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. 27d): GS 9520, J41/f8029, Awamoa Creek, North Otago, Altonian (GNS) |
 (Pl. 27f): GS 9520, J41/f8029, Awamoa Creek, North Otago, Altonian (GNS) |
Beu & Maxwell (1990): Chapter 12; p. 244; pl. 27 d,f.
Synonymy: Raeta tenuiplicata Bartrum 1919, p. 97; Macoma tenuiplicata
Type species of Bartrumia Marwick, 1934
Classification: Tellinidae: Macominae
Description: Moderate-sized for family (length 30-40 mm), ovate- trigonal, strongly inflated, thin-shelled; umbones sloping backwards; beaks orthogyrous or slightly prosogyrous, at or somewhat behind middle of length. Low, broadly rounded ridges extend from umbo to antero-ventral and posteroventral junctions. Anterior margin strongly and broadly convex, posterior end with short, narrowly rounded and weakly twisted rostrum. Commarginal sculpture of fine, low, well spaced ridges; radial sculpture of feeble striae. Hinge narrow, left valve with lamellar anterior and posterior cardinal teeth; right valve with narrowly triangular anterior cardinal and larger, bifid median cardinal; no lateral teeth. Ligamental groove long and narrow, attachment area for inner ligament narrowly triangular, slightly concave. Anterior adductor muscle scar very elongated parallel to anterior margin of shell, posterior scar much smaller, subrectangular. Pallial sinus moderately deep, extending beyond middle of shell, ventral margin partly confluent with pallial line.
Comparison: Bartrumia tenuiplicata is distinguished from other New Zealand tellinids by its relatively short shell, its strong inflation, its weak rostral twist and its very long anterior adductor muscle scar. The holotype and topotypes of B. tenuiplicata are articulated and largely decorticated specimens and are therefore difficult to compare with shells from other localities, so the limits of the species (and its stratigraphic range) must be uncertain. The only other species named to date, B. oneroaensis (Otaian, Oneroa, Waiheke Island), has more erect umbones than B. tenuiplicata and is probably distinct. Specimens from the Mount Harris Formation (Otaian), Tengawai River near Sutherland's, South Canterbury, are more elongate and have more widely spaced commarginal sculpture than either B. tenuiplicata or B. oneroaensis and probably represent a third species.
Bartrumia is known definitely only from New Zealand, where it ranges from at least Duntroonian to Tongaporutuan. It may be represented in the modern West African fauna by Macoma cancellata (Sowerby, 1873), type species of Rostrimacoma Salisbury, 1934. Bartrumia seems to be closely related to Leporimetis Iredale, 1930 (type species: L. spectabilis (Hanley, 1844), Recent, Australia), which has a similar anterior adductor muscle scar but differs in having a much stronger rostral twist. Bartrumia occurs commonly in massive siltstone and mudstone of probably bathyal environment, but it is also present in much shallower-water faunules.
Distribution: Altonian-Tongaporutuan; western end of Okahukura tunnel, Taranaki, Lillburnian? (type) and other localities in Taranaki and southwest Auckland; Awamoa Creek, Oamaru; Stanton River, North Canterbury.
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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