Nudibranch Similarities

Glossodoris cruenta group

Author: Bill Rudman

Glossodoris rubroannulata is quite similar in colour to Glossodoris cruenta which differs in having a row of red spots along the inner edge of the white rather than a thin red line along the outer edge.


Glossodoris electra group

Ardeadoris egretta from Panglao, Philippines
(102 photos)
Glossodoris pallida from Sodwana Bay, South AfricaIdentification reviewed by Richard Willan
(116 photos)

Halgerda batangas group

Author: Dr. Richard C. Willan

Halgerda carlsoni is most similar to Halgerda batangas. However, Halgerda carlsoni has microscopic orange speckles between the ridges (very rarely these speckles join up to form lines) and even when they are lines, they never form into a network of intersecting lines as in Halgerda batangas.

Halgerda malesso has much lower pustules, yellow spots and yellow lines. There are far fewer yellow lines than in Halgerda batangas.

Halgerda bacalusia has the summits of the ridges with strong dark orange lines and microscopic orange speckles between the ridges.

Here a description from Dr. Dave Behrens:
Halgerda bacalusia: broad orange lines follow the ridges to the orange tipped tubercles
Halgerda batangas: network of orange lines between the tubercles, rather than a series of spots
Halgerda carlsoni: the are lines of minute orange spots between the tubercles
Halgerda malesso: no lines between the tubercles, only along the margin
Halgerda stricklandi: orange tubercles arranged randomly, not in ridges. Orange spots not connected

Halgerda bacalusia from West Java, IndonesiaIdentification reviewed by Richard Willan
(22 photos)
Halgerda batangas from Lembeh, IndonesiaIdentification reviewed by Nathalie Yonow
(288 photos)
Halgerda carlsoni from Lembeh, IndonesiaIdentification reviewed by Richard Willan
(94 photos)
Halgerda malesso from Saipan, Nthn. Mariana Islands
(13 photos)

Hoplodoris nodulosa group


Hypselodoris bullocki group

Author: Nila Murti

There are still some debates as to whether these two Hypselodoris nudibranch with the same body form are separate species or just colour variations of the same species. The main difference is in colouration. Hypselodoris apolegma has a darker and deeper purple colour that grades towards the mantle margin into purple dots and finally into solid white along the edge of the mantle. The base of the gills and antennas (rhinophores) are also rich purple in colours, but changed to deep yellow at the ends.

Hypselodoris bullocki has several pale purple shade variations, from very pale, almost white, whitish purple to purple, but never as dark as the purple found in Hypselodoris apolegma. The colour is uniform over the whole mantle, with a narrow band of white or dark purple at the mantle edge. The gills and antennas are yellow with purplish base or pale purple all over.

Risbecia apolegma from Anilao, Philippines
(224 photos)