Nembrotha cristata? from Sulawesi

July 23, 2000
From: Lindsay Warren

Dear Bill

I found this Nembrotha on 25 October 1999 at a depth of 10.7 m heading down some coralline algae on a vertical wall of Pulau Hoga,  [Tukang Besi Archipelago, SE Sulawesi, Indonesia - Operation Wallacea].  Size: 43 mm.

Is this simply a colour variant of Nembrotha cristata which we normally find with only all green markings rather than green and orange as in this specimen. 
Photo:  Lindsay Warren

All the best

Warren, L., 2000 (Jul 23) Nembrotha cristata? from Sulawesi. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Lindsay,
This is an interesting photo. I wouldn't mind seeing some photos of 'normal Nembrotha cristata from Sulawesi. On first appearances it seems that it could be one of the colour forms of Nembrotha kubaryana but in all of those there is red or orange on the margin of the flattened oral tentacles (lappets).

Perhaps N. cristata and N. kubaryana are just part of a very variable species. Your photo showing both green and orange-red spots is very interesting. I'll put it on the N. cristata page, more from convenience than conviction.

Another interesting connection is Nembrotha guttata Yonow, 1993. It was described as
'Body pitch black with bright orange pustules scattered randomly ... approx 30% of pustules are edged in green. There are fewer than half a dozen dark green pustlues scattered between the orange ones.. The foot bears an orange edge - sole pitch black. Increased concentration of orange on oral tentacles which are quite prominent. Rhinophores black with orange dusting on anterior sides of lamellae.  Black rhinophore sheath has orange edge with a touch of green on posterior side between black and orange. Gills black with light green rachides'.

Although your photo has points of difference with Yonow's description. it does make me wonder whether there is more colour variation in some of these species than we have considered possible. The pustules / tubercles on both your animal and Yonow's suggest they could both be in a change over phase between orange and green. It is certainly worth looking out for some more individuals and to check out whether they are ever found together, eat the same food etc.

Reference: Yonow (1993)  Opisthobranchs from the Maldive Islands, includng descriptions of seven new species (Mollusca, Gastropoda). Revue fr. Aquariol., 20: 97-130

Best wishes,
Bill Rudman.

Rudman, W.B., 2000 (Jul 23). Comment on Nembrotha cristata? from Sulawesi by Lindsay Warren. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from


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