Bornella johnsonorum from Reunion Island [1]

Dear Sully,

I am pretty sure this is Bornella johnsonorum, which as I noted yesterday [message #22194] is only a few days old! The colour and shape of the dorso-lateral mantle processes fit exactly. Considering it was known only from the Marshall Islands in the tropical north Pacific, this is a huge range extension to the western Indian Ocean

It is probably appropriate to mention Bornella simplex Eliot, 1904 which was described from Zanzibar, also in the western Indian Ocean. Eliot described the animal as transparent with an orange network on the back but without orange rings on the tips of the dorsolateral processes. He also described the rhinophore sheaths as bearing six short digitations and a larger rounded knob behind. The remaining description is poorly detailed and the reproductive system was not described. The only unique feature for the species is that rather than having digitate lobes, the oral tentacles are short and simple. As Eliot stated that this character could be a monstrosity, and gave no drawings of the living animal, and no type material can be found, this species is almost certainly unidentifiable.

Eliot (1904) also tentatively identifed another specimen from Zanzibar as Bornella excepta Bergh, 1884 but as Eliot gave no good description of his specimens, and as Bergh gave no description of the colour of the live animal, and as no type specimen exists, Bornella excepta is unidentifiable as well.

• Bergh, L.S.R. (1884) Report on the Nudibranchiata dredged by H.M.S. Challenger during the years 1873–1876. Challenger Reports, Zoology, 10, 1–154, pls. 1–14.
• Eliot, C. (1904) On some nudibranchs from east Africa and Zanzibar. Part V. Proceedings of the Zoological Society of London, 2, 83–105, pls. 3–4.

Thanks for this nice find
Best wishes,
Bill Rudman