Cameroon, Central African Republic, Congo [The Democratic Republic of the], Congo [The Democratic Republic of the], Equatorial Guinea, Gabon, Nigeria, Tanzania [United Republic of], Uganda.
Extreme south-eastern Nigeria and western Cameroon east to south-western Central African Republic, south to central Gabon and north-eastern PRCongo. Also east-central DRCongo east to western and southern Uganda and extreme north-western Tanzania. Distribution probably not fully resolved owing to confusion with Icterine Greenbul (Phyllastrephus icterinus).
Population
Estimated population is unknown (2010).
Xavier's Greenbul (Phyllastrephus xavieri) [XC855563]
by GO-AWAY-BIRDING with Michael Mills from Belize, Cabinda, Angola (?)
Xavier's Greenbul (Phyllastrephus xavieri) [XC284881]
by Abdulrahman Adam from Kirimia, Semuliki National Park, Bundibugyo, Western Region, Uganda (call)
Subspecies
Sibling species of Icterine Greenbul (Phyllastrephus icterinus), widely sympatric and very similar in appearance. Birds from Cameroon (northern and west of Mt Cameroon) described as subspecies serlei on basis of paler and duller yellow underparts, with darker olive wash on breast, but these characters fall within range of variation of the species elsewhere.
The following 2 subspecies are recognised:
serlei Chapin, 1949 - Lowlands and foothills of Mt. Cameroon.
BirdLife International Species Factsheet