Radula of Gastropteron bicornutum from Koumac

January 16, 2004
From: Bill Rudman

Here are some scanning electron photographs of the radula of the specimen of Gastropteron bicornutum from Koumac in northern New Caledonia, which I reported in a separate message.

• Chenal de la Passe de Koumac, N of Ilot Kendac, 20°38.8'S, 164°15.6'E, New Caledonia. 32-37m, 8 Oct. 1993. 6mm live length 1 specimen, AM C200414

• Upper right - whole radular ribbon. Note change in denticulation of innermost teeth from old teeth [at top of photo] to new teeth [at bottom]. Scale = 200 microns.
• Lower Left - outer teeth on right side. Scale = 50 microns.
• Lower Right - Deveoping innermost teeth showing aberrant denticulation. Scale = 50 microns. Photos: Alison Miller.

The radular formula was 18(+2) x 3-
In the mount the outermost of the 4 lateral teeth was often missing, probably lost in prepartion of the mount. The denticulation along the edge of the large innermost lateral teeth appears to be aberrant. In the oldest teeth [uppermost rows in upper right photo] there are a series of small denticles along the whole of the cutting edge of the tooth, while in the younger teeth [lower rows in upper most photo] the teeth are irregularly shaped and restricted to the inner end of the tooth. Both Baba & Tokioka (1965) and Gosliner (1989) describe small denticles right along the cutting edge.
Best wishes
Bill Rudman

Rudman, W.B., 2004 (Jan 16) Radula of Gastropteron bicornutum from Koumac. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/11926

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