Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 2a): GS10195, I44/f8486, Boulder Hill, Wangaloan (GNS)
Beu & Maxwell (1990): Chapter 5; p. 80; pl. 2 a.
Synonymy: Heliacus conicus Marshall 1917, p. 453
Type species of Conominolia Finlay, 1926
Description: Rather small for family (height 7-10 mm), turbiniform, widely umbilicate. Protoconch small, apparently smooth, of a little more than 1 whorl. Teleoconch of 5-5.5 whorls, spire whorls biangulate, upper (adapical) angulation descending during growth. Last whorl with additional angulation on periphery (exposed on penultimate whorl of some shells). Sutural shelf moderately wide, horizontal on early whorls, sloping on later ones. Spiral sculpture on spire of 2 narrow cords marking angulations, with considerably finer threads between and on sutural shelf. Base with additional cord marking peribasal angulation, and 8-10 fine, closely spaced cords between it and umbilicus. On well preserved shells spirals are finely beaded by the numerous, closely spaced growth lines. No other axial sculpture. Umbilicus with 7-10 fine cords within. Aperture subcircular.
Comparison: The Whaingaroan species Conominolia sulcatina (PI. 91) has more evenly convex whorls, a narrower sutural shelf, crisper spiral cords, stronger basal spirals and much weaker axial sculpture than C. conica. Several other trochoideans ranging in age from Duntroonian to Mangapanian or Nukumaruan have been assigned to Conominolia, but these are much smaller and have less strongly convex whorls and fewer umbilical spirals than either C. conica or C. sulcatina. Most records of the genus are from shallow-water (inner shelf) sandstone or shellbeds.
Distribution: Wangaloan, Wangaloa Formation, Wangaloa (type); Boulder Hill (common at both localities).
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)