Flagellated, who are Diphylleia or Sulcomonas?

[carlos.uruguay]

We have found these small flagellates in a bottle of fresh water swimming among Elodea algae.
They measure between 25 and 30um long.
They have two flagella directed forward.
One longer than the other.
They are born their end more narrow.
Its front end has something similar to a cleavage.
I've added images of two possible genres that these organisms can belong.
What do you think?
They belong to the genus Diphylleia?
They belong to the genus Sulcomonas?
I am grateful to Bruce Taylor:
http://www.youtube.com/user/BruceDSTaylor
and to David Patterson:
http://www.itcamefromthepond.com/2014/0 ... patterson/
Without whose valuable and generous aid I would have never been able to understand organism I am showing
Oblique light and phase contrast
40X and 100X objectives
Link:
http://www.youtube.com/watch?v=oEdQvYEW7cY
Regards
carlos