Borinquena

Borinquena
 

I want to say Puerto Rican and find the spelling unusual that is 'borinquena' and 'borinqueño'. The presence or absence of the 'ñ' I find interesting almost confusing.
Are there many other adjectives like this: where there is another spelling change in the adjective besides the change to show the difference in gender, the change from 'o' to 'a'?

The spelling difference is the result of somebody not using a correct spelling. :(
Both the feminine and the masculine adjective contain the letter 'ñ'.

Here are other adjectives describing someone/something from Puerto Rico (except for the first one, all have a masculine and a feminine form, and respective plurals):
boricua
borincano
borincana
borinqueño
borinqueña
puertorriqueño
puertorriqueña
portorriqueño
portorriqueña
taíno
taína

Borinqueno
 

Thank you for such a thorough response. You have cleared up a misconception I got from looking at an entry in a popular dictionary. Thank you.