Reasoning recorded at review

• •Long slender translucent pink-orange Hypselodoris body
• •Four narrow opaque-white longitudinal dorsal lines
• •Rows of red-purple spots between the white lines
• •Broad orange-red mantle margin with opaque white spots and diffuse purple pigment anteriorly
• •White rhinophore clubs crossed by multiple orange-red bands
• •Gills white internally with bright orange-red pigment on the outer faces and apices

Alternatives considered

• Hypselodoris maculosa

  Why plausible: The closest traditional lookalike and formerly confused with H. decorata

  Comparison: H. maculosa generally has two rhinophore rings and a less white-spotted orange margin; the photographed combination and apparent additional band favour H. decorata

• Hypselodoris skyleri

  Why plausible: A small Papua New Guinea species with three rhinophore rings and a superficially similar line-and-spot pattern

  Comparison: H. skyleri has raised opaque-white mantle spots and pale brown irregular lines, rather than the continuous white lines and red-purple spotted orange margin visible here