Subspecies
Malachite Kingfisher (Corythornis cristatus), Madagascar Kingfisher (Corythornis vintsioides) and Sao Tome Kingfisher (Corythornis thomensis) (Sibley and Monroe 1990, 1993) were retained as separate species contra Dowsett and Forbes-Watson (1993) who include vintsioides and thomensis as subspecies of Malachite Kingfisher (Corythornis cristatus). Malachite Kingfisher (Corythornis cristatus), Sao Tome Kingfisher (Corythornis thomensis) and Principe Kingfisher (Corythornis nais) (Sibley and Monroe 1990, 1993) have been lumped into Alcedo cristata following Melo and Fuchs (2008) who provide morphological and phylogenetic evidence in support of this treatment and demostrate that nais shares no affinity with White-bellied Kingfisher (Corythornis leucogaster) with which it has been treated as conspecific.
Has often been considered a subspecies of White-bellied Kingfisher (Corythornis leucogaster) or of Malachite Kingfisher (Corythornis cristatus), but its geographical isolation and very distinctive immature plumage suggest that it is better treated as a distinct species.
Considered by some authors to be a subspecies of Malachite Kingfisher (Corythornis cristatus).
BirdLife International Species Factsheet