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enter image description here It never comes out during the day so it's been hard to get a decent picture. We have been battling over ownership of my mailbox. It's a house box and every morning it's covered in cobweb from it to the siding or across the top of it if the lid was left up. Very strong web, it takes effort to get it off. I was going to put up a new one with a sealed lid but would kind of like to know if it's poisonous before I go messing about the battle grounds.enter image description here

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Even with lightening your photo: enter image description here

It is difficult to ID this to genus. If you are only interested in knowing whether it is a medically significant spider, you can rest assured that it is not. The (few) markings and shape of it are enough to rule out widows and recluses.

From its shape and habitus, it is likely a cobweb weaver of some kind (family Theridiidae), but there are many possible choices for genus unless you can get a clearer photo. While black widows are also Theridiidae, the medically-significant female widows have solid black legs while we can see leg banding in this specimen. As @anongoodnurse points out in the comments, the legs here are shorter than a black widow's legs, so I would even rule out a male widow. The abdomen here is rounder shape than the tear-drop abdomen with a tapered end that a widow has. (Similarly, recluses do not have banded legs and do not hang in webs like this Araneoid is. And there are no other medically significant spiders you need to worry about in your geographic area).

The leg banding, general shape, and the slight white marking on the abdomen we can see in the lightened photo make this a little reminiscent of Enoplognatha marmorata (like this one https://bugguide.net/node/view/646186/bgimage). It is very rare to find Enoplognatha indoors.

Here is an example of an E. marmorata found in Indiana: https://www.inaturalist.org/observations/107343897

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  • $\begingroup$ It would be helpful if you could explain how/why you know it's not a widow-type spider, and even better if you could actually identify the spider. I'm not an arachnophobe by any means, but I would approach this one with some caution, as it's habitus is similar (though the legs don't appear to be as long.) Good answers on this site are backed by sources. Thanks! $\endgroup$ Sep 23, 2023 at 12:05
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    $\begingroup$ @anongoodnurse thanks - added additional info with my best hypothesis of a feasible ID. $\endgroup$
    – JimN
    Sep 23, 2023 at 14:31
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The globular abdomen, posture in the web and general shape certainly suggest a Theridiid. The glossy black body and banded legs are consistent with both the pretty harmless Steatoda species of "False Widows"and their more problematic cousins the Black Widows. In both cases, the abdominal stripes and leg bands fade to black as the female matures, and while it would be unusual, I bet that having an all-black abdomen and still have traces of the brown banding on the legs is not too uncommon. However, Latrodectus mactans, which I think is the more likely Black Widow species in Indiana, would be expected to still show some of the red spots on the abdomen at this point in its growth. So I'm leaning toward a Steatoda. Both are noted for strong webs, with the real Widows having a particularly strong silk; the simple ID solution is to check the underside - a real Widow will have the classic red "hourglass" marking, while a Steatoda will not.

The image below is Steatoda grossa, the bigger of the common "False Widows". Steatoda borealis females commonly feature a white midline on the back, but I'm not sure if the photograph shows a real feature or just an artifact of the flash.

enter image description here

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