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IPN places this species in the genus Doris
Gosliner, Terrence M., David W. Behrens & Ángel Valdés. 2008. Indo-Pacific Nudibranchs and Sea Slugs. Sea Challengers Natural History Books.
Gig Harbor, Washington. 426pp. at page 157
Let me quote from the Identification of Doris granulosa: "Species with a pectinate gill where often placed in a separate genus, Doriopsis, but are now considered to be a subgroup within Doris."
More information on Doris pecten as Doriopsis pecten are on Bill Rudman's Sea-Slug Forum!