Hi Art,
Nice pic! Much better color rendition than mine (http://striweb.si.edu/bocas_database/details.php?id=3155), and a good opportunity for a plug for the Bocas Species Database.
I first saw a picture 20 years ago of this worm on a fan coral off Puerto Rico and recognized it as undescribed. Since that time I've collected about 50 species of nemerteans in four 2-week trips to the Belize Barrier Reef, all the while being on the lookout for this unusually colorful character and failing to find it. Leslie may remember my excitement in finding it in Bocas del Toro two years ago, only to be told by a Panama veteran diver/invertebrate zoologist that this thing is common and often much bigger than the ones I was finding. Art's picture also looks to be of a larger individual. I did find it to be a weed species, being particularly fond of hiding among the epibiota on surfaces like dead coral rubble. Well, it is new and in process of being described. One of its remarkable features is an amazing length to width ratio. I had specimens in aquaria stretching themselves to less than 0.1 mm in diameter and over 50 cm long. From what we know of their closest relations, we can reliably assume that this is a predator... and that it can get into almost any space it wishes. The fantastic collage of almost fluorescent colors caused my younger associate to dub it "skittles" after a rainbow-colored candy (which meant nothing to me).
So, Art, would you be willing to part with one of your pics (with proper credit) for inclusion in our nemertean site (nemertes.si.edu) and on the Bocas site?
--Jon