A New Hummingbird from Southern Mexico

J. Stuart Rowley, Robert T. Orr
1964 The Condor  
The genus Eupherusa, as presently understood, comprises a small group of hummingbirds ranging from southern Mexico to Panama. The several recognized species possess a bill that is about as long as the head, with the distal edges of the maxillary tomia minutely serrate, and have rufous secondaries and a rounded tail as well as undertail coverts that are loose and plume-like with the barbules free from one another. Eupherusa is close to the genera Elvira and Chalybura both of which have minute
more » ... hich have minute serrations on the distal part of the maxillary tomia and possess loose, plume-like, undertail coverts. The latter character is most pronounced in Chulybura whose members are known by the vernacular name of "plumeleteers" (see Eisenmann and Howell, 1962) . Ridgway ( 1911) recognized three species of Eupherusa. These were E. eximia of southeastern Mexico (Veracruz and Oaxaca), Guatemala and Nicaragua, E. egregia of Costa Rica and western Panama, and E. poliocerca of southwestern Mexico (Guerrero and extreme western Oaxaca). He agreed with Elliot (1879) in placing Eupherusa nigriventris Lawrence in a separate genus, Callipharus. Regarding this relationship he states (p.399): "Were it not for the strikingly different and quite unique coloration of the adult male, involving structural differences in the feathers of the pileum and under parts (which are beautifully blended and velvety instead of harsh and conspicuously imbricated and squamate), and the decidedly more rounded tail, it might well be merged with Eupherusa." Cory (1918) followed Ridgway' s arrangement. Peters (1945: 76-77) included Callipharus in the genus Eupherusa, regarded E. egregk as a race of E. eximia, and apparently questioned the status of poliocerca by listing it as Eupkusa (eximia) poliocerca. This is the treatment followed in the Mexican Check-list (Pacific Coast Avifauna, 1950) and, in essence, by Eisenmann (1955:49). The latter, in a footnote under Eupherusa eximia says: "Includes E. poliocerca, White-tailed Hummingbird, of S.W. Mexico, which may be entitled to specific status." We have examined 10 specimens of Eupherusa poliocerca, 73 of E. eximia (including the races eximia, nelsoni and egregia) and 10 of E. nigriventris. On the basis of these specimens, we feel that there is excellent justification for regarding poliocerca as a distinct species. It is separated from other members of the genus by its decidedly larger size, broader outer rectrices (9 to 11 mm. as opposed to 8 mm. or less in eximia) , and by the color pattern of the tail. In E. poliocerca all but the central pair of rectrices have the inner web white except at the tip where it gradually becomes dusky, faintly tinged with bronze, like the entire outer web. In every specimen of eximia seen, the tip and outer web of these same feathers are black, and on the inner web the black terminates abruptly instead of blending gradually with the white. Our interest in this group developed in the summer of 1963 when one of us (Rowley), in company with Dr. Allan Phillips of Mexico City, secured a small series of hummingbirds of the genus Eupherusa in southwestern Oaxaca, considerably southeast of the published range of E. poliocerca. This rare and little known species has only [81 J 82 THE CONDOR Vol. 66
doi:10.2307/1365387 fatcat:n55277p5ojcbnbn4zppu46bgg4