cactus flowers identification

hi people,

some cacti I was harvesting bloomed these days,
and got some big yet beautiful flowers, so I decided
to take some pictures and also let see what's the
cactuses' exact specie.
I think this should be a quite easy identification
due to the least-mistakeable flowers.

Thank you in advance

 

Actually there are many with flowers like this, the whole plant is needed to tell. If these are local native ones it might be possible to tell from a basic description of the plant and where it was found.

 

sorry, I have forgotten to post the other pictures related to
the main cactus that bloomed...here they are:

even if not really noticed, the main cactus body
is somewhat conical shaped, not spherical.

Thank you all

 

bump :)

 

Although they all look somewhat similar, I believe it to be one of the cereus'. When did the bloom open? Night or Day?

 

Easter lily cactus (Echinopsis).

 

they bloomed on early morning...sunlight did not yet hit them directly...and
also I saw these flowers lasts less than a day...hope this helps

thank you all