Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 2n): holotype, Boulder Hill, Wangaloan (Auckland Museum)
(Pl. 2o): holotype, Boulder Hill, Wangaloan (Auckland Museum)
Beu & Maxwell (1990): Chapter 5; p. 86; pl. 2 n, o.
Synonymy: Taioma tricarinata Finlay & Marwick 1937, p. 72
Type species of Taioma Finlay & Marwick, 1937
Description: Moderately large for superfamily (height 25-50 mm), broadly fusiform, spire strongly gradate. Protoconch not known. Teleoconch of 6- 7 whorls, strongly shouldered near or below middle on spire, last whorl with 2 additional, less prominent keels, upper one emerging from suture, sutural ramp flat or slightly concave. Last whorl strongly excavated with short, curved neck. Axial sculpture of prominent nodules on shoulder angulation (16-18 per whorl) and much less well defined ones on lower keels. Spiral sculpture of subequal threads over whole surface. Aperture pyriform, columella twisted to left medially to form moderately long, unnotched siphonal canal. Inner lip smooth, thinly callused; outer lip thin, with broadly arcuate sinus on ramp, its apex much closer to suture than to periphery.
Comparison: Taioma is of uncertain affinity and was placed by Finlay & Marwick (1937) in its own family as it seems to combine characters of several muricoidean families. T. tricarinata is the only known New Zealand species, but the genus is recorded from the Late Eocene of Seymour Island (Zinsmeister 1982, table 3; Stilwell & Zinsmeister 1992, pp. 137-138) and possibly also from the Paleocene of Greenland (specimen figured by Kollmann & Peel (1983, fig. 220) as "Clinura sp. 1"; also cast in NZGS, presented by A. Rosenkrantz). Since publication (Beu & Maxwell 1990) this genus has proved to be moderately widespread, but its affiniities are no clearer. Although Taioma appears to be broadly buccinoidean-muricoidean, some specimens referred to conoidean genera (e.g., Clinura sp.; Kollmann & Peel 1983, p. 97, fig. 220) have only a broad, shallow posterior sinus and closely resemble Taioma, so it is even possible that Taioma is a conoidean, perhaps related to such large taxa as Speightia spinosa (Suter, 1917). Better-preserved material with protoconchs would help classifiy it.
Distribution: Wangaloan, Boulder Hill (type) (rather uncommon); Wangaloa (rare).
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)