We report the discovery of a novel neo-sex chromosome in an African warbler, Sylvietta brachyura (northern crombec; Macrosphenidae). This species is part of the Sylvioidea superfamily, where four separate autosome–sex chromosome translocation events have previously been discovered via comparative genomics of 11 of the 22 families in this clade. Our discovery here resulted from analyses of genomic data of single-species representatives from three additional Sylvioidea families (Macrosphenidae, Pycnonotidae, and Leiothrichidae). In all three species, we...