FRESHWATER DIATOMS FROM CAROLINA BAYS AND OTHER ISOLATED WETLANDS ON THE ATLANTIC COASTAL PLAIN OF SOUTH CAROLINA, U.S.A., WITH DESCRIPTIONS OF SEVEN TAXA NEW TO SCIENCE

Abstract

This study represents the first taxonomic and ecological description of the diatom flora of Carolina bays, the most abundant, natural lentic systems on the Atlantic Coastal Plain of the United States. Diatoms were collected from surface sediments and benthic and planktonic microhabitats in Carolina bays and other isolated wetland ponds in South Carolina during three seasons to survey the extant flora and document habitat affinities. The ponds ranged from marshes and grass/sedge meadows to forested swamps and were prone to episodic drying. All were acidic, dystrophic and nutrient-poor. At the generic level, diatom assemblages resembled those of other acidic, shallow ponds, being dominated by Eunotia, Pinnularia, Frustulia and Neidium. Diatom assemblages were distinct from neighboring lotic and reservoir systems, and contained several taxa new to science. Considerable variation in diatom assemblage composition among ponds was attributable, in part, to differences in susceptibility of the ponds to drying. In basins that dry frequently, aerophilic taxa such as Orthoseira dendroteres (Ehrenberg) Crawford, Pinnularia borealis var. scalaris (Ehrenberg) Rabhenhorst and Luticola saxophila (Bock ex Hustedt) Mann were common. Permanent pond assemblages were dominated by species of Frustulia, Tabellaria and Stenopterobia. Habitat fidelity was low; most taxa were associated with a diversity of substrates and did not exhibit marked seasonality. Substrate and seasonal associations are given for taxa with notable affinities. Taxonomic descriptions are provided for Eunotia pocosinensis sp. nov., Eunotia sarraceniae sp. nov., Stauroneis anceps var. subrostrata var. nov., Pinnularia turfosiphila sp. nov., Pinnularia bigibba sp. nov., Pinnularia subgibba var. gracilis var. nov. and Pinnularia subgibba var. lanceolata var. nov.