Risbecia tryoni

(Garrett, 1873)

Risbecia tryoni
Photographed by: Hengky Dotulong

Kingdom:Animalia
Phylum:Mollusca
Class:Gastropoda
Subclass:Opisthobranchia
Order:Nudibranchia
Suborder:Doridina
Family:Chromodorididae
Species:Risbecia tryoni

Comment from Scott Johnson on photo #27960
Juvenile coloration.

Comment from Richard Willan on photo #17298
This individual has a developmental aberration on the centre of its mantle.

Comment from Scott Johnson on photo #16187
These large chromodorids belong to one of the few kinds that we see out in the open here in the Marshalls, where pairs can occasionally be found trailing after each other during the day.

Comment from Scott Johnson on photo #16188
Risbecia tryoni, with somewhat smaller spots than usual.

Comment from Richard Willan on photo #9235
Note the 2 pink egg sacs of an internal parasitic copepod (Crustacea) alongside the gills.

Comment from Richard Willan on photo #8446
A juvenile individual

Comment from Richard Willan on photo #6001
Two individuals displaying trailing behaviour, which is characteristic of all species of Risbecia.

Comment from Richard Willan on photo #4617
It is interesting to see an individual (the larger one here), with open ‘leopard-like’ circles, a pattern like that of Chromodoris leopardus.

Comment from Richard Willan on photo #2715
When individuals of this species are crawling, their body is high and narrow, but resting individuals (like this one) adopt a low and flattened body posture. It could be easy to interpret them as different species.

Comment from Richard Willan on photo #2250
This animal is resting so its shape is circular, it would be elongate when it is crawling. In the similar-looking Chromodoris leopardus, the dark markings form definite open circles instead of closed spots.

Locality:

 

Pictures of Risbecia tryoni

Risbecia tryoni from Loloata, PNG
Location: Loloata, PNG
Posted 8 years ago
Viewed 1655 times
 
 

Similar Species

Author: Nila Murti

Risbecia tryoni has somewhat longish body form compared to Chromodoris leopardus which is more oval like. It also has a reduced mantle overlap, while Chromodoris leopardus has a wide mantle overlap. Both have very narrow purple colour band at the mantle edge. However in Chromodoris leopardus there is a second, broader white border immediately inside.

Perhaps the clearest difference is in the markings on the purplish or brownish mantle; Risbecia tryoni has dark round spots encircled by whites, while in Chromodoris leopardus the white-haloed markings are hollow rings, like in its namesake, the leopard.

 
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