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. 2w): GS10195, I44/f8486, Boulder Hill, Wangaloan (hypotype of Finlay & Marwick, 1937, pl. 10, fig. 1, 2) (GNS) |
Beu & Maxwell (1990): Chapter 5; p. 82; pl. 2 w.
Synonymy: Perissolax obtusa Marshall 1917, p. 454; Proficus obtusus
Type species of Proficus Finlay & Marwick, 1937, synonymised with Priscoficus Conrad, 1866 by Beu & Maxwell (1990, p. 82)
Classification: Ficidae
Description: Moderately large for family (available specimens 41-47 mm high, complete specimens probably at least 65 mm). Protoconch not known. Spire low, dome-shaped; teleoconch whorls strongly clasping, so that the sutural ramp extends up to shoulder angle of previous whorl. Last whorl very large, with 3 prominent keels, middle one on the periphery and slightly closer to abapical than to adapical one, interspaces concave; base gently excavated below lowest keel. Sutural ramp becoming wider and steeper on later part of last whorl, so causing keels to descend near outer lip. Axial sculpture, apart from growth lines and ill-defined folds, of prominent rounded nodules on keels, 20-25 on adapical row, those on lower keels not consistently corresponding to those on adapical row in position or number. Spiral sculpture of numerous low, narrow threads with moderately wide interspaces, over whole surface. Aperture large, polygonal, contracted anteriorly to gradually narrowed siphonal canal of unknown length; columella gently twisted to left near middle, otherwise almost straight. Inner lip with thin callus wash over columella and parietal nodules. Outer lip thin, polygonal, smooth within, "sagging" because of widening sutural ramp.
Comparison: Finlay & Marwick (1937, p. 75) proposed the genus Proficus for this species, distinguishing it from Priscoficus on the basis of its "sagging" aperture and supposedly broad and short siphonal canal. The former character (more marked on the figured specimen than on other shells) is regarded as a specific character of little taxonomic significance. The siphonal canal appears very short on the figured shell but is severely broken; another, larger shell from Boulder Hill has a notably longer and narrower canal, like that in typical species of Priscoficus. P. obtusa is the oldest known member of the genus; the only older ficid is Protopirula capensis Rennie, 1931 from the Late Cretaceous of South Africa (Wenz 1941, p. 1079), a species that is possibly not correctly assigned here.
Distribution: Wangaloan, Wangaloa Formation, Wangaloa (type); Boulder Hill (uncommon at both localities).
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)