On the taxonomic status and denomination of the Iberian Chiffchaffs

We carried out a Principal Component Analysis on 196 Iberian and Common Chiffchaffs of both sexes (live and collection specimens), characterized by seven variables derived from wing, tarsus and bill measures. This method, complemented by colour comparison of the taxa, led us to the following conclusions. (1) Phyllopneuste brehmii , Homeyer, 1871, is a junior synonym of Sylvia collybita , Vieillot, 1817. The correct name for the Iberian Chiffchaff is Phylloscopus ibericus (Ticehurst 1937). (2) P. ibericus is itself represented by two subspecies: the southern form P. i. ibericus (Ticehurst 1937), and the northern form, for which we propose the name P. i. biscayensis ssp. nov . (3) The Common and Iberian Chiffchaffs are very distinct in the contact zone. But an overall geographical variation following Bergmann's and Allen's rules within both taxa generates an ecomorphological convergence, i.e. P. i. ibericus and the populations of P. c. collybita from northern central Europe have similar sizes. This may explain why previous authors were unable to diagnose the two taxa on morphological criteria alone.