Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 36k): GS10951, P29/f6582, mouth of Upton Brook, Awatere Valley, Marlborough, Opoitian (GNS)
Beu & Maxwell (1990): Chapter 14; p. 292; pl. 36 k.
Synonymy: ?Struthiolaria cingulata Zittel 1864, p. 35; Struthiolaria dolorosa King 1934, p. 22
Description: Moderately large for genus (53 to at least 70 mm high), with moderately tall, stepped spire (equal to or slightly taller than height of aperture), narrow sutural channel, wide, flat, steeply sloping sutural ramp, a strong, slightly rounded angulation at upper third of spire whorls, a rounded peribasal angle, a normal oval S. (Struthiolaria) aperture with narrow varix and thin inner lip, and no axial sculpture other than weak growth lines. Sculpture of many wide, flat-topped, square-sided spiral cords, slightly irregular in development and width; in most specimens, relatively widely spaced and with a single narrow intermediate spiral thread over sutural ramp and whorl side, but much more closely spaced over base. Protoconch not seen, presumably as in S. papulosa.
Comparison: The status and evolutionary history of the three Awatere Valley Kapitean-Opoitian species Struthiolaria cincta (? late Tongaporutuan; Kapitean), S. cingulata (Kapitean ?-Opoitian ?) and S. dolorosa (Opoitian) are poorly known. Zittel's (1864, pl. 15, fig. 2) illustration of S. cingulata and a poor cast of the holotype in NZGS show few differences from S. dolorosa but the name S. cingulata has been used in NZGS collections for a more weakly sculptured form, regarded by Dr J. Marwick (in NZGS manuscript labels) as intermediate in a short-lived lineage between S. cincta and S. dolorosa. The earliest member, S. cincta, has narrow, finely nodulous upper and lower angulations and an evenly concave, weakly sculptured mid-whorl, and so is possibly descended from S. praenuntia (Pl. 29 i), differing in lacking the median cord of S. praenuntia. Specimens identified as S. cingulata (Kapitean-Opoitian?) are similar to S. dolorosa, but have lower, narrower, more widely spaced spiral cords. The comprehension of this sequence needs study of much more complete material. S. dolorosa is illustrated here as an example of the complex lineages of Struthiolaria in New Zealand Late Miocene and early Pliocene rocks. S. dolorosa has a close resemblance to S. frazeri (Mangapanian-Nukumaruan) (Pl. 42f), but the similarity probably is superficial, as S. frazeri is much larger and appears to have evolved from the Nukumaruan-Recent species S. papulosa. Recent examination of the type material of S. cingulata suggests that it is, indeed, conspecific with S. dolorosa (Beu, research in progress).
Distribution: Opoitian; mouth of Upton Brook, Awatere River, Marlborough (type), common, also common at a few other localities at the same horizon in Marlborough (notably shellbeds in Stace Stream, a tributary of Blind River). Not known elsewhere.
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)