The B.44 lumbu-bwisi grouping is represented by five surveys. Two come from Gabon: coastal lumbu between the punu area and the sea north of Mayumba, and a variety associated with the Libreville estuary. Three come from Congo: Nkola in Kouilou, Banda in Niari, and bwisi at Loubetsi in Niari.

The coastal lumbu variety is the only one that attaches clearly to B.40 punu-sangu, and it is also geographically closest to that group. The other lumbu-bwisi varieties remain mutually connected with yombe-vili and, through an intermediate node, with zone H. The tree therefore places the coastal variety at a greater distance from the other varieties than those varieties are from yombe-vili.

This pattern raises a fundamental classificatory question. Coastal lumbu may have a B.40 genealogy but have absorbed strong influence from neighbouring yombe and vili varieties; alternatively, lumbu varieties may be genealogically related to B.40 while some have been deeply reshaped by contact. The extract also records a claim that lumbu and bwisi speakers associate themselves with the koongo group H.10, a position described as conflicting with the classification in zone B.

Bwisi is especially closely linked to lumbu of Banda in Niari, a relationship presented as geographically coherent. The case demonstrates how dialectal variation can reveal the superposition of inherited affiliations and lateral influence without resolving which process is primary.