Known only from New South Wales and Victoria, southeastern Australia.
Flinders, Westernport Bay, Victoria,, Australia. March 1986. 14mm long alive. PHOTO: Bill Rudman.
The background colour is a pale reddish brown with a close covering of yellow or white specks. There are a series of symmetrical white patches on the body which are scattered with large yellow spots. It is somewhat similar externally to T. brunnea but in that species the background colour is a uniform dark brown and there are no yellow spots in the large white patches.They differ considerably in tooth morphology.
• Rudman,W.B.(1987). The genus Trapania (Nudibranchia: Goniodorididae) in the Indo-West Pacific. Journal of Molluscan Studies, 53: 189-212.
Rudman, W.B., 2001 (April 4) Trapania benni Rudman, 1987. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/trapbenn
March 13, 2008
From: Brent Murdoch
I can't find this one anywhere in my books. I would appreciate it you can have a look at it for me.
Locality: Swan River, Fremantle, 5m, Western Australia, Indian, 19 October 2007, Sandy bottom. Length: 10mm. Photographer: Brent Murdoch.
email@example.comMurdoch, B.D., 2008 (Mar 13) Trapania benni from southwestern Western Australia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/21002
After sorting throught a lot of Trapania species for yesterday's large post, I thought it would be a good time to sort through the backlog for any messages concerning this genus and came across your interesting message.
This is Trapania benni which is at present known only from New South Wales, Victoria and South Australia. So your record from Fremantle in SW Western Australia increases it known distribution a considerable distance. It is not surprising that it is found right across southern Australia, but it is very valuable to get the evidence.
March 12, 2008
From: Bill Rudman
To complement today's posting of many new species of Trapania here are some SEM photos showing aspects of the morphology of the radula of Trapania benni.
SEM photos showing sections of the radular ribbon. Flinders, Westernport Bay, Victoria, Australia. March 1986. 14 mm long alive. AM C149528. SEM Photos: G. Avern. Scale = 10 µm.
- Rudman, W.B. (1987) The genus Trapania (Nudibranchia: Goniodorididae) in the Indo-West Pacific. Journal of Molluscan Studies, 53: 189-212.
March 4, 2002
From: John Chuk
Here is an in situ shot of a very small specimen of Trapania benni. The specimen was photographed on a night dive at Flinders pier, Victoria, Australia, on March 25, 2001. It was found on a pink Darwinella sp. sponge on a pier pylon at a depth of 3m and measured 5mm in length.
Close inspection reveals the presence of minute, dark centred polyps living on the surface of the sponge. Your recent comments on Trapania food made me wonder if these polyps may be the food source for T. benni. Could they be entoprocts? All the diagrams I have been able to find of entoprocts show them to have relatively short tentacles whereas these polyps have relatively long tentacles and look very hydroid-like in morphology. I'd be interested in your thoughts on the subject.
firstname.lastname@example.orgChuk, J., 2002 (Mar 4) Trapania benni from S.E. Australia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/6337
Thanks for the photo. I am pretty sure the little brown spots with a whitish 'ring' around then are entoprocts. I am preparing a page on entoprocts so hopefully that will answer your questions. At the moment I am having difficulty finding any detailed information on Australian species, but from my observations they can have quite long tentacles. I am not sure what the brown pigment patch is. There are often one or two brown patches in each individual but I don't know if they are waste material in the gut or what.
January 19, 2002
From: John Chuk
The shape of the egg-mass produced by the Trapania benni specimens was rather difficult to determine, as the egg ribbon was only 1-1.5mm in diameter. Underwater it appeared to be cylindrical but close examination of the slides I took does suggest that it is somewhat flattened.
I watched the specimens egg-laying for about 20 minutes and one of them did produce a spiral ribbon of about one and a quarter whorls on the blade of a small red alga but then it ran out of space and continued to lay the ribbon in a seemingly haphazard manner. This may suggest that the irregular nature of the substrate chosen to lay the eggs on has determined the resultant shape of the egg-mass, which, on a more even surface, may have had a more spiral arrangement. In this case any pattern to the egg-mass is complicated, by having two specimens laying eggs at the same time!
email@example.comChuk, J., 2002 (Jan 19) Egg-laying Trapania benni from S.E. Australia (2). [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/6042
January 17, 2002
From: John Chuk
Here are images of an egg-laying specimen of Trapania benni and the egg ribbon. The specimen was found on a dive at Portsea Pier, Victoria, Australia on 30/Nov/2001. It measured 11mm in length and was found at a depth of 4m on a pier pylon.
I spotted the egg mass first and had to search to find the nudibranch responsible. It was very well disguised against the red alga it was on. After observing this specimen for about five minutes I discovered that there was a second specimen present and it too was egg laying. The egg ribbon was wrapped around a red alga and the stems of a small hydroid colony.
Both specimens were observed on or near the egg ribbon for the next three days but when I dived the site ten days later there was no sign of either the nudibranchs or their egg ribbon.
firstname.lastname@example.orgChuk, J., 2002 (Jan 17) Egg-laying Trapania benni from S.E. Australia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/5992
I don't recall seeing this animal laying eggs before. I am not sure from the photos abut the shape of the egg mass. Is it a flat ribbon, like most dorids, or is it cylindrical?
January 24, 2000
From: Stuart Hutchison
Here is one from - Rapid Bay early Dec this year - about 5mm long. Only sighting. [Rapid Bay Jetty, 10m. About 80 km south of Adelaide, South Australia,]
email@example.comStuart Hutchison, S., 2000 (Jan 24) Trapania benni from South Australia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/1760
This is Trapania benni. Although previously known from New South Wales and Victoria, I think this is the first record I have from South Australia.