Cervera, Garcia & Garcia, 1986
Originally described from Portil, Huelva, [SW] Spain. Until the taxonomy of this group is better understood, its true distribution is impossible to determine.
Locality: Platja de Caials, Cadaqués, Costa Brava, 6 metres, Spain, Mediterranean Sea, 27 October 2007, Rocks over muddy bottom. Length: 2 cm. and 1 cm. aprox.. Photographer: Miquel Pontes.
Similar in external appearance to Jorunna tomentosa, ranging in colour from greyish to greyish maroon. In a recent revision, Camacho-García & Gosliner (2008) repeat a statement found in the original description of J. tomentosa saying that J. tomentosa differs in colour from J. onubensis in having 5-6 brown spots on the sides of the body which are absent in J. onubensis. I can't find any photo or description reporting these spots in J. tomentosa. Both species seem to have dark spots on the mantle, sometimes, but not always.
The only clear differences seem to be internal with J. onubensis having an unusual section of the male reproductive duct which includes both a swollen prostate gland and then a much thinner, non-glandular, coiled vas deferens, while J. tomentosa lacks the large coiled vas deferens. In the foregut, J. tomentosa lacks jaw plates, while J. onubensis possesses them.
It is possible animals identified here as J. tomentosa may be J. onubensis or indeed other species, but until animals of this genus from the Atlantic and Mediterranean coast are studied in more detail we cannot be sure of identificatios from external features alone.
Cervera J. L., Garcia J. C. & Garcia F. J., 1986. Il genere Jorunna Bergh, 1876 (Mollusca: Gastropoda: Nudibranchia) nel litorale Iberico. Lavori, Società Italiana di Malacologia 22: 111-134
Yolanda E. Camacho-García and Terrence M. Gosliner, 2008. Systematic revision of Jorunna Bergh, 1876 (Nudibranchia: Discodorididae) with a morphological phylogenetic analysis. Journal of Molluscan Studies 74(2):143-181
Rudman, W.B., 2008 (October 8) Jorunna onubensis Cervera, Garcia & Garcia, 1986. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/joruonub