Phidiana newcombi
(Angas, 1864)

Family: Glaucidae


Known throughout New South Wales, Australia, [with records from Eden, in the south, to Angourie in the north] and Victoria.


UPPER: Two-Fold Bay, New South Wales, 17mm long alive, March 1986
LOWER: Callala Point, Jervis Bay, New South Wales, 20mm long alive, November 1984. PHOTOS: Bill Rudman.

The colour pattern is somewhat variable but the head is usually reddish-brown with a white or translucent straw coloured streak up the midline between the rhinophores, and a streak on each side, which runs below the rhinophores and beneath the first ceratal cluster on each side. There is also a diamond-shaped patch, often outlined in white over the heart. A broken white line, runs back from the heart along the dorsal midline. The distal third of the oral tentacles have a yellow or whitish pigmentation while the rest is either red-brown or translucent in colour. There is often a whitish band, sometimes incomplete, halfway up the oral tentacles. The rhinophores can have 4 or 5 ridges or lamellae (see inset on upper photo), but in may specimens these are absent, apparently after regrowth of damaged rhinophores. Another character is that complete specimens uusually have a long tapering "tail" but this is often absent.

Interestingly, a high proportion of animals of this species have damaged "extremities" - rhinophores, oral tentacles and posterior end of foot. Perhaps living in the intertidal makes them more vulnerable to attack from predators, but if this was the single reason I would expect other intertidal species to show a similar level of damage.

• Angas, G.F. (1864). Description d'espèces nouvelles appartenant à plusieurs genres de Mollusques Nudibranches des environs de Port-Jackson (Nouvelles-Galles du Sud), accompagnée de dessins faits d'après nature. Journal de Conchyliologie, 12: 43-70

Authorship details
Rudman, W.B., 1999 (March 9) Phidiana newcombi (Angas, 1864). [In] Sea Slug Forum. Australian Museum, Sydney. Available from

Related messages

Phidiana newcombi? from South Australia

February 1, 2005
From: Dennis Hutson

Does anybody know what type of sea slug this is? I found it under the Edithburgh jetty.

Locality: Edithburgh Jetty, South Australia.Depth: 6 metres. Length:  5 mm. 23 Jan. 2005. Pylons and rocky bottom. Photographer: Dennis Hutson


Hutson, D.G., 2005 (Feb 1) Phidiana newcombi? from South Australia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Dennis,
I think this is Phidiana newcombi but it is a bit hard to be sure because I can't see the rhinophores, and I need them to see some vital characters. The colour is not a perfect match but it's the best I can do
Best wishes,
Bill Rudman

Rudman, W.B., 2005 (Feb 1). Comment on Phidiana newcombi? from South Australia by Dennis Hutson. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Phidiana? from Port Stephens

March 9, 1999
From: Carol Buchanan

Hi Bill
Here is another nudi from Port Stephens I would like you to check. It is about 18mm long.



Buchanan, C., 1999 (Mar 9) Phidiana? from Port Stephens. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Carol,
I'm pretty sure its Phidiana newcombi. I can't be sure from the picture that your animals have the characteristic ridges or lamellae on the rhinophores, but as I say above, the rhinophores are often damaged in this species, and the replacement structures do not have the ridges.

Best wishes,
Bill Rudman.

Rudman, W.B., 1999 (Mar 9). Comment on Phidiana? from Port Stephens by Carol Buchanan. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from