Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 49e): Castlecliff, Wanganui, Castlecliffian (GNS, early collection)
Beu & Maxwell (1990): Chapter 16; p. 364; pl. 49 e.
Synonymy: Eucominia elegantula Finlay 1926b, p. 240; E. elegantula verrucosa Finlay 1926b, p. 241; Cominella (Eucominia) marlboroughensis Powell 1946b, p. 143.
Description: Small for subgenus (28-35 mm high), with moderately tall spire, short inflated last whorl, and short, strongly twisted canal, forming a prominent fasciole. Sutural ramp weakly concave. Sculpture of low, narrow axial costae, otherwise smooth apart from a few low spiral threads around base. Protoconch large, dome-shaped, of 2.5 smooth whorls.
Comparison: Cominella elegantula differs from the southern, cool-water species Cominella (Eucominia) nassoides Reeve (e.g., Pl. 42d) in its smaller size, weaker subsutural constriction (a narrow, concave sutural ramp) and much weaker spiral sculpture. C. elegantula verrucosa was proposed for coarsely sculptured variants in the Castlecliff C. elegantula population, and is of no taxonomic significance. Beu (2009) revised the status of C. marlboroughensis, and concluded that this name is based on modern specimens of C. elegantula, which still lives in the Cook Strait region (and is probably merely the northernmost form of C. nassoides; B.A. Marshall, NMNZ pers. comm.). Some specimens from Hawke's Bay Nukumaruan rocks are a little more coarsely sculptured than typical Castlecliff ones, but others agree exactly, so this form has a Nukumaruan-Recent time range.
Distribution: Nukumaruan-Recent. Castlecliff, Wanganui, Castlecliffian (types of Eucominia elegantula and E. elegantula verrucosa); Recent, 150 m, 40 km east of Cape Campbell, Cook Strait (type of Cominella marlboroughensis). Moderately common in offshore siltstone and sandstone (particularly Pinnacle Sand, Tainui Shellbed, and Upper Castlecliff Shellbed) at Castlecliff, Wanganui; uncommon in Nukumaruan siltstone in Hawke's Bay and Wairarapa; the same species still lives uncommonly in Cook Strait today.
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)