Nudibranch Similarities
Noumea varians group
Author: Richard Willan
Durvilledoris pusilla always has an opaque mantle. The pattern on the central area of the mantle is always scalloped with 'lobes' or 'tongues' of colour that almost reach the margin; one pair of these lobes is immediately behind the rhinophores and the other pair is in front of the gills. The midline has 2 white circles. The colour pattern on the tail repeats that of the central mantle. Thius is definitely a good species.
Noumea varians can have either an opaque or a semi-transparent mantle. The pattern on the central area is not actually lobed, but it often looks that way in photos because of the way the body is deformed when crawling over irregular terrain. The midline has 3 white streaks or a single continuous narrow stripe. The tail is uniformly purple. There is evey indication that what we presently call Noumea varians may, in fact, cover several different species.
Philinopsis cyanea group
Phyllidia varicosa group
Author: Nila Murti
To untrained eye, Phyllidia coelestis can easily be mistaken for Phyllidia varicosa and vice versa. Understandable, as these two posses very similar basic form, coloration and pattern. Both have tubercles with blue bases and yellow caps.
To differentiate the two look at the dorsal pattern. If the nudibranch has a median ridge it's a Phyllidia varicosa. If it doesn't have a median ridge and the ridge forms a Y shape arrangement instead, it's a Phyllidia coelestis.
Phyllidia coelestis also shows a broader mantle margin with smaller tubercles that has no yellow caps.
And also juvenile form of sea cucumber, Pearsonothuria graffei, mimic Phyllidia varicosa
Phyllidiella pustulosa group
Author: Dr. Richard C. Willan
The main differences between Phyllidiella and Phyllidiopsis are internal – to do with the anatomy of the foregut. Externally these three species are indeed quite similar in colouration and in having compound tubercles, and all three species vary a great deal between individuals. The main external differences are:
Phyllidiella pustulosa and Phyllidiopsis burni have entirely black rhinophores (bicoloured in Phyllidiopsis krempfi);
Phyllidiella pustulosa and Phyllidiopsis krempfi have narrow black lines (very broad black areas in Phyllidiopsis burni).
Phyllidiopsis pipeki group
Author: Dr. Richard C. Willan
In Phyllidiopsis shireenae, if the rhinophores were extended they would have been completely red. By contrast, Phyllidiopsis pipeki has half pink/half black rhinophores and compound pustules (the pustules are simple in Phyllidiopsis shireenae).
