Naiara is not a form of Nuria (and Nuria doesn't mean "of Virgin Mary"). It is a Basque name, related with Virgin Mary and the Mediaeval form of the Spanish place name Nájera.
http://www.euskaltzaindia.com/eoda/izenak.asp?onoma=izenak&hizkuntza=es&testua=naiara
And, regarding Nuria, you can check:
http://www.behindthename.com/bb/arcview.php?id=204476&board=gen
Lumia
http://onomastica.mailcatala.com