Diagnoses Of Hybrid Hummingbirds (Aves : Trochilidae). 7. Probable Parentage Of Calliphlox Iridescens Gould, 1860

8 Pages·1999·3.8 MB·

by  G R Graves

PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
112(2):443-450. 1999.
Diagnoses of hybrid hummingbirds (Aves: Trochilidae).
7. Probable parentage of Calliphlox iridescens Gould, 1860
Gary R. Graves
Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution,
Washington, D.C. 20560, U.S.A.
—
Abstract. Calliphlox iridescens Gould, 1860 is hypothesized to be a hybrid
between Calliphlox amethystina and Chlorostilbon aureoventris. The hybrid,
collected at Nova Friburgo, Rio de Janeiro, Brazil, exhibits a blended mosaic
ofplumage characters of the presumed parental species. External measurements
of the hybrid fall between the character means of the parental species and
approach the values expected from least squares regression of parental mea-
surements.
C
The miniature woodstar, Calliphlox iri- taxonomic status of iridescens is still un-
descens Gould, 1860, was described from a certain, however, because the accounts of
unique specimen collected at Nova Fribur- Butler (1931) and Berlioz (1932, 1938) did
go, about 100 km northeast of Rio de Ja- not adequately review the morphological
neiro, Brazil. Gould (1860:310) observed. characters of the specimen in question and
those of its putative parental species. In this
"If, as I believe, I am right in referring this little
paper, I confirm the hybrid origin of Calli-
bird to the genus Calliphlox, it is one of the most
remarkable Humming-birds that it has fallen to my phlox iridescens employing the methods
&
lot to describe. In its size and form it is very similar outlined in Graves (1990) and Graves
to C. amethystina, but in colouring it is like a Chlo- Zusi (1990).
rostilbon."
The singular appearance of the specimen Material and Methods
prompted Gould (1861:plate 359) to make
it the type of a new genus, Smaragdochry- The type of Calliphlox iridescens
sis, which was adopted by Elliot (1878) and (BMNH 1888.7.25.102 in The Natural His-
Salvin (1892). The taxonomic validity of ir- tory Museum, formerly British Museum of
idescens was not questioned until Butler Natural History) appears to be an adult
(1931:347) remarked in a brief note: male in definitive plumage. This opinion is
based upon the absence of striations on the
"May I regard my belief that the little Humming- maxillary ramphotheca (Ortiz-Crespo
bird which Gould described (P.Z.S. 1860, p. 310) as
1972), the presence of an iridescent gorget,
Calliphlox? iridescens ... is really a hybrid be-
tween Calliphloxamethystina (Gm.) and Chlorostil- and moderately elongated outer rectrices
bon [aureoventris] prasinus (Less.)? ... I have ex- which lack terminal spots or markings.
amined it repeatedly, and to my eye its external I compared the specimen with series of
characters are entirely a mixture of those of these all species in the subfamily Trochilinae, the
two species." &
typical hummingbirds (Zusi Bentz 1982,
Subsequent authorities listed Calliphlox Sibley & Monroe 1990, Bleiweiss et al.
