Subspecies amauropteryx has in the past been treated as a distinct species. Subspecies neumanni and centralis intergrade in NE Africa. Green-glossed birds in Senegal sometimes separated as subspecies aenea, but occur together with blue and greenish-blue birds. Proposed taxon incognita (from SE DRCongo) is regarded as a synonym of centralis.
The following 6 subspecies are recognised:
chalybeata (Müller, 1776) - Southern Mauritania and Senegambia east to central Mali (Mopti), south to northern Sierra Leone and Guinea.
neumanni (Alexander, 1908) - Eastern Mali and northern Ivory Coast east to southern Chad, northern Central African Republic and Sudan.
ultramarina (Gmelin, JF, 1789) - Ethiopia and northern Eritrea.
centralis (Neunzig, 1928) - Southern and eastern DRCongo (Kasai, Katanga, and around lakes Albert, Edward, Kivu and Tanganyika) east to Uganda, inland Kenya and inland Tanzania.
okavangoensis Payne, 1973 - Western and southern Angola, northern Namibia, western Zambia (upper R Zambezi) and northern Botswana.
amauropteryx (Sharpe, 1890) - Coastal eastern Africa from southern Somalia south to southern Tanzania, Mozambique, and inland from southern and eastern Zambia, Malawi and Zimbabwe (R Zambezi below Kazungula) south to northern South Africa (south to North West Province, Free State, and northern KwaZulu-Natal at Ndumu and Hluhluwe. Also southern eastern Cape and Swaziland.
BirdLife International Species Factsheet