A rare form of frontal shield development in the new cheilostome bryozoan genus Uharella from the Eocene of Antarctica

摘要

A new cheilostome bryozoan, Uharella seymourensis n. gen., n. sp., is described from the Eocene of Seymour Island, Antarctic Peninsula. Colonies of U. seymourensis encrust lithoclasts, locally in high densities with 1-2 mm-wide strips of unencrusted substrate between neighbouring colonies. This unusual patterning could indicate chemical defence against encroaching colonies or may have resulted from grazing. U. seymourensis is an ascophoran-grade cheilostome with an unusual umbonuloid frontal shield apparently derived entirely or in part from kenozooidal overgrowth. The most closely related genus appears to be the European Maastrichtian and Danian genus Brydonella BERTHELSEN, 1962 with which Uharella is here united in Brydonellidae n. fam.