Re: Elysia ornata and E. grandifolia

November 26, 2001
From: Kathe R. Jensen

Dear Bill, Lucas and Baki,

The Elysia ornata/grandifolia complex is a very difficult problem. In 1992 I published my anatomical studies on specimens from the Canary Islands, Phuket (Thailand), Guam and Western Australia. I had also studied specimens from Florida, when I was working in Kerry Clark's lab. I could find no consistent differences between Atlantic Ocean, Indian Ocean and West Pacific specimens, so I concluded that they were the same species.

In 1997 I had a postdoc. from India staying with me in Copenhagen for about a month. He brought specimens and photos of something he had tentatively identified as Elysia grandifolia. The specimens had been collected from Bryopsis, and he had studied chemical from both animal and alga, so no doubt about the food. The pictures, however, were indistinguishable from E. ornata. We then dissected several specimens and made SEM of its radular teeth. The anatomy was indistinguishable from that of E. ornata. BUT: the radular teeth were very finely denticulate. The reason I have not yet published anything about this is that Dr. K. Padmakumar from India also brought specimens of 2 species of Elysia from Caulerpa, one of which has a black line along the parapodial margins. We did publish an abstract about these 3 species (Phuket Marine Biological Center Special Publication, 19(1): 245-46 (1999).

Let me try to outline some of the confusion about this species complex: Elysia ornata (Swainson, 1840) was originally described as Thallepus ornatus from the West Indies and trasferred to Elysia by Verrill (1901). I don't think we will ever know exactly what Swainson described, but since Verrill an Elysia ornata (Swainson) has been recorded from many localities in the Caribbean. Kelaart described Elysia grandifolia from Ceylon (Sri Lanka) in 1858. The description was very brief and without illustration. Pease described a species called Pterogasteron ornatum from "Sandwich Islands" (Hawaii) in 1860. Again without illustration. Pease's illustrations were published in Bergh (1881), and the species placed in the genus Elysia. In 1871 Pease described Pterogasteron marginatus from Tahiti, and this was illustrated in colour by Garrett.
Eliot (1906) examined Kelaart's specimens and unpublished illustrations, and although the specimens were unlabelled, picked out one as E. grandifolia, and used it for dissection. He described a long renopericardial ridge with 7 pairs of dorsal vessels, and finely denticulate teeth. This corresponds more to a Caulerpa-feeding species. O'Donoghue (1932) described specimens from the Gulf of Manaar, which he referred to E. grandifolia. The figure of the teeth, however, shows blunt tips and rather broad, denticulate blades, as in Caulerpa-feeding specimens.

There has been a series of other records from different localities in the Indo-West Pacific, some reporting smooth radular teeth, others denticulate. Carlson & Hoff (1978) reported both E. marginata and E. grandifolia from Bryopsis in Guam. E. marginata had smooth teeth, E. grandifolia denticulate teeth. In my 1992 paper I list a number of species with black and/or orange (red or yellow) marginal bands, which should also be considered for synonymy in this species complex.

So, I think there is one circumtropical species with black and orange parapodial margins, black and white spots, pointed teeth with or without fine denticles, and feeding on Bryopsis. However, we do not know whether this species includes E. grandifolia, since Eliot's description of Kelaart's specimen may not have been the one Kelaart had assigned to E. grandifolia. He had also described E. punctata from the same locality.

I don't know if this has clarified anything. At least I need to look at more specimens from more localities before the mess can be sorted out.

• Jensen, K.R. (1992) Anatomy of some Indo-Pacific Elysiidae (Opisthobranchia: Sacoglossa (=Ascoglossa), with a discussion of the generic division and phylogeny. J. Moll. Stud. 58(3): 257-296.

Greetings,
Kathe

jensen@ait.ac.th

Jensen, K.R., 2001 (Nov 26) Re: Elysia ornata and E. grandifolia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/5727

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