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. 54l): Orbitestella praetoreuma Laws, 1939; topotype, GS9730, Q8/f9828, Holland's Point, Pakaurangi, Kaipara Harbour (Otaian) |
  (Pl. 54m): Orbitestella praetoreuma Laws, 1939; topotype, GS9730, Q8/f9828, Holland's Point, Pakaurangi, Kaipara Harbour (Otaian) (showing elaborately sculptured protoconch). |
 (Pl. 54n): Orbitestella praetoreuma Laws, 1939; topotype, GS9730, Q8/f9828, Holland's Point, Pakaurangi, Kaipara Harbour (Otaian) |
Beu & Maxwell (1990): Chapter 17; p. 378; pl. 54 l,m,n.
Classification: Orbitestellidae
Description: Diameter 0.8-1 mm, discoidal, widely umbilicate. Protoconch with partly immersed initial whorl, upper edge strongly keeled, in some species elaborately sculptured. Teleoconch with 2 prominent keels or angulations, spire almost flat. Some species almost smooth except for fine spiral threads, others with prominent nodules on upper surface and on keels, and with axial costae on base. Aperture quadrate, outer lip sinuous.
Comparison: The suprafamilial position of the Orbitestellidae has been uncertain, but it is now resolved as a member of the informal group "lower Heterobranchia" (Bouchet et al. 2005, p. 257). It is easily recognised by its minute size, its planispiral shape and its dominantly spiral sculpture, quite unlike tha characters of almost any other marine gastropods.
Distribution: Waitakian-Recent, New Zealand; Late Eocene-Recent, Australia. Orbitestellids are now known from most Jurassic-Recent faunas of the world.
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)