Elysia patina from Florida

August 25, 2006
From: Sidney Pierce

Hi Bill
Attached are a couple of pictures (taken by my post-doc, Nick Curtis and colleague Ray Martinez) of one of several specimens of an Elysia that crawled out of Penicillus capitatus that I collected at Sunset Beach, Tarpon Springs, FL. They were either juveniles or an unnoticed egg mass when collected. They appeared in our lab aquaria a couple of weeks after the algae had been collected. I was collecting the algae for food for Elysia clarki, which does not occur as far north as Tarpon Springs. I've seen these guys before, but never paid too much attention to them as they are too small and too few for us to work on. We always have glibly identified them as Elysia papillosa. However, I'm wondering about that identification. I've looked at Verrill's original description (Verrill is a hero to me, by the way) and the Tarpon Springs specimens do not match his brief description of E. papillosa very well (except that they do swim!!) nor his drawing-even assuming some artistic license-(nor the Marcus' cartoons) nor do they look much like some of the pictures identified as E. papillosa on the Forum, especially some of those from the Bahamas. On the other hand, other Forum photos, in the E. papillosa group (eg. Anna Bass', K. Archer's, maybe Montoya's-from various sites in the Bahamas and Caribbean) look just like the Tarpon Springs slugs. Since Verrill's description of E. papillosa was based on ("rare") specimens from Bermuda and seems to be a closer match to some of the Bahamas photos-I initially thought the Tarpon Springs slugs might be a new species. However, I was watching some swim the other day and as the parapodia flailed away, two "gametolytic vesicles" were uncovered on the dorsal surface (see the photo). I have no idea what gametolytic vesicles are in a functional sense, but there are not many species of Elysia that have them-and E. papillosa does not as near as I can tell. Of those species that seem to have that structure, only the elusive E. patina, which Marcus described from a single specimen collected in the Keys, seems to fit (Jensen and Clark (1983) also reported collecting some at Key Largo, subsequent to Marcus' (1980) description, mostly without comment). I agree with your comments about the problems caused by describing a new species on the basis of a single, preserved specimen, which is exactly what Marcus did in this case. But maybe she was right?? What do you think??

By the way, these guys do eat and grow very rapidly on Penicillus capitatus (which is the alga in the picture) and, if they have a chloroplast symbiosis, it does not last long-maybe a week or two. You and others have noted that Kerry Clark predicted that E. papillosa was likely composed of more than one species - maybe E. patina is part of the confusion?? Or maybe I'm confused.

Locality: Sunset Beach, Tarpon Springs, just subtidal, Florida, USA, Gulf of Mexico, many times throught the year, on Penicillus capitatus. Length: 5-7mm. Photographer: Nick Curtis and Ray Martinez.

Skip

pierce@cas.usf.edu

Pierce. S. K., 2006 (Aug 25) Elysia patina from Florida. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/17468

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