Thought to form a superspecies with Kenya Yellow-rumped Seedeater (Crithagra reichenowi) and Yellow-rumped Seedeater (Crithagra xanthopygia), and previously considered conspecific with both. Was often considered to form a superspecies with White-rumped Seedeater (Crithagra leucopygia), but relationships with latter unclear. Previously treated as conspecific with Arabian Serin (Crithagra rothschildi). Subspecies somereni tentatively recognized, but morphological and vocal differences from nominate not well established. Further study is desirable. Birds from south-western Zambia (Chunga pool, in Sesheke) with cinnamon-buff tinge on underparts described as subspecies seshekeensis, but differences from semideserti considered minimal.
The following 7 subspecies are recognised:
somereni (Hartert, 1912) - North-eastern DRCongo, central, south-western and south-eastern Uganda, western Kenya, Rwanda, Burundi and north-western Tanzania.
lwenarum (White, CMN, 1944) - South-eastern Gabon, southern PRCongo, central and southern DRCongo, central Angola, northern and central Zambia and south-western Tanzania.
semideserti (Roberts, 1932) - Southern and eastern Angola and south-western Zambia south to north-eastern Namibia, northern Botswana, western Zimbabwe and northern South Africa (north-western Limpopo).
deserti (Reichenow, 1918) - South-western Angola south to southern Namibia and western South Africa (Northern Cape and North West Province).
atrogularis (Smith, 1836) - Zimbabwe (except west), south-eastern Botswana and northern South Africa (south-western Limpopo).
impigra Clancey, 1959 - Central South Africa (south-eastern North West Province and Mpumalanga south to Free State, northern eastern Cape and western KwaZulu-Natal) and Lesotho.
seshekeensis Grant & Mackworth-Praed, 1958 - South-western Zimbabwe.