GNS Science

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

New Zealand Cenozoic Mollusca

Marshallaria spiralis (Allan, 1926)


(Pl. 8 x): GS9480, J40/f8801, McCulloch's Bridge, Kaiatan (GNS)

Beu & Maxwell (1990): Chapter 8; p. 124; pl. 8 x.

Synonymy: Verconella spiralis Allan 1926, p. 340; Marshallena spiralis

Type species of Marshallaria Finlay and Marwick, 1937

Classification: Turridae: Pseudotominae

Description: Size moderate for subfamily (height 20-25 mm), broadly fusiform, spire 0.4-0.5 total height. Protoconch conical, of about 4.5 moderately convex whorls, last 1.25-1.5 whorls with prominent spiral cords, crossed on last 0.25-0.5 whorl by narrow axial costellae, remainder smooth. Teleoconch of up to 4.5 whorls, bluntly shouldered near middle on spire, sutural ramp almost flat or somewhat concave because of subsutural fold; last whorl contracted gradually, broadly excavated. Axial sculpture of rounded or subtriangular costae reaching from near middle of sutural ramp to lower suture on spire whorls, fading out on upper part of base of last whorl; 12-16 on penultimate whorl. Spiral sculpture highly variable, commencing as 6-9 narrow, rather flattened cords, those (4 or 5) on whorl sides stronger than those on ramp. Spirals remaining constant in number during growth on some shells, but typically joined by secondary spirals on ramp and between primaries, some eventually rivalling primaries in strength. Last whorl with 14-16 additional cords, some with interstitial threads, on base and neck. Spirals crossing axial costae with little or no thickening, but finely crenulated by growth lines. Aperture subrectangular, columella smooth with a gentle twist to left at inception of short, unnotched siphonal canal. Outer lip thin, edge weakly crenulate, with a broadly arcuate, shallow anal sinus on ramp.

Comparison: Marshallaria senilis (Bortonian, Hampden Beach) is very similar to M. spiralis and may be conspecific, but the few specimens that we have seen from Hampden have more rounded teleoconch whorls and more prominently crenulate teleoconch spirals than McCulloch's Bridge shells. M. serotina (Bortonian, Waihao Downs) is also similar to M. spiralis, but is considerably larger (height about 35 mm) and has more numerous, finer spiral cords. Most other species traditionally included here, following Powell (1942), were transferred to his new genus Zeatoma by Maxwell (1992, p. 157).

Marshallaria superficially resembles Austrotoma, but Austrotoma differs in having a prominent siphonal notch and a ridge-margined fasciole. Marshallaria seems to be much closer to the Northern Hemisphere genus Pseudotoma Bellardi, 1875 (available, Bouchet et al. 2005, p. 145; = Acamptogenotia Rovereto, 1899), differing from it only in relatively minor characters. All three taxa, as well as Marshallena, Notogenota, Zeatoma, Belophos, Tahuia and several other Australasian taxa, belong in the subfamily Pseudotominae, recognised by Maxwell (1992, p. 153). On conchological grounds, at least, this has some claim to be the most primitive subfamily in the Turridae. Marshallaria has a recorded range of Wangaloan to Altonian in New Zealand. We are not aware of any undoubted occurrences outside New Zealand, although it seems likely that the "Australian" group Belatomina Powell, 1944 is a synonym. The relatively few records suggest that Marshallena favoured moderately deep waters (mid shelf to upper bathyal zones).

Distribution: Kaiatan; Waihao Greensand, McCulloch's Bridge (type) (not uncommon); Kapua Tuff, Waihao River (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
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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