If in a given language there are only two Primary Nasal Consonants, the other one is /m/, that is its most characteristic allophone is labial.
Standardized
IF there are only two Primary Nasal Consonants, THEN the first one is apical (/n/), and the other is /m/, that is its most characteristic allophone is labial.
A Primary Nasal Consonant (PNC) is a phoneme of which the most characteristic allophone is a voiced nasal stop, that is, a sound produced by a complete oral stoppage (e.g., apical, labial), velic opening, and vibration of the vocal cords. (Ferguson 1963: 56).
A Primary Nasal Consonant (PNC) is a phoneme of which the most characteristic allophone is a voiced nasal stop, that is, a sound produced by a complete oral stoppage (e.g., apical, labial), velic opening, and vibration of the vocal cords. (Ferguson 1963: 56).