Brown Thornbill (Acanthiza pusilla) - HBW 12, p. 603

Taxonomy: Motacilla Pusilla Shaw, 1790, region of Port Jackson, New South Wales, Australia.
Taxonomy complex. Has been thought to form a superspecies with A. katherina. Probably forms a superspecies with A. apicalis, with which has often been treated as conspecific; some hybridization between the two likely in SE South Australia, where individuals with intermediate plumage occur. A. ewingii would possibly belong with this superspecies, but sympatric with present species in Tasmania; was presumably the original colonizer, present species having colonized or recolonized via land-bridges when climate was warmer and drier. Molecular-genetic studies suggest existence of two genetically differentiated assemblages, one in New South Wales and E Victoria, the other in South Australia and Australian Capital Territory; race diemenensis seems to be genetically more like A. apicalis; general trend of increasing flavenoid pigmentation from S to N, also of broader white edges of rectrices and smaller size. Proposed race mcgilli (Clarke Range N to Proserpine, in E Queensland) is considered synonymous with dawsonensis; proposed race bunya (E Queensland S from Broad Sound, and NE New South Wales S, E of Great Dividing Range, to R Tweed) seems to relate to an intergrade population between nominate and dawsonensis. Name archibaldi was unnecessarily introduced as a replacement name for magnirostris, mistakenly believed to be preoccupied, but latter can not now be reinstated. Five subspecies recognized.