THE GERBERA COMPLEX (ASTERACEAE: MUTISIEAE): TO SPLIT OR NOT TO SPLIT

2004·2.8 MB·English

by  Liliana Katinas

THEGERBERACOMPLEX(ASTERACEAE:MUTISIEAE):
TOSPLITORNOTTOSPLIT
Liliana Katinas
DepartamentoCienti'ficodePlantasVosculares
MuseodeLaPlata
PaseodelBosque
1900LaPlata,ARGENTINA
ABSTRACT
ThetransferofChaptaliahintoniitotfiegenusGerberawasrejectedbyNesom(thisissue),whoretains
thespeciesinChaptahasect.Chaptalia.GhaptaliaandGerberabelongtotheGerherti-complex,a
groupofscaposegenerawhosecircumscriptionsarestillinfluxandwhoselargestgenerastilllack
compieterevisionsTmportantmorphologicalcharactersofthecorollas,staminodes,andcypselahairs
arediscussed,andakeytogeneraoftheGerbera-complexisprovided.Theshort,filiformcorollasof
theinnerrayfloretsandthelackofstaminodesarecharactersthatallowthecircumscriptionof
Chaptalia.Certainspeciesmustbeexcludedfromthisgenusandthesectionswithinitmustberede-
fined.Staminodesandinnerrayfloretswithbilabiatecorollasthatarelongerthanthestylearetwo
charactersthatconfirmthetranslerofChaptaliahintoniiintothegenusGerbera.
Keywords:Gerberahutionh,Chaptalia,Gerbera-complex,corollas,staminodes,cypselahairs
RESUMEN
LatransferenciadeChaptaliahinloniialgeneroGerberafuerechazadaporNesom(estevolumen),
quienretieneestaespecieenChaptaliasect.Chaptalia.ChaptaliayGerberapertenecenalcomplejo
Gerbera.ungrupodegenerosdehabitoherbaceoescaposo,cuyacircumscripcionnoestadefmiday
cuyosgenerosmasnumerososaimcarecenderevisionestaxonomicas.Sediscutenloscaracteres
morfologicosmasimportantesdecorola,estaminodiosypelosdelacipsela,yseproveeunaclavede
losgenerosdelcomplejoGerbera.Lascorolascortasyfiliformesdelasfloresmasinternasdelradioy
laausenciadeestaminodiossoncaracteresquepermitenlacircumscripciondeChaptalia.Ciertas
especiesdebenserexcluidasdeChaptalia.ylasseccionesdeestegenerodebenserredefinidas.La
presenciadeestaminodiosyde1loresmternasdelradioconcorolabilabiadamaslargaqueelestilo
constituyendoscaracteresqueconfirmanlatransferenciadeChaptaliahinloniialgeneroGerbera.
Inarecentpaper(thisissue),NesomrejectedKatinas'(1998)placementofthe
south-centralMexicanspeciesChaptalia hintonii Bullock (Asteraceae,
Mutisieae)mtheOldWorldgenusGerbera.Hearguedthatnoclearposition
withinGerberawasgivenforthespeciesinKatinas'paperandthatthemor-
phologicalevidencemorestronglysupportsmcludingC. hintoniiwithin
ChaptaliaratherthaninGerbera.ChaptaliaandGerberabelongtotheGer-
bera-complex,agroupofsevengenerawhoselimitsareasyetinflux.
1agreewithNesom'sargumentthatataxonomicdecisionshouldbemade
inabroadcontext.Therefore,Itakethisopportunitytoclarifyandextendmy
earlierremarksonGerberahintonii(Bullock)Katinasconsideringheretheen-
tireGerbera-complex.
SIDA21(2):935-940.2004
936 BRIT.ORG/SIDA21(2)
ArevisionofthegenusChaptaliainprogress,ledmetoexamineallthespe-
ciesol thistaxonandmanyofthespeciesol theothergeneraottheGcrhcnt-
complex.Thisbroadperspectiveallowedmetodeterminethepotencialkeychar-
actersthatcanbeusedtocircumscribethegeneraofthecomplex.Furthermore,
Ifoundca.15speciesincludedinChaptaliathatarebestexcludedfromthisge-
nus(Katinas,inprep.),someofwhichprobablyarebetterplacedwithinGcrhcra.
ThetransferofC.hinioniitoGcrhcrawasafirststeptowardthisgoal.
Itshouldberemarkedthatsincethestudiesonthisgrouparenotlinished
yet(e.g.,revisionsol Chaptalia,Gcrhcra,andLcihnitzia),someconclusions
presentedhereshouldberegardedasprovisional.Themainpurposeolthispre-
sentationistoprovideanoverviewolthetransferofChaptaliahintoniitoGcr-
herainthebroadercontextoltheGerhcra-complex.
Theproblem
TheGcrbcrcz-complexorthescapose-complex(Jeffrey1967;Hansen1985a,1990)
belongstoMutisiinae(tribeMutisieae)apredominantlyAmericansubtribewith
afewgeneraandspeciesocurringinAsiaandAfrica.Thecomplex,withca.100
speciescharacterizedbymonocephalousscapes,consistsofthegeneraChaptaHa
Vent.(ca.35species),GcrhcraL.(29species),LcihnitziaCass,(sixspecies),Lulia
Zardini(onespecies),PcrdiciumL.(twospecies),TrichoclincCass.(22species),
and UcchiritziaFreyn(threespecies). Recently,Hind(2001)transferred
Trichoclincspalhulata,theonlyAustralianspeciesoftheSouthAmericangenus
Trichoclinc,tothegenusAmhlyspcrma.Are-examinationol bothgenerahow-
ever,ledtoreturnAmhlyspcrmatothesynonymyofTrichoclinc(Katinas2004).
Thecircumscriptionoi taxawithinthismorphologicallyhomogeneous
group,whichlackscompletetreatmentsforitslargestgenera,hasbeenvery
problematic.ExceptforthesmallgeneraLulia,PcrdiciumandUechtritzia,the
onlycompletesystematicrevisionwithinthecomplexisforTrichoclