Elysia cf. tomentosa Jensen, 1997 (37mm)
OPISTHOBRANCH OF THE WEEK
Opisthobranch of the Week Data
Frequency on Okinawa:
- Order: SACOGLOSSA
- Family: Plakobranchidae
[brackets indicate range for all Okinawa-collected specimens of the species]
- Individual Collection No: RFB #3320
- Location: Seragaki, Okinawa (26o 30.4'N, 127o 52.6'E) [Horseshoe Cliffs, Seragaki]
- Date: 18 November, 1994 [18 Nov '94, 11 Aug '98]
- Depth: 20ft (6m) [10ft, 20ft]
- Water temperature at collection depth: 74oF @10ft (23oC @ 3m)
- Size: TL 37mm [16mm, 37mm]
- Specimen deposited: California Academy of Sciences
- Photo Data: Original Kodachrome shot at 1:1
Elysia cf. tomentosa is considered to be very rare on Okinawa's main island as I have seen and collected only two individuals. The above featured animal was found crawling on the surface of mixed sand and coral rubble (it was not found associated with any alga). Clay Carlson in an old E-mail message (pers. comm., 12 Sept., 1998) mentions this to be found on Guam and that it's relatively common on Caulerpa racemosa but can be difficult to see.
The "cf." designation is being used here in as much as it has similarities to Elysia tomentosa, but at the same time it has apparent differences as well (notably the bright opaque white patch on the pericardium). There are several species of Elysia which have papillae on the parapodia which are close to Kathe Jensen's description of Elysia tomentosa (1997) but the above animal may well turn out to be an undescribed species. Kathe Jensen (2001) in commenting in the Sea Slug Forum mentions that none of her specimens had a white pericardium and goes on to say that the pericardium was completely covered by the parapodia in the living animals. Bill Rudman (2001) has a series of these animals having a opaque white patch on the pericardium
featured on the Sea Slug Forum.
I've added a second page illustrating two images of a second 16mm specimen.
- Jensen, K.R. 1997. Sacoglossa (Mollusca, Opisthobranchia) from the Houtman Abrolhos Islands and central Western Australia. In: F.E. Wells (ed.). The marine flora and fauna of the Houtman Abrolhos Islands, Western Australia: Proceedings of the Seventh International Marine Biological Workshop. Perth, Western Australian Museum, pp. 307-333. [publ. not seen by RFB]
- Jensen, K.R., 2001 (December 10). Re: Elysia tomentosa from Heron Id (2) [In] Sea Slug Forum. http://www.seaslugforum.net/find.cfm?id=5789.
- Rudman, W.B., 2001 (November 29) Elysia cf. tomentosa. [In] Sea Slug Forum. http://seaslugforum.net/elyscftome.htm.
Page Date: 29 Sep '03
Page Modification Date: 09 Mar '05
Digitally manipulated photo
Copyright © 2005 Robert F. Bolland