iridescens as a hybrid (e.g., Berlioz 1932, 1997), in the collection of The Natural His-
1938; Peters 1945; Gray 1958; Wolters tory Museum. Color transparencies and
1976) or omitted it altogether (e.g., Morony videotape of the specimen were also com-
&
et al. 1975, Sibley Monroe 1990). The pared with the collections of the National
— —
4 I I' I i^
444 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
Museum of Natural History, Smithsonian 25>< ^13
6
A
Institution. second specimen of Calli- ~•S^- <4o-4
a
phlox iridescens, reported by Ruschi (1951) U (A o
daendJadneepiorsoit(eMd.iNn.th1e82M7u5;se"uBraNsaicli)o,nawla,sRnioot •"s^»S;»^ 6<3c(uU ICO0000 -eO^nn (^—N"I r—r-n^I O(^N Or0Nn4 f0^s0j Orrnn
00
examined. For the purposes of hybrid di-
agnosis (Graves 1990), I considered all
hummingbirds (Trochilinae) that occur in K O,(-N^
ng
the state of Rio de Janeiro as potential pa-
»o
(N
renMtealassupreceimeesnt(sApopfenwdiinxg 1c)h.ord, bill length S 00t~00-^ ^^ ot^ O^ O^' (_N; C^O -^^
(from anterior extension of feathers), and 4O-1 0KT—0 ~ 0+10 0+10 0+01 ^+1 (+N1 v+o1 m+1
rectrix length (from point of insertion of the ^ z s 0^0 u-HS 0(S0| OCNNl O(NN 0(N0 l(>N
central rectrices to the tip of each rectrix) 13 PsQ c c iOo 00 —d m ^^ (^M »o
M^D m -mh' m m ON
were taken with digital calipers and round- 3 in (N
S
mm rnI ONI enI inI OnI (NI ^I
ed to the nearest 0.1 (Table 1). Color 00 t^ '^nT t^ t^ MD MD >n
descriptions were made under na—tural light. Cc(^U 2^ 'sf <N (N (N CN (N
e 3
I considered four alternatives the spec- o
O
imen represents an unrecognized color a
(/) ^
morph of a species listed in Appendix 1, a
>;
chemically-altered artifact, a hybrid, or a 03 ^"4;
valid species. Because Calliphlox irides- <C/u5 *^** dON d00 d^ duo —^I OdN ^
t -!
cens differs significantly in size and shape Cu •K
^ -Si o+1 +1 +1 +1 +1 +1 +1
from all species in the subfamily Trochili- to4H "•CSS- in (N O^—N en tO^n m00
nae, it does not represent a previously un- _,s<-»^ "ua I c^ (M rn
discovered color morph or chemically-al- B ^II' -rm;nIVe^DnI-»;o.'isi>.; qin ON
itnerezdooalrotgiifaccatl. Anosmehnycblraitdusreh,avtehenobusrtdaenndinogf Mc(g(UU .•CQ^S 'de^n -'—^-^'< eee^nnnI ^^^ 0(dCN0NI Oe0(n0NI (e<eNnNnI c'A
proof rests on the systematist to refute the ;3-i *?iu I—
S
possibility of hybridization before bestow- (U a O
g u
ing species status on a unique specimen. I ^oM
X
was unable to reject the hypothesis of hy-
'c
_o &5
bridity and thus refer to the specimen as a
hybrid in the remainder of the paper. ."(2>U ^> en (N 00 00 q ON 3 V3
calTlyh.eTdhieagpnoooslisofwaposteanptpiarloapcarheendtahliesrpaercciheis- -T'u^a3O ^Vsa doc« ^v^+o1 O'—+sN1t (-+NH1 i(+Sn1) ''+s^1^ oi+>1 00 U aCJ ^PLh
