Ercolania cf. boodleae & E. margaritae

October 6, 2002
From: Cynthia Trowbridge

Dear John and Bill,
The comment about Point Lonsdale reminded me about Ercolania margaritae described by Robert Burn for those high pools you mentioned. There is also an undescribed Ercolania sp. for the region as well. I regret that I do not have the papers available to help distinguish the species. Good luck!

Trowbridge, C., 2002 (Oct 6) Ercolania cf. boodleae & E. margaritae. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Cynthia,
You are absolutely right about Ercolania margaritae. I hadn't considered it because the cerata were described as black. However in John's latest message he says that in most specimens the cerata are completely black, which would suggest they are Burn's Ercolania margaritae. Burn notes that it is seasonally abundant on the rock platform at Point Lonsdale. He observed egg ribbons in August and September, which he describes as approx 5mm long, 0.6mm diameter, containing a tight spiral of yellow eggs. I guess what needs to be done now is to decide whether E. margaritae is a synonym of E. boodleae.

I have included figures from Burn's (1974) description of Ercolania margaritae.
Fig 8 shows the pericardium, with the chracteristic dorsal vessel and raised anal papilla in the posterior right quarter. Baba & Hamatani (1970) state that in Ercolania boodleae the "anus does not form a papilla, is situated in the anterior region (not in the posterior region as stated in Baba, 1938, p.7) of the pericardial prominence, and opens slightly on the right of the median line". The colour and radular morphology of the two species seems very similar, as does the egg ribbon (Baba & Hamatani, 1952). I am not sure how significant the shape and position of the anal papilla is. If it is important, and the two species prove to be consistently different, Then I guess the animals from Victoria should be recognised as Ercolania margaritae.

• Baba, K. & Hamatani, I (1952) Observations on the spawning habits of some of the Japanese Opisthobranchia. 1. Publications of the Seto Marine Biological Laboratory 2(2): 87-90. (Pl.7)
• Baba, K. & Hamatani, I. (1970) The anatomy of Ercolania boodleae (Baba, 1938) from Seto, Kii, middle Japan (Opisthobranchia: Sacoglossa). Publications of the Seto Marine Biological Laboratory, 18(4): 215-222.
• Burn, R.F. (1974) Notes on some benthonic opisthobranchs from Port Philip Bay, Victoria. J. Mal. Soc. Aust., 3(1): 43-57.

Best wishes,
Bill Rudman

Rudman, w.B., 2002 (Oct 6). Comment on Ercolania cf. boodleae & E. margaritae by Cynthia Trowbridge. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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