The Lesser Whitethroat (Sylvia curruca) is a common and widespread typical warbler which breeds in temperate Europe, except the southwest, and in western and central Asia.
Rather, the Lesser Whitethroat and its closest relatives Hume’s Whitethroat and the Small Whitethroat appear more related to a group of morphologically quite dissimilar species. These vary much in size and color pattern, but also lack chestnut wing patches and have a strong contrast between the usually dark head sides and the white or whitisch throat. The latter group occurs from the southern parts of the Lesser Whitethroat complex’ range into Africa and include the Orphean Warbler group, the Arabian Warbler, and the Brown and Yemen Warblers sometimes placed in Parisoma. Thus, it rather appears as if the divergence of the Lesser Whitethroat complex and its closest living relatives is more ancient than assumed, and that it did not involve separation by ice sheets building up in Europe, but by aridification of the Arabian region (which also occurred throughout the Ice Ages).
Two more taxa occur in the intergradation zone with the Small Whitethroat, stretching from the northern Caspian Sea area into Mongolia.The phylogeny of these is not well-researched, and they might eventually turn out to belong to either species or be stereotyped hybrids:
Sylvia curruca/minula halimodendri
Sylvia curruca/minula telengitica
Similarly, Sylvia curruca caucasica is intermediate between the Lesser and Hume’s Whitethroats.
A bird which wintered at Landsort Bird Observatory, Sweden, differed in the analyzed mtDNA sequences from all known taxa in the complex, although it most closely resembled halimodendri in the field. As mtDNA is inherited from the mother only, were this bird a hybrid this should have been recognizable.