Volutidae (Mollusca: Gastropoda) of the Lakhra Formation (Earliest Eocene, Sindh, Pakistan): systematics, biostratigraphy and paleobiogeography
Author
Merle, Didier
Author
Pacaud, Jean-Michel
Author
Métais, Grégoire
Author
Bartolini, Annachiara
Author
Lashari, Rafiq A.
Author
Brohi, Imdad A.
Author
Solangi, Sarfraz H.
Author
Marivaux, Laurent
Author
Welcomme, Jean-Loup
text
Zootaxa
2014
2014-06-27
3826
1
101
138
journal article
10.11646/zootaxa.3826.1.3
6f4b1535-6c6b-4446-aa26-b1ba83ad9126
1175-5326
228537
53549D58-8F38-47B5-879F-0245E900C131
Athleta (Volutocorbis) eugeniae
Vredenburg, 1923
(
Fig. 8
E–J)
Athleta (Volutocorbis) eugeniae
Vredenburg, 1923: 259
, pl. 15, figs 5, 7.
Volutospina sykesi
(non
Voluta sykesi
d’Archiac & Haime, 1853
).
Cossmann & Pissarro, 1909: 23
, pl. 2, figs 32–33.
Athleta (Volutocorbis) eugeniae
.
Cotter
in
Vredenburg 1928: 36
.
Volutocorbis eugeniae
.
Glibert 1960: 49
; Ibbal 1972: 63, pl. 18, figs 5–6, pl. 20, figs 10–11 [new combination].
Volutocorbis engeniae
.
Iqbal 1969: 60
(misspelling of
eugeniae
).
Description.
Shell biconic, slightly fusiform, H 30–38, D
15–20 mm
. Protoconch conical, multispiral, of three whorls. Teleoconch of 5 to 5.5 whorls. Spire moderately high, occupying 18% of total shell height. Spire whorls weakly convex, last whorl oval. Spiral sculpture on spire consisting of first row of subsutural nodules, becoming more developed and slightly spiny on penultimate whorl (
Fig. 8
F); abapically, three rows of nodules including shoulder row, which is weaker than other two. Shoulder row bears spiny nodules on some specimens. On last whorl, spiral sculpture displaying: 1) subsutural row of nodules; 2) shoulder row of nodules spiny on a few specimens, and 3) abapically, 13 rows of nodulose crenulations, becoming less prominent on base. From second to last whorls, costae interrupted by rows of nodules. On last whorl, costae moderately high, cut into prominent, regular, nodulose crenulations by broad spiral grooves. Third whorl: 16 costae; fourth whorl: 13–15 costae; fifth and last whorl: 15–17 costae. Aperture ovate, rather narrow, occupying 55% of total height, 39% of diameter. Inner lip feebly sinuous, columella with one oblique fold succeeded posteriorly by 3 or 4 weak folds; inner lip callus very narrow, not spreading. Outer lip thin, not thickened externally. Siphonal canal slightly elongate; siphonal notch shallow.
Material.
33 spm (stn 4: 3 spm
CPAG
.RAN.
I.28–30
, cast
MNHN
.F.A50366–68 and 30 spm
MNHN
).
Comments.
According to
Cossmann & Pissarro (1909)
and
Vredenburg (1923)
,
Athleta (Volutocorbis) eugeniae
is closely similar to
A. (Volutocorbis) elevatus
(Sowerby, 1840)
from the Ypresian of northern Europe, particularly in the spiny shape of the subsutural and shoulder nodules. The European species differs in its other adapical spiral elements including flatter cords separated by narrow spiral grooves, producing an imbricate effect, but lacking nodules.
A. (V.) rouaulti
Cossmann, 1923
from the late Ypresian of southwestern
France
superficially resembles
A. (V.) elevatus
and
A. (V.) eugeniae
, but can easily be distinguished by its subsutural nodules disappearing progressively during growth.
Stratigraphic range.
Lakhra Formation: Jakhmari, Jhirak (
Cossmann & Pissarro 1909
;
Vredenburg 1923
) and Lakhra Dome (this paper).