nc(aaotmimpoaanrsxa.itmAipvuepmeanondfailfxysi1=s) w3oaf51splnpuaamirrarwgoiweseedancbdoymsbtoihf-et \+V(Co^1iU^ -'AU.>CD6. c"Psouoiih en ot—^e^l^nII ^(o(eo^NNnoI (O(i^ONNnI fe(i(—NnN>NI (deI^TNnI) (feeVNsnnOI Ce/^oI/nI5V e^^CycnHi« 'ICcId
ptaivret choylpoortsheasnids ftehaetnherwasshaptee.stTedhewiretshtriacn- (c<(/nU3 X^3c)d ^T3<33u -sf (N (N (N (N (c013) ^IsI:' o033
S O >-> " J3
analysis of size and external proportions. In T3 O. I_jc -(oD Mr31 ."yt]i
previous papers I used bivariate plots of C/5 Ay'*S c(u3U 5o P)Q-i P;Q-! T3
mgreensssuiroanllicnheasrac(tWeirlskiannsdonle1a9s8t9)squparroejsectree-d ^&cC30 TCc33 c^Se ^ 0/—0*s ^/"^•V ,(-N-^ 'm^
Nttehsheeirwzofreuiedgelhlatpdpiaaorrne1esn9nht9tia6apl,lomfseGphearycasbivureerissedms(ee1tn.o9gt.9s,t8hate,Goirrialh1vly9uep9ssot8rtbah)&t.-e _^XHc;)13 ••E^Sa^>^sQSt\ ^Uis1^<cQ4s:^!J ^TrSg^bS3;^X) ^=r—P'S;2QS5<o .'w—cP"(ii^C^uii .<(DwaCo(i-NN;u; .'eeOwoo(-Cniinu 'pT'Dwo-(iCt^iui ii"wpCo(-!iCnnu^^ APC<f1Q1A3f xP"0rIK—;QI3t .P^r0IfCQI^t3f (*Uco(Xi"4Ui"x
VOLUME NUMBER
112, 2 445
Fig. 1. Ventral and dorsal views of adult male Chlorostilbon aureoventris (top), Calliphlox amethystina
(bottom), and their putative hybrid, C. aureoventris X C. amethystina, {^Calliphlox iridescens Gould, 1860;
BMNH
1888.7.25.102).
446 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
10 20 25 30 35
Length Rectrix 1 Length Rectrix 5
40 45 30 35
Wing Length Length Rectrix 5
Fig. 2. Bivariate plots of selected measurements (see Table 1) of adult male Chlorostilbon aureoventris (A),
Calliphlox amethystina (•), and their putative hybrid (), C. aureoventris X C amethystina, (—CaUiphlox
BMNH
iridescens Gould, 1860; 1888.7.25.102). Least squares regression lines are illustrated for comparison.
—
Table 2. The percent difference between measurements (mm) of the hybrid {=Calliphlox iridescens Gould,
BMNH
1860; 1888.7.25.102) and the mensural midpoints (average of character means from Table 1) of species
combinations.
Chlorestes notatus & Chlorostilbon aureoventris &
Calliphloxamethystina Hybrid Calliphlox amethystina Hybrid
Parental Percent Parental Percent
Midpoint Difference Midpoint Difference
Wing chord 40.4 3.2 39.3 0.4
Bill Length 14.4 0.5 13.7 3.8
Rl 21.5 24.0 17.7 2.3
R2 23.2 10.2 19.7 6.7
R3 26.1 9.2 23.7 0.9
R4 29.2 2.0 28.3 1.0
R5 30.5 0.8 31.3 3.3
VOLUME 112, NUMBER 2 447
Close proximity of hybrids and regression lections of birds from Nova Friburgo often
lines (for all pairwise combinations of var- contained species from nearby lowlands
iables) was interpreted as evidence consis- (fide J. F. Pacheco, pers. comm.). C. notatus
tent with the specified hybrid hypothesis, and C. aureoventris are similar in size and
assuming polygenic inheritance of external plumage color, differing most noticeably in
—
morphology. Concordance of results from tail shape square or slightly rounded in C.
