Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
| | Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990) |
|
  (Pl. 56d): Spiratella ferax Laws, 1944; topotype, GS9730, Q8/f9828, Holland's Point, Pakaurangi, Kaipara Harbour (Otaian) |
 (Pl. 56e): Spiratella ferax Laws, 1944; topotype, GS9730, Q8/f9828, Holland's Point, Pakaurangi, Kaipara Harbour (Otaian) |
Beu & Maxwell (1990): Chapter 17; p. 391; pl. 56 d,e.
Synonymy: Limacina Bosc, 1817 (see Curry 1981, p. 36)
Classification: Spiratellidae
Description: Diameter 0.5-5 mm, sinistral, spire of variable height, elevated in some species, flat or sunken in others; some species non-umbilicate, others widely umbilicate. Most species smooth, weak spiral threads present in at least 1 species. Aperture ovate, columella vertical, somewhat twisted in some species; outer lip thin and simple, or reflected, or slightly thickened within, or with triangular protrusions.
Comparison: Spiratella is the least derived genus of thecosome (i.e. shelled) pteropods, and probably represents the stem-group from which all other taxa have arisen. Numerous genus-group taxa have been proposed for spiratellids, based primarily on such characters as spire height, umbilical width, and the presence or absence of processes on the outer lip. Many of these taxa are recognised by Janssen (1989, 2002, 2006), e.g. Altaspiratella Korobkov, 1966 for the tall-spired, non-umbilicate (or very narrowly umbilicate) Early Eocene species, some of which are recorded from New Zealand. Marwick (1926b, p. 316) proposed Lornia for a relatively large, flat-spired, broadly umbilicate Late Eocene species. The group it represents is worth segregating from Spiratella, but it is likely to be a synonym of Valvatina Bornemann, 1855. Janssen (1990) pointed out that Lornia marwicki Powell, 1935 (Altonian, W Auckland) is a synonym of Sphaerocina formae Audenino, 1897, described from near Torino in northern Italy. Jansssen (e.g., 1990, 2000, 2002) has recognised many more genera of fossil pteropods than previous authors did, and has used them very successfully for long-distance correlation.
Distribution: Wangaloan-Recent, New Zealand; cosmopolitan (planktonic), Paleocene-Recent.
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)