Very cool! Congratulations on the range extension! It's funny how it almost seems obvious now that I/we know what it is, lol.

Thanks for your comments. They are very helpful. I went back with my friend and fellow naturalist, Mike Martinez to find more specimens. We found several with varying color patterns. Mike keyed it to Araneus pegnia using Levi 1973 and has sent it on to the California Academy of Sciences for further review. I am including a couple of views of two specimens with different color variations.

What a difference it makes to see the carapace. I'm thinking it may not even be an Araneus? Some of the other genera look much like this, like the Parazygiella, Zygiella, Metazygia.

See my comment above.

Although it bears a truly remarkable resemblance to Kim's photo, I have some doubts as to whether that species has a range within CA. Thus far, all of the photo submissions to BugGuide have been considerably east of here and this map showing collection localities from the reference The orb-weaving spiders of Canada and Alaska (Dondale) seems to also indicate a more easterly distribution. (Sadly, "Google books" does not give you access to the pages that follow, which might have elaborated further on the range/habitat issue.)

Mandy, as you study spiders with considerable more intensity than I, perhaps you would be interested in the candidates put forth in this list of CA spider species (which strives to be comprehensive, but I have been assured by the author that it is now in need of updating and definitely has some holes). Still, perhaps it is notable that A. thaddeus also does not appear on this list. I also note that A. marmoreus is not on the list, nor do we have any images from CA on BugGuide for that species. While A. trifolium is a good candidate to find in CA, it seems like all the images I've looked at show very prominent black/white banding on the legs, which I don't really see in Kim's photo.

So, with all that being said (whew!), I wonder if there isn't a similar-looking western counterpart to A. thaddeus that has yet to be identified on BugGuide yet?

Thank you, I'm glad that you brought that up, Harsi. I would have had it been me. lol. I need to stop 'loosely' suggesting ID's. I really was only saying that the spider resembled a thaddeus and that it also looked like a trifolium or a marmoreus. I hope I don't come across as 'defensive' or anything...that's not my goal here at all. I just thought I'd explain myself. I did read in a few places (the same places you read it seems, lol) that A. thaddeus seems to be more of an eastern spider (it's in fact listed as an Eastern Neacrtic species by the USGS of Manitoba). Then I also saw that if you scroll a little further down the pages of the Dondale source, there is an A. diadematus range map that is super out-dated (in my opinion). That species inhabits WAY more area than is listed on that map. The book came out in 2003 (I think?) so I was stuck turning the idea around in my head wondering how far they could've progressed in that time? I checked the Nearctic Spider Database and also the CA Spiders List that you also used...and saw no recorded evidence of A. thaddeus in California. But some little impulsive voice in me figured that if they can survive as far north as Manitoba, as far south as Texas, and as far west as Arizona and Utah...then why not California? Plus, Los Angeles County (where the spider was found) is practically across the street from Arizona.

In all reality though, as we all know, Araneus orb weaver patterns and colors can vary HUGELY, even within the same species. And of course we'd need an epigyne photo to be sure of anything at all. I hate to be pessimistic about this one, but (truly) we'll never know what she is.

...I had meant to respond yesterday. Regarding historical reference ranges for species, I am always willing to believe that these can change over time. So, that's certainly not a possibility I'm willing to rule out with respect to A. thaddeus.

You know, whenever I'm pretty sure that I've found a good visual match for a mystery arthropod, I just can't stop myself from wondering: Yes, but what about all those other species for which I can't find photos, but are also supposed to occur in my area?! For instance, based on that CA Spider List, there are 4 Araneus species (A. bispinosus, A. illaudatus, A. mariposa, and A. monica) that I can't find images for and remain mystery possibilities.

As you stated, it may be near impossible for those of us who are only interested in taking photos to get reliable species ID for most spiders, but (fortunately!) they are always fascinating to observe and there is always something to be gained and learned from the process of trying to obtain an ID!

I couldn't agree with you more! Especially on the subject of the 'unphotographed' species. Bug Guide only lists 28 Araneus species (not counting the five no taxon groups)...but as of 1973, there were 51 widespread Araneus species in the United States (Levi). I bet some of those haven't been fully described. And I'm pretty confident there's even more species that have been found in the last 36 years. It's like a scavenger hunt looking for spider articles by authoritative, experienced researchers. Sometimes it can take me a whole day's work to locate one single page of info that I wanted about one single species. lol.

I also love doing the research and trying to obtain an ID...but really how far can a person go for a spider whose identifiable parts aren't visible? I think that's why sometimes I suggest a species that they can match to on Bug Guide, rather than say something like "sorry, but we can't identify your spider and we'll never know what it is...unless you can take some microscopic photos for us." Lol, that's a little harsh I guess...but still true. I could be more of a 'Debbie Downer' and mention that I would estimate that nearly 30% of the BG spiders are probably misidentified due to lack of epigyne, chelicerae, palp, leg setae, etc. photos. I guess I might have just made myself come across as a grump...but I'm really not! :) Just stating some inner thoughts that were probably better left unspoken, lol.

I think you were on the right track of looking at spiders even if they are not identified in the range!

Thanks. It looks like that photo, but I don't recall the web. I will keep an eye out in the future. It certainly was unusual.