Species limits in Pale-tipped Tyrannulets (Inezia : Tyrannidae)

New information on the vocalizations and behavior of populations of the Pal e-tipped Tyrannulet (Inezia subflava), along with analysis of biometric and plumage characters, reveal that it actually consists of two species-level groups: a northern/Guianan group, the member taxa of which are weakly diffe rentiated from one another; and a group whose distribution is primarily Ama zonian, the member taxa of which are morphologically distinct but vocally a nd behaviorally similar to one another. The two groups differ from one anot her in several vocal, plumage, and biometric characters. Tape playback expe riments suggest that the vocal differences alone present effective mechanis ms for reproductive isolation between the two groups. Analysis of vocalizat ions further suggests a possible link between the Amazonian representatives of Inezia subflava and the Yellow Tyrannulet (Capsiempis flaveola).