Genus Olssonia n. gen.

urn:lsid:zoobank.org:act: 9BB6F0C9-71ED-4F96-BAE8-3BA325B57714

TYPE SPECIES. — Bursa chira Olsson, 1930 .

DERIVATIO NOMINIS. — Dedicated to the American palaeontologist A. A. Olsson.

SPECIES INCLUDED. — Olssonia chira (Olsson, 1930) n. comb., O. yasila (Olsson, 1930) n. comb.

DISTRIBUTION. — Olssonia n. gen. is a genus restricted to the Eocene to early Miocene of Peru.

DIAGNOSIS. — Shell biconic, dorsoventrally compressed, shortspired, with 7 primary cords on the convex part of the whorl, all but P1 evenly reduced in variceal and intervariceal intervals of each whorl (P1 hardly more expressed than other cords); posterior siphonal canal short; varices strictly aligned; prominent columellar callus.

COMPARISONS. — Olssonia n. gen. resembles Marsupina but possesses a lesser number of primary cords on the convex part of the whorl (7 in Olssonia n. gen., 8 in Marsupina). It resembles Aspa but has a much more prominent columellar callus, it is much more granulose, and it has a more sharply defined shoulder and a wider spire angle. Olssonia n. gen. resemble Bufonaria (Fig. 3B), with the same straight anterior siphonal canal, but lacks a spine or blade on the posterior siphonal canal (Fig. 3B; white arrow).

REMARKS

The representatives of this genus are the oldest confirmed Bursidae; as such they can be used to calibrate the node Bursidae .