Identification: please help identify

I purchased this plant last week from HD and it has no tags. The closest that I can find on the net is a 'Selenicereus'. I am keeping it away from my other plants as it has small rust coloured spots on some of the branches.

 

I agree with Selenicereus, either macdonaldiae or pteranthus?

 

I'm thinking that it resembles an unidentified Rhipsalis that I own.

 

Thank you for help, I shall continue my quest.