Known only from Indonesia, Philippines.
Malapascua Is., Philippines, divesite "Japanese Cargo Wreck". Depth: 25m. Length: 18-20cm. 23 Feb. 2003. Photo: Erwin Koehler
Large purplish brown pleurobranch with white double rings on the mantle. Mantle with small rounded tubercles. Apart from a record from Mindinao, Philippines on Mike Miller's site [http://slugsite.us/bow/nudwk132.htm], I know of no other published record of this species since its original description from Saleyer Is., S of Celebes, Indonesia (Bergh, 1905). The colour plate [Plate 2, fig 1 - as Oscanius weberi] clearly shows the conspicuous double white rings on the mantle. This species has colour similarities to the dark purple colour form of Pleurobranchus forskali, but in that species if white rings are present, they are single half circles which line the outer edge of each of the mantle tubercles. In P. weberi, the mantle tuberles are much smaller, and the white circles are independent of the tubercles. Like P. forskalii this species apparently grows to quite a large size - at last 20cm.
• Bergh, L.S.R. (1905). Die Opisthobranchiata. Siboga Expeditie Report, 50: 248pp., Pls 1-20.
Rudman, W.B., 2003 (April 13) Pleurobranchus weberi (Bergh, 1905). [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/pleuwebe
July 19, 2007
From: Erwin Koehler
Concerning message #20130:
here is a large shot from my earlier message [#9569] so you can take a more detailed look at the mantle.
Philippines, Malapascua Is., divesite "Japanese Cargo Wreck", near Tapilon Village. Depth: 25 m, 23 Feb. 2003. Size: 18-20 cm (!). Photo: Erwin Koehler
Erwin@Philippine-Sea-Slugs.comKoehler, E., 2007 (Jul 19) Re: Pleurobranchus weberi? from Western Australia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/20251
Thanks very much for this. I have never seen this species alive so from all the previous photos the white rings appeared to be solid white pigment so I was a bit puzzled by Brad Cox's animal yesterday in which the rings seemed to be caused by small white sand grains stuck around the two rings of the large compound tubercles. From the two close-ups I have posted from your higher resolution photo, it seem the same situation exist with your 'typical' P. weberi from the Philippines. perhaps the tubercles secrete a sticky secretions which captures small white detritus. It is certainly a strange way to build a colour pattern but it seems to show that Brad's animal is indeed P. weberi, which greatly increases is geographic range.
July 18, 2007
From: Brad Cox
I have a question regarding Pleurobranchus weberi. I have looked on the forum for a similar looking Nudibranch but have only found Pleurobranchus weberi. You have in the forum they are rare and known only from Indonesia & the Philippines. Is this the case or is this in fact another species.
Locality: One Mile Jetty Carnarvon, 6-7 meters, Western Australia , Indian Ocean , 02 October 2005, Muddy sandy Bottom. Length: 200mm. Photographer: Damien Preston .
Cox, B., 2007 (Jul 18) Pleurobranchus weberi? from Western Australia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/20130
Information on any species is only as good as the state of our knowledge, so there is always the chance that you can improve the information on the Forum. That is especially true of geographical distributions.
So I wouldn't be surprised if P. weberi turned up in Western Australia. Your animal certainly looks like P. weberi but its colours are not quite the deep purple and white found in other specimens. However it could be a colour variant. The large compound tubercles in your photo look like those of Pleurobranchus grandis, but I would need to see a higher resolution photo of typical P. weberi to see what its tubercles were like. I can't be 100% sure, but I think we should tentatively consider it to be P. weberi.
May 5, 2005
From: Paul Osmond
I have been meaning to send you this image for quite some time.
Two things - firstly a wideangle shot of a sea slug which is rare enough, however more importantly this is Pleurobranchus weberi.
This image was likely taken on the same shipwreck as the image from Erwin Köhler from 2003 [#9569 ], although he doesn't specify the Tapilon as the Japanese Cargo wreck he saw this on (there are two other wrecks at the same depth in the area).
Locality: Wreck of Japanese cargo ship, near Tapilon Village, Malapascua Island, Cebu, The Philippines. Depth: 30 m. Length: 250 mm. 03 March 2004. Ship Wreck. Photographer: Paul T. Osmond
In my notes I have this specimen as almost a foot in length [30 cm].
firstname.lastname@example.orgOsmond, Paul T., 2005 (May 5) Pleurobranchus weberi from The Philippines. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/13707
Thanks for these photos. It is great to get more information on such a seldom recorded species.
December 11, 2003
From: H.Haluk Akbatur
They were all seen on 18 November 2003, Dive site: Just front in (North-east of Bali, Amlapura, Scuba Seraya Resort,] Size: 15 cm, Depth: 3-15m.
Thanks for any help in identifying them.
Lasergoz@ttnet.net.trAkbatur, H.H., 2003 (Dec 11) Pleurobranchus weberi - another sighting. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/11652
This is an interesting find. It is Pleurobranchus weberi. As I discuss on the Fact Sheet this rarely found species has only been reported twice since its original description from Indonesia in 1905.
April 15, 2003
From: Erwin Köhler
My photo is from the Philippines, Malapascua Is., divesite "Japanese Cargo Wreck".
Size: 18-20cm (!)
Date: 23 Feb. 2003
Erwin@medslugs.deKöhler, E., 2003 (Apr 15) Pleurobranchus weberi from the Philippines. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/9569
This is a very interesting find. Apart from the record you mention on Mike Miller's site [from Mindinao, Philippines], I don't know of a published record of this since its original description from Saleyer Is., S of Celebes, Indonesia (Bergh, 1905). The colour plate [Plate 2, fig 1 - as Oscanius weberi] clearly shows the conspicuous double white rings on the mantle. I have looked at the plate a few times, wondering if it is a colour form of Pleurobranchus forskalii, but in the dark purple form of that species if white rings are present, they are single half circles which line the outer edge of each of the mantle tubercles. In P. weberi, the mantle tuberles are much smaller, and the white circles are independent of the tubercles. Like P. forskalii this species apparently grows to quite a large size.