From Figure 15. Rostanga muscula, radular morphology, Auckland, New Zealand, AM C152369. A, B, Central region of two specimens; C, central region and inner right laterals; D, transition zone on right; E, outermost right lateral teeth. Scale bar = 30µm in all cases. Photos: G. J. Avern. [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]
Return to Rostanga muscula.
The innermost lateral teeth have a broad basal plate and a recurved triangular blade with a fringe of about 40 short rounded denticles down the whole of the inside edge (Figs A-C). There are no outer denticles. The inner lateral teeth from Tooth 2 are similar in size to Tooth 1 but the triangular blade is replaced by a non-denticulate pointed hook (Fig C). The inner lateral teeth begin to increase in size about three-quarters of the way out. At this transition point a relatively long denticle or secondary cusp appears on the outside of the tooth about one-quarter of the way down from the tip (Fig 15). There are two or three of these 'transition' teeth in each row and then all the remaining teeth develop a set of two to four long rounded rods which attach, often by a common base, in the fork between the original cusp and the secondary outer denticle of the transition teeth. The rod-like denticles are of gradually diminishing length, the inner one being slightly shorter than the original cusp and the outermost one slightly longer than the outer denticle (Fig E). The jaw plates although well-developed, are small when compared with similar sized specimens of R. arbutus or R. calumus. There are three or four rows of exposed rodlets and approximately the same number with a membranous cover.
The radular formulae of two specimens from Auckland, New Zealand (AM C152369) are:
70.0.70 x 64 (+ 2) - 19 mm alive
50.0.50 x 46 (+ 2) - 8 mm alive
Rudman, W.B., 2002 (February 5) Rostanga muscula - Radula. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/rostmuscrad