Haminoea cymbalum: Description. Globose shell thin, transparent, too small to accommodate body
completely; shell 15 mm, living animal up to 25 mm. Body pale green with large and
small orange spots, part contained within the shell much darker green than both head
and tail. Larger orange spots and patches underlying shell outlined with white or very
pale green.
Infrequently, huge mating congregations are observed, with numbers of up to 100
individuals per m2 in February 2007 in La Réunion, which lasted approximately one
week (P Bidgrain, pers. comm. and http://seaslugs.free.fr/nudibranche/a_intro.htm).
These aggregations were not observed again until 2010, but with a much smaller number
of animals, only 100 individuals in total (P Bidgrain, pers. comm.).
Distribution/Remarks. Haminoea cf. cymbalum has been rarely recorded in
the Indian Ocean; it is more common in the western Pacific. Diffculties arise with
the name of this well-known species: both Burn (in Marshall and Willan 1999)
and Carlson and Hoff (Sea Slug Forum 1999) suggested that the shell representing
the type in the MNHN (Paris) is not the same species; therefore this species would
take the next available name, which is H. simillina (Pease). Additionally, there are
several other species differing in colour, radula, and gizzard plates, so further work
is needed; deposits of individual specimens such as these in museums with their
descriptions and photographs will ensure that enough material is made available for
future workers.