Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 38f): holotype, GS191, V21/f8463, "Shrimpton's", Kikowhero Stream, Matapiro Station, Ngaruroro River, central Hawke's Bay, Nukumaruan (TM4145, GNS)
(Pl. 38g): holotype, GS191, V21/f8463, "Shrimpton's", Kikowhero Stream, Matapiro Station, Ngaruroro River, central Hawke's Bay, Nukumaruan (TM4145, GNS)
Beu & Maxwell (1990): Chapter 15; p. 308; pl. 38 f, g.
Synonymy: Glycymeris shrimptoni Marwick 1923, p. 75
Classification: Glycymerididae: Glycymeridinae
Description: Small for genus (40-60 mm high), thick and solid, almost circular to slightly elongate (either dorso-ventrally or antero-posteriorly elongated), moderately well inflated, with low umbo and very weak sculpture. Sculpture of low, close, exceedingly fine, radial threads and grooves over whole exterior, every 8th or 10th groove slightly more prominent than the others. Evenly and closely chevron- grooved ligamental area fills low, wide triangle between umbo and hinge, growing downwards to obliterate central hinge teeth of large shells. Hinge plate wide, thick, and symmetrically arched, with many similar, low, narrow, elongate teeth along whole hinge; teeth vertical, straight, and short in central 0.2-0.3, but shallowly V-shaped and sloping outward radially over anterior and posterior ends. Interior of ventral margin deeply and coarsely crenulate. Adductor scars almost identical; no pallial sinus.
Comparison: The Waipipian Glycymeris waipipiensis is markedly larger and more consistently antero-posteriorly elongate than G. shrimptoni; Mangapanian specimens are difficult to distinguish from both G. waipipiensis and G. shrimptoni, and the distinction is obviously unimportant and probably not tenable. Extinction of relatively large species of the subgenus G. (Glycymeris) in the New Zealand area is an important index of the end of Nukumaruan time.
Distribution: Mangapanian?; Nukumaruan. "Shrimpton's" i.e., Kikowhero Stream, Matapiro Station, north of Ngaruroro River, central Hawke's Bay, Nukumaruan (type); abundant in shallow-water, high-energy environments (i.e., commonly found in coquina limestone) of Nukumaruan age throughout Wanganui basin, Hawke's Bay, Wairarapa, and North Canterbury.
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)