Immature female Latrodectus hesperus?? - Steatoda grossa

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Home » Guide » Arthropods (Arthropoda) » Chelicerates (Chelicerata) » Arachnids (Arachnida) » Spiders (Araneae) » True Spiders (Araneomorphae) » Entelegynae » Cobweb Spiders (Theridiidae) » Steatoda » False Black Widow (Steatoda grossa)

Photo#446918

Copyright © 2010 Jack Owicki

Immature female Latrodectus hesperus?? - Steatoda grossa

Pescadero, San Mateo County, California, USA
August 25, 2010
Size: 7 mm

This is one of several (max body length about 10 mm)individuals nesting near the ceiling of a utility shed. They all looked about the same: dark purplish brown with creamish markings on the abdomen. I only got a good look at the ventral abdomen of this one, and there's no red. The web is classic theridiid and is quite strong. With some effort I was able to photograph tarsus IV, and I think I see a comb (see later photo). The AM eyes are nearly fused (see later photo). The spider's eyes are quite reflective.

Whaddya think? Immature female western widow? There seems to be enough variability of the reported markings that I'm confused. Or maybe some sort of Steatoda, etc.?

Images of this individual: tag all

Immature female Latrodectus hesperus?? - Steatoda grossa

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Contributed by Jack Owicki on 25 August, 2010 - 6:32pm
Last updated 28 July, 2012 - 10:19am

Moved to Steatoda grossa

Moved from Steatoda. Based on your proximity to the coast & the purplish color of the spider I've moved this to S. grossa.

… Lynette Elliott, 28 July, 2012 - 10:19am

Moved

Moved from Cobweb Spiders.

… Jack Owicki, 26 August, 2010 - 10:53am

Yes, Steatoda; there are seve

Yes, Steatoda; there are several species. It's a common cobweb spider.

-K

… Kevin Pfeiffer, 26 August, 2010 - 12:44am

Thanks

The owner of the outbuilding where I found this thought they were widows. I can now advise him to the contrary.

… Jack Owicki, 26 August, 2010 - 1:03am

Hi, Jack,

This is a theridiid all right, but not Latrodectus. In that genus the outside pair of eyes (the posterior and anterior laterals) are separated by about the diameter of an eye. Your spider looks like a Steatoda sp. of some kind to me.

… John Sloan, 25 August, 2010 - 7:31pm

Not Latrodectus, but what about the comb?

Thanks much, John.

So, does Steatoda have a comb on tarsus IV? And do you think that what we see in the photo is a comb?

...Jack

… Jack Owicki, 25 August, 2010 - 8:04pm

Yes, to both questions. :)

… John Sloan, 25 August, 2010 - 9:48pm

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