6 April 1998 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON 111(1)28-34 1948. Diagnoses of hybrid (Aves: Trochiiidae). 5. Probable hybrid origin of distans Wetmore & Phelps

Gary R. Graves Depart men I of Vertebrate Zoology. National Museum of Natural History, Smithsonian Institution. Washington. DC. 20560, U.S.A.

Abstract.—Amazilia distans Wei more & Phelps, 1956, is believed to be a hybrid between eyamts and Amazilia fimbriata. The hybrid, col- lected in Estado Tachira. Venezuela, exhibits a blended mosaic of plumage characters of the parental . External measurements of the hybrid fall between the character means; of the parental species which overlap in size.

The unique holotype of Amazilia distans attributed to mutation or developmental Wetmore & Phelps, 1956 was collected by variation of any known taxon. Nor does it Ramon Urbano at "El Salao" (300 m) near seem to represent a morphologically dis- Burgua, Estado Tachira, Venezuela, on 17 tinctive or geographically isolated popula- July 1954. Originally deposited in the Co- tion of another species of Amazilia. Con- leccidn Omitologica Phelps (No. 60790). sequently, A. distans appears either to be a Caracas, the type was cataloged on 9 Oc- valid species or a hybrid. As hybrids have tober 1956, in the National Museum of Nat- no standing in zoological nomenclature, the ural History (USNM 461695), Smithsonian burden of proof lies with the taxonomist to Institution. Collar et al.'s (1992) report of a reject conclusively the hybrid origin of A. second specimen in the Coleccion Phelps distans before bestowing species status on was based on a misreading of the Phelps it. I was unable to reject I he hypothesis of card catalog (fide M. Lentino, N. Collar). hybridity. References treat A. distans as a valid spe- Hybridization between species from dif- cies (e.g.. Morony et al. 1975, Meyer de ferent subfamilies, Phaethornithinae and Schauensee & Phelps 1978, Hilly & Brown . is unknown (Graves 1990). As- 1986. Sibley & Monroe 1990, Collar et al. suming a hybrid origin for A. distans, the 1992). Analyses reported here suggest that pool of potential parental species ( = geo- it represents a hybrid between Hylocharis graphic pool) can be limited to the species cyanns and Amazilia fimbriata. I provide a of trochiline hummingbirds (« — 23; see detailed hybrid diagnosis employing the Appendix 1) that occur regularly below methods and assumptions outlined in 1000 m elevation in the region immediately Graves (1990) and Graves & Zusi (1990). south and east of the Andes in Estado Tach- ira and Estado A pure. Venezuela (Phelps & Materials and Methods Phelps 1958, Meyer de Schauensee & Phelps 1978. Hilty & Brown 1986). 1 com- The holotype of Amazilia distans was pared A. distans directly with specimens of sexed as male (testes drawn on original la- all species in the collections bel). The unstriated maxillary ramphotheca of the National Museum of Natural History. (see Ortiz-Crespo 1972) and brilliant plum- Smithsonian Institution, paying particular age of the specimen indicate that it is an attention to those listed in Appendix 1. adult in definitive plumage (Pigs. 1, 2). The Notes, photographs, and videotape of the unique appearance of A. distans cannot be holotype were compared with the extensive VOLUME III. NUMBER I 29

table I.—Ranges and means (± one standard ile- ferred to as a hybrid in the remainder of viation) of measurements (mm) of representative spec- this paper. imens i.i.liilr male) of Hylm-harix cyanus, Amazitutfim- lustiiii, and the Hybrid, Hylwhans cvanus x Amazilia fiinhriaia i= Amazilia distorts Wctmore & Phelps. Results and Discussion 1956: USNM 461695). Several characters of the hybrid permit fi'tih mil*! in = I*) Hybrid its parental species to be identified: (a) bill red tipped with black in life; (b) base of bill Win^ ehord 47.1-53.0 52.4-56.5 51 0 49.8 ±15 54.7 t 1.4 conspicuously swollen, nasal flanges un- Bill length 14.8-18.5 17,3-22.0 IS,6 feathered and exposed; (c) crown glittering 16.9 ± I.I 19,8 ± 1.3 bluish-green; (d) throat glittering bluish- Reetrix 1 24.1-27.4 26.2-30.1 26.6 green, chin and upper throat streaked with 25.9 i 1.2 28.8 ± 1.0 white; (e) indistinct white pectoral spot; (f) Reetrix 5 25.1-28.1 27.7-32.5 27.4 26.7 ± 1.0 30.6 ± 1.4 abdomen gray along midline; and (g) rec- trices black, innermost and outermost about •Colombia

