Procerithium (Rhabdocolpus)

Szabó, János & Jaitly, Anand Kumar, 2019, Additional Middle Jurassic gastropods from Kachchh (western India) in the collections of the Banaras Hindu University (Varanasi, India), Fragmenta Palaeontologica Hungarica 36, pp. 3-30 : 14-15

Procerithium (Rhabdocolpus) ? aff. lorieri (Hebert et Deslongchamps, 1860)

( Figs 34–35)

aff. 1860 Cerithium Lorieri Hebert et Deslongchamps – p. 192, Pl. 6, Fig. 2a, b.

aff. 1913 Procerithium (Rhabdocolpus) Lorierei (Hebert et Deslongchamps, 1860) – COSSMANN, p. 77, Pl. 4, Figs 42–43.

Material – Single specimen without earliest latest shell parts.

Measurements – Inv. No.: BHU 2020I 8; H dam. = 11.5 mm, D = 4.5 mm.

Description – Nine teleoconch whorls of a high turriculate shell represent this species. All whorls are convex and a rather deeply impressed suture separates them; the suture itself is like a thin groove between two thin threads. Along its both sides, narrow ramps developed on the early whorls with a wider, flattened outer face between them. This biangular whorl surface gradually changes into almost evenly arched during the growth. Base seems conoidal as a whole with markedly convex wall that has a flattened belt next the periphery. Approaching the axis, the basal wall changes into a neck like axial process that is not fully preserved but suggests presence of a siphonal protrusion. No peristome part is preserved.

On the earliest part of the available shell fragment, three cords mean the spiral ornament beside the single spiral threads along both sides of the suture. Subsequently, the formerly supra-sutural thread adapically shifts and strengthens while a new thread appears closely above the suture. Sparse, collabral ribs cross the cords; they terminate at the sutural threads. The ribs are similarly strong like the cords but less sharp. The two ornamental elements form a network, with small, pointed nodes only along the earliest three spiral cords. The shape of the ribs and the growth lines are slightly opisthocyrt, besides, they are slightly opisthocline on the earliest visible whorls but orthocline on the last whorls.

Remarks – Key shell parts, the apical whorls and the peristome, are lacking for a perfect identification. This single, fragmentary teleoconch is similar to the same shell part of Cerithium lorieri Hebert et Deslongchamps, 1860 (Bathonian) but different in the concave wall of the base. COSSMANN (1906) identified this species as Procerithium Cossmann, 1902 in P. (Rhabdocolpus) subgenus ( COSSMANN 1913).

Occurrence – Ler, Chari Formation, Callovian.