C
plumage and size analyses is regarded as notatus, shallowly forked in aureoventris
strong support for the hypothesis (Graves (Table 1). —
&
1990, Graves Zusi 1990). External measurements. I evaluated the
two parental hypotheses by inspecting raw
Results and Discussion data, bivariate plots, and least squares re-
gressions of measurements. Measurements
—
Plumage characters. The hybrid pos- of the hybrid fell within the character
sesses several characters that facilitate the means of both possible parental combina-
identification of its parental species: (a) tions, Chlorestes notatus X Calliphlox ame-
brilliant silvery-green gorget; (b) moderate- thystina and Chlorostilbon aureoventris X
ly forked tail (fork depth = 43% of tail Calliphlox amethystina. External measure-
length); and (c) mandibular ramphotheca ments of the hybrid most closely approxi-
yellowish-brown (Fig. 1). Perhaps as infor- mate the values expected from least squares
mative, the hybrid lacks several conspicu- regression of measurements of Chlorostil-
ous traits that are present among source bon aureoventris X Calliphlox amethystina
pool species (Appendix 1): (a) contrasting (Fig. 2, Appendix 2). Hybrid characters dif-
rump band; (b) brilliant frontlet or coronal fer from the parental midpoints (average of
patch; (c) rufous or chestnut pigmentation parental character means. Table 2) of C. au-
C
on rectrices; (d) pronounced blue or violet reoventris X amethystina by 0.4—6.7%,
iridescence on body plumage; (e) white rec- and from C. notatus X C. amethystina by
tricial spots; (f) white bases or margins of 0.5-24%. Measurements of the hybrid are
gorget feathers; (g) thickened primary ra- closer to the parental midpoint of C. au-
chises; and (h) racket-tipped or attenuated reoventris X C. amethystina for 5 of the 7
rectrix tips. characters.
This association of characters can be de- In summary, both plumage and external
rived from only two of the possible pair- morphology are consistent with the hypoth-
wise combinations of species (Appendix 1): esis that Calliphlox iridescens represents a
Chlorestes notatus X Calliphlox amethys- hybrid between Chlorostilbon aureoventris
tina and Chlorostilbon aureoventris X Cal- and Calliphlox amethystina. For taxonomic
liphlox amethystina. Other combinations of purposes, Calliphlox iridescens Gould is
species can be eliminated from consider- available only for the purpose of homony-
ation because they either lack characters ex- my.
hibited by the hybrid, or possess one or
more distinctive characters that are not ex- Acknowledgments
pressed, even subtly, in the hybrid. The
geographic ranges of C. aureoventris and I thank Robert Prys-Jones, Michael Wal-
C
amethystina overlap extensively in Bra- ters, and Mark Adams of The Natural His-
zil, and both are found in the vicinity of tory Museum, Tring, for permitting me to
Nova Friburgo. C. notatus appears to reach study the type of Calliphlox iridescens on
its southern limit on the Atlantic coastal two different occasions, and Jose Fernando
plain near the city of Rio de Janeiro and is Pacheco (Rio de Janeiro) for providing the
not known to occur in the uplands near list of species in Appendix 1 and distribu-
Nova Friburgo. However, 19th century col- tional data for Chlorestes notatus. The man-
—— —
448 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
W
&
uscript was reviewed by Richard Banks, Morony, J. J., Jr., J. Bock, J. Farrand, Jr. 1975.
Jose Fernando Pacheco, Robert Prys-Jones, Reference list of the birds of the world. Amer-
Michael Walters, and Richard Zusi, whom Ortiz-CirceasnpoM,usF.eIu.m1o9f72N.atAuranlewHismteortyh,odNet—wo sYeoprakr.ate
I thank for their comments. Leslie Over- immature and adult hummingbirds. Auk 89:
street helped with literature. The Smithson- 851-857.
ian photographic services prepared the Peters, J. 1945. Check-list of birds of the world, vol.
prints. Travel was supported by the Alex- 5. Museum of Comparative Zoology, Cam-
ander Wetmore Fund and the Research Op- bridge, Massachusetts, 306 pp.
Ruschi, A. 1951. Trochilideos do Museu Nacional.
portunities Fund, Smithsonian Institution. Boletim do Museu de Biologia Prof. Mello-Lei-
tao, Serie Biologia 10:1—111.
