Nudibranch Similarities
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
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.
Hypselodoris kanga group
Author: Erwin Kodiat
To distinguish between Hypselodoris kanga and similar looking Hypselodoris infucata is by looking at the gills. If they are triangular in cross section, and edged in red (blue in other parts of the world) and with a row of yellow spots up the broad outer face, then it is Hypselodoris kanga. Otherwise it is Hypselodoris infucata
Hypselodoris maculosa group
Author: Erwin Kodiat
Hypselodoris maculosa has 2 orange rings on the rhinophores, white longitudinal lines, purple spots, and white speckles while Thorunna australis has ring of purple spots around the mantle margin.
