Favoritos de nudibitch

Please leave at genus for now. Preliminary ID by @tgosliner is Catriona group of Tenellia species. Thank you also @jeffgoddard for your ID help.

They were not tiny -- all were between 15-25 mm long.

Non-scientific description:

Body was translucent white with no other markings. No foot corners that I could see.

Ceratal cores were brown with orange tips, with varying degrees of faint opaque white frosting on the leading edge of the cerata, ranging from virtually none on the smaller individuals to obvious on the largest individual.

Rhinophores were smooth with opaque white on the backside of the tips, with a small orange-red patch just below that (barely extended to the front of the rhinophore, so not really a "band").

Oral tentacles were about the same length as the cerata, with a red-orange patch on the leading edge that did not extend to the tip. As with the rhinophores, the oral tentacles had varying degrees of opaque white frosting on the leading edge of the cerata, ranging from virtually none on the smaller individuals to obvious on the largest individual. On only the largest individual, the opaque frosting extended into the head.

Found in rocky intertidal. I've been finding specimens of this species in the rocky intertidal of central California since 1968. As far as I know it is still undescribed. Photo scanned from 35mm slide.