Dzubukuá language

Dzubukuá (Dzubucua), or Kiriri, is an extinct Karirian language of Brazil. It is sometimes considered a dialect of a single Kariri language. A short grammatical description is available.

It was spoken on the São Francisco River islands, in the Cabrobó area of Pernambuco.

Phonology
Phonology of the Dzubukuá language:

Vowels
Vowel sounds are presented as [i, ɨ, u, e, o, a] and [œ] which is written out as a double vowel oe. Nasal vowels are pronounced as [ɐ̃, ẽ, ĩ, õ, ũ] along with nasalized double vowels oê and aê, not pronounced as diphthongs, but as nasalized monophthongs [œ̃, æ̃].