Fig, I. Lateral and ventral views of male Amazilia fimhriam (top), Hylmhuris cyanus (bottom), and llieir putative hybrid, A. dhtans Wetmore & Phetps (USNM 461695I, VOLUME 111, NUMBER 1 33

Fig. 2. Lateral view of head and hill of the type of AmuzitUt distorts Wemiore & Phelps (USNM 4AloV5). mingbirds is poorly understood (Graves undertail coverts), Chalybura buffonii 1990, Graves & Zusi 1990). In this case, (lengthened silky white undertail coverts). however, I assume that hybridization be- Heliomaster (ongirostris (tail spots, brilliant tween two purple-crowned species would magenta gorget). Thalurania furcata (pur- not result in offspring with a bluish-green ple lower breast, deeply forked tail), Heiiu- crown. The glittering bluish-green crown doxa leadbeateri (violet crown patch), Ster- and throat of the hybrid suggest that the noclyta cyanopectus (violet breast patch, second parental species has iridescent green white-tipped rectrices, heavy curved bill), plumage in these areas, ruling out Klais Coeligena coeligena (brown plumage), guimeti (purple chin and upper throat) as a Ocreatus underwoodii (racket-tipped rectri- parental species. In another example, the ces, tibial "puffs"), Agtaiocercus kingi rectrices of oentme are shining (greatly elongated rectrices with metallic coppery-gold on both dorsal and ventral bluish-green dorsal surfaces), and Chaeto- surfaces, whereas the rec trices of the hybrid cercus jourdanii (rufous shafts of rectrices. are black, similar to those of H. cyanus rose throat), can be removed from the list (bluish-black). Hybridization of C. oenone of potential parental species because they and H. cyanus would likely produce off- exhibit plumage characters not expressed in spring with bronze-colored or dark brown the hybrid. By the process of elimination, rectrices that are significantly paler, less the second parental species appears to be melanized, than those of the hybrid. In a one of three species of Amazitia that are similar fashion. Campy lopterus falcatus sympatric with Hylocharis cyanus in Taeh- (chestnut rectrices, thickened primary ra- ira. Venezuela (Appendix I). chises), Colibri thalas.tinus and C. corus- Wetmore & Phelps (1956:4) noted that cans (purple auricular tufts, banded rectri- the type of A. distans had the general ap- ces), ChtorostHbon poortmani (shining pearance of Amazjlia fimbriata. differing golden-green tail), notatus (bril- from that species "in the glittering blue liant bluish-green plumage from breast to foreneck and upper breast, and in possess- 32 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON

22 A A V . 20 A ^0*^• A A *f*A IB - • • ** A ^--* • s 16 * *

24 26 28 30 32 34 Length Reclrn 5

Fig. 3. Bivariatc plots of selected measurements (see Table 1) of mate Hyttxharis cyanus (diamonds I. Ama- ziliti fimhritiia (triangles), ami their putative hybrid (tilled circle), A. distanx Weimore & Phelps (USNM 461695) Least squares regression lines are illustrated for comparison.

