Athleta (Volutocorbis) cf. wynnei Cox, 1930

Merle, Didier, Pacaud, Jean-Michel, Métais, Grégoire, Bartolini, Annachiara, Lashari, Rafiq A., Brohi, Imdad A., Solangi, Sarfraz H., Marivaux, Laurent & Welcomme, Jean-Loup, 2014, Volutidae (Mollusca: Gastropoda) of the Lakhra Formation (Earliest Eocene, Sindh, Pakistan): systematics, biostratigraphy and paleobiogeography, Zootaxa 3826 (1), pp. 101-138 : 122-124

Athleta (Volutocorbis) cf. wynnei Cox, 1930

( Fig. 9 H–L)

Athleta (Volutospina) wynnei Cox, 1930: 199 , pl. 31, figs 7–8, 11.

Description. Shell biconic, ventricose, H ca. 40 mm (spire broken in adult specimen), D 25 mm. Protoconch and first teleoconch whorl unknown; at least 5.5 teleoconch whorls. Spire apparently moderately high. Spire whorls convex, last whorl rather inflated. Spiral sculpture on spire of four or five rows of small nodules, subsutural row better developed than others ( Fig. 9 J). On last whorl, spiral sculpture displaying: 1) subsutural row of rounded nodules; 2) shoulder row of rounded nodules; 3) from shoulder to base, around 20 almost flat cords separated by thin spiral grooves. From second to penultimate whorl, costae interrupted by rows of nodules. On last whorl, costae obsolete between subsutural and shoulder nodules, thin but relatively low below shoulder angle, extending across base, becoming almost obsolete towards close of last whorl. Second whorl: 15 costae; third whorl: 15 costae; fourth whorl: 16–17 costae; fifth and last whorl: 19 costae. Aperture ovate, rather wide. Inner lip straight, columella with two folds succeeded posteriorly by two or three smaller, weaker folds; inner lip callus narrow, apparently not spreading anteriorly. Outer lip thin, not thickened externally. Siphonal canal slightly elongate; siphonal notch shallow.

Material. 4 spm (stn 4: 3 spm CPAG.RAN. I.34 –36, cast MNHN.F.A50372–74 and 1 spm MNHN).

Comments. The material collected from the Lakhra Dome includes three juvenile specimens and a broken adult. The juvenile specimens can be compared with a paratype of Athleta (Volutocorbis) wynnei Cox, 1930 (GSI no. 14,700) from the Hangu Formation, which is also a juvenile. With these young specimens of A. (V.) wynnei , the Sindh specimens share close similarities, particularly the elongate shape of the spire, the sculpture on the spire (with four to five rows of small nodules) and the deep crenulations of costae on the last whorl. The adult specimens of A. (V.) wynnei , as for example the holotype (GSI no. 14,698), apparently differ by their more crenulated costae on the last whorl, and by their less ventricose shape. Because of these small differences, the present identification of A. (V.) wynnei from the Lakhra Formation should be confirmed by the examination of more material.

Stratigraphic range. Lakhra Formation: Lakhra Dome.

Figures

FIGURE 9. A – G. Athleta (Volutocorbis) burtoni Vredenburg, 1923, A (CPAG. RAN. I. 31, dorsal view, stn 2), B (CPAG. RAN. I. 32, ventral view, stn 3), C (CPAG. RAN. I. 33, dorsal view, stn 1), D – F (MNHN. F. J 13433, Cossmann coll., ventral (D) and dorsal (E) views, enlarged view of the spire (F), Jhirak), G (MNHN. F. J 13434, Cossmann coll., dorsal view, Jhirak); H – L. Athleta (Volutocorbis) cf. wynnei Cox, 1930, H – I (CPAG. RAN. I. 35, dorsal view (H) and enlarged view of the spire (I), stn 4), J (CPAG. RAN. I. 36, ventral view, stn 4), K – L (CPAG. RAN. I. 34, ventral (K) and dorsal (L) views). Scale bars: A – E, G – H, J – L = 10 mm; F, I = 5 mm.