June 27, 2000
From: Jeff Goddard
Here are two photos of an unidentified, 5 mm long, Stiliger I inadvertently collected with some Codium fragile and Elysia hedgpethi from 5 km south of Punta Rosarito, on the west coast of Baja California, Mexico last March. As in Placida dendritica (but not in the Stiliger sp. posted on Mike Miller's Slug Site), the digestive diverticula extend into the head, tail and rhinophores. The rhinophores of this Stiliger, however, are simple (instead of rolled) and are nearly one half as long as the body, much longer than in Placida dendritica.
I did not even notice this animal until nearly two months after returning to Santa Barbara, when I spotted it crawling upside down on the surface film of the water in the container holding the Codium. It may have laid some fertile eggs prior to my noticing it, but by the time I had isolated the slug to observe its egg masses, the eggs were infertile. Nevertheless, I was still able to obtain some information on its egg masses and mode of development. The egg masses were translucent, flattened, tight coils of a few turns. The eggs averaged 58 µm in diameter, were deposited one per capsule in capsules measuring 120 x 85 µm, and were surrounded in their capsules by a slightly refractile, grainy looking albumin or extra zygotic yolk. Eggs of this size, even with a little extra yolk, could only have produced planktotrophic veligers.
firstname.lastname@example.orgGoddard, J., 2000 (Jun 27) Stiliger sp. from Baja California, Mexico. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/2620
It certainly looks like one of the Placida dendritica group, but the simple unrolled rhinophores are a useful distinguishing feature. There is clearly still a lot of work to be done.