Borinquena

[pierrre]

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'?

[Rusty]

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

[pierrre]

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.