The Clavatulidae (Gastropoda, Conoidea) of the Miocene Paratethys Sea with considerations on fossil and extant Clavatulidae genera
Author
Harzhauser, Mathias
0000-0002-4471-6655
mathias.harzhauser@nhm-wien.ac.at
Author
Landau, Bernard
0000-0002-7768-8494
bernardmlandau@gmail.com
Author
Janssen, Ronald
0000-0002-4471-6655
mathias.harzhauser@nhm-wien.ac.at
text
Zootaxa
2022
2022-03-30
5123
1
1
172
http://dx.doi.org/10.11646/zootaxa.5123.1.1
journal article
10.11646/zootaxa.5123.1.1
1175-5326
6399827
036F6B4D-CDCC-4CD7-A914-9A1D8C7A097A
Genus
Megaclavatula
nov. gen.
Type
species.
Megaclavatula grunerti
nov. sp.
, middle
Miocene
,
Langhian
(Badenian),
Austria
,
Central Paratethys Sea
.
Etymology.
Combination of
Mega
- (Greek: large) and
Clavatula
.
Diagnosis.
Medium to large sized, moderately slender fusiform, with high conical spire characterized by tripartite sculpture on early teleoconch whorls with two prominent, beaded adsutural cords and weaker, beaded mid-whorl cord. Subsutural collar coronate with pointed tubercles or spines. Base with weak sculpture; siphonal canal moderately long to long.
Description
. Medium to large sized, moderately slender fusiform, with high conical spire. Protoconch not preserved. Early teleoconch whorls with prominent tripartite spiral sculpture comprising prominent, beaded subsutural cord. Slightly weaker, beaded cord in concave mid-whorl portion, and prominent beaded suprasutural cord. Beads in mid-whorl position and at the suprasutural cord form at ends of comma-shaped axial riblets. On later teleoconch whorls subsutural collar usually swollen, coronate, with small, pointed tubercles or trigonal spines (tubercles may be reduced in some species, e.g.,
M. evae
). Mid-whorl cord weakens, suprasutural cord weakens to subobsolete, bearing weak, wide-spaced tubercles. Secondary spiral threads may be present on spire whorls. Suture narrowly incised, weakly undulating. Last whorl typically ~ 55–60% of total height, attaining up to 65% in species with lower spire (e.g.,
M. pilleri
nov. sp.
). Weakly concave subsutural ramp, rounded periphery. Weakly delimited shoulder. Base moderately constricted, sculpture weak. Siphonal fasciole of medium length, weakly delimited. Aperture moderately wide, pyriform. Outer lip not thickened, smooth within. Anal sinus wide, moderately deep to deep, asymmetrically V-shaped, with apex below subsutural collar in deepest part of subsutural concavity. Siphonal canal moderately long to long, wide, often twisted and recurved, shallowly notched at tip. Columella straight to weakly twisted, smooth. Columellar and parietal callus thickened, sharply delimited, forming broad callus rim, without forming pseudoumbilicus.
Stratigraphic and geographic range.
Middle Miocene (Langhian to Serravallian) of the Central Paratethys. Additional occurrences in the Miocene of the northeastern Atlantic and the Proto-Mediterranean Sea will need verification.
Clavatula taurofusulata
Sacco, 1890
and
Clavatula subdepressa
Sacco, 1890
, from the Burdigalian of the Colli Torinesi (
Italy
), might be a
Megaclavatula
, but the early teleoconch whorls are poorly preserved and do not allow a clear identification. Similarly,
Clavatula tortonica
Peyrot, 1931
, might represent
Megaclavatula
, judging from the illustrations in
Peyrot (1931)
, but we have not seen specimens.
Pleurotoma asperulata
Lamarck, 1822
, however, can clearly be placed in
Megaclavatula
based on early teleoconch sculpture.
Included species.
Paratethys: Miocene:
Megaclavatula grunerti
nov. sp.
,
Pleurotoma
(
Clavatula
)
amaliae
Hoernes & Auinger, 1891
,
Pleurotoma
(
Clavatula
)
antoniae
Hoernes & Auinger, 1891
,
Pleurotoma
(
Clavatula
)
evae
Hoernes & Auinger, 1891
,
Clavatula kowalewskii
Bałuk, 2003
(=
antoniae
),
Pleurotoma laevigatum
Eichwald, 1830
,
Pleurotoma neudorfensis
Schaffer, 1898
,
Megaclavatula pilleri
nov. sp.
, and
Pleurotoma tuberculosa polonica
Pusch, 1837
.
Proto-Mediterranean Sea: Miocene:
Clavatula taurofusulata
Sacco, 1890
,
Clavatula subdepressa
Sacco, 1890
,
Pleurotoma ernesti
Toula
, 1901
. Northeastern Atlantic:
Pleurotoma asperulata
Lamarck, 1822
,
Clavatula tortonica
Peyrot, 1931
,
Clavatula saubrigiana laurensii
Peyrot, 1931
.
Discussion.
Megaclavatula
is reminiscent of
Clavatula
in general shape and the coronate spire, but differs distinctly in its tripartite early teleoconch sculpture and larger size. In addition,
Megaclavatula
species
have a more constricted base and longer siphonal canal resulting in a more slender outline. A further difference is the deep U-shaped anal sinus of
Clavatula
, which contrasts with the moderately deep, broad V-shaped anal sinus of
Megaclavatula
.
Megaclavatula
is mainly known so far from the Central Paratethys Sea and for most species from the Proto- Mediterraean Sea and the northeastern Atlantic, included in
Megaclavatula
above, we have not seen early teleoconch whorls. Some morphologically similar species from the Serravallian of
Turkey
, described by
Landau
et al.
(2013)
, display distinctly different early teleoconch morphology.
Clavatula gracilis
Erünal-Erentöz, 1958
, has two beaded adsutural spiral cords and
Pleurotoma
(
Clavatula
)
francisci
(
Toula, 1901
)
, develops a
Perrona
-like sculpture of opisthocline axial riblets (see
Landau
et al.
2013
, pl. 70, figs 6–9).
Paleoenvironment.
Coastal inner neritic to outer neritic environments.