Fragilaria pennsylvanica, a new diatom (Bacillariophyceae) species from North America, with comments on the taxonomy of the genus Synedra Ehrenberg

Abstract

A new taxon, Fragilaria pennsylvanica, is described based on light microscopy (LM) and scanning electron microscopy (SEM). This diatom is mainly characterized by the fusiform valve outline, wide central sternum, and short striae composed of small round areolae. The new taxon was found in four small shallow streams from Pennsylvania, U.S.A., and it may be endemic to this region. The sites where the taxon was found are characterized by slightly acidic to circumneutral pH, but highest relative abundance was found in higher water temperature suggesting that the growth of the taxon might be partly related to this latter factor. The taxonomic position of F. pennsylvanica is discussed in the light of recent revisions of the genera Fragilaria, Synedra, and Ulnaria. Morphological and ecological differences of the new taxon with closely related taxa are discussed.