Literature Cited Salvin, O. 1892. Catalogue of the Picariae in the col-
lection ofthe British Museum. Upupae and Tro-
Berlioz, J. 1932. Notes critiques—sur quelques Trochil- chili. Catalogue ofbirds ofthe British Museum,
ides du British Museum. L'Oiseau (new se- vol. 16:1-433.
ries) 2:530-534. Sibley, C. G., & B. L. Monroe, Jr. 1990. Distribution
. 1938. Notes critiques sur des Trochilides. and taxonomy of birds of the world. Yale Uni-
L'Oiseau (new series) 8:3-19. versity Press, New Haven, Connecticut, 1111
Bleiweiss, R., J. A. W. Kirsch, & J. C. Matheus. 1997. pp.
DNA
hybridization evidence for the principal Wilkinson, L. 1989. SYSTAT: the system for statistics.
lineages ofhummingirds (Aves: Trochilidae). SYSTAT, Inc., Evanston, Illinois, 822 pp.
Molecular Biology and Evolution 14:325-343. Wolters, H. E. 1976. Die Vogelarten der Erde: eine
Butler, A. L.—1931. On the types of two Humming- systematische Liste mit Verbreitungsangaben
birds. Ibis (Thirteenth Series) 1:347-348. sowie deutschen und englischen Namen. Num-
Elliot, D. G. 1878. A—classification and synopsis ofthe ber 2. Pp. 161-240. Parey, Hamburg & Berlin,
Trochilidae. Smithsonian Contributions to Germany.
Knowledge 317, 277 pp. Zusi, R. L., & G. D. Bentz. 1982. Variation ofamuscle
Gould, J. 1860. Descriptions of—twenty-two new spe- in hummingbi—rds and swifts and its systematic
cies of humming-birds. Proceedings of the implications. Proceedings of the Biological
Zoological Society of London 28:304-312. Society of Washington 95:412-420.
. 1861. Monograph of the Trochilidae, part 5.
Published by the author, London, unpaginated.
Graves, G. R. 1990. Systematics ofthe "green-throat- Appendix 1
ed sunangels" (Aves: Trochilidae): valid taxa or
—
hybrids? Proceedings of the Biological Soci- Species oftrochiline hummingbirds that occurinthe
ety of Washington 103:6-25. state ofRio de Janeiro, Brazil (fide J. F. Pacheco, pers.
1998a. Diagnoses of hybrid hummingbirds comm.). Vagrant species (less than three records inRio
.
(Aves: Trochilidae). 5. Probable hybrid origin de Janeiro) are marked by an asterisk. Parentheses en-
—
of Amazilia distans Wetmore & Phelps. Pro- close a representative list of characters or traits that
ceedings of the Biological Society of Washing- would probably be expressed in hybrid progeny of
ton 110:314-319. these species, but that do not occur in Calliphlox iri-
1998b. Diagnoses of hybrid hummingbirds descens Gould, 1860 (BMNH 1888.7.25.102). Taxon-
.
