Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 20i): GS9500, J41/f8028, excavation for Oamaru Borough Council septic tank, South Oamaru, Altonian (GNS)
Beu & Maxwell (1990): Chapter 11; p. 190; pl. 20 i.
Synonymy: Natica consortis Finlay 1924b, p. 451; Cochlis socius Finlay 1927b, p. 499 (invalid new name for N. consortis); Tanea socia
Classification: Naticidae: Naticinae
Description: Small for genus (height 8-11 mm), globose, spire slightly gradate, 0.25-0.3 total height. Protoconch moderately large, depressed, of about 2.5 smooth whorls. Teleoconch of 2.5-3 whorls, strongly convex except adapically where they are distinctly flattened and turned in towards suture, forming a sutural shelf; last whorl capacious, with a moderately wide umbilicus. No sculpture apart from weak growth lines and feeble spiral ridges, surface polished in well preserved shells. Umbilicus with a moderately large, smooth funicle. Aperture ovate, inner lip shallowly grooved along its length to take operculum; parietal callus thin. Outer lip prosocline, inclined at about 20° from vertical, almost straight except near suture where it is slightly retracted.
Comparison: Another Altonian species, Tanea sublata (Marwick, 1924) (White Rock River; Sutherlands) differs from T. consortis in its noticeably narrower shape and its higher spire. Both species are much smaller than T. zelandica (Nukumaruan-Recent) and have a relatively smaller funicle. The earliest member of the genus, T. praeconsors (Bortonian-Kaiatan, Waihao River), is smaller than T. consortis (height 7 mm) and has a narrow infra-umbilical ridge as well as a minute funicle.
Finlay (1927b, p. 499) claimed that the epithet "consortis" was an error for "consors", even though the former name appears no fewer than nine times in the original paper, and as the name Natica consors was used by Dall in 1909, he thought a replacement name was needed for N. consors Finlay. Finlay's emendation is here regarded as unjustified - if he intended the epithet to be an adjective then "consortis" is correct ("consors" is the masculine form); if on the other hand he was using the epithet as a noun then there is no conflict between "consors" (a brother) and "consortis" (a sister). Under the Code of Zoological Nomenclature (Article 57.6) these names are clearly not homonyms, and the name consortis should not have been replaced.
Distribution: Altonian-Opoitian; Mount Harris Formation, Pukeuri road cutting, Oamaru, Altonian (type) and other Altonian North Otago localities; Pakaurangi Formation, Pakaurangi Point, Kaipara Harbour, Otaian-Altonian; Kaawa Creek, Opoitian.
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)