Amuaco

General information
Amuaco is a Tupian spoken by a small community in Paraguay. It was first described by Spanish settlers, and its modern writing system is a subset of the Latin alphabet with grapheme values based on Spanish.

Consonants
Amuaco has 39 consonants, notable for extensive coarticulation. It historically had a simpler system with 15 consonants, but is now generally analyzed with a more complex consonant system due to mergers and a transfer of certain vowel qualities onto consonants. Voiced stops may become fricatives intervocalically. Every consonant in Amuaco also has a nasalized variant. For most consonants, this takes the form of a prenasalization, but the voiced stops become simple nasal stops. Fricatives and tenuis stops become voiced in addition to prenasalization.

Vowels
Amuaco may be analyzed as having two vowels /a ɨ/. It historically had a twelve-vowel system identical to that of modern Guarani, but vowel frontness, rounding, and nasalization became transferred onto consonants. Phonetically, it exhibits a five-vowel system [a e i o u], but due to morphemic patterns [e i o u] are analyzed as realizations of underlying /a ɨ/ after particular consonant coarticulations. [i u] are realizations of /ɨ/ after a palatal and labial consonant, respectively, and [e o] are realizations of /a/ after a palatal and labial consonant in an unstressed or word-final position. In nonfinal stress syllables with no offglide, /a/ is always pronounced [a].

Phonotactics
Basic Amuaco syllables follow the pattern (N)CV(G), where C is a consonant, V is a vowel, (N) represents phonemic nasalization, and G is an offglide [i u] that may only come after /a/.