OKINAWAN
OPISTHOBRANCH OF THE WEEK
Elysia amakusana Baba, 1955 (4mm)
Photo by Atsushi Ono
Opisthobranch of the Week Data
Taxonomy:
- Order: SACOGLOSSA
- Family: Plakobranchidae
Frequency on Okinawa:
- Very rare (none seen on Okinawa's main island, only a single animal seen in the Keramas)
Collection Data:
- Individual Collection No: Atsushi Ono, photo only (without specimen)
- Location: Aka Island, Kerama Islands, Okinawa
- Date: June, 2003 [photo only]
- Depth: 49ft (15m) [no specimen collected; only a single indiv. seen]
- Water temperature at collection depth: ca. 79oF (ca. 26oC)
- Size: TL 4mm [no specimen collected; only a single indiv. seen]
- Specimen deposited: Photo only, without specimen
[brackets indicate range for all Okinawa-collected specimens of the species]
Species Account:
The above featured little plakobranchid, Elysia amakusana, was photographed by Atsushi Ono from the waters of Aka Island in the Kerama Islands, one of a series of islands in the Kerama Islands Group, which are located 30 ~ 40 kilometers west of the Okinawa Capitol, Naha. This featured animal was photographed by Atsushi during June of 2003 in 15m of water from a sandy bottom. I've not personally seen E. amakusana in the waters of Okinawa's main island and Atsushi reports (pers. comm.) seeing only the above single individual and of course considers the animal to be very rare in the Kerama Islands.
The animal was originally listed in Baba (1949) as Elysia japonica Eliot, 1913. The name was subsequently altered by Baba (1955) to E. amakusana. In the more recent publication by Baba (1955), he mentions "the species amakusana differs from japonica of ELLIOT in having finely denticulate teeth". I've added
a second page with the original illustration of Baba's animal (Baba, 1949 {as E. japonica }) of E. amakusana.
Bill Rudman (2000) has a series of photos of E. amakusana posted on the Sea Slug Forum from both South Korea and Japan.
In addition to the above featured Elysia amakusana, the following Elysia have been previously featured on these pages:
E. cf. bennettae
E. lobata
E. mercieri
E. obtusa
E. ornata
E. rufescens
E. cf. tomentosa
E. thompsoni
E. yaeyamana
Etymology:
- Baba (1955) didn't give the derivation of the specific name amakusa, but he probably chose the name as it is one of the collection sites from which it was found (Amakusa, Japan). The animal was originally listed in Baba (1949) as Elysia japonica Eliot, 1913. The name was subsequently altered by Baba (1955) to E. amakusana.
Literature Cited:
- Baba, K. 1949. Opisthobranchia of Sagami Bay collected by His Majesty The Emperor of Japan. Iwanami Shoten, Tokyo. 194pp., 50 pls.
- Baba, K. 1955. Opisthobranchia of Sagami Bay: Supplement. Iwanami Shoten, Tokyo. 59pp., 20 pls.
- Rudman, W.B., 2000 (February 27). Elysia amakusana Baba, 1955. [In] Sea Slug Forum. http://www.seaslugforum.net/elysamak.htm.
Page Date: 12 Jul '04
Page Modification Date: 05 Feb '07
Digitally manipulated photo
Copyright © 2007 Robert F. Bolland