Excerpt from change request document:
Northern Nambikaura is a language cluster, not an individual language. The speech varieties listed as dialects of Northern Nambikuara [mbg] have been determined to be several separate but closely related languages / language dialect groups. Northern Nambikuara [mbg] should be changed from a language name to a part of the classification of the Nambiquaran languages.
For the classification of Nambiquaran languages, there should now be a distinction made between a Northern cluster and a Southern cluster. Currently there is only a distinction between two language groups Northern Nambikuara [mbg] and Southern Nambikaura [nab]. They are both listed in the Ethnologue as "Class: Nambiquaran". I am recommending that the Northern Nambikuara [mbg] language be split into potentially 6 separate languages / language dialect groups and that these 6 will receive new ISO language identity codes and should be classified as "Class: Nambiquaran, Northern". The Southern Nambikuara [nab] language should then be classified as "Class: Nambiquaran, Southern". The [nab] language has several dialects listed. These may be split into separate languages / language dialect groups at a later time. More research is needed before this can be done.
Intelligibilty testing and interviews indicate that the dialects listed for this language, Northern Nambikuara [mbg], are actually separate languages / language dialect groups. These finding are also supported by ethnololinguistic identity as speakers of these separate languages do not view themselves as a single ethnic group, but rather as at least 8 separate ethnic groups with at least 6 separate languages being spoken by these 8 ethnic groups.