. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. Biogeography of Todirostrum ' Fitzpatrick 455 andrei. Figure 10. Distributions of Todirostrum capitate, Taeniotriccus andrei, and Poecilotriccus ruficeps. The latter two genera are monotypic. Morphologic and biogeographic evidence (see text and Figure 3) indicate that these three species comprise a single, relict Tody-tyrant lineage. Vertical hatching = distribution of Poecilo- triccus ruficeps (small dots — collecting localities); horizontal hatching — distribution of two populations of Todirostrum capitate (triangle
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. Biogeography of Todirostrum ' Fitzpatrick 455 andrei. Figure 10. Distributions of Todirostrum capitate, Taeniotriccus andrei, and Poecilotriccus ruficeps. The latter two genera are monotypic. Morphologic and biogeographic evidence (see text and Figure 3) indicate that these three species comprise a single, relict Tody-tyrant lineage. Vertical hatching = distribution of Poecilo- triccus ruficeps (small dots — collecting localities); horizontal hatching — distribution of two populations of Todirostrum capitate (triangles — collecting localities); stippling = distribution of Taeniotriccus andrei (open circles = collecting localities). species, discussed in the taxonomic com- ments above, suggest that the capitale lineage is at least as old as the two major Todirostrum species groups. Most im- portant, the pronounced sexual dimorphism in capitale implies a long period of be- havioral as well as morphologic divergence, and attests to the species' long isolation from the other Todirostrum species. In fact, the capitale lineage is probably much older than the two larger species groups, and appears to contain two additional, equally divergent relicts, as shown in the taxo- nomic section. In addition to their peculiar plumage patterns and bill structures, each of the three species exhibits a secondarily restricted distribution, further indicating the age and relict position of this lineage relative to the other two species groups. Although Poecilotriccus ruficeps is lo- cally common within its range, its distri- bution is restricted to a narrow forest zone between 1900 and 2700 m in the Andes from northern Peru to extreme western Venezuela (Fig. 10). Without adequate field data it is impossible to speculate on the precise ecological pressures constrain- ing the distribution of ruficeps. However, nearly every Euscarthmine species occupies lowland habitats, and ruficeps undoubtedly differentiate
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