White-browed Scrubwren (Sericornis frontalis) - HBW 12, p. 582

Taxonomy: Acanthiza frontalis Vigors and Horsfield, 1827, region of Sydney, New South Wales, Australia.
Closely related to, and often treated as conspecific with, S. humilis; Bass Strait populations (race flindersi) apparently represent intermediates, and King I race tregellasi of latter species sometimes included in present species; genetic studies required in order to clarify relationships and help in defining species boundaries. Appears to be closely related also to S. keri, which has probably hybridized with race laevigaster and may be a fairly recent divergence. Otherwise, races of present species form three broad groups, “nominate group” (containing also tweedi, harterti, rosinae and flindersi), W “maculatus group” (also with balstoni, ashbyi and mellori) and single-species NE “laevigaster group”; plumage and vocal differences suggest that these could perhaps be treated as three distinct species, but laevigaster intergrades with tweedi over a 100-km zone in S Queensland and N New South Wales, and in South Australia mellori probaby intergraded with rosinae around Gulf St Vincent prior to foundation of metropolitan Adelaide (intergrades from this area described as taxon osculans). Additional proposed races are longirostris (from coastal parts of SE South Australia), synonymized with nominate; in Bass Strait, gularis (Kent Group) and insularis (from nearby Forsyth I), evidently intermediates between nominate and flindersi and merged with latter; and mondraini (Archipelago of the Recherche, in Western Australia), merged with mellori. Ten subspecies currently recognized.