Goniobranchus sp. 03  Genus: Pease, 1866

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Goniobranchus sp. 03 is one species of a complex of species with a reticulated network of red lines on the mantle, IPN lists:
Chromodoris cf. alderi, Chromodoris sp. 2, Chromodoris sp. 3, Chromodoris sp. 4, Chromodoris sp. 5, Chromodoris tinctoria,
Chromodoris sp. 6, Chromodoris sp. 7, Chromodoris sp. 8, and Chromodoris sp. 9.
Goniobranchus sp. 03 is characterized by its diffuse reticulated pattern and by its orange marginal band, there is in some specimens a thin white submarginal band.
It is Chromodoris sp. 6 in IPN at page 212:
Gosliner, Terrence M., David W. Behrens & Ángel Valdés. 2008. Indo-Pacific Nudibranchs and Sea Slugs. Sea Challengers Natural History Books.
Gig Harbor, Washington. 426pp.
Pretty similar are:
Goniobranchus reticulatus which has commonly no marginal band and differs by distinct tubercles and by its opaque white gill rachis
Goniobranchus sp. 04 which differs by purple tipped white tubercles.
It was originally posted at these websites as Chromodoris sp. C  Genus: Alder & Hancock, 1855,
then changed into Chromodoris sp. 03  Genus: Alder & Hancock, 1855,
for some genera, such as Trinchesia was the alphabet almost through. I had to change the distinguishing alphabetic character into a number. I have chosen 2-digit numbers, even though '01' looks a little bit stupid, and now is only the genus italic written.
I follow the recent article (published: 10 April 2012)
Rebecca Fay Johnson & Terrence M. Gosliner. 2012.
Traditional Taxonomic Groupings Mask Evolutionary History:
A Molecular Phylogeny and New Classification of the Chromodorid Nudibranchs. online at
and move Chromodoris sp. 03 to the reerected ("rescued from synonymy") genus Goniobranchus  Pease, 1866, on which Rebecca and Terry state: "This clade includes all of the Indo-Pacific species of Chromodoris that are not part of the black-lined, planar egg mass clade, except Chromodoris alternata and Chromodoris ambiguus."
Bill Rudman's Sea-Slug Forum has all species of this complex as Chromodoris tinctoria.