Sindhiluta

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 : 128

Genus Sindhiluta gen. nov.

Type species. Sindhiluta lakhraensis nov. sp. Early Eocene, Lakhra Formation (Sindh, Pakistan).

Etymology. From Sindh (province of Pakistan) and luta, the two last syllables of Voluta . Gender feminine.

Diagnosis. Shape elongate, high-spired. First teleoconch whorls subcarinate; last whorl smooth, poorly terraced at shoulder, not excavated anteriorly. Costae on spire rounded, and orthocline, fading out progressively over last whorl. Outer lip not thickened externally. Four strong, oblique columellar folds. Parietal callus thick.

Included species. Sindhiluta lakhraensis sp. nov. (Lakhra Formation, Ypresian, Sindh Province, Pakistan) and Voluta prevosti Rouault, 1850 [= Psephaea (Eopsephaea) atacica Doncieux, 1908 ; Psephaea (Eopsephaea) rabetensis Doncieux, 1908 ; Volutilithes ogormani Cossmann, 1923 ] (Ypresian, Aquitaine Basin, France).

Discussion. Pilsbry and Olsson (1954) when introducing the new subfamily Volutilithinae included two genera: Volutilithes and Lapparia Conrad, 1855 (type species: Mitra dumosa Conrad, 1854 , Middle Eocene, USA). Subsequent authors such as Pacaud & Le Renard (1996) and Merle et al. (2008) also included Pseudaulicina in this subfamily. Sindhiluta shares characters of the axial sculpture with Volutilithes and columellar characters with Pseudaulicina and Lapparia and therefore is assigned to the Volutilithinae . Rounded and subcarinate costae and a lack of spiral sculpture are characters usually found in species of Volutilithes , such as: V. angustus (Deshayes, 1835) from the Ypresian of the Paris Basin, V. deshayesianus (Rouault, 1850) from the Ypresian of the Aquitaine Basin, and V. torulosus (Deshayes, 1835) and V. c os t ar i u s ( Lamarck, 1803) from the Lutetian of the Paris Basin. However, Sindhiluta differs obviously from Volutilithes in two characters. First, Sindhiluta lacks costae on its last whorls, whereas they are present on Volutilithes . Second, Sindhiluta has four strong columellar folds, whereas members of Volutilithes have only two or three weaker columellar folds. The number and development of the columellar folds are more nearly similar to those of Pseudaulicina than to Volutilithes . Nevertheless, the persistence of the costae on the last whorls, associated with variably developed shoulder spines, an excavated base and the presence of spiral sculpture in most species of Pseudaulicina contrast greatly with the morphology of Sindhiluta . As in Sindhiluta , Lapparia has four strong columellar folds, the most anterior being weaker, but it is distinguished by its axial sculpture, which continues to persist down the shell and finishes with the appearance of acute shoulder spines.