Jumaramaria, Szabó & Jaitly, 2019

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 : 4-5

Genus Jumaramaria n. gen.

Type species – Jumaramaria jumaraensis n. sp.

Derivation of name – After the name of the locality, Jumara Dome; remaining part refers to the probable relations.

Diagnosis – Low spired, broadly phaneromphalous, rather rapidly expanding shell with convex whorls. Early whorls evenly arched but last whorl subangular since feebly concave outer face formed below selenizone. Transition to convex base widely rounded angular. Selenizone flush on early teleoconch then increasingly convex. Peristome and aperture nearly radial with abaperturally concave umbilical lip, having narrow, flat frontal face. Shallow collabral undulation visible on base. Whole surface ornamented by spiral threads. Growth lines parasigmoidal and orthocline or just prosocline between upper suture and selenizone; prosocyrt between selenizone and periphery; markedly prosocline, straight or shallowly parasigmoidal between periphery and umbilicus.

Remarks – In general, Jumaramaria n. gen. differs from the pleurotomariid genera in formation of the growth lines, which more or less indicate also the shape of the peristome that is incompletely preserved on the available specimen. Jumaramaria n. gen. has parasigmoidal, orthocline or barely prosocline growth lines between the upper suture and the selenizone while other genera of the family have prosocline-prosocyrt growth lines in this area. At the same time, the basal growth lines are strongly prosocline and straight or feebly parasigmoidal in Jumaramaria n. gen. but usually markedly parasigmoidal, frequently sickleshaped, and moderately prosocline in doubtless pleurotomariids.

The shape of Jumaramaria n. gen. shows some similarity to conoidal, nongradate, low or medium high spired genera of Pleurotomariidae like Perotrochus or Mikadotrochus . In both genera, the shape is trochiform, the selenizone is flush, and the angulation with outer face is lacking from the last whorl besides the differences in the growth line form and orientation. In the presence of the rudimentary angulation and outer face on the last whorl, some Laevitomaria species may be similar but the form and orientation of growth lines distinguish them. In Bathrotomaria , the angulation with coinciding selenizone is not restricted to the last whorl but already develop in the early teleoconch. Similarly, some Obornella species may have comparable shape but their peripheral carina or swollen belt at the rim of the base distinguish them.

Distribution – Kachchh, India, Bathonian.