ing a crown spot differing in color from the (11.2%); and rectrix 5 (14.6%). Consistent rest of the head .... the appearance of the with the hypothesis derived from plumage specimen is so distinct from that of other color and pattern, measurements of ihe hy- species of the [Amazdia] that we brid fall between the character means of the have no hesttance in describing it as rep- parental species (Table 1, Fig, 3). Had the resenting a new species." I concur with hybrid's measurements fallen outside the Wetmore and Phelps that A. fimbriata bears range of those of Hylocharis cyanus and more than a fleeting resemblance to Ama- Amazilia fimbriata, this particular hybrid zilia distans in plumage pattern. In fact, the hypothesis would have been rejected. hybrid is nearly intermediate in appearance In summary, both plumage and morpho- between Hylocharis cyanus and Amazilia logical data are consistent with the hypoth- fimbriata. Significantly, the hybrid lacks esis that Amazilia distans represents a hy- plumage traits that characterize A. versicol- brid between Hylocharis cyanus and Ama- or (e.g., dark subterminal band on the out- zilia fimbriata. These species overlap ex- ermost rectrices) and A. viridif>aster (e.g., tensively in Amazonia. For taxonomic pur- brown or buff undertail coverts). In conclu- poses the Amazilia distans Wetmore & sion, evidence gleaned from bill and plum- Phelps is available only for the purpose of age characters suggest that A. distans rep- homonymy. resents a hybrid of Hylocharis cyanus and Berlioz (1929) described a supposed hy- Amazilia fimbriata. brid specimen, Hylocharis cyanus X Ama- External measurements.—Measurements of avian hybrids fall within the mensural zilia fimbriata. prepared in the "Bahia" ranges exhibited by their parental species as style and presumably collected in Brazil. a consequence of a poly genie mode of in- Unfortunately, he failed to report the spec- heritance (see Buckley 1982). External imen's registration number or in what mu- measurements of adult male Hylocharis cy- seum the specimen was deposited. Later, he anus and Amazilia fimbriata overlap and (Berlioz 1951:287 equivocated in his iden- the difference in character means (larger tification, suggesting that the specimen species divided by smaller) is modest: wing might represent Hylocharis pyropygia (Sal- chord (9.8%) bill length (17.2%); rectrix I vin & Godman 1881), poorly known and VOLUME III. NUMBER I H somewhat doubtful species from Bahia, Carl Hansen (Smithsonian photographic Brazil (see Sibley & Monroe 1990): services) for providing good photographs.

