In my database of five parishes south of Cork City I show 13 spelling variants of CULNANE: CULLNANE, CULLANANE, CULLENANE, CULLINANE, CLENANE, CLINANE, CALANAN, CALLINANE, CALLANAN, CALLANANE, CALNAN, CALNANE. It appears that most priests considered the forms in CU- to represent the same name as those in CA-, though they were apparently different names in Irish. On the same stone in Douglas Catholic graveyard I saw CULLINANE and CALLANAN . Note also that the names Wallis or Wallace were considered by some priests to be variants of Walsh. In looking for these surnames in the Tithe Applotment books, you probably have to enter an exact spelling.