Taxonomic Notes On Hummingbirds (Aves : Trochilidae). 1. Eriocnemis Dyselius Elliot, 1872 Is A Melanistic Specimen Of Eriocnemis Cupreoventris (Fraser, 1840)

5 Pages·1998·1.6 MB·English

by  G R Graves

PROCEEDINGSOFTHEBIOLOGICALSOCIETYOFWASHINGTON
lll(2):420-424. 1998.
Taxonomic notes on hummingbirds (Aves: Trochilidae). 1.
Eriocnemis dyselius Elliot, 1872 is a melanistic specimen of
Eriocnemis cupreoventris (Fraser, 1840)
Gary R. Graves
DepartmentofVertebrateZoology,NationalMuseumofNaturalHistory,SmithsonianInstitution,
Washington,D.C. 20560,U.S.A.
—
Abstract. Eriocnemis dyselius Elliot, 1872 is hypothesized to be a mela-
nistic specimen of Eriocnemis cupreoventris (Fraser, 1840), a puffleg hum-
mingbirdrestrictedto the Andes Mountains ofColombiaandVenezuela.
Amongthefamiliesofbirds,thesystem- mountwithglasseyes, is adultasjudgedby
atics of the Trochilidae are the most con- the lack ofstriations on the maxillary ram-
fused, inabsolutenumbers,byhybrids, ge- phothecum (see Ortiz-Crespo 1972). Previ-
netic variants, and the problems associated ouslyhousedinboththeBourcierandElliot
withtaxadescribedfromuniquespecimens collections (see Greenway 1978), the speci-
(e.g., Berlioz & Jouanin 1944; Banks & menisnowcataloguedintheAmericanMu-
Johnson 1961; Greenway 1978; Bleiweiss seum ofNatural History (AMNH 38452). I
1988; Graves 1990, 1993, 1996, 1997a, studiedthespecimentakingtheapproachout-
1997b; Hinkelmann et al. 1991). One such lined in Graves (1990) and Graves & Zusi
questionable taxon is Eriocnemis dyselius (1990). In determining the scope ofthe spe-
Elliot, 1872 a puffleg hummingbird ofin- cies pool to be investigated, Elliot's (1872:
determinate origin. Salvin (1892:369) sug- 294) descriptionoffers littleguidance:
gested that the black-plumaged specimen "Four specimens, precisely alike, were,
was "perhaps amelanismofE. cupreiven- asIwasinformed,containedinthesmall
tris," an inhabitant of forest borders and collection of birds from which my ex-
shrubby slopes (1950-3000m)oftheVen- amplewastaken;and, althoughnolocal-
te1hz9eu8e6l,CaonFljAoenlmddbseiasan&andAKnrtadhbeebsEeas(1tH9ei9rl0nt)yC.orS&daillvBliernroadwiondf iistytwheashagbiivteant,oiftitshesuspppeocsieesd."thatEcuador
not elaborate on this proposal. Subsequent The existence of four similar specimens of
authors (Cory 1918, Berlioz & Jouanin unknownorigin shouldnotbe interpretedas
1944,Peters 1945,Greenway 1978,Fjeldsa evidence ofa differentiatedpopulation. Mil-
& Krabbe 1990) agreed with Salvin but linery dealers inthe 19thcentury sortedand
likewise provided no further support for high-gradedshipmentsofhummingbirdskins
this hypothesis. Consequently, the taxono- for unusual specimens to offer to collectors
my ofE. dyselius is still uncertain. Here I of natural history specimens. Although the
present evidence that supports Salvin's circumstancesofElliot'sacquisitionofE.dy-
(1892) conjecture that the holotype of E. seliusareunknown,thefourblack-plumaged
dyselius is a melanistic specimenofErioc- specimens could have been gleaned from
nemis cupreoventris (Fraser, 1840). commercial lots consisting of tens of
thousandsofspecimens(Doughty 1975).For
Materials andMethods the purpose of analysis, the holotype ofE.
The unsexed holotype of Eriocnemis dy- dyselius may have originated anywhere in
selius (Fig. 1), apartially relaxedtaxidermy northwestern South America (see Berlioz &
VOLUME 111.NUMBER2
Fig. HolotypeofEriocnemisdyseliusElliot, 1872(AMNH38452).
Jouanin 1944), a region inhabited by more member of Eriocnemis. I took standard
than 150 species ofhummingbirds (Hilty & measurements (rounded to the nearest 0.1
Brown 1986, Graves 1990). mm) of adult male and female specimens
I considered Salvin's hypothesis as the ofEriocnemiscupreoventris, E. nigrivestis,
most likely, apriori. The possibilityofhy- andE. vestitus (thethree speciesmostsim-
bridization wasjudgedtobe negligiblebe- ilarin size and shapetotheholotypeofE.
cause the plumage of E. dyselius is sub- dyselius) with digital calipers: wing chord;
stantiallydarkerandlessreflectivethanthat lengths ofrectrices (frompointofinsertion
of any potential parental species in north- of central rectrices); and bill length (from
western South America (i.e., Coeligena anterior extension of feathers) (Table 1).
prunellei, Eriocnemis nigrivestis, Helian- Color comparisons were made under natu-
geluszusii, H. regalis). ral light; theplumage was examinedunder
Thedownytibialpuffs andbodypropor- 10X magnification (Appendix).
tions of E. dyselius clearly mark it as a I used principal components analysis
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Table 1. Rangesandmeans(± standarddeviation)ofmeasurements(mm)ofEriocnemiscupreoventris,E.
vestitus, andthetypespecimenofEriocnemisdyseliusElliot, 1872.
cupreoventris vestitus
66 99 66 99
(n=15) (/>=6) (n=15) («=11) AMNH38452
Wingchord 59.6-63.8 57.2-60.7 57.8-61.3 54.7-59.4 58.8
61.6 ± 1.3 58.8 ± 1.1 59.4 ± 1.1 57.7 ± 1.4
Billlength 16.6-18.6 17.0-19.6 15.9-18.8 17.4-19.2 17.5
17.8 ± 0.5 18.5 ± 1.0 17.5 ± 0.8 18.5 ±0.5
Rectrix 1 24.5-28.2 24.6-26.6 26.2-29.7 29.7-32.8 26.9
26.4± 1.1 25.8 ±0.7 28.4± 1.1 31.1 ±0.9
Rectrix2 26.9-31.2 26.1-28.2 28.0-31.5 31.3-35.1 29.8
28.6 ± 1.3 27.4 ±0.8 29.9 ± 1.1 32.9 ± 1.1
Rectrix3 31.9-36.6 30.7-33.3 31.1-35.3 33.5-37.7 34.6
33.8 ± 1.5 32.1 ±0.9 33.1 ± 1.4 35.9 ± 1.3
Rectrix4 36.9^12.4 34.8-38.5 35.3-39.7 35.9-41.0 37.9
39.5 ± 1.8 37.0 ± 1.3 37.9 ± 1.5 38.9 ± 1.5
Rectrix5 40.4^6.3 36.0-40.1 40.6^15.3 37.6^12.2 39.5
42.9 ± 1.7 38.6 ± 1.6 42.7 ± 1.4 39.7 ± 1.5
Allmeasurementsonleftside.
(PCA) on log, transformed measurements lacks glittering iridescence, an observation
to reduce the dimensionality of data. Un- consistentwiththehypothesisofmelanism.
rotated principal components were extract- Althoughmelanismisthoughttooccurata
ed from covariance matrices (Wilkinson verylowfrequencyintheTrochilidae(e.g.,
1989). Factor scores were projected on a Salvin 1892, Greenway 1978), the fine
bivariateplottoillustratetherelationshipof structureofmelanisminhummingbirdshas
rectricial measurements inEriocnemis (Ta- not been formally investigated, and I will
ble 2, Fig. 2). Forbrevity, the holotype of only briefly address the topic here. Irides-
E. dyseliuswillbereferredtoasdyseliusin cenceinhummingbirdsiscausedbythein-
the remainderofthepaper. terference oflightreflectedfromtheupper
and lower surfaces ofair-filledvacuoles in
Results and Discussion melaningranules,whicharecloselystacked
Currently recognized species of Erioc- in 7-15 layers in the outer keratin of the
nemis (Sibley & Monroe 1990, Graves expandeddorsalflangesoffeatherbarbules
1996) exhibit areas ofglitteringorbrilliant (Dorst 1951, Greenewaltetal. 1960,Lucas
plumagewhichprobably serveassignaling &Stettenheim1972).Perceivedcolorsvary
badges during agonistic and sexual dis- according to the size of the vacuoles, the
plays. The dull black plumage ofdyselius thickness ofmelanin granules, and the an-
—
Table2. Factorloadingsfromaprincipalcomponentsanalysis(PCA)ofrectricialmeasurementsofErioc-
nemiscupreoventris,E. vestitus, andtheholotypeofEriocnemisdyseliusElliot, 1872.
Variables
Rectrix 1 (innermost) 0.0314 -0.0054 0.0076
Rectrix2 0.0298 -0.0035 0.0005
Rectrix3 0.0195 0.0055 -0.0102
Rectrix4 0.0093 0.0150 -0.0071
Rectrix5 0.0012 0.0228 0.0090
Percentvarianceexplained 66.2% 23.1% 8.3%
VOLUME 111.NUMBER2 423
004 —A 1 thus eliminating that species as apossibili-
003 A A ^A ty-
A A Feather shape ofdyseliusprovides addi-
002 &A tionalcluesastoitsidentity.Theoutermost
CO 0.01 o A *Aaa.* A rceucptrreiocveesnatnridsloanrgeestsluipgphetrltyailnacrorvoerwtesrofanE.d
8< 0.00 00*> moreattenuatethanthoseofE. vestitusand
-001 - Oo E. nigrivestis, although some overlap oc-
-002 • ° fceuartshearmsoinngdytsheelispuesciisesm.oTshtesismhialpaertooftthhoessee
-0.03 o . ofE. cupreoventris.
-nnA Whenviewedhead-onunderdirectlight,
-010 -005 0.00 0.05 10 015 the throat of dyselius emits a dull plum-
PCA 1 beous iridescence but exhibits no evidence
Fig.2. Bivariaterelationshipoffactorscores(PCA ofa centrally demarcated areacorrespond-
1 &PCA3,seeTable2)fromaprincipalcomponents ingto thegorget foundinboth sexesofE.
parneaolyvseinstroifsr(edcitarimcoinadlsm:efaesmuarleemsen=tsfilolfed;Ermiaolcensem=isemcpu-- nigrivestis and E. vestitus. Eriocnemis cu-
ty), E. vestitus (triangles: females = filled; males = preoventris lacks adefinedgorget. Instead,
empty);andtheholotypeofEriocnemisdyseliusElliot, the entire throat and upper breast exhibits
1872(filledcircle). brilliantiridescenceinbothsexes.Thegra-
dationoffeathersize,shape,andreflectivity
across the throat ofdyseliusresemblesthat
gleofobservation. Theintensityofcoloris ofE. cupreoventris. Moreover, the pattern
enhancedby reflectance frommultiplelay- ofmelanizationindyseliuscorrespondspre-
ersofgranules.Anoverabundanceandran- cisely with the distribution of iridescent
dom placement ofmelanin granules in the plumage inE. cupreoventris.
keratin would lead to a disarrangement of In summary, the holotype ofEriocnemis
dyseliuscorrespondswellinsizetomaleE.
thereflectivelayers,theabsorptionoflight,
and a damping ofiridescentbrilliance. cupreoventris. Subtleties of rectrix shape,
thelackofawell-developedgorget,andthe
EriocnemiscupreoventrisandE. vestitus
general pattern ofmelanization ofdyselius
are remarkably similar in size and shape
also areconsistentwithSalvin's(1892)hy-
taonddmiesltianngiusitsihc.spTehceimmenesanwoubilldlbaenddiffwiicunlgt paomtphleesisoftEh.atcudpyrseeolvieunstriiss,aamnedlapnriosvtiidceenxo-
lengths of the respective sexes ofthe two reasontobelievethatdyseliusrepresentsei-
species differby to 3.7%. The difference ther a hybrid or a valid species. Thus, the
in mean rectrix length varies from0.4% to nameEriocnemisdyseliusElliot, 1872cor-
7.5% in males and 5.1% to 20.9% in fe- rectly is placed in the synonymy ofErioc-
males. Comparison of raw measurements nemiscupreoventris (Fraser, 1840).
and inspection of bivariate plots of PCA
variables extractedfromrectricialmeasure-
Acknowledgments
ments showthatdyseliusis mostsimilarin
size and shape to male E. cupreoventris The critiques of Richard Banks, Tom
(Table 1,Fig. 2).Thebilllengthofdyselius Schulenberg, MichaelWalters, andRichard
(17.5 mm) falls outside the range ofmea- Zusisignificantlyimprovedthemanuscript.
surementsforE. nigrivestis(males:n = 15; Iamgratefultothecuratorsandstaffofthe
14.4-15.8 mm, X = 15.1 ± 0.5, and fe- AmericanMuseumofNaturalHistory,New
males: n = 6; 15.6-16.5 mm, X = 16.0 ± York, for permitting me to study the spec-
0.3; see measurements in Graves 1996), imen.Photographicprintswerepreparedby
—
424 PROCEEDINGSOFTHEBIOLOGICALSOCIETYOFWASHINGTON
the Smithsonian photographic services. hummingbird (Heliodoxa leadbeateri X Helian-
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WteebtrmatoerZeooFluongdy,anSdmitthhesoDneipaanrtImnestnittuotifonV.er- GreenewCiadolents,dcoeCnr.t9cH2o.:l,o7r5Ws4-o7fB6rh0au.nmdtm,in&gbDi.rdD.feaFtrhieerls..—19J6o0u.rnIarl-
oftheAmericanOpticalSociety50:1005-1016.
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(Aves:Troc—hilidae).3.ParentageofLesbiaortoni beous iridescence in direct light (dull black in diffuse
Lawrence. ProceedingsoftheBiologicalSociety light).Thebasalmarginsofsomethroatfeathersarebuf-
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(Aves:Trochilidae).—4.HybridoriginofCalothor- bluishsheen.Primariesaredullblackbutpalerthanthe
axdecoratusGould. ProceedingsoftheBiolog- dorsalbody plumage. Rectrices areglossybluish-black
icalSociety 110:320-325. on the dorsal andventral surfaces.Thewell-developed
, & R. L. Zusi. 1990. An intergeneric hybrid tibial "puffs"arewhite.