Sohgenia palauensis
Hamatani, 1991

Family: Caliphyllidae


Probably widespread in tropical Indo-west Pacific. Originally reported from Palau, there are now records on the Forum from the tropical NW Pacific and southwestern India.


UPPER: Hachijo Island, Japan. Depth 5m, length 8mm, photographed only once at a shallow reef. Photo: Shoichi Kato.
LOWER: From Hamatani, 1991 - Figure 1.

Until reported on the Forum this species was known only from the original description which is summarised below:

"Body leaf-shaped and very thin 4.5mm long. Foot undivided and occupies the whole ventral surface of the body. General body colour is grass green due to presence of green pigments possibly derived from the animal's food. The rhinophores are very close together and bifurcate very close to the base. The upper half of the rear branch (of the rhinophores) is tinged slightly with brown. The cerata are stick-shaped with a spherical swelling at the top, wholly transparent and colourless. The stalk can have some minute conical protuberances. No gut branches penetrate into the cerata"

In the original description the cerata are quite a bit smaller and there are no brown spots, but the pericardial hump has two swellings like in these photos, and the general shape is very similar. It has similarities to a species of Cyerce or Polybranchia which have autotomised most of their cerata, but the swollen tip of the cerata, and the brown pigmentation on the rhinophores is quite unusual for those genera.

• Hamatani,I (1991) Sohgenia palauensis n. gen. & sp., a new ascoglossan opisthobranch from the Palau Islands collected by the R/V Sohgen-Maru. The Venus, The Japanese Journal of Malacology, 50(2): 85-92.

Authorship details
Rudman, W.B., 2002 (February 1) Sohgenia palauensis Hamatani, 1991. [In] Sea Slug Forum. Australian Museum, Sydney. Available from

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