(Aves: Trochilidae). 6. An intergeneric hybrid, omy follows Sibley & Monroe (1990): Eupetomena
Aglaiocercus kingi X Metallura tyrianthina, macroura (violet-blue head and breast, thickened pri-
—
from Venezuela. Proceedings of the Biologi- mary rachises); Melanotrochilus fuscus (black body
cal Society of Washington 111:511-520. plumage, white outer rectrices); Colibri serrirostris
, & N. L. Newfield. 1996. Diagnoses ofhybrid (purple auricular tufts, subterminal band on rectrices);
hummingbirds (Aves: Trochilidae). 1. Charac- Anthracothorax nigricollis (black ventral plumage, ru-
terization of Calypte anna X Stellula calliope fous pigmentation on rectrices); ^Chrysolampis mos-
and the possible effects of egg volume on hy- quitus (brilliant coronal patch, rufous pigmentation on
—
bridization potential. Proceedings of the Bio- rectrices); Stephanoxis lalandi (brilliant coronal patch,
logical Society of Washington 109:755-763. elongated crest plumes, blue ventral plumage); Lo-
, & R. L. Zusi. 1990. An intergeneric hybrid phomis magnificus (rufous crest, contrasting rump
hummingbird (Heliodoxa leadbeateri X Helian- band); Lophornis chalybeus (white-tipped gorget
gelus amethysticollis) from northern Colom- feathers, contrasting rump band); Popelairia langs-
bia.—Condor 92:754-760. dorffi (contrasting rump band, attenuated rectrices);
Gray, A. P. 1958. Bird hybrids. Commonwealth Agri- ^Discosura longicauda (contrasting rump band, rack-
cultural Bureaux, Bucks, England, 390 pp. et-tipped rectrices), Chlorestes notatus, Chlorostilbon
VOLUME NUMBER
112, 2 449
aureoventris, *Thalurania furcata (violet breast and ial plumes, which extend past the base of the hallux,
belly); Thalurania glaucopis (brilliant coronal patch), are dark gray, broadly tipped with buffy-white. Un-
Hylocharis sapphirina (rufous chin and rectrices, vio- dertail coverts are grayish-buff fading to white or pale
let head and breast); Hylocharis cyanus (white chin, buffy-white at the margins (subterminally glossed with
violet head and upper breast); *Hylocharis chrysura green in some individuals).
(cinnamomeus chin, golden-bronze tail); Leucochloris With the exception ofwhite vent plumes, the ventral
albicollis (white throat, white-tipped rectrices); Polyt- plumage of aureoventris exhibits brilliant iridescence
mus guainumbi (white-tipped rectrices); Amazilia ver- when viewed head-on. Although there is considerable
sicolor (white throat, dark subterminal band on outer color variation among individuals, iridescence is pre-
rectrices); Amazilia fimbriata (white-margined throat dominately bluish-green on the throat, upper breast,
feathers); Amazilia lactea (violet-blue throat andupper and undertail coverts, tending toward golden-green on
breast); Aphantochroa cirrochloris (dull plumage, the lower breast, sides and belly. Throat feathers are
large size); Clytolaema rubricauda (rufous rectrices); medium gray basally, becoming dark gray distally, and
Heliothryx aurita (brilliant coronal patch, white outer abruptly tipped with a bluish-green disk (from lower
rectrices); Heliomaster squamosus (brilliant coronal throat, 1.6-2.0 mm deep, 3.0-3.3 mm wide). Gorget
patch, white malar mark, white medial stripe from up- feathers (5.1-5.8 mm) are relatively shorter than in
per breast to vent); Calliphlox amethystina. amethystina. Tibial feathers are dark gray and reach
but do not exceed the base of the hallux.
The gorget of iridescens, similar in shape to that of
Appendix 2
amethystina, exhibits a peculiar pattern of iridescence,
predominately pale silvery-green viewed head-on, but
General comparative description of definitive plum-
irregularly marked with a coppery hue, especially on
ages of male Chlorostilbon aureoventris, Calliphlox
amethystina, and the hybrid, C. aureoventris X C. the sides of the throat. Closer inspection reveals this
amethystina {=Calliphlox iridescens Gould, 1860; is due to coppery or bronze iridescence emanating
BMNH 1888.7.25.102). Descriptions of structural col- from barb tips of otherwise silvery-green disks (or sil-
ors are unusually subjective, as color seen by the ob- very-bluemimn certain lights). Lateral gorget feathers
(5.9-6.0 long) are dark gray basally, broadly
server varies according to the angle of inspection and mm
tipped with a silvery-green disk (2.1-2.2 deep,
direction of light. For this reason I use general color 2.7—2.8 mm wide). The depth (usually <1.0 mm) and
descriptions.
