A taxonomic puzzle

This sunny bird, the yellow-breasted chat (Icteria virens), is traditionally classified in the family Parulidae, the New World warblers. However, it is a good deal larger than most of its closest relatives, and its songs are strident and not in the least warbling. In addition, mature males and females are equally colourful, something which cannot be said for most parulids. The only member of its genus, this species has yet to find a taxonomic home. A molecular phylogeny in 2010 ousted the yellow-breasted chat from "the core Parulidae group", but failed to clarify which of several "non-Parulidae outgroup taxa" it is most closely related to.

Yellow-breasted chat (Icteria virens)

References:

Lovette, Irby J.; Perez-Eman, Jorge L.; Sullivan, John P.; et al. 2010 A comprehensive multilocus phylogeny for the wood-warblers and a revised classification of the Parulidae (Ayes)MOLECULAR PHYLOGENETICS AND EVOLUTION  57: 753-770