Gastropoda - Sorbeoconcha - Naticidae

Popenoe et al. (1987) reported Gyrodes (Sohlella) quercus from the Late Cretaceous Chico Formation of California (p. 81, fig. 5.3, 5.4, 5.7, 5.125.14, 5.17, 5.18, 5.22, etc.). The present species is closely comparable with the American species in having a small-sized shell, obscurely biangulate umbilical margin, and convex whorl profile. Gyrodes (S.) quercus, however, has more whorls. Popenoe et al. (1987) also mentioned that G. (S.) quercus has tabulate and angulate shoulder and prosocline growth lines, whereas the shoulder is broadly rounded and growth lines are not discernible in G. mahalanobisi n. sp. The spire in G. (S.) quercus occupies 0.25 of the total height and the aperture is obliquely teardrop shaped, whereas G. mahalanobisi n. sp. has a characteristically semi-circular aperture and the spire occupies ~0.16 of the total height. Gyrodes mahalanobisi n. sp. may be compared with Gyrodes (Gyrodes) robustus Waring (1917, p. 84, p1. 13, figs. 11, 12; also see Popenoe et al., 1987, p. 77, fig. 4.2, 4.8) from the Paleocene of Lower Santa Susana Formation of Simi Hills, California, in having similar whorl profile, aperture, and spire height. However, the Paleocene species attains a large size compared to the present species. In G. mahalanobisi n. sp., the shoulder is broadly rounded with suture impressed and open umbilicus, whereas in G. (G.) robustus the shoulder is tabulate, angulate with adpressed suture. In addition, G. (G.) robustus growth lines are slightly prosocline, whereas growth lines are unknown in the Kutch species. The present species is comparable with the Cretaceous species, Gyrodes (Gyrodes) garudamangalami from southern India described by Bandel (2000b, p. 87, pl. 3, figs. 8, 9) in their overall shell shape, but the Kutch species is smaller (maximum observed height is 12 mm and diameter is 10 mm) than the Cretaceous species (having more or less similar height and diameter, i.e., 25 mm). Besides, the umbilical inner wall of the Cretaceous species, G. (G.) garudamangalami, has distinct growth lines that cannot be studied in the present species because of preservational state. Also, the present species has a rounded shoulder, whereas the Cretaceous species has a concave flattened shoulder.

Full reference: S.S. Das, S. Mondal, S. Das, S. Bardhan, and R. Saha. 2019. Family Naticidae (Gastropoda) from the Upper Jurassic of Kutch, India and a critical reappraisal of taxonomy and time of origination of the family. Journal of Paleontology

Belongs to Gyrodes according to S.S. Das et al. 2019

Sister taxa: Gyrodes (Gyrodes), Gyrodes (Hypterita), Gyrodes (Sigaretopsis), Gyrodes (Sohlella), Gyrodes allisoni, Gyrodes amplissima, Gyrodes brunsvicensis, Gyrodes depressa, Gyrodes edura, Gyrodes expansa, Gyrodes globosus, Gyrodes greeni, Gyrodes major, Gyrodes onensis, Gyrodes pacificum, Gyrodes robustus, Natica (Gyrodes) conradiana

Type specimen: ISI/g/Jur/N 1, ISI/g/Jur/N 2-76, a shell

Ecology: infaunal carnivore

Distribution: there are no occurrences of Gyrodes mahalanobisi in the database

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Specimen images are retrieved through the ePANDDA API.