Trapania euryeia
Gosliner & Fahey, 2008

Suborder: DORIDINA
Family: Goniodorididae


This species has been reported from Reunion, Papua New Guinea, Indonesia: Sulawesi and Bali, Okinawa, Marshall Islands, Midway Atoll and Hawaii (present study). [see messages below for possible records from South Africa and Queensland, Australia].


Upper: Marshall Islands, showing variation in distribution of white and brown coloration on the body, and one of the specimens, e050a-1, has orange anterior tentacles. Size range: e050a-1 = 6 mm, e050 = 16 mm long. Photos: Scott Johnson. Lower left: CASIZ 097448, Maui, Hawaiian Islands, 7 mm. Photo: T. Gosliner. Lower right: CASIZ 172858. Radular morphology. Scale = 10 µm.

The body is translucent brown often punctuated with small translucent straw coloured spots. Overlaying this background colour is a symmetrical pattern of white - ranging from opaque white to cream-white. The white pattern is not consistent enough to describe in detail but it usually includes a white median patch on the head, a Y or V shape in the midline between the gills and the rhinophores, and a broken median band down the posterior part of the body/foot behind the gills. The pattern is very symmetrical, the left side being a mirror image of the right.

The oral tentacles may be brown and white speckled like the body, or they can have a yellowish tinge, sometimes without any brown speckling. A similar variation can be seen in the colour of the dorso-lateral preocesses. Similarly, the gills and rhinophores are translucent celar with varying amounts of brown, white and sometimes yellowish colouration.

This species is similar in colour and radular morphology to T. brunnea. Records of this species have previously been clustered in the Forum as Trapania cf brunnea, but as I have mentioned in comments to previous messages, I can't even be sure from external photos if they are all the same species. Now that we know the radula is very similar in shape to that of T. brunnea, the relationship between these similarly coloured animals is unfortunately no clearer. It is possible that T. brunnea is a temperate population of a widespread tropical species, which would be unusual, but not unique. Clearly we still have work to do on this colour complex.

The living animal is reported to grow to at least 10 mm in length.

Note: This animal was previously known on the Forum as Trapania cf. brunnea.

  • Gosliner, T.M. & Fahey, S.H. (2008) Systematics of Trapania (Mollusca: Nudibranchia: Goniodorididae) with descriptions of 16 new species Systematics and Biodiversity, 6 (1): 53-98

Authorship details
Rudman, W.B., 2008 (March 10) Trapania euryeia Gosliner & Fahey, 2008. [In] Sea Slug Forum. Australian Museum, Sydney. Available from

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