Rostanga dentacus
Rudman & Avern, 1989
Order: NUDIBRANCHIA
Suborder: DORIDINA
Superfamily: EUDORIDOIDEA
Family: Dorididae
PHOTO
W. side of Chek Chan, Mirs Bay, Hong Kong; 2-5 m, one specimen (6 mm long preserved), 13 April 1983, PARATYPE, AM C139173. Photos: Brian Darvell.
See also R. dentacus - Radula.
From the available colour photographs and field notes the body is a deep orange with brown specks on the basal mantle epithelium. There are also scattered white specks on the mantle skirt. The rhinophore stalk is transparent and the club is translucent white heavily speckled in brown with some white patches. The tip of the club is white. The gills are a translucent orange with a dusting of brown and some white specks especially near the edge. The animal is typical for the genus with a dense covering of caryophyllidia on the mantle and a circle of short erect gills. The rhinophore club is ovate with about five almost horizontal lamellae surmounted by a short rounded knob. No information on egg mass or developmental biology is available. The specimen from Heron Is. was found "on some sort of orange encrustation-sponge?" according to the collectors. Unfortunately the 'encrustation' was not collected. No information on the food of Hong Kong specimens is available.
Rostanga dentacus is one of the few species of Rostanga with horizontally arranged lamellae on the rhinophore club. The shape of the radular teeth is unique with all but the innermost tooth having long pointed non-denticulate cusps. The elongate innermost tooth has a few long pointed inner denticles. The name dentacus (Latin: dentis = tooth; acus = needle) refers to the shape of the teeth. At present the species is known from Hong Kong and the Great Barrier Reef, Queensland, suggesting a wide distribution, at least in the western Pacific.
Reference:
• 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 dentacus Rudman & Avern, 1989. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/rostdent
