@JAFUENTES Quite welcome. All species of this genus may be sexed this way. I will say however that the dot is not always this prominent. It will actually be a RAISED part of the exoskeleton, as opposed to a spot of contrast. I think you may be able to notice the raised region by the arrow point.
On my rufi it was extremely obvious, but I've seen male Poki's with better pictures than my smartphone that were not this obvious.