Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 21a): GS951A, J41/f8475, Target Gully Shellbed, Oamaru, Altonian (GNS)
Beu & Maxwell (1990): Chapter 11; p. 201; pl. 21 a.
Synonymy: Tritonidea acuticingulata Suter 1917, p. 35; Zeapollia acuticingulata
Type species of Zeapollia Finlay, 1926
Description: Small for family (height 9-13 mm), ovate, spire about half total height. Protoconch mamillate, of 1 smooth whorl. Teleoconch of 4-4.5 whorls, spire whorls convex, last whorl weakly excavated, contracted gradually to short, ill-defined neck. Axial sculpture of prominent, rounded, prosocline costae with interspaces of similar or greater width, reaching from suture to suture on spire, and onto lower part of base of last whorl; 10 or 11 costae on penultimate whorl. Spiral sculpture commencing at beginning of teleoconch as 2 cords, 1 near middle, the other between it and lower suture, and 1 or 2 much weaker spirals on upper half. Cords prominent on later whorls, the 2 anterior ones remaining stronger than those above, joined on last whorl by a peribasal cord of similar strength (visible above suture on penultimate whorl on some shells) and 4 or 5 prominent cords on base, and 4 or 5 much weaker, crowded ones on neck. Some shells with interstitial threads as well. Spirals noticeably thickened where they cross axial costae, particularly on lower part of base where they are distinctly nodulose. Aperture ovate, columella slightly concave and subvertical above, strongly twisted to left below, with a low ridge on twist. Siphonal canal short, strongly notched; fasciole low, rounded. Inner lip moderately callused, with a prominent denticle or ridge immediately above the one on the columellar twist, and 2 weaker parietal denticles, some shells with an additional, oblique ridge on upper part of columella. Outer lip thickened externally by a broad, rounded varix, and bearing 5-7 prominent denticles within.
Comparison: Cantharus acuticingulatus is readily distinguished from the many other New Zealand buccinulids by its small size, its prominent axial and spiral sculpture, its relatively strongly armoured aperture and its short siphonal canal. An undescribed species from the Slip Point Siltstone, Clifden (Clifdenian) differs from C. (Zeapollia) acuticingulatus in its more slender shell, and in having less prominent axial costae, but more prominent secondary spiral sculpture. Zeapollia is represented in Australia by C. (Zeapollia) purpuroides (Johnston, 1880) (Longfordian (basal Miocene), Table Cape, Tasmania) (Finlay 1926c, p. 418). Finlay also referred the extant Tritonidea colensoi Suter, 1908 to Zeapollia, but it was regarded as a subspecies of Buccinulum vittatum by Ponder (1971b, p. 262) and certainly belongs in Buccinulum.
Distribution: Altonian, Target Gully Shellbed, Oamaru (type) (abundant); not recorded elsewhere.
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)