Comprehensive DescriptionRead full entry
“Genus Maoricrater n.gen.
Type species: Notoacmea explorata Dell, Recent, New Zealand.
Shell small, patelliform, outline oval, anterior slope concave below apex, posterior slope gently convex. Sculpture of radial rows of very fine raised nodules. Muscle-scar horse-shoe shaped. Animal with edge of mantle thickened and hearing continuous band of fine cilia-like outgrowths. Radula formula (1)+1+(1), centrals tricuspid but apparently formed by the coalesence [sic] of three teeth.
This species, which proves to be common on the shelf and down to at least 330 fathoms in New Zealand, has a remarkable general similarity in shell characters and gross anatomy to Cocculina and Tectisumen, but has a very different radula and gill.
Whatever the true relationships of the Lepetellids and Cocculinids may be, there can be little doubt that Maoricrater is derived from a limpet group of the Patellid stock, and it seems best placed in the family Lepetidae, although the radula is rather different from the usual one in the family. The radula (Figs. A 11, 12, 13, 14) bears a single row of what are at first sight single teeth. These are stout dark brown, and hooked with a small lateral cusp in each side. On close examination, these lateral cusps prove to be separated from the central tooth, although closely appressed, and the apparent single central is probably the result of coalescence of a central and two laterals. The formula may therefore be written (1)+1+(1).
The small size, elongate shape, and the radular characters separate Maoricrater from any other genus of the family. “
(Dell, 1956: 57-58)