Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
| | Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990) |
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  (Pl. 21h): Mt Harris, South Canterbury, Otaian or Altonian (GNS, from an early collection) |
Beu & Maxwell (1990): Chapter 11; p. 196; pl. 21 h.
Synonymy: Fusus dentatus Hutton 1877b, p. 594; Fusinus spiralis dentatus
Type species of Coluzea Finlay in Allan, 1926
Classification: Turbinellidae: Columbariinae
Description: Moderately large to large for genus (height 45-120 mm), broadly fusiform; spire pagodiform, about 0.4 total height. Protoconch mamillate, of about 2.5 whorls, initial whorl bulbous, deviated, last 1.5 whorls angled near middle, last whorl narrower than preceding whorl, with 1 or 2 weak axial costellae near end. Teleoconch of 9-10 whorls, sharply angled at or below middle on spire, sutural ramp broad, almost flat, whorl sides sloping inwards; last whorl with well developed peribasal angulation, excavated below with a very long, straight, slender neck. Axial sculpture on first 5 whorls or so of low, rounded folds with much broader interspaces, reaching more or less from suture to suture and forming triangular serrations on peripheral keel; during growth, folds tending to become obsolete on ramp and sides, but peripheral serrations becoming more prominent, more strongly vertically compressed, and more rounded; mature shells with 12-16 serrations on penultimate and last whorl. (On a very large shell (original length c. 120 mm) from Awamoa Creek, axial sculpture on last 3 whorls is reduced to growth ridges and numerous small, irregular peripheral serrations). Spiral sculpture commencing at beginning of teleoconch as a narrow peripheral cord, accompanied by a weaker one between it and lower suture, and 2 or 3 on ramp. A narrow cord margining lower suture appears at about same stage. During growth an additional cord may appear on sides and another on ramp, but basic spiral sculptural plan remains much the same. Adult shells with some Very fine interstitial threads. Supramargining cord emerging on last whorl as peribasal angulation, accompanied by about 14 narrower cords on base and neck. Aperture ovate, columella straight; siphonal canal very long and slender, usually straight, but slightly recurved in largest shell seen. Inner lip thinly callused, outer lip thin, smooth within.
Comparison: Coluzea dentata is always uncommon or rare and difficult to collect in a reasonably complete condition, so its variation and relationship to other species is not well understood. The three Tongaporutuan shells are very similar to Otaian and Altonian specimens in most respects, but all have more numerous spiral cords on the base than typical C. dentata. The absence of records of Coluzea of this kind from the intervening Southland Series makes it difficult to know if this difference is taxonomically significant. C. dentata seems to be closely related to C. macrior (Altonian, Ardgowan and Target Gully Shellbeds) and C. paucispinosa (Waitakian, Otiake). According to Finlay (1930e, p. 269), C. macrior differs from C. dentata (with which it occurs at both localities) in its more slender shape, more rounded periphery and much weaker peripheral serrations. Although it may seem unlikely that there were two, possibly sympatric, species of Coluzea in the North Otago area during the Altonian, the limited available material does seem to bear out Finlay's contention that C. macrior is a distinct species. C. paucispinosa is poorly known, but it seems to differ from C. dentata in having a smaller and much less strongly angled protoconch, finer spiral sculpture, more numerous spirals on the base and neck, and fewer peripheral serrations (only 9 to 11 per whorl). It may also be significant that available specimens are much smaller than C. dentata (height only 18-30 mm). Specimens of Coluzea from another Waitakian locality (Brother's Stream, Hakataramea Valley— probably of deeper-water facies than Trig Z) are more like C. dentata in overall size, protoconch size and spiral sculpture, but have larger and more strongly compressed peripheral serrations, and have a more prominent peribasal keel which is also serrated by the axial folds.
Coluzea is recorded from Mangaorapan to Recent in New Zealand, from the Middle to Upper Eocene of the Paris Basin and as extant species from southern Africa (Darragh 1969, p. 106-109) and the eastern Indian Ocean (Harasewych 1986). We agree with Harasewych (1983) that a position in the Turbinellidae seems the most reasonable one for Columbariinae.
Distribution: Otaian-Altonian, Tongaporutuan?; Mount Harris Formation, Mt Harris, South Canterbury, Otaian or Altonian (type) and other Otaian or Altonian localities in North Otago and South Canterbury; Blind River, Marlborough(?); Kaiwara River, North Canterbury(?); Hurupi Stream, Palliser Bay(?).
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
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