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I found this spider near La Paz, Bolivia. I have been looking all over the internet to try and identify it, but with no luck. Could someone please help me?😁

Initially I thought that it was a black widow, due to the red marks and the body shape, but what threw me off is the lack of a distinct hourglass and the yellowish stripes in the middle of the abdomen. Also, the top of its abdomen is mostly red, much more than what is typical for black widows as far as I know. Also, the web doesn't look like a typical black widow web…

The locals told me that they think its a black widow, and that would probably be my best guess, but I'm not 100% convinced… if anyone knows, please let me know!😁

I have attatched 2 photos below:

enter image description here enter image description here

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Black widows (Latrodectus sp.) are in the Family Theridiidae, or Cobweb Weavers. Your spider's web is an orb web. Cobwebs are messy tangle webs while orb webs are the spiral-like planar polygon figure, sometimes completely vertical and sometimes at an angle, depending on which orb-weaving family made the web. So this spider is clearly not a Black Widow from the web alone. Further, your spider's legs are too short to fit the profile of a Latrodectus.

Searching iNaturalist records for Araneoid spiders (spiders that typically live suspended in webs) in Bolivia, we see the second most-commonly observed spider is one that is black and red.

enter image description here

The second-most observed spider here is from the Alpaida genus, which is in the orb-weaving family Araneidae. And looking at the hundreds of photos available for it, it does indeed build orb webs. However, the ventral markings in the photos of A.versicolor do not match your photos and the legs of A.versicolor are striped/banded while yours are not.

In many spider families, it is difficult to get an identification to species level through photos. But we can try: browsing those top 15 most-observed Araneoid spiders image in Bolivia, we see a number of species in this genus:

  • Alpaida versicolor
  • Alpaida veniliae
  • Alpaida carminea
  • Alpaida bicornuta
  • Alpaida rubellula

Some of these look drastically different from yours. But A. carminea matches the general shape, colour and ventral markings.

I am very confident this is from the genus Alpaida, and I lean towards A. carminea but it could still possibly be A. versicolor or some less-common species. A photo of the dorsal (top-side) markings would help distinguish these species.

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    $\begingroup$ Thanks! That makes sense😁 yeah, in hindsight I am very upset with myself that I didn’t get a picture of topside markings haha, but the spider’s web was very close to the ground. Anyways, thanks for the help! $\endgroup$
    – Henri
    Jan 5 at 12:05

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