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Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)

New Zealand Cenozoic Mollusca

Aethocola (Neocola) apudalpha (Finlay, 1926)


(Pl. 21j): Bluecliffs, Otaio River, Otaian (Canterbury Museum)

Beu & Maxwell (1990): Chapter 11; p. 197; pl. 21 j.

Synonymy: Austrofusus (Neocola) apudalpha Finlay, 1926b, p. 235.

Classification: Buccinulidae

Description: Size moderate for genus (height 25-40 mm), bucciniform, spire 0.4-0.5 total height. Protoconch conical, of 4.5 convex whorls, last quarter whorl with a few opisthocyrt costellae, remainder smooth. Teleoconch of 6-7 whorls, convex at first but soon becoming angled near middle, sutural ramp almost flat on early whorls, distinctly concave with a weak subsutural swelling on later whorls; base weakly subangled, neck moderately long, twisted. Axial sculpture commencing as narrow costae reaching from suture to suture, gradually increasing in strength except on ramp where they eventually become obsolete; on adult whorls consisting of prominent, broadly rounded costae with concave interspaces of similar or greater width, dying out on upper part of base on early portion of last whorl, but reduced to little more than low nodules on shoulder angulation on latter half of last whorl on many shells; penultimate whorl with 10-12 costae. Other axial sculpture of very numerous fine growth ridges. Spiral sculpture commencing as 5 or 6 fine cords, additional spirals appearing by intercalation during growth and tending to become as strong as primaries on later whorls; penultimate whorl with 12-16 subequal, low, narrow cords with much wider interspaces, some with interstitial threads and exceedingly fine threadlets. Last whorl with about 15 additional cords (some with interstitial threads) on base and neck, 3 or 4 of them on lower base noticeably coarser than the others. Aperture ovate, columella strongly inclined to right but almost straight above, strongly twisted to left and away from aperture below; siphonal canal moderately long, notched with narrow, prominently raised fasciole. Inner lip thinly callused; outer lip thin, prosocline, almost straight except for a shallow indentation near abapical end.

Comparison: Aethocola apudalpha is readily distinguished from A. (Neocola) alpha and its presumed relatives (Pl. 25b-d) by its broader shell and its markedly longer siphonal canal, and by lacking a continuous ridge along the outer edge of the fasciole. The basal spiral cords are much less strongly differentiated than in either A. (Neocola) beta or A. (Neocola) gamma, but are comparable with those of some specimens of A. (Neocola) alpha. A. (Neocola) flexuosa (Pl. 25g) has a similar siphonal canal to A. apudalpha but differs in its much more slender shape and in having axial sculpture becoming obsolete for a short distance on the spire. A closely similar species occurring in the Ardgowan and Target Gully Shellbeds, Oamaru (Altonian) differs from A. apudalpha in its larger size (height 35-50 mm), broader shell and coarser spiral sculpture. For further comments on Aethocola (Neocola) see under A. (Neocola) alpha, beta and gamma (below).

Distribution: Waitakian-Otaian; Otekaike Limestone, Trig Z, Otiake, Waitakian (type); Mount Harris Formation, Bluecliffs, Otaio River; Mt Horrible, Pareora River; Tengawai River near Clelland's Bridge. Uncommon at Trig Z, but common to very common at other 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
ISBN 978-0-478-19705-1
ISSN 1177-2441
(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)


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