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Summary
This study is basic research for the correlation of the geographical distribution with the morphological variability. A morphological comparison was examined in three samples from Cuzco, the Pyrenees (Spain) and Marrakech.
Length is 9–18 μm and the order of size is as follows: Cuzco < the Pyrenees < Marrakech. The sizes in our samples are within the range of previous data and the specimens in this study belong to those with smaller valves.
Breadth at the centre is 3–4.5 μm which is within the range of previous reports. The relation of the size between three sampling localities is as follows: Cuzco ≒ the Pyrenees < Marrakech.
Striae in 10 μm at the centre are 20–28 which is within the range of previous data. The order is as follows: Marrakech < Cuzco < the Pyrenees. The relative frequencies of each morphological characteristics generally vary depending on the sampling localities.
On the basis of analysis in various morphological characteristics, significant correlation between geographical distribution and morphological variability is not observed.