Re: Ercolania boodleae? on Valonia

May 25, 2000
From: Kathe R. Jensen

Dear Bill,
Another sacoglossan message I missed during my first few weeks in Thailand. The photos make me 99% certain that the species I described as Ercolania emarginata from Hong Kong (in 1985) is identical to E. boodleaea. I was uncertain at the time. I dissected several specimens from Japan, and they differed very slightly by consistently. There is, however, another "sibling" species, as yet undescribed, in Hong Kong. I only noticed it the last time I went there. I was trying to do some copulation experiments, and couldn't understand why one specimen (with white rather than orange tips of cerata) was not interested at all - until it was placed with another specimen without the orange tips. The eggs also differed in size, so they must be different (if the old definition of a species as interbreeding populations is still valid).

Concerning its eating Valonia, there is no reason why it shouldn't. Valonia has the same cell wall structure as Chaetomorpha and Cladophora. It would be interesting to see if the radular teeth of Valonia-eating specimens are larger than those of animals feeding on filamentous algae.


Jensen, K.R., 2000 (May 25) Re: Ercolania boodleae? on Valonia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Thanks Kathe,
I am glad the Forum helped you to sort out some Hong Kong animals. This is why I am always asking for photos. It is so much help in identifying and comparing animals from different places.
Best wishes,
Bill Rudman.

Rudman, W.B., 2000 (May 25). Comment on Re: Ercolania boodleae? on Valonia by Kathe R. Jensen. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from


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