SPICATICRIBRA KINGSTONII, GEN. NOV. ET SP. NOV. (THALASSIOSIRALES, BACILLARIOPHYTA) FROM GREAT SMOKY MOUNTAINS NATIONAL PARK, U.S.A.

Abstract

A new genus and species in the Thalassiosiraceae, Thalassiosirales is described from Fontana Lake, a reservoir in the Tennessee River drainage, North Carolina, which makes up much of the southern boundary of Great Smoky Mountains National Park. The newly described taxon, Spicaticribra kingstonii, most closely resembles Thalassiosira, but differs in several key aspects. The newly proposed genus is based upon the presence of spicate cribra that do not match up to the external openings of the areolae and the absence of fultoportulae on the valve face. The internal cribra of Spicaticribra are superficially similar to the cribral patterns of T. pseudonana and T. guillardii, but these species are lightly silicified forms that do not have round or hexagonal areolae visible in external views. Additionally, Spicaticribra lacks external extensions on the marginal fultoportulae, a condition which is unusual for Thalassiosira.