Rostanga rubra
(Risso, 1818)

Order: NUDIBRANCHIA
Suborder: DORIDINA
Superfamily: EUDORIDOIDEA
Family: Dorididae

DISTRIBUTION

Recorded from the Atlantic coast of Europe and North Africa, and from the Mediterranean.

PHOTO

Upper: Cerbere, France, Mediterranean coast, July 11, 2003. Size: 8-10mm. Photo: Marina Poddubetskaia
Lower: 15/05/2002
Place: Kemer, Turkey, 15 May 2002, Depth: 15m, Size: 6-7cm. Photo: Levent Konuk

Thompson & Brown, (1984) and Schmekel & Portmann (1982) considered Rostanga coccinea and R. perspicillata to be synonymous with R. rubra (Risso), and R. rufescens to be an unnecessary replacement name for R. coccinea. Not mentioned in these reviews is R. temarana Pruvot-Fol, 1953, described from the Atlantic coast of Morocco which shows no difference in radular morphology from R. rubra and at 3-4 mm long, is almost certainly based on juveniles.

Rostanga rubra is red with vertically arranged rhinophore lamellae. The bifid outer lateral teeth are similar to those of the Indo-West Pacific species R. bifurcata, from which it differs in rhinophore shape and shape of inner lateral teeth. The inner lateral teeth of R. rubra have been described as bicuspid by many authors because of a prominent pointed projection on the outside of the main cusp. This secondary 'cusp' is derived from the angular shoulder present on the inner lateral teeth of many species of Rostanga.

The egg-ribbon has been described as white (Alder & Hancock, 1848) and 'rose-coloured' (Kress, 1971). Kress has carefully observed and measured all stages in development from single-celled egg to hatching Type 1, planktotrophic veliger in 12 days (15-18°C). The egg ribbon of almost two whorls is a stiff jelly-like structure similar to that of Rostanga arbutus but the eggs are much smaller.

Because of the well-known problems concerning sponge taxonomy and misidentifications, food records for this species must be treated with some caution. Kress (1971) records it from Microciona atrosanguinea and rarely from Hymeniacidon sanguinea while Thompson & Brown (1984) state that it "feeds upon red siliceous sponges such as Microciona sanguinea Bowerbank". Brown & Picton (1979) note that it "feeds on sponges (e.g. Ophlitaspongia seriata)".

References:
• Rudman, W.B. & Avern, G.J. (1989) The genus Rostanga Bergh, 1879 (Nudibranchia:
Dorididae) in the Indo-West Pacific. Zoological Journal of the Linnean Society, 96: 281-338.
• Schmekel, R. L., & Portmann, A. (1982) Opisthobranchia des Mittelmeeres, Nudibranchia und Saccoglossa. Fauna e flora del Golfo di Napoli 40, Monografia della Stazione Zoologica di Napoli, pp. i-viii, 1-410, pls. 1-36. Springer-Verlag.
• Thompson, T. E. & Brown, G.H. (1984) Biology of opisthobranch molluscs, vol. 2, 229 pp., 41 pls. Ray Society, no. 156.

Authorship details
Rudman, W.B., 2002 (February 17) Rostanga rubra (Risso, 1818). [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/rostrubr

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