Nudibranch Similarities

Ceratosoma trilobatum group

Ceratosoma gracillimum can be distinguished externally by the complete absence of the mantle edge between the head and the well-developed lateral lobes on each side.

Ceratosoma trilobatum has the mantle edge, edged in purple, between the head and the lateral lobes. Both species have a similar range of colour variations, as does Ceratosoma tenue, but they differ from each other externally by the lack of a mantle edge in Ceratosoma gracillimum and the extra pair of small lateral lobes in Ceratosoma tenue.

Ceratosoma tenue from Lembeh, IndonesiaIdentification reviewed by Richard Willan
(136 photos)
 

Chelidonura varians group

 

Chromodoris annae group

Author: Nila Murti

Both have elongated bodyform, both have yellowish or orange-ish gills and rhinophones, both have similar mantle colouration and colour variation - pale to bright blue in the middle with black elongated lines bordering the blue area, and faded to bright orange mantle margin.

Chromodoris elisabethina normally has more elongated black lines in the blue area, sometimes a median line, often some broken shorter lines.

Chromodoris annae usually has no or less black lines, but some have been found to have multi black lines like Chromodoris elisabethina.

So what's the telltale difference? Apparently it's the uniformity of the blue colour. If it's smooth and uniformly coloured then it's Chromodoris elisabethina, while if the blue area has tiny dark speckles hence not uniform (zoom your photos to see it!) then it's Chromodoris annae.

Chromodoris annae from Lembeh, IndonesiaIdentification reviewed by Nathalie Yonow
(457 photos)
 

Chromodoris coi group

Chromodoris coi from Bali, Indonesia
(288 photos)
 

Chromodoris kuniei group

Author: Nila Murti

Both Chromodoris geminus and Chromodoris kuniei have oval body form and wide mantle overlap. Both have purplish or brownish mantle with dark round spots with white haloes in the mantle.

The difference between the two is in Chromodoris kuniei the mantle edge is broad with purple colour followed by a narrow dark ring and an uneven yellow in the innermost band.
In Chromodoris geminus the mantle border consists of four different coloured rings – an outermost white, then faded purple, followed by another white and finally yellow.

Chromodoris geminus from IndiaIdentification reviewed by Nathalie Yonow
(105 photos)
Chromodoris kuniei from Alor, IndonesiaIdentification reviewed by Richard Willan
(275 photos)