I sent the pictures into the Spider expert (Brent Karner) at the Los Angeles Natural History Museum and asked him what the spider in the images was. He very kindly replied with this:


"The spider in the picture that you sent looks to be Araneus gemma, but to be sure I would have to get a look at some of the “naughty bits” that I can’t see in the pictures that you sent. It is certainly Araneus and because A. gemma is one of the most common, I would guess that that’s what you have. Telling spiders apart can be very difficult and often requires a bit of practice. It is usually something that comes with just seeing the same things over and over again and getting used to who might be who. Unless you capture certain spiders and put them in alcohol, some identifications can be virtually impossible. As far as our local orb weavers go, you will generally be dealing with either Neoscona or Araneus as you suggest."

I asked him how to tell the Neoscona and Araneus genuses apart and he replied with this:

"Without giving you the textbook descriptions (which deal with eye placement, median furrows, the epigynum and such), the best way is that if you have a Neoscona, you will have a spider with a nice rounded abdomen that has triangular patches in the middle near the base (where it attaches to the cephalothorax) when looking down at the spider. By default, almost any other large orb weaver will be Araneus. Most of our Araneus will also exhibit a pair of humps at the base of the abdomen and they often do not have perfectly rounded abdomens. Hopefully this is not too confusing."

Well, I was still confused, but I did go off looking for more similar spiders to see if I couldn't get a better picture. I didn't succeed at that but one thing I did notice was that there were quite a few very similar spiders but colored differently. I think whatever spider this is it might come in pink and putty gray. But I'm not sure.

Well he may certainly be right, but here are my thoughts on this particular spider.

1. I can see no visible 'shoulders' on the front of the abdomen. The shoulders are an indication of most Araneus. In gemma they are not as pronounced as some other species like gemmoides, and I suppose they may be hard to see from some angles or at some stages in the spider's development. See gemma here:

2. In Araneus there is a groove in the carapace that is transverse vs. the longitudinal groove of Neoscona. This feature is not visible in your images.
3. The ventral views of Araneus and Neoscona are quite different and would clear this up quickly, but again we have no ventral view here. You can see what I mean here.
4. Neoscona crucifera can look very similar to A. gemma. See crucifera here:


Please note the amount of long hair at the front of the abdomen. This is one feature that I think matches your spider well. However, I don't know how reliable that is.

So, I still think this may be crucifera, but I would love for you to go get more shots of this creature this year and prove to me that you have a population of gemma. We certainly need more gemma images for the guide.