Three New Species of Gymnodoris Stimpson, 1855 
(Opisthobranchia, Nudibranchia) from the Philippines 
Vanessa L. Knutson and Terrence M. Gosliner 
Department of Invertebrate Zoology and Geology, California Academy of Sciences, 55 Music Concourse 
Drive, San Francisco, CA 94118; email: vknutson@calacademy.org, tgosliner@calacademy.org 
Three new species of nudibranchs in the genus Gymnodoris are described. All three 
have radulae typical of the genus, with no rachidian tooth and featuring hook¬ 
shaped, pointed lateral teeth. Gymnodoris brunnea, sp. nov. is translucent with a 
brownish tinge, covered in small, deep-orange, conical pustules and has gills 
arranged in a linear row. It can also be distinguished from all other Gymnodoris 
species that possess a linear gill by a short, broad, triangular second lateral tooth 
with a bifid cusp. Gymnodoris tuberculosa, sp. nov. differs in pigment from all previ¬ 
ously described Gymnodoris species by its uniformly translucent white coloration, 
including the tubercles that cover the body and a gill arranged in a complete circle. 
Gymnnodorispseudobrunnea, sp. nov. externally resembles G. brunnea, sp. nov., with 
small, deep-orange, conical pustules, and gills arranged in a linear row, though it 
does not always have a brownish tinge. These two species can be differentiated exter¬ 
nally by the shape of a white patch seen dorsally through the skin, the outline of 
which is more irregularly shaped in G. pseudobrunnea, sp. nov. than in G. brunnea, 
sp. nov., and by the dark intestine that can be seen through the skin in G. brunnea, 
but not in G. pseudobrunnea, sp. nov.. Internally, they are differentiated by the radu- 
la, the radula of G. pseudobrunnea, sp. nov. lacks a bicuspid second inner lateral 
tooth, and by the position of the receptaculum seminis duct,which enters the middle 
of the vagina in G. pseudobrunnea, sp. nov. rather than the at the proxutial end as in 
G. brunnea, sp. nov. Additionally, G. brunnea, sp. nov. specimens sequenced for a 
fragment of the COI gene differed from a G. pseudobrunnea, sp. nov. specimen by 
an uncorrected p-distance of 10.3% to ll.lVo, further supporting these as two dis¬ 
tinct species. All three species are found in the Anilao region of the Philippines, while 
G. tuberculosa, sp. nov. has been additionally recorded from Madang, Papua New 
Guinea and the Marshall Islands. 
Key Words: Gymnodoris, Gymnodorididae, new species, Philippmes 
Following the trend of many marine taxa, the opisthobranch diversity of the Coral Triangle in 
the Indo-Pacific is exceptionally rich, with the Philippines being home to over 700 species (Goslin¬ 
er et al. 2008). New species continue to be found in this region. On the recent Hearst Philippine 
Biodiversity Expedition to the “Anilao” region of the Philippines, the team of scientists found 25 
species of “opisthobranchs” that are new records for the region, and at least 50 additional species 
that are new to science. A taxon that was especially well-represented by collections on the expedi¬ 
tion was the nudibranch genus Gymnodoris. 
There has been some disagreement over the placement of Gymnodoris, whether it belongs in 
an independent family, Gymnodorididae and whether this family should be treated as a subfamily, 
Gymnodoridinae, within Polyceridae (summarized in Macnae 1958). The current generally accept¬ 
ed classification recognizes Gymnodorididae Odhner, 1941 (Bouchet and Rocroi 2005) including 
Gymnodoris along with several other genera (Bouchet 2014; McDonald 2009), though there has 
been no comprehensive review of the family. A recent molecular phylogenetic study found that 
Gymnodoris, represented by G. alba and G. striata, nests within the polycerid subfamily Polyceri- 
nae with liigh support (Palomar et al. 2013). However, the study also suggested that additional taxa 
need to be sampled to clarify the issue, and no taxonomic change was made. The taxonomic status 
of this family is beyond the scope of this paper, and until there is a fonnal change in the taxono¬ 
my, we follow the current accepted taxonomy here. 
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