For reference I live in Northern California, US (North America), 2 hours south of San Francisco in a mountainous area with the Monterey Bay Pacific ocean being 15-20 minutes away.
I found two spiders last night that looked like Black Widow Spiders because it was dark and it scared me, one was almost in the house and the other was right outside. They look a little different, one if them looked more like a black widow and it was just coincidence that I started spraying under the house and the other one came out from hiding. The one that was hiding that did not alarm me as much is the one in the picture. The one that almost got in the house was darker but definitely did not have the red black widow marking.
I was able to spray them so they are intact and I put them in a container. After looking at them in the daylight they are probably Steatoda Grossa or the "False Widow Spider" but I want to make sure plus I have heard that even the False Widow Spider has an unpleasant bite and I also read about a Brown Widow? and I have two small cats that like to hunt and eat insects and spiders. I have included a picture of one of them. I also happen to be going up to San Francisco on Monday and might bring the spiders for further identification to a contact a made at the California Academy of Sciences that has helped me with some spider/scorpion identifications in the past. A quick answer would be sooo greatly appreciated as I am still freaked out.
-Erica from California
Yes, I would be inclined to agree with Steatoda grossa but I can't be certain because the photo's not too clear (sorry).
I was able to confirm with my guy at the California Academy of Sciences in the spider department about the two I caught that they are a Steatoda i.e. False Widow Spider. Big sigh if relief that a Black Widow was not inches from bring inside my house or near my cats!
Glad you got it sorted out.
Sorry for the delay in replying by the way - I normally leave Steatoda enquiries to others more familar with them than me. S . grossa hasn't got to my part of the UK yet.