"D'ailleurs. fame de connaitrc alors ties Hyl. pyr- opygia auihcniiqucs. j'avais primitive mcni decritce Literature Cited specimen . . . comme titan) probablcmcnt un hy- bride: Aityrtrinn \.\niiiTitiii\ iimhriahi nigrirtttttUi X Banks. R. C. & N. K. Johnson. 1961 A revision of ffylocharis eycuua. Sans rcjeter definitivement cettc North American hybrid hummingbirds.—Con- hypothese. tres justifiable par I'apparence de dor 63:3-28. I'Oiseau. il DM semble pourtant plausible, mainten- tk-iliu/. J. I>>.,i>. In cas riouveau iThybridiie chey ie\ anl i|ue I'identification, com me espece il 1st mete, Trochllidtis.—L'Oiscau 10:340-343. d'Hyl. pyrapygia s'est afftrmee par I'existenee de . 1938, Notes critiques sur des Trochilides.— plusieurs specimens identiques, de considcrcr dub- L" Oiscau (new series) 8:3-19. iiauvcment vei Oiscau commc referable atisst it cettc , 1951, Etude systernalique de quctques espfc- demiere cspiee." ccs liligieuses de Trochilides,—l.'Oiseau 21: 278-288. To further complicate matters, Berlioz Buckley. P, A, 1982. Avian genetics. Pp. 21-1 10 in (1938) had proposed in earlier paper that M Petrak. ed . Diseases of cage and aviary Hylocharis pyropygia was actually a hybrid birds :r,.J ed I c.i and Febigcr. Philadelphia, between aureoventris and 680 pp. Hylocharis cyanus. In any case, there ap- Collar, N. J., L. R Gonzaga, N. Krabbc. A. Madrono Nicto. L, G, Naranjo. T. A. Parker, 111, & D. C. pears to be no previous verified examples Wege, 1992, Threatened birds of I he Americas: of the hybrid combination reported here The ICBP/IUCN Red Data Book. 3rd edition. (Hylocharis cyanus X Amazilia fimbriata). part 2. International Conned lor Preser Sight records.—Sight records of "Ama- vation. Cambridge. ILK., 1150 pp. zilia distans" in northwestern Venezuela Graves, G. R, 1990, Systeniatics of the " green-dtroat- and adjacent Colombia (see Hilty & Brown ed sunangcls" (Avcs: Trochilidac): valid tax a or hybrids?—Proceedings of the Biological Soci- 1986, Collar et al. 1992) are problematic, ety of Washington 103:6-25. and, to my knowledge, none is supported -. 199.1a. Relic ol a last world: a new species by diagnostic photographs. Although these of sunangel (Trochilidae: Heliunxelutt) from sightings may refer to Hylocharis X Ama- "Bogota."'—Auk 1 10:1-8. zilia hybrids, they more likely represent the . 1993b. A new hybrid manakin iliixiphia pi- pra x Pipra jilkauda) (Avcs: Pipridae) from manifestation of imaginations fertilized by the Andean foothills of eastern Ecuador.—Pro- the possibility of observing a narrowly dis- ceedings of the Biological Society of Washing- tributed endemic. Identification of hum- ton 106:J.36—Ul. mingbird hybrids under field conditions is . 1996a. Hybrid wood warblers, Dcndmint virtually impossible (Graves 1996b). striatit X liendroicit rtistanea (Avcs: Fringilli- dae: Tribe Parulini) and the diagnostic predict- ability of avian hybrid phenoiypc.s.—Proceed- Acknowledgments ings of the Biological Society of Washington 109:373-390. I thank Nigel Collar, Steve Hilty, Miguel . !996h Diagnoses of hybrid hummingbirds Lentino. and David Wege for clarifying the (Aves: Trochilidac). I, Characterization of Ctt- status of Amazilia distans in the Coleccion lypte anna X Stiilula calliope and the possible Ornitologica Phelps. The manuscript was effects of egg volume on hybridization poten- tial.—Proceedings of the Biological Society of improved by the reviews of Richard Banks, Washington 109:755-763. Douglas Stotz. and Richard Zusi. I thank . & R. L. Zusi. 1990. An intcrgeneric hybrid Leo Joseph and David Agro (Academy of hummingbird iHelitxInxa leatlhcdteri X Hefian- Natural Sciences of Philadelphia) for loan- gelux amethysliiotlis\ from northern Colom- ing comparative material, and the curators bia. -^Condor 92:754-760. Hilty. S. I.., & W. L Brown. 1986. A guide to the and staff of the American Museum of Nat- birds of Colombia. Princeton University Press. ural History, New York, for permitting me Princeton, New Jersey, 836 pp. to work in their collections. Finally, I thank Meyer de Schaucnsee. R., & W, H. Phelps. Jr. 1978. 34 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON

