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 3826 1 101 138 journal article 45364 10.11646/zootaxa.3826.1.3 6f4b1535-6c6b-4446-aa26-b1ba83ad9126 1175-5326 228537 53549D58-8F38-47B5-879F-0245E900C131 Sindhiluta lakhraensis sp. nov. ( Fig. 12A–F ) Etymology. From the type locality (Lakhra village). Type locality. Stn 4: Lakhra Dome, Lakhra village section, base of the Lakhra Formation. Type material. Holotype (stn 4: CPAG .RAN. I.48 , cast MNHN .F.A50386), paratype 1 (stn 4: CPAG .RAN. I.49 , cast MNHN .F. A50387 ), paratype 2 (stn 4: CPAG .RAN. I.50 , cast MNHN .F.A50388). Other material. 4 spm (stn 4: MNHN ). Description. Shell elongate, H 56–58, D 21–23 mm ( holotype H 53.6 not complete, D 31.9 mm ). Protoconch not preserved. Teleoconch of 7 whorls. Spire relatively high, occupying 31% of total shell height. Spiral whorls convex to subcarinate. Last whorl narrow, convex posteriorly, not excavated anteriorly. Suture linear with weak undulation between bases of costae. Axial sculpture of strong but rounded costae on spire. Costae orthocline, subcarinate at shoulder, not spinous. On penultimate whorl, costae decreasing in prominence, becoming obsolete, disappearing on last whorl. First whorl: not preserved; second whorl: 11 costae; third whorl: 10 costae; fourth and fifth whorls: 9–10 costae; sixth whorl: 8–9 costae, becoming obsolete; seventh whorl: no costae. No apparent spiral sculpture. Aperture narrow, lenticular, occupying 63% of total height, 26% of diameter. Outer lip thin, not thickened externally. Parietal callus thick posteriorly. Four strong, oblique columellar folds, anterior-most weaker. Siphonal canal not preserved. Comparisons. From the Ypresian of the Aquitaine Basin, Voluta prevosti Rouault, 1850 [ Mitra prevosti Rouault, 1848 is a nomen nudum ] is the single Paleogene volutid that shares rounded, subcarinate costae disappearing progressively at the end of growth with Sindhiluta . In addition, as in S. lakhraensis sp. nov. , the last whorls of V. prevosti are rounded and not shouldered posteriorly, its base is not excavated, its outer lip is not thickened and a parietal callus is present. Regarding the columellar folds, their numbers vary between three and six, but their construction is rather similar to that of S. lakhraensis sp. nov. The most anterior fold is present in young specimens, but is weaker than the three adapical folds or tends to disappear in adult specimens. In S. lakhraensis sp. nov. , this anterior fold is also weaker even if it persists at the end of growth. Adapically, the columella of V. prevosti displays three strong folds as in S. lakhraensis . In its posterior part, the columella displays two weak folds in a few specimens, but they are missing in S. lakhraensis . Considering the large number of shared characters with the Pakistani species, we do not hesitate to assign Voluta prevosti to the genus Sindhiluta . On biogeographic grounds, it seems unlikely that these species, located at two extremities of Tethyan Ocean, belong to a same genus. However, the both extremities of the Tethyan Ocean share numerous common genera and even some common species ( Pacaud 1997 ). In addition, examples of range disjunction in tropical marine area are also known ( Lozouet et al. 1994 ). Stratigraphic range. Lakhra formation: Lakhra Dome.