Tropical Western Pacific.
Koumac, New Caledonia, October 1993. PHOTO: Bill Rudman.
One of a group of species with a white background and orange markings, Halgerda carlsoni is characterised by the orange-tipped rounded tubercles and the scattering of small orange specks all over the mantle between the tubercles. There is a band around the mantle edge devoid of small orange specks. The gills and rhinophores are speckled with black and in some animals the speckling can be dense leading to some sections of th gills being almost completely black. Other similar coloured species include Halgerda malesso, Halgerda sp. 1 and Halgerda aurantiomaculata.
• Rudman, W.B. (1978). The dorid opisthobranch genera Halgerda and Sclerodoris Eliot from the Indo-West Pacific. Zoological Journal of the Linnean Society, 62: 59-88.
Rudman, W.B., 1999 (February 4) Halgerda carlsoni Rudman, 1978. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/halgcarl
February 10, 2009
From: Sully et Monika Bachel
Concerning message #2015:
Here are 3 Halgerda carlsoni observed at "Ile Ste Marie" on the East Coast of Madagascar.
The orange colour seems to be more brilliant and the black rhinopores look different than the East Africa Halgerda.
Locality: Ile Ste Marie, 15 - 20 m, Madagascar, Indian Ocean, october 2008. Length: 20 - 40 mm. Photographer: Sully Bachel.
These Halgerda seem to be common on this island.
firstname.lastname@example.orgBachel, S., 2009 (Feb 10) Re: Halgerda carlsoni from East Africa. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/22233
I suspect the paler colour in the photos of the animals from Tanzania are because they are a little over exposed. A photo from Sth Africa [message #3623] shows a much brighter coloured animal. All the western Indian Ocean animals, including yours, show the black on the gills and rhinophores as lines, while animals from the Pacific have black spots, so the two may turn out to be distinct species.
October 1, 2008
From: Marcel Tanke
Concerning message #21570:
Dear Bill and Carrie,
Your message of 19 September 2008 (picture taken at 24 Dec. 2008?? :-)) triggered me to check my own pictures of, what I had labeled as, H. batangas. And sure enough, I found new species for my species list. I will make 2 other separate messages on this [#21916, #21917 ].
The picture attached here is, I believe, Halgerda carlsoni. In enlargement the fine spots allover the mantle are clearly visible.
Locality: Dive site Sunken Island, Moalboal, 25 meters, Cebu Island, Philippines, 2 May 2008. Length: about 5 cm. Photographer: Marcel Tanke.
email@example.comTanke, M.A., 2008 (Oct 1) Halgerda carlsoni from Philippines. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/21915
Yes this is H. carlsoni.
August 8, 2003
From: Francis & Pirjo Pellet
We found these Halgerda in Kapalai, Malaysia, 22nd of May 2003. Dive site "Mantis Ground", depth 14m. It seems to us that we have two different species. Could the photo here be of Halgerda carlsoni ( size 4 cm) and the one in the separate message be Halgerda batangas ( size 7 cm).
Francis and Pirjo
Pellet, F. & P., 2003 (Aug 8) Halgerda carlsoni from Malaysia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/10629
Dear Francis & Pirjo,
Yes this is Halgerda carlsoni, and your other photos are of Halgerda batangas. It's nice to get a photo of Halgerda with its gills fully extended, because it shows how sparse the pinnae are on the gills of species of this genus.
June 26, 2003
From: Mary Jane Adams
I found this slug under a slab of rubble near Gau Island, Fiji on May 14, 2003. I believe it is Halgerda carlsoni. The enlargement shows the fine orange stippling and some damage to the mantle.
Length: about 20mm
Depth: about 15 meters
firstname.lastname@example.orgAdams, M.J., 2003 (Jun 26) Halgerda carlsoni from Fiji. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/10141
Thanks Mary Jane,
September 5, 2001
From: Mary Jane Adams
I believe this is Halgerda carlsoni. Length: 18 mm, Depth: 10 meters.
Divesite: Palua Abadi, Lembeh Straits, Sulawesi, Indonesia,
Aug. 10, 2001
email@example.comAdams, M.J., 2001 (Sep 5) Halgerda carlsoni from Sulawesi. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/5191
Dear Mary Jane,
I am pretty sure this is H. carlsoni, but the small orange spots on the mantle are not very much in evidence.
May 29, 2001
From: Don Barclay
Here is another one for you, Halgerda carlsoni if I'm not mistaken. This nudibranch was found on rubble in 10 meters of water across the channel from the Tongan Beach Resort, Utungake Island, Vava'u, Tonga. It was found about noon on 16 February 2001. Size 25mm.
firstname.lastname@example.orgBarclay, D., 2001 (May 29) Tonga Records: Halgerda carlsoni. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/4405
Yes this is Halgerda carlsoni.
March 7, 2001
From: Valda Fraser
I'm not sure about this Halgerda. Please help!
Locality: Sodwana, north coast KwaZulu-Natal, SOUTH AFRICA - 18m
Date: Jan 2001
valda email@example.comFraser, V., 2001 (Mar 7) Halgerda carlsoni from South Africa. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/3623
Almost exactly a year ago I posted a message from Bernard Picton reporting Halgerda carlsoni from Tanzania, the first record from the western Indian Ocean. Your animal seems identical to Bernard's. They differ from western Pacific specimens in having black lines on the gills and rhinophores rather than spots, but in your photo the lines on the rhinophores seem to be aggregated spots so perhaps the difference is more apparent than real. It is an interesting find.
March 5, 2000
From: Bernard Picton
Here is another Halgerda. It is a picture of H. carlsoni from Pemba Is., Tanzania in February 1999, with a close-up of the speckled orange pattern of spots.
firstname.lastname@example.orgPicton, B., 2000 (Mar 5) Halgerda carlsoni from East Africa. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/2015
I had previously thought of this species as a Western Pacific animal. I am not sure how important the colour of the gills and rhinophores are in this species but in western Pacific H. carlsoni the gills and rhinophores are white with small black spots and some traces of a line along the gill rachis. In your animal there seems to be a black line up the posterior side of the rhinophore stalk and black bands up each side of the club. The gills have no spots but a heavy black line along the rachis. Whether these differences are important or not will obviously need some more information on colour variation in the species and anatomical infomation.
A species identified in Sea Slugs of Western Australia [Fig 129] as Halgerda cf. carlsoni [and elevated to Halgerda carlsoni in Debelius's book], differs in having no fine orange spots and having a black rhinophore club and black-lined gills.