Crowned and orange-lined crowned nudibranchs about to mate.
Photo Andrew Taylor
Protea dorid
Different view of the same Protea dorid, about 10mm long.
Rugby-ball dorid, showing the raised mid-dorsal ridge.
Rugby-ball dorid from the top, showing the ring of black dots surrouding the raised ridge.
Two scribbled nudibranchs.
All other photos Guido Zsilavecz
With the summer season in full swing the diving is now largely limited to the Atlantic side of the Cape Peninsula. SURG members report seeing high numbers as well as diversity of nudibranch species, including a few rare and unusual ones, as well as a very interesting sighting.
Mating Polycera capensis and Polycera sp.2?
The crowned nudibranch Polycera capensis is a well-known species. The orange-lined crowned nudibranch is listed as a possibly distinct species in "Nudibranchs of the Cape Peninsula and False Bay" as "species 2". The differences are the presence of orange lines or line segments along the body, and rhinophores and gills which are white with black tips only, rather than the all-black ones of the normal crowned nudibranch (both species can have the tips of the gills in yellow.) The consistency of these features seemed relevant enough to list it separately. Andrew Taylor however photographed what clearly looks like a crowned nudibranch about to mate with an orange-lined nudibranch. While the two species have been found in relatively close proximity, and it is known that similar species may attempt to mate, this could also mean that the two species are actually one and the same, and that the orange-lined ones are simply a colour variation. DNA sequencing or the production of fertile offspring is the only way to determine this, however.
Protea dorid Noumea protea
A sighting of this species was reported on this site in 1 March. Now another individual was spotted close in-shore, in a cave.
Rugby-ball dorid Atagema rugosa
This is a rare dorid, only seen a few times before. This specimen was found at Justin's, on the other side of a rock where another one was spotted some time ago.
Scribbled nudibranch Doriopsilla miniata
While not as such a rare nudibranch, both Andrew and Guido report a sudden proliferation of this species in some areas, with higher densities than usual. Generally only found singly, now numerous were found in the same area. Interesting is that, as usual, the Atlantic individuals are much more uniform yellow than those in False Bay, which have a much darker central notum.
For more details on all these nudibranchs, see "Nudibranchs of the Cape Peninsula and False Bay", available directly from SURG or leading Cape Town dive stores.
Nudibranchs of the Cape Peninsula and False Bay, G Zsilavecz, 2007
Nudibranchs of Southern Africa - a guide to the opisthobranch molluscs of southern Africa, T Gosliner, 1987.