SEPERATION OF MALLOMONAS DUERRSCHMIDTIAE SP. NOV. FROM M. CRASSISQUAMA AND M. PSEUDOCORONATA: IMPLICATIONS FOR PALEOLIMNOLOGICAL RESEARCH1

A new species, Mallomonas duerrschmidtiae, with characteristics common to both Mallomonas crassisquama (Asmund) Fott and Mallomonas pseudocoronata Prescott, is described from acidic lakes low in specific conductance and total phosphorus concentration. Characteristics of scales, bristles and spines serve to separate the three taxa. The length and area of scales of M. duerrschmidtiae are significantly larger than those of M. crassisquama but smaller than those of M. pseudocoronata. Although the anterior submarginal ribs of scales of M. duerrschmidtiae may become extended to form short wings, the scales lack the large forward projecting anterior wings characteristic of scales of M. pseudocoronata. Features of the dome and junction between the arms of the V-rib and anterior submarginal ribs also serve to distinguish between the three species. Cells of M. duerrschmidtiae also possess long, smooth and thick spines on their posterior scales and lack helmet bristles. M. duerrschmidtiae has different maxima along pH, temperature, specific conductance, total phosphorus and seasonal gradients than either M. crassisquama or M. pseudocoronata. Discriminant analysis, based on nine morphological characters, was used to successfully classify body scales of the three species. The importance of M. duerrschmidtiae as a bioindicator in future lake monitoring and paleolimnological inference studies is discussed.