According to one of our Ukrainian members, Маркіян (Markiyan) is an informal spelling. The proper Ukrainian spelling is Маркіан (Markian), and thus that is the standard Ukrainian form of Marcianus.Here is their comment in full:"Markian is a name recognized by the Ukrainian Orthodox Church in Ukraine and its Ukrainian diaspora. It it properly written as Маркіан (no letter я) People also use various versions with the letter yah(Я) but it is the informal aka common version and therefore not for use in documentation, etc."Source: https://www.behindthename.com/name/markian/submitted (in English; scroll down to the now-deleted entry at the bottom)
Here is their comment in full:
"Markian is a name recognized by the Ukrainian Orthodox Church in Ukraine and its Ukrainian diaspora.
It it properly written as Маркіан (no letter я)
People also use various versions with the letter yah(Я) but it is the informal aka common version and therefore not for use in documentation, etc."
Source: https://www.behindthename.com/name/markian/submitted (in English; scroll down to the now-deleted entry at the bottom)