I've added a couple more images.

i think Anoplius (Lophopompilus) cleora or aethiops... certainly looks the part being that hairy. i like calling it A. cleora, but it does not look to have that deeply emarginate clypeus. i would wait for Nick to give the final word. great pictures.

since it apprently has a very bristly apicotergite. I'm not going to go any further with it right now, being that it is from CA. If I had a specimen in hand it would be a different story. I'll have to do a little digging to get a species ID from a photo. I think the photos are probably good enough to do that, but it might take a little time since I'm not familiar with the local fauna. In any case, I CAN rule some things out. The emarginate clypeus is the primary character for Lophopompilus, not hairiness, so I seriously doubt it is aethiops or cleora. It's too big and dark and the wing venation is all wrong for the subgenus Pompilinus. It has a tarsal comb so the subgenus Anoplius is immediately ruled out. It's too hairy to be Notiochares and also lacks a clypeal emargination that is also characteristic of that subgenus. We're essentially left with Arachnophroctonus, but the only two species found in CA that are entirely dark are A. nigritus (=relativus) and A. xerophilus. It is apparently too hairy for nigritus and the eyes are way too convergent to be the very distinctive xerophilus (even being from CA I would have recognized that species immediately). I'll just have to look some things up, I guess. Unless the "spines" we are seeing is an artifact in the photo and we have the genus wrong. Larger, higher resolution photos would help. If these are sized down, maybe loading the originals will help (I can see that size...I don't think you guys can).

i was working under the impression the hairiness was a determining character of Lophopompilus... thanks for the correction. i guess i need some work on said genus. i have little idea what occurs in CA.

it is...it's just not the MOST important. A few species of other subgenera are occasionally nearly as hairy as Lophopompilus, so combinations of characters are more helpful. In other words, you're probably not going to find a "silver bullet" for identifying spider wasps, at least not in a genus as diverse as Anoplius. It's just a tough genus.

I can upload or email higher resolution photos (3872x2592). Those posted were downsized to 560 as per BugGuide guidelines. Should I try to upload or email directly? Thank you.

Tony Thomas has expressed the merits of submitting larger sized photos so editors or experts can make better IDs (or it will at least be easier). It's up to you. I submit very large photos all the time, but they are just diagnostic images and have little aesthetic value (unlike these). Once we get an ID you can probably re-submit the smaller ones in place of the larger ones. However, I think sending me the photos by e-mail would be easier than replacing these photos with different sizes two or three times...provided I can open any attached photos.