PCAs of three external measurements (two different sets used to allow inclusion of all holotypes) of skin specimens of taxa of the Z. mollissima–Z. dixoni complex, showing position of holotypes (identified by first letter of species name; see key to types; symbols as for their respective taxon but filled grey); and sequenced specimens (numbered as in Additional File 1: Table S1; symbols as for their respective taxon but larger and black with white lettering). a Analysis using bill width, wing, and tarsus. b Analysis using wing, tail, and tarsus, including Blyth’s measurements of the female holotype of T.
mollissimus Blyth, 1842 (symbol m). c PCA of external measurements of skin specimens (males only) of taxa of the Z. mollissima–Z. dixoni complex, showing position of male holotypes. For summary statistics, see Table 2