Rudman & Avern, 1989
Known only from Darwin, Northern Territory, Australia.
East Point, Darwin Harbour, Darwin, Northern Territory, Australia, 8 m; 9 mm long preserved, 15 May 1986, (AM C150085) Holotype.
See also R. aliusrubens - Radula.
The only information we have on the living animal is from the attached photo. The mantle is red, very closely approximating the colour of the sponge on which it was found. There are scattered blackish specks over the mantle in the preserved specimen. The gills and rhinophores are similarly coloured with some white marks on the tip of the rhinophore and the upper parts of the rhinophore club. The mantle is ovate and covered with a dense covering of caryophyllidia. The gills form a raised cup-like circlet, each gill having a flattened tip. The rhinophore club has four or five almost vertically arranged lamellae and a knob-like tip, similar to that illustrated for R. bassia.
The specimen was found on a colony of the sponge Clathria (Thalysias) lendenfeldi Ridley & Dendy, 1886 (Family Microcionidae). The red mantle and rhinophores with vertically arranged lamellae are similar to many other species of the genus. Rostanga aliusrubens can easily be distinguished on radular morphology. Only two other species, R. arbutus and R. byga, have outer lateral teeth with many long terminal denticles. It differs from R. arbutus in rhinophore shape and from both species in having many short inner denticles on the innermost lateral tooth, both the other species having a few large teeth. The name aliusrubens (Latin: alius = another, rubens = red) is a comment on the colour of this and most species of the genus. At present this species is only known from Darwin in northern Australia.
• 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.
Rudman, W.B., 2002 (February 4) Rostanga aliusrubens Rudman & Avern, 1989. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/rostaliu