Three variations of the same theme: Chromodoris hamiltoni
Top two photos Paul Papenfus, third and next image Guido Zsilavecz
Chromodoris africana. Note the thick bars along the top.
Superficially similar, these two species do have their characteristic differences. As such the thickness of the black lines sets them apart, but in both "Two Oceans" and Gosliner's guide, the difference is described as follows:
- Chromodoris hamiltoni: Vivid blue back, with three thin black strips. The blue can be pale, and under too much flash can appear white. The black lines may, as the photos show, branch, double-up, or be segmented.
- Chromodoris africana: black back (or ground colour) with two pale blue (or white) stripes, and a white margin.
The two images Paul submitted do show what could easily be mistaken for two different species - (the second one he called the "liquorice" one) except that nudibranchs very often have variations in their pattern and colour, so while it may confuse at first, looking at the basic characteristics is bound to reveal the right species - especially if one eliminates all those it cannot be in the process!
Nudibranchs of Southern Africa - a guide to the opisthobranch molluscs of southern Africa, T. Gosliner, 1987
Nudibranchs of the world, H. Debelius, R. Kuiter, 2007
Two Oceans, A guide to the marine life of Southern Africa, GM Branch, CL Griffiths, ML Branch and LE Beckley, 1994, Revised Edition 2010