Re: Dendrodoris grandiflora from southern Portugal

Dear Marina,
I agree with your puzzlement. All I can go on is the latest comprehensive study (Valdes, et al, 1996) which reviewed the Atlantic species. Angel Valdes comments on the northeastern species in an earlier message [#2461] but does not include a discussion about 'lookalikes' of D. grandiflora. That study gives the distribution of D. grandiflora as the Mediterranean and the Atlantic coast from Portugal south to Mauritania, and out to the Canary Islands. D. senegalensis, they say, is only known from Senegal.

My feeling is that some European workers still have a fairly eurocentric view of the world. Where as I would feel quite comfortable with a species extending from southern Europe down the west coast of Africa, they are more comfortable with a European species and a few similar but distinct species from surrounding regions. Defining species of Dendrodoris is difficult because one of the main characters we use in other dorid families - the radula - is absent. Valdes et. al. consider the shape of the spines on the penis to be a useful character in separating species of Dendrodoris but I must say I am less sure of their usefulness. They consider these two species can be separated on spine shape, D. grandiflora having a large base and D. senegalensis having a narrow base. However there is so much variation in spine shape and base size in the spines of just one penis of one species, that I find this a very shaky character on which to separate species.

We have similar problems with the Indo-West Pacific species D. nigra and D. fumata, where there is considerable colour variability within the species, and colour similarity between species. And like the Atlantic species, they start as red juveniles and change to their adult colour pattern as they develop. I suspect we will have to wait until DNA testing is sophisticated enough to give us unambiguous answers, but at present I think we should continue to build up observations on their biology and natural history - what are their eggs and egg ribbons like, what sponges do they feed on etc?

• Valdes, A., Ortea, J., Avila, C. & Ballesteros, M. (1996) Review of the genus Dendrodoris Ehrenberg, 1831 (Gastropoda: Nudibranchia) in the Atlantic Ocean. Journal of Molluscan Studies, 62: 1-31.

Best wishes,
Bill Rudman