A guide to the birds of Venezuela. Princeton the crown at I he rear of the orbits) of cyanux are glit- University Press. 424 pp. tering purple, bordered posteriorly by dark bluish- Morony. J. J.. Jr.. W. J. Bock. & J. Farrand, Jr. 1975. green on the hinderown. The hind neck, upper back, Reference list of the birds of the world. Amer- and scapulars are dark green, gradually turning to ican Museum of Natural History, New York. bronzy green and then coppery on the lower back and 207 pp. rump, respectively; the upper-tail covens arc purplish Ortiz-Crcspo. F I. 1972. A new method to separate black- In fimbriaia the dorsal plumage {capital and spi- immature and adult hummingbirds.—Auk 80: nal tracts) is primarily dark green, with bronze reflec- 851-857. tions on the clown and upper-tail coverts. The dorsum Phelps, W. H.. & W. H Phelps, Jr. 1958. Lisla de las of the hybrid is intermediate in appearance between aves de Venezuela con su distribution. To mo 2. tyanus and ftirtbiUna. but more closely resembling the Pane I Editorial Sucre. Caracas. 317 pp. latter species. The forecrown is glittering greenish-blue Satvin. O.. &FD. Godman. 1881. On some new and and the upper tail coverts are dark bronzy green. little-known species of Trochilidae.—Ibis Ise- The sides of the head, throat, and upper breast of ries 4) 5:595-597. cyanus are deep glittering purple; exposed white feath- Sibley. C. G., & B. L. Monroe. Jr. 1990. Distribution er bases on the chin impart a spotted or mottled an and of birds of the world. Yule Uni- pcamnce. Fculhcrs of the lower breast, sides, and versity Press. New Haven. Connecticut, MM flanks arc dark brownish-gray tipped with a dark green PP. disc: greenish leather lips are less apparent near the Wetmore, A . & W H Phelps, Jr. 1956. Further ad- mid line. Vent leathers are white and the under-tail co- ditions to the list of birds of Venezuela.—Pro- verts are dull hrownish-black (blue reflections in bright ceedings of the Biological Society of Washing- light). Feathers of the chin, throat, and upper breast of ton 69:1-10. fimbriaia have glittering green discs (when viewed Wilkinson. L. 1989. SYSTAT: the system for statis- head-on): leathers are white ha sally, narrowly fringed tics. SYSTAT. Inc.. Evanston. Illinois. 822 pp. with white. White feather margins and a few complete- ly white feathers form an indistinct spot near the center of the lower breast. The belly, sides, and flanks are Appendix I green with an indistinct grayish-while stripe along the Species of hummingbirds thai occur regularly below mid line. Vent feathers are white: under-tail coverts are 1000 111 elevation in southwestern Eslado Tachira and dark gray (with greenish reflections) moderately mar- extreme western Estado Apurc. Venezuela: Campytop- gined with white or pale grayish-white. The venter of terus fiilcatus, Colibri tftalajsttwt, C corvscans, Kluis the hybrid more closely resembles that of fimbriaia. guimtti, hophomis dtlattrei, /.. stictolophus, Cklorei- Feather discs of the ehin, throat, and upper breast are tes miututs, CM-orostilbon inrllixuRus, C pootimaiti. bluish-green, a few are distinctly purple. Traces of the iiutlitraniti furcula. Hylorharix cyanus. CHtysUftMia white pectoral spot of fimbriaia arc present (one com in-nime. Amazilia wr\icnitir, .1 fimbriaia. A. viridi- pletely white leather): under (ail covens are dark slate gaster. Chalybura bufftmii. Hetiodoxa leadbcateri. gray margined with dull white. Suntoctyu cytmopeaus, Codigtna coeligena. Ocrea- The tail of ryartus is bluish-black. In fimhriata, the nix lauterwoodU, AgtaUtctmu kiniii. HeHomaster km- outer rcctrices (2-5) are dull bluish black: the outer girostris, C'haenicercus jtmntanii. margins of reetrices 2—4 are glossed with dark green. The central rectrices ill are dark green, becoming dull biuish-hlaek dislally. The tail of the hybrid is similar Appendix 2 in color lo that of cyanus. but the outer margins of General comparative description of definitive plum- rectrices 2-4 are faintly glossed wuh bronzy-green: the ages of male Hylociutris cyanus. Amazilia fimbriaia. basal two-thirds of the central rectrices (I * are glossed and the hybrid. H. cytmus X A. fimbriaia i = Amazilia with bronzy-green. distant Wetmore & Phelps. 1956; USNM 461695). The maxillary ramphotheca is red. tipped with black Descriptions of structural colors are unusually subjec- in eyanus, and moderately to heavily mclanized (pink- tive, as color seen by the observer varies according to ish-brown to black in life) in fimbriaia. Ramphotheca the angle of inspection and direction of light. For ibis of the hybrid exhibits an intermediate amount of mel- reason 1 use general color descriptions. anin; the specimen tag notes thai the bill was red with The forecrown and crown (to a line drawn across a black tip in life.