Location not in error. This is a recently described disjunct population in Santa Clara Co.
This looks a lot like the lichenmarked orbweaver (A. bicentenarius), but that's supposed to be an eastern species. Could it be some variant of A. saevus? But A. bicentenatius looks closer, judging by Bradley & Buchanan (CSoNA).
Body length ~12 mm
Seen amid lichen on the trunk of a coast live oak tree, above its orb web. It was about seven feet above the ground, so a bit hard to see and photograph. And in a preserve, so no collecting allowed.
About 3 mm long, near mouth of harvester ant nest (Vermessor, formerly Messor).
Probably M. oregonensis based mostly on location, but maybe M. manni or something similar.
Barely active in the cool afternoon.
Golden Aster Heterotheca sessilflora ssp echioides. Open grasslands. Only know stand on the Preserve