Roboastra leonis
Pola, Cervera & Gosliner, 2005

Suborder: DORIDINA
Family: Polyceridae
Subfamily: Nembrothinae


Gulf of California to Galapagos Ids.


North Seymour Island, Galapagos Ids., July, 2003. 30-40 feet. Approx 30 mm long. Photo: Patty Dilworth

Body high and elongate with a long and pointed posterior end of the foot.  There are numerous longitudinal lines of yellow ochre, green and bluish-black
on the notum and both sides of the body. Some of the lines are lighter in shade and can be continuous or broken. Pola et al describe the body  surface as 'strongly wrinkled'.  The edge of the foot is blue-black. The head is rounded with a pair of conical, completely retractile, perfoliate rhinophores
with approximately 40 tightly packed lamellae. The base of the rhinophores is blue-black with a similarly coloured core; while the rhinophore lamellae range from a pale yellowish colour to bright orange. The oral tentacles are strongly developed and enrolled - they are also blue-black.
There are five nonretractile tripinnate gills; the three anteriormost gills being larger than the others. The gills are white, with a blue-black tip to each leaflet giving each gill the appearance of being white with a dark blue edge. Pola et al describe a yellow line up the inner side of the rachis. The genital pore is dark blue and opens on the right side, midway between the gills and the rhinophores. Pola et al describe preserved animals measuring 25–80 mm in length.

This species is illustrated in A Field Guide to Marine Mollusks of the Galapagos by Cleveland Hickman Jr [1999 - p. 127 as Roboastra sp.].

"The edge of the foot is blue-black. The body is patterned with yellow ochre and blue-black stripes. The rhinophores are bright orange with blue-black at their bases and tips. The gills are white with blue-black tips." It is found in the Gulf of California and the Galapagos. It feeds on Tambja mullineri in the Galapagos and Tambja spp. in the Gulf. [See Ray Simpson's message].

Note added 21 July 2005: Previously known on Forum as Roboastra sp.2.

  • Pola, M.., Cervera, J.L. & Gosliner, T.M. (2005) Review of the systematics of the genus Roboastra Bergh, 1877 (Nudibranchia, Polyceridae, Nembrothinae) with the description of a new species from the Galápagos Islands. Zoological Journal of the Linnean Society,144, 167–189. With 12 figures
Authorship details
Rudman, W.B., 2005 (July 21) Roboastra leonis Pola, Cervera & Gosliner, 2005. [In] Sea Slug Forum. Australian Museum, Sydney. Available from

Related messages

  1. Roboastra leonis - Feeding behaviour
    From: Alicia Hermosillo, July 26, 2007
  2. Roboastra leonis from the eastern Pacific
    From: Bill Rudman, July 22, 2005
  3. Re: Roboastra tigris? from Galapagos
    From: Ray Simpson, January 25, 2004
  4. Roboastra tigris? from Galapagos
    From: Patty Dilworth, January 23, 2004

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