Morphological observations of Synurophycean algae from some acidic habitats, including the description of a sub-specific taxon

Morphological observations of the siliceous cell coverings of five taxa of Synurophyceae are made based on specimens collected from acidic, seepage lakes situated in either the Ocala National Forest, Florida, U.S.A. or the Cape Cod National Seashore, Massachusetts, U.S.A. All but one of the lakes, Lake Dorr, were clearwater in nature. A new taxon, Mallomonas corymbosa var. poseidonii var. nov., is described based on differences in bristle structure. New morphological features of four additional taxa, Synura echinulata, Mallomonas mangofera f. foveata, M. acaroides var. muskokana, and M. duerrschmidtiae are presented and discussed in relation to their existing taxonomic descriptions. Other taxa of Synurophyceae, Dinobryon spp., Aulacoseira spp., Asterionella ralfsii, and dinofiagellates were common constituents of the phytoplankton from the seven study lakes at the times of collection.