Bulletin of the American Museum of Natural History: Volume 161, Article 4, 427-628.

Abstract:
"I have spent more than 10 years in the field and in museum study in revising the South American species of the genus Myiarchus, the largest genus in the avian family Tyrannidae and one that has given systematists great difficulty. Specific limits and distributions are defined. An analysis of geographical variation provides a consistent basis for the recognition of subspecies. Four monotypic species (venezuelensis, apicalis, semirufus, and magnirostris) and seven polytypic species (tuberculifer, swainsoni, phaeocephalus, cephalotes, panamensis, ferox, and tyrannulus), with 20 subspecies, are admitted. No new forms are described. Diagnoses and keys are based on morphological and vocal characters. Data on vocal repertoires, breeding, and the timing of the annual cycle are summarized for each species. Special attention is given to documenting cavity-nesting behavior and the nature of the nest lining, as these behavior patterns help to diagnose the genus. Standardized playback of sound recordings and the resulting responses of territorial birds are used to assess the biological significance of differences in vocal characters, particularly in critical studies of allopatric populations. The sequence followed in the presentation of species accounts represents relationships suggested by an analysis of vocal and morphological characters, but the identification of primitive and derived character states must await a comprehensive examination of other genera of tyrannids presumed to be the closest relatives of Myiarchus" --P. 431. Original Wrappers