STANDARDIZING THE TAXONOMY OF SALINE LAKE CYCLOTELLA SPP.

Abstract

To obtain more accurate reconstructions of past salinities and climate it is necessary to merge regional datasets of saline lake diatoms and water chemistry; a prerequisite of which is to standardize taxonomic practice. To illustrate this process, an investigation of the identity of a small Cyclotella species, frequently observed in the diatom community of saline lakes, is described. This taxon, which has been referred to in earlier literature as Cyclotella caspia, is of interest because it is present in fossil African assemblages, yet is absent from the modem flora of this region. Uncertainties over its correct identification prevented material in a North American dataset from being used as an analogue in salinity reconstructions. LM and SEM investigations reveal that there are no significant differences between Recent North American and Holocene sub-fossil North American and African material which suggests that the salinity optimum calculated from the North American water chemistry data can be used for salinity reconstructions in Africa. The species occurring in saline lakes is clearly different from C. caspia Grunow, but conforms with the description of Cyclotella choctuwhatcheeana Prasad.