Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 16b): GS9521, J41/f8030, Ardgowan Shellbed, Oamaru, Altonian (GNS)
(Pl. 16d): holotype, Boby's Creek, Waipara River, Altonian (TM4075, GNS)
(Pl. 16f): holotype, Boby's Creek, Waipara River, Altonian (TM4075, GNS)
Beu & Maxwell (1990): Chapter 11; p. 175; pl. 16 b,d,f.
Synonymy: Nucula sagittata Suter 1917, p. 65
Classification: Nuculidae: Nuculinae
Description: Moderately large for family (length 9-12 mm), ovate, strongly inequilateral, moderately inflated, interior nacreous. Lunule and escutcheon narrow, slightly flattened. Radial sculpture of numerous fine costellae, more prominent on flanks than on lunule or escutcheon. Commarginal sculpture of narrow, low, locally anastomosing, rounded ridges with interspaces of similar width to 1 ridge or slightly wider, relatively prominent and stronger than radial costellae on flanks, but almost obsolete on lunule and escutcheon. Lunule with short, rather irregular ridges transverse to both radial and commarginal elements, producing a chevron pattern on articulated shells. Hinge with 8-10 posterior and 16-20 anterior teeth, proximal teeth small, almost straight- sectioned, distal teeth chevron-sectioned. Resilifer projecting strongly, directed forwards, upper edge fused to lower part of hinge plate. Ventral margin finely crenulate.
Comparison: Varinucula is an endemic genus that differs from other nuculid genera in having short transverse ridges along the lunule, as well as relatively distinct commarginal sculpture. The Recent type species, V. gallinacea (Finlay, 1930), is less strongly inflated than V. sagittata and has more regular transverse ridges. The only other species of the genus so far described, V. crepida (Lillburnian-Waiauan), has more prominent radial sculpture than V. sagittata.
Distribution: Altonian; Mount Brown Formation, Boby's Creek, Waipara (type); Southburn Sand, Sutherlands, Tengawai River; Ardgowan Shellbed, Oamaru (moderately common).
Cite this publication as: "A.G. Beu and J.I. Raine (2009). Revised
descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990). GNS
Science miscellaneous series no. 27."
© GNS Science, 2009
(Included with a PDF facsimile file copy of New Zealand Geological Survey Paleontological Bulletin 58 in CD version from: Publications Officer, GNS Science, P.O. Box 30368 Lower Hutt, New Zealand)