Early Carboniferous nautiloids from the Central Sahara, southern Algeria
Author
Korn, Dieter
286CA4F3-7EBC-4AEF-A66A-B2508D001367
Museum für Naturkunde, Leibniz Institut for Research on Evolution and Biodiversity, Invalidenstrasse 43, 10115 Berlin, Germany.
dieter.korn@mfn.berlin
Author
Bockwinkel, Jürgen
F7FE7EEA-B678-4FEE-879C-8C429F66BF3A
Dechant-Fein-Strasse 22, 51375 Leverkusen, Germany.
jbockwinkel@t-online.de
text
European Journal of Taxonomy
2022
2022-07-20
831
67
108
http://dx.doi.org/10.5852/ejt.2022.831.1871
journal article
105313
10.5852/ejt.2022.831.1871
e697ba5c-5a96-4a28-985c-748890333d6c
2118-9773
6885198
EAA2EAE2-DA8B-4516-B332-CB8423B8EEAA
Stroboceras mane
sp. nov.
urn:lsid:zoobank.org:act:
D423198E-EA1D-44F1-A1E3-C1E31F6FDC4E
Fig. 10
,
Table 5
Diagnosis
Species of
Stroboceras
with weakly depressed, rounded-trapezoidal whorl profile (ww/wh ~1.45), venter strongly flattened, ventrolateral shoulder angular with sharp longitudinal ridges. Whorls not embracing. Whorl profile with wide longitudinal groove on the outer flank near the ventrolateral margin.
Etymology
From the Latin ‘
mane
’, meaning ‘early, morning’ and referring to the stratigraphically early occurrence of the species.
Type material
Holotype
ALGERIA
•
Mouydir
,
south of Oued Temertasset (locality MOU-Y)
;
Argiles de Teguentour
(
Lower
Pericyclus-Progoniatites
Assemblage; early late Tournaisian
);
Korn
et al
.
2002 Coll.; illustrated in
Fig. 10A
;
MB.C.30458.1
.
Paratype
ALGERIA
•
Mouydir
,
south of Oued Temertasset (locality MOU-Y)
;
Argiles de Teguentour
(
Lower
Pericyclus-Progoniatites
Assemblage; early late Tournaisian
);
Korn
et al
.
2002 Coll.;
MB.C.30458.2
.
Fig. 10.
Stroboceras mane
sp. nov.
from Oued Temertasset, holotype MB.C.30458.1 (Korn
et al
. 2002 Coll.).
A
. Ventral and lateral views.
B
. Cross section.
C
. Suture line, at ww =9.9 mm, wh=5.5 mm. Scale bar units =
1 mm
.
Table 5.
Conch dimensions (in mm) and ratios of
Stroboceras mane
sp. nov.
| Specimen |
dm |
ww |
wh |
uw |
ah |
ww/dm |
ww/wh |
uw/dm |
WER
|
IZW
|
|
MB
.C.30458.1
|
22.0 |
11.2 |
7.6 |
9.9 |
7.6 |
0.51 |
1.47 |
0.45 |
2.34 |
0.0 |
Description
Holotype
MB.C.30458.1 is a phragmocone fragment with about
22 mm
conch diameter; it is partly embedded in a haematite nodule (
Fig. 10A
) and was sectioned for the study of the whorl profile. The conch is discoidal and evolute (ww/dm=0.51; uw/dm= 0.45). The whorl profile is rounded-trapezoidal with almost flat venter separated from the convex flanks by an angular ventrolateral shoulder. Next to this shoulder is a shallow, wide longitudinal groove (
Fig. 10B
). The whorls apparently do not touch each other, but this may be caused by dissolution of the shell wall.
The suture line has a very broad external lobe, an angular ventrolateral saddle in the area of the ventrolateral shoulder and a flat, somewhat undulating lateral lobe (
Fig. 10C
). The siphuncle has a subcentral position.
Remarks
Stroboceras mane
sp. nov.
is an ancestral species of the genus and differs from almost all other species by the non-embracing whorls. Another distinguishing criterion is the very weak formation of longitudinal ridges and grooves.