Gastropods from the Cretaceous-Palaeogene boundary in Denmark
Author
Hansen, Thomas
text
Zootaxa
2019
2019-08-12
4654
1
1
196
journal article
26049
10.11646/zootaxa.4654.1.1
9ce1d103-9234-4fbe-9544-f1c294bb8783
1175-5326
3365803
CFD82CC0-3110-472E-972B-7ADC0C523A04
Conomitra glabra
(
Ravn, 1902
)
Figs 31
K–N
1902
Fasciolaria glabra
n. sp.
Ravn: 231–232, pl. 2, figs 19–20.
1903
Fasciolaria glabra
Ravn—Ravn
: 381, 394–395.
Diagnosis.
Whorls flat and smooth with narrow adapical shoulder accentuated by spiral rib; whorl height corresponding to 40 % of width. Outer lip smooth or with weak, beaded lirae. Canal moderately long and narrow.
Material.
Syntype
MGUH 116
,
MGUH 33267
,
MGUH 33268
,
ØSM
.10042-80,
ØSM
.10042-81,
30 specimens
with informal sample numbers SH.178, SH.202, SH.325.C, SH.393, SH.407.A–B, SH.510, SS.179.A–B, SS.189. A–B, SS.203.A–B, SR.304.A–B, SR.313, SR.373, SR.397, SR.403.A (
2 specimens
), SR.465, SR.481, SR.569, SR.621.A–B, SR.644, SO.93, SO.111, DN.3, DN.31.A–B, DN.32.A–B, DN.50 and DN.51.A–B, and an additional 78 external and internal moulds in the uncatalogued old collections of the
Natural History Museum
of
Denmark
.
Type
stratum and
type
locality.
Cerithium Limestone Member
at Stevns Klint.
Occurrence.
Conomitra glabra
(
Ravn, 1902
)
ranges from the base of the
Cerithium Limestone Member
of the Rødvig Formation and up into the base of the succeeding Korsnaeb Member of the Stevns Klint Formation at Stevns. Additionally it is found in the upper part of the ‘dead layer’ at Vokslev and Dania in Northern Jutland.
Description.
Shell fusiform, width corresponding to between 40 and 45 % of height. Spire taking up one third of shell height. Protoconch rounded conical,
0.7 mm
wide and
0.55 mm
high, consisting of 2 ¼ smooth whorls. Transition to teleoconch indistinct.
Teleoconch with up to around six weakly convex whorls with narrow but distinct shoulder accentuating adapical suture; whorls low, height corresponding to approximately 40 % of width. Aperture high and narrow, the height taking up 55 % of shell height, while the width corresponds to just over one quarter the aperture height. Outer lip smooth or with around 10 weakly developed lirae or rows of teeth. Columella with four strong and sharp columellar folds, the adapical one located on transition to parietal region. Canal well developed. Teleoconch smooth but for a weakly developed spiral rib on shoulder and fine, slightly prosocyrt growth lines.
Measurements.
Largest specimen at least
12.4 mm
high.
Remarks.
Conomitra glabra
resembles the approximately contemporaneous
C. montense
Glibert, 1973
from
Belgium
, but differs in the more pronounced shoulder, the less compact shell and less developed lirae on outer lip. It differs from the Danian
Conomitra
sp. 2 sensu
Kollmann & Peel (1983)
from
Greenland
through the higher whorls and seemingly more slender canal and from the middle Danian
Conomitra
sp.
sensu
Ravn (1933)
from
Denmark
in the pronounced suture and less convex whorls.