The Dichotomous Key...
Is the cell diameter between 1.0 and 2.2 micron and is the cell
septa present
( 1 )
or is the cell diameter less than 1.0 micron
( 2 )
...?
Both the average diameter and its range in micron should be
measured; it is important to note whether the diameter is greater
than 1 micron or less than 1 micron.
