances.

I'll admit that Levi's description of the abdomen leaves me wanting more details. What is an "indistinct median white band"? If we assume that yours has a median white band, like many of the other Theridion species, yours is very indistinct, being separated into pale circles. The marginal pale areas are also perplexing.

I've learned that there is a lot of individual variation within species and it helps to approach unknowns with some flexibility. I like this one for T. llano, but would like further data. Can you get a picture of the sternum? Levi mentions a couple of additional characteristics about that and the venter. Can you also get to this genus using SONA?

It's a pretty spider and clearly one of the species in North America which we know very little about. That's where BugGuide is really pushing things forward.

comparing with T. llano
Thanks for looking into this. I added a photo so you could see the large bump of an epigynum. If I were more confident that I wouldn't smush this tiny critter while trying to examine fangs and teeth, I might be able to provide more data. For now, let's compare Levi's description of the female Theridion llano. There are many possible similarities. First, I think we need to define the to possible white colors. One is the white we see in the above photos ("above-white"). The other is the relatively transparent pale we see.
  • "carapace white, with median dusky band and dusky margin" - This matches if Levi's white refers to the transparency, and if "dusky" can also be dark. (MAYBE)
  • "eyes reddish" - The eye protuberances are reddish. (YES)
  • "sternum white, with dusky spots along margin" - This matches if Levi's white refers to transparency and "dusky" can also be dark. (MAYBE)
  • "legs white, with ventral and reddish spots at middle and ends of segments" - This appears to match only femur 1 and tibia 4. (MAYBE)
  • "legs... with... red line on dorsal surface" - matches tibia 1 only (MAYBE)
  • "[dorsal] abdomen dusky, with an indistinct median white band" - This specimen has red-encircled yellow spots enclosed in some white spotting. (NO)
  • "venter darker dusky except for area behind epigastric furrow which is whitish or has a pair of white spots" - This venter is actually generally lighter than the dorsum. It has white posterior to the epigastric furrow whether white is transparent or spots; but if the white spots were to define what Levi means by "white," none of the previous "maybe" matches would match, because they assumed what was the transparent color. (YES)
  • "anterior median eyes one and one-quarter diameters apart" - They appear to be less than one diameter apart. (NO)
  • "anterior median eyes... one-quarter of a diameter from laterals" - The AMEs are virtually touching the ALEs. (NO)
  • "posterior median eyes one diameter apart" - They appear to be just over half a diameter apart. (NO)
  • "posterior median eyes... three-quarters of a diameter from laterals" - This depends on whether Levi is including the apparent tubercles. Including the tubercles, the PMEs and PLEs are virtually touching. Excluding the tubercles, they appear to be at least one diameter apart. That's a broad range of possible separations, depending on interpretation. (MAYBE)
  • "anterior medians slightly smaller than others" - They appear to be equal in size to the ALEs and PMEs, while the PLEs appear smaller than the others. (NO)
  • "epigynum a depression with posterior and lateral borders" - the epigynum *includes* a depression with posterior and lateral borders, but the entire epigynum is actually a rather large protrusion, per the image I just added. This may be ambiguous language. (MAYBE)
That's 2 YESes, 6 MAYBEs, and 6 NOs. Of course, these characters aren't all equal in value, but the characterization of the epigynum is somewhat ambiguous. Does Levi mean to preclude a strongly protruding epigynum? Or does he only mean to characterize the ventral aspect of the epigynum? Theridion llano does appear to be a close match, and this specimen could be within variability of the species, but I don't think we have a good enough match to the description to confidently call it a match. It could be something else; it could even be something undescribed. I'll make another attempt to positively key the genus.

I just posted a stacked ventral shot. Unfortunately, the entire sternum is a dusky brown, dropping one of the YESes from above.

On the other hand, metatarsus 1 is also dorsally striped, improving the matching to Levi's words "legs... with... red line on dorsal surface."

I attempted to get a better look at the fangs and teeth. The fangs are very long and thin, and I could not find any teeth. I did not get a good look retrolaterally, though.

I cannot resect the epigynum. My attempt to set things up for this operation made it clear that I would destroy the spider were I to proceed. I'm not skilled enough to work with a 0.3mm epigynum on a 1.5mm spider.

I also scanned revisions for other possible genera as indicated by SONA, and the drawing for Theridion llano remains the best match.

Notice also that the translucent portions of the spider are turning white in alcohol.

The problem with trying to identify spiders from pictures, even good pictures, is that you just can't see the details. I like your approach. While I suspect this is still T. llano, I wouldn't say that for sure. If you key it out again and get to Theridion using SONA, the only epigynum that matches (in Levi, 1857) is this species (unless we want to start arguing for a new, undescribed sister taxon). Keep in mind that Levi was looking at 3 individuals, 2 of them male, when he described this species. Who knows what variation occurs in the much larger population. I look forward to seeing how this plays out.

Out of curiosity, where are you getting the specimen count that Levi was using? Under "type locality" he mentions one male, and under "records" he mentions two females.

Ah yes
Me without coffee. I was just looking at his type locality specimens. Perhaps that should have read: 2 males and 3 females (still a very small sample size).

Moved from ID Request.

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