Dusky-capped Flycatcher (Myiarchus tuberculifer) - HBW 9, p. 432

Taxonomy: T[yrannus] tuberculifer d’Orbigny and Lafresnaye, 1837, Guarayos, Santa Cruz, Bolivia.
Taxonomy highly complex; almost certainly more than one species involved. Phylogenetic analysis of mitochondrial DNA indicates that those Mexican and Panamanian populations examined are more closely related to M. barbirostris of Caribbean than to most South American populations of present species; populations of nominate race from Argentina, lowland Ecuador and Guyana formed a well-supported clade. Taxonomic status of atriceps particularly doubtful: birds from N extremity of range (Ecuador) found to be closely related to Mexican and Panamanian populations of platyrhynchus (sensu lato) and nigricapillus, whereas those from S extremity (Argentina) were closer to nominate (these findings may be due to introgression, hybridization, faulty taxonomy, or a combination of these factors); further, minor but constant morphological differences in plumage and size exist between N (Ecuador, Peru, N Bolivia) and S populations; molecular diversity in C part of its range in Bolivia should be studied in order to understand patterns of diversity, and to assess the merit of raising atriceps to species rank. In addition, races intergrade widely throughout most of species’ range, and differences among many of them are at present described in unconvincing and unsatisfactory terms of degrees of shading on dorsal surface. Long-overdue revision needed, with attention paid especially to whether phenotypic variation is clinal and where major disjunctions (if any) occur, the nature of any phylogenetic relationships among races, and the nature of morphological and molecular variation in zones of contact and parapatry; moreover, thorough reassessment of variation in Middle and North American populations required. Thirteen subspecies tentatively recognized.