Red-billed quelea closely related to the fodies ("Foudia"), a genus of six or seven species that occur on the islands of the western Indian Ocean. These two genera are in turn the sister clade to the Asian species of the genus "Ploceus". The following tree represents current insight of the relationships between the species of "Quelea", and their closest relatives. Interbreeding between red-billed and red-headed queleas has been observed in captivity. The red-billed quelea is a small sparrow-like bird, approximately long and weighing , with a heavy, cone-shaped bill, which is red (in females outside the breeding season and males) or orange
Red-headed quelea science for the first time by Gustav Hartlaub in 1848, who named it "Ploceus erythrops". In 1951, Hans von Boetticher regarded the cardinal quelea and red-headed quelea sufficiently different from the red-billed quelea to create a new genus "Queleopsis". The species epithet "erythrops" derives from the Greek word ἐρυθρός (eruthros), meaning "red" and ὄψ (ops) meaning "eye" or "face", referring to the rufous or red face. Ludwig Reichenbach gave the species its first English name in 1863: red-headed dioch. Other vernacular names in the English language include pokerhead, and red-headed weaver. Its vernacular name in Swahili is "kwelea kichwa-chekundu". Based