van Hasselt, 1824
Upper: Pulau Dayang, off the East Coast of Malaysia. Depth approx 15-23m, 14 April 2002. Photo: Kheong Sann Chan.
Lower: South coast KwaZulu-Natal, SOUTH AFRICA. Park Rynie - 25m, June 1999. Size: 30mm PHOTO: Valda Fraser.
Translucent greyish body with raised longitudinal ridges. Both the mantle and the foot can have scattered black or dark grey patches and spots. The edge of the mantle is thrown into wave-like folds. The ridges range in colour from an entire black line, a broken black line, or alternating broken black and yellow lines. There is an orange or yellow band around the edge of the mantle and the oral veil. The rhinophore club at black. Gosliner, Behrens & Williams (1996) Coral Reef Animals of the Indo-Pacific [#617] report this species feeding on the soft coral Eleuthorobia grayi.
Since Bergh (1905), the animal illustrated here has been identified with van Hasselt's species. I have doubts about this identification and until 10 Feb 2003, I have identified this species on the Forum as Dermatobranchus cf. gonatophora. However I have decided it is simpler to follow accepted usage until evidence to the contrary comes to light.
• Bergh, L. S. R. (1905). Die Opisthobranchiata der Siboga-Expedition. Monographie, 50: 1-248, pls. 1-20.
• Gosliner, T.M., Behrens, D.W. & Williams, G.C. (1996) Coral Reef Animals of the Indo-Pacific. Sea Challengers: Monterey. 1-314.
• van Hasselt, J.C. (1824) Uittreksel uit eenem brief van Dr J.C. van Hasselt, aan Prof. van Swinderen. Tjuringa op Java, den 25 Mei 1823. Allgem Konst en letterbode. 16 January, 34-39.
Rudman, W.B., 2000 (April 1) Dermatobranchus gonatophora van Hasselt, 1824. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/dermcfgona
January 6, 2004
From: Valérie Grando
I took these pictures in the south of the Red Sea at Wadi Lahami [sthn Egypt] in June 2003. Is it a Dermatobranchus gonatophora? It looks like the pictures of one taken in Japan
email@example.comGrando, V., 2004 (Jan 6) Dermatobranchus gonatophora from Red Sea. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/11751
Yes this is what we are calling ">Dermatobranchus gonatophora. It looks quite similar to the photo in Valda Fraser's message from South Africa.
April 28, 2003
From: Yoshinori Fukuyo
This Dermatobranchus gonatophora was seen at Osezaki, Izu Peninsula, Japan at a depth of 14 meters.
It is quite uncommon at Osezaki. It was approx 30 mm. long I photographed it on 1 February, 2003.
firstname.lastname@example.orgFukuyo, Y., 2003 (Apr 28) Dermatobranchus gonatophora from Japan. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/9740
It's nice to get a photograph from Japan. It certainly has similarities to D. nigropunctata Baba, 1949, which was desribed from Japan, but in that species there are black spots along the ridges, and the rhinophore clubs are orange not black.
February 13, 2003
From: Phil Cromwell
Yes you are quite right, they are all the same species. I have been calling it Dermatobranchus cf. gonatophora because I have doubts over whether it is really what van Hasselt named as Dermatobranchus gonatophorus. However since Bergh (1905) identified this species with van Hasselt's, other authors have followed this identification, so I guess I might as well follow suit. I have just noticed an interesting observation in Gosliner, Behrens & Williams (1996) Coral Reef Animals of the Indo-Pacific [#617]. They have a photo of this species feeding on the soft coral Eleuthorobia grayi.
April 24, 2002
From: Kheong Sann Chan
Hi Dr. Rudman,
Here is another nudibranch I photographed at Pulau Dayang off the East Coast of Malaysia. Depth approximately 15-23m, Date: 14 april 2002.
email@example.comSann Chan, K., 2002 (Apr 24) Dermatobranchus from Malaysia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/6750
Note added 10 Feb. 2003: This has been identified as Dermatobranchus gonatophora.
This has similarities Dermatobranchus nigropunctatus Baba, 1949, but in that species there are a series of black specks along the dorsal ridges not black lines. I don't know of any published record of your animal so it may be another unnamed species
January 28, 2001
From: Erwin Koehler
Here are 2 Dermatobranchus gonatophora from Thailand.,
UPPER PHOTO is from the Phi Phi Islands, divesite "Koh Bida Nok", depth 17m, size 51mm, date Dec. 17, 2000.
LOWER PHOTO is from the Similan Islands, divesite "Richelieu Rock", depth 18m, size 57mm, date Dec. 24, 2000.
Medslugs.Koehler@t-online.deKoehler, E., 2001 (Jan 28) Dermatobranchus gonatophora from Thailand. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/3606
April 2, 2000
From: Valda Fraser
Maybe this photo will be more helpful. Unfortunately I don't have any photos to illustrate the colour variation which I have mentioned. It will be a project for the future.
Locality: South coast KwaZulu-Natal SOUTH AFRICA
ParkRynie - 25m
Date: July 1999
Thanks for the second photo which definitely shows that the head tentacles are arminid rhinophores not flatworm tentacles.
Not that it gets us much further ahead with an identification, but its defintiely an arminid.
March 30, 2000
From: Valda Fraser
I have not had too much luck trying to identify this nudibranch. It looks like Dermatobranchus gonatophora to me, but the location is a problem. In the winter months these nudibranchs are plentiful in certain areas. I have also noticed quite a colour variation. I was lucky with this photo .... note the fish!
Locality: South coast KwaZulu-Natal SOUTH AFRICA. Park Rynie - 25m
Date: June 1999
firstname.lastname@example.orgFraser, V., 2000 (Mar 30) Dermatobranchus gonatophora? from South Africa. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/2146
I guess you got the name from the book by Debelius. I'm afraid I don't know who advised him on that name but it is a bit of a jump from van Hasselt's problematic description from Indonesia.
I suppose it is a nudibranch? I can't see the head region very clearly so can't make out the nature of the rhinophores. There is a possibility that it is a flatworm. If you have a photo of the head region showing the rhinophores it would be a help. It would also be quite good to see some of the colour variation you mention.