GNS Science

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

New Zealand Cenozoic Mollusca

Inquisitor awamoaensis (Hutton, 1873)


(Pl. 22j): GS9500, J41/f8028, excavation for Oamaru Borough Council septic tank, South Oamaru, Altonian (GNS)

Beu & Maxwell (1990): Chapter 11; p. 211; pl. 22 j.

Synonymy: Pleurotoma awamoaensis Hutton 1873b, p. 4; Drillia awamoaensis; Pseudoinquisitor problematicus Powell 1942, p. 96; Inquisitor (Pseudoinquisitor) problematicus

Type species (as P. problematicus) of Pseudoinquisitor Powell, 1942

Classification: Turridae: Crassispirinae

Description: Size moderate for genus (height 20-30 mm), narrowly fusiform, spire 0.7 total height. Protoconch mamillate, of 1.5 smooth, convex whorls. Teleoconch of 8-9 whorls, weakly shouldered at about 0.7 whorl height on spire; sutural ramp concave with pronounced subsutural fold, sides strongly convex. Last whorl shallowly excavated. Axial sculpture of prominent, rounded opisthocline costae with concave interspaces, reaching from lower part of ramp to lower suture on spire, dying out on upper part of base of last whorl; 10-13 costae on penultimate whorl. Spiral sculpture on ramp of subdued threads, typically with 1 or 2 somewhat stronger cords on subsutural fold; whorl sides with much stronger, low, rounded cords, 5 or 6 on penultimate whorl, some with interstitial threads; last whorl with about 20 additional, similar cords on base and neck. Aperture narrow, columella gently convex, siphonal canal short, shallowly notched. Inner lip with parietal callus pad, narrowly and more thinly callused below. Outer lip thin, with deep but rather narrow anal sinus on ramp, convex below except for shallow stromboid notch near anterior end.

Comparison: Powell (1942, p. 93-94) noted that two superficially similar turrids, differing mainly in protoconch characters, are present in Altonian beds in the Oamaru district. One of these, with a conical protoconch, he identified as Inquisitor awamoaensis; the other, with a mamillate protoconch, he named Pseudoinquisitor problematicus, and selected it as the type species of his new genus Pseudoinquisitor. He later synonymised Pseudoinquisitor with Inquisitor but continued to recognise I. problematicus as a distinct species (Powell 1966, p. 79-80). Unfortunately, the type specimen of Pleurotoma awamoaensis has a mamillate protoconch so P. problematicus becomes a synonym of Inquisitor awamoaensis, leaving the other Inquisitor (which occurs in the Mount Harris Formation at Awamoa Creek (not the same locality as Awamoa Beach), Target Gully Shellbed and Mt Harris) without a name. Quite apart from the protoconch, this unnamed species differs from I. awamoaensis in having considerably finer spiral sculpture, a character that also distinguishes it from I. komiticus (Otaian-Altonian, Pakaurangi Point, Kaipara Harbour).

Inquisitor includes slender, fusiform turrids with a distinct subsutural fold, a concave sutural ramp, axial sculpture of prominent costae below the ramp, a parietal callus pad, and a U-shaped anal sinus on the ramp. In New Zealand it is doubtfully recorded from the Wangaloan, but Maxwell (1992, p. 152) removed the supposed Kaiatan species to Comitas (with some hesitation, suggesting it is more similar to Pseudofusia Shuto, 1969 than to Comitas). It is recorded more definitely from Waitakian to Tongaporutuan. Many extant species occur in the tropical Indo-West Pacific.

Distribution: Altonian; "Awamoa", Oamaru (probably former outcrops of Mount Harris Formation, on beach at mouth of Awamoa Creek — type locality of P. awamoaensis); Pukeuri road cutting, Oamaru (type locality of P. problematicus) (common); Old Rifle Butts; excavation for Oamaru Borough Council septic tank, South Oamaru (common).

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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