In my family from various towns in Galicia (now Western Ukraine), we have an ancestor with the name of Kuna.
I find Phillip Trauring's 'blood and frogs' website a good source of information for first names. Mr Trauring helpfully cites the source of his information. So, courtesy of Mr Trauring's website we can see the following:
אלקנה Elkana Elkan, Elkun, Kuna
i'm inclined to 'go with' this source for the name Kuna, unless of course A. N. Other has a different explanation.