The dorsal plumage in amethystina, from crown to intensity of coppery disk margins increase laterally, a
uppertail coverts, is weakly iridescent and dull green few gorget feathers lacking coppery iridescence are
to pale bronzy-green in coloration; the iridescence is juxtaposed among margined feathers in the center of
brighter from a "tail-on" view, as opposed to a "head- the throat. The breast and sides of iridescens are dark
on" view. The crown is dull dark green viewed head- green (dark gray with only a hint of green iridescence
on. The dorsum of aureoventris is significantly more viewed head-on); featherbases are dark gray and gray-
iridescent than that of amethystina, appearing golden- ish feather margins are largely restricted to the lower
green to bluish-green, depending on the angle of ob- midline above the vent. Evidence ofthe white pectoral
servation. The crown is brilliant golden-green, viewed band of amethystina is limited in iridescens to a scat-
head-on, with coppery reflections on the periphery. tering ofwhite and pale gray basal featherbarbs. Tibial
The quality and brightness of dorsal iridescence in plumes, which are dark brownish-gray lightly tipped
iridescens is intermediate to those of the parental spe- pale buffy-gray, are intermediate in length between
cies, but closer in overall appearance to amethystina. those of amethystina and aureoventris, narrowly pass-
The crown reflects a pale, but variable, bluish-green ing the base of the hallux. Undertail coverts are buffy
iridescence when viewed head-on. gray with a weakly-defined subterminal green spot of
The brilliant rosy-red to purplish-red gorget ofame- variable size and extensively margined with pale buf-
thystina, which extends from the chin laterally to the fy-gray.
eye and posterior to the upper throat, is bordered pos- The tail of amethystina is moderately forked. The
mm
teriorly by a white or grayish-white pectoral band that outer rectrices (R2-R5) are narrow (3.3-3.6 wide)
blends posteriorly into dull green on the sides. Gorget and dull purplish-black in coloration. The outer vane
feathers are ofmoderate length (6.1-7.0 mm), medium is faintly (R3) or moderately (R2) glossed with green.
gray basally bordered distally by a narrow transitional R3-R5 are faintly tipped with green in some individ-
band of gray glossed with green and tipped with a uals (unstriated ramphotheca). Both vanes of Rl are
rosy-red terminal disk (from posterior margin of gor- extensively glossed with dark green. Rachises are dark
get: 2.1-2.4 mm deep, 1.7-2.9 mm wide). Feathers of brown on both surfaces. The shallowly forked tail of
the lower breast, sides, and flanks are dark gray ba- aureoventris, which is shining steel-blue on both sur-
sally, tipped subterminally with a weakly-iridescent faces, contrasts highly with the brilliant bluish-green
mm
green disk, and fringed (heavily along the midline) tail coverts. Outer rectrices are 5.4-6.8 wide.
with grayish-buff or buff. Vent feathers are white. Tib- The color and shape of the hybrid's tail are inter-
450 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
mediate between those of atnethystina and aureoven- ly, medium brown at the base of the bill. Feathering
tris. The right outer rectrix (R5) is 4.0 mm wide. The on the maxillary ramphotheca extends to the anterior
outer vane of R2 and both vanes of Rl are glossed edge of the nasal operculum but does not obscure it.
with green. The mandibular ramphotheca and the proximal % of
Remiges of amethystina are dark purplish-brown, the maxillary ramphotheca ofaureoventris is lightyel-
whereas those ofaureoventris are bluish-blackand sig- lowish-brown (red in life). Feathering does not reach
nificantly glossier. Neither species shows unusual the anterioredge ofthe nasal operculum, which is fully
exposed. The bill of the hybrid is almost perfectly in-
notching or emargination ofthe primaries and second-
termediate in color. The maxillary ramphothecais dark
aries. The remiges of the hybrid are intermediate in brown proximally becoming black distally. The man-
color between those of the hypothesized parental spe- dibular ramphotheca is pale yellowish-brown, gradu-
cies. ally darkening to brownish-black on the distal fifth.
The maxillary ramphotheca in amethystina is black, Feathering extends to the anterior edge of the nasal
the mandibular ramphotheca is brownish-black distal- operculum, which is slightly inflated.