Richard Klim
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Jackson 2014. The taxonomic status of Rwenzori Nightjar Caprimulgus ruwenzorii Ogilvie-Grant, 1909, and Benguela Nightjar C. koesteri Neumann, 1931. Bull BOC 134(1): 62–69.
Koesteri is recognised as a valid taxon by H&M4 and IOC; but not by Cleere 2010 or eBird/Clements.
Cleere 1999 (HBW 5):
Caprimulgus ruwenzorii is lumped with C poliocephalus by H&M4 following Dowsett et al 2008 (Birds of Zambia); but not by Cleere 2010, BirdLife, IOC or eBird/Clements.SUMMARY.—Doubts concerning the species status of Rwenzori Nightjar Caprimulgus ruwenzorii, and inclusion of Benguela Nightjar C. koesteri in its synonymy, are considered using mensural data for the Afrotropical montane nightjar complex, and by re-examining the plumage of C. koesteri. I conclude that both these taxa are subspecies of Montane Nightjar C. poliocephalus.
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Conclusion ... My conclusion is that the four forms should be re-united under Montane Nightjar C. poliocephalus as a polytypic species, with subspecies Abyssinian Nightjar C. p. poliocephalus, Rwenzori Nightjar C. p. ruwenzorii, Usambara Nightjar C. p. guttifer and Benguela Nightjar C. p. koesteri.
Koesteri is recognised as a valid taxon by H&M4 and IOC; but not by Cleere 2010 or eBird/Clements.
Cleere 1999 (HBW 5):