Jumaramaria jumaraensis, 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 : 5-6

Jumaramaria jumaraensis n. sp.

( Figs 1–6)

Type specimen – Holotype Inv. No.: BHU 2020I 1.

Type locality – Jumara Dome , Kachchh, western India .

Type strata – Jhurio Formation, Bathonian.

Derivation of name – From Jumara Dome.

Diagnosis – Same as for the genus above.

Material – Single, multi-damaged shell.

Measurements – H dam. = 27 mm, HL = 21.6 mm, HP = 15.3 mm, D = 43 mm, W dam. = 23.5 mm, pleural angle: 113°.

Description – The available specimen has a rather low turbiniform, rapidly expanding shell of convex whorls, which have no angulation between the pairs of sutures on the early teleoconch. Last whorl joins to the base through a widely rounded angulation that is followed by the suture on former whorls. On the last whorl, the area between the selenizone and the rim of the base becomes slightly concave so a narrow, obscure outer face develops in the latest growth phases. The selenizone itself runs below the mid-whorl; it is rather wide along the whole shell. Its surface is flat on the early teleoconch then changes into convex. The suture is impressed and it is accompanied abapically by an upward bent, narrow belt of the shell, which causes a shallow, subsutural concavity of the whorl surface. The base is flattened as a whole with a moderately convex wall, and has a broad umbilicus. Rim of the umbilicus is also widely rounded angular. The peristome is incompletely preserved but the remnants indicate an abaxially elongated aperture that is almost in radial position as the form of the growth lines suggests it. Its parietal lip appears as the edge of thin shell enamel; the umbilical lip is slightly thickened and backward oriented from the parietal wall towards the basal lip; it has also a narrow outer face and a wide, shallow sinus between the parietal and basal lip.

Spiral ornament of the shell consists of threads on the whole surface of the shell, including also the selenizone. On the last whorl, the selenizone bears three threads beside its edges, which appear also as threads where not damaged. These spiral threads are nearly equally strong almost everywhere, except the subsutural area where thinner and stronger threads alternate. Much thinner and somewhat denser threads cross the spiral ones collabrally on the whorls and form togeth- er a characteristic network. In the basal region, only differently strong growth threads and striae cross irregularly the spiral threads. Shallow, collabral surface undulation is also observable on the base; it is clearer in the parietal region.

The growth lines are orthocline or just barely prosocline, and slightly parasigmoidal between the adapical suture and the selenizone, orthocline and strongly prosocyrt between the selenizone and the obscure angulation at the abaxial rim of the base; strongly prosocline and almost straight or barely parasigmoidal on the base.

Remarks – No other species, fitting with the description of the genus has been found.

Occurrence – Jumara Dome, Jhurio Formation, Bathonian.