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. 6i): GS11216, J40/f068, South Branch, Waihao River, near Waihao Downs, Bortonian (GNS) |
Beu & Maxwell (1990): Chapter 7; p. 108; pl. 6 i.
Synonymy: Fusinus bensoni Allan 1926, p. 339-340; Falsicolus bensoni, Beu & Maxwell 1990, p. 108, pl. 6i; Falsicolus (Liracolus) bensoni, Maxwell 1992, p. 125
Classification: Fasciolariidae
Description: Size moderate for genus (height 50-70 mm), fusiform, spire about half total height. Protoconch not known but probably conical, of about 3 whorls. Teleoconch of 7-8 whorls, typically sharply angled medially on spire but angulation becoming obsolete on last whorl of some shells; sutural ramp flat or slightly concave. Last whorl strongly excavated with long, straight or somewhat twisted neck. Axial sculpture of rounded orthocline costae with concave interspaces of similar or greater width, reaching from suture to suture on earliest whorls but quickly becoming obsolete on upper part of ramp on later whorls and on some shells becoming restricted to rather sharp peripheral tubercles on last whorl or so; 9-11 on penultimate whorl. Some shells with axial sculpture other than growth lines —absent from last whorl. Spiral sculpture commencing as a narrow peripheral cord with 1 or 2 of similar strength between it and lower suture, and fine threads on sutural ramp, some of which become as prominent as the primaries on later whorls. Threads also present between primaries on later whorls. Last whorl with 15-18 additional narrow cords, some with interstitial threads, on base and neck. Aperture pyriform, with a long, almost straight siphonal canal; columella almost straight except for blunt twist near top of canal. Inner lip with thin callus smear; outer lip thin, finely lirate within.
Comparison: Fusinis altus Marshall, 1919 may be the same as this species, but the available material (Bortonian, Hampden Beach) is too poorly preserved to compare satisfactorily with Waihao shells. F. solidus Suter, 1917 (Kaiatan, McCulloch's Bridge, Westland and Nelson) is similar in size and overall shape but has evenly convex or only feebly angled teleoconch whorls, so that axial costae do not become tubercular on later whorls. These species previously have been placed uncritically in Falsicolus, an endemic genus which is now limited to F. obruta Finlay, 1930 (Kaiatan), F. allani Finlay, 1930 (Duntroonian), F. kaiparaensis (Suter, 1917) (the type species; Otaian-Altonian of Northland), and F. teuriensis Fleming, 1943 (Lillburnian) (Maxwell 2009, p. 245). Species of Falsicolus have strongly angled teleoconch whorls with prominent conical or vertically compressed peripheral tubercles. However, species such as Fusinus altus and F. solidus with axial sculpture of rounded costae, tubercular on the periphery of some species but not as prominently so as in the former group, seem best placed in Fusinus. This is a large, very widespread genus of tropical Recent species, now recognised as occurring from the Red Bluff Tuff on Pitt Island (Waipawan) to as young as Kapitean in New Zealand. These species were transferred to Falsicolus (Liracolus n. subgen.) by Maxwell (1992, p. 125), but Maxwell (2009, p. 245) evidently considered Liracolus to be a synonym of Fusinus Rafinesque, 1815, as he assigned them all there. Still other species formerly placed in Falsicolus (Gemmocolus gemmata (PI. 25t) and G. ectypa (Marwick, 1931)) have distinct gemmate sculpture over most of whorl surface, produced by the intersection of axial and spiral elements, and have been transferred to genus Gemmocolus Maxwell, 1992 (p. 125). All these fossil species occur in faunas that indicate outer shelf to upper bathyal depths of deposition.
Distribution: Bortonian, Waihao Greensand, Waihao Downs (uncommon).
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)