The Rufiji–Ruvuma languages are a group of Bantu languages

Bantu languages

The Bantu languages constitute a traditional sub-branch of the Niger–Congo languages. There are about 250 Bantu languages by the criterion of mutual intelligibility, though the distinction between language and dialect is often unclear, and Ethnologue counts 535 languages...

 established by Gloria Waite (1979) and subsequent researchers: N10 (less Manda

Manda language (Tanzania)

Manda, or Manda-Matumba, is a Bantu language of Tanzania. It was assigned to the Bena–Kinga group by Nurse , though Ehret retains it in N10 Rufiji–Ruvuma ....

), P10 (Ngindo moved to N10), P20.

The languages, or clusters, along with their Guthrie identifications are:

• Ruvuma (P20):
  • Yao–Mwera
  • Makonde: Makonde
    Makonde language
    Makonde is the language spoken by the Makonde, an ethnic group in southeast Tanzania and northern Mozambique. Makonde is a central Bantu language closely related to Yao...
    
    –Machinga, Mabiha
• Mbinga
  • Ruhuhu (N10): Matengo
    Matengo language
    Matengo is a Bantu language of Tanzania. Speakers are mostly monolingual, and neighboring languages are not intelligible....
    
    , Mpoto
  • Matandu (P10): Matumbi, Ndengereko–Rufiji
  • Lwegu: Ngindo (P10), Ndendeule (Ndwewe) (N10)
• Songea (N10): Ngoni
  Ngoni language
  Ngoni is a Bantu language of Tanzania and Mozambique. It is one of several languages of the Ngoni people, who descend from the Nguni people of southern Africa. Despite its name, it is not descended from an Nguni language, but only retains the name...
  
  

Among the Guthrie languages not specifically classified are Ndonde/Mawanda (P20); Nindi (N10, said to be close to Ndendeule); and Tonga of Malawi (N10).

Nurse moves Manda to Bena–Kinga

Northeast Bantu

The Northeast Bantu languages are a group of Bantu languages of East African which share a phonological innovation called Dahl's Law that is unlikely to be borrowed...

, but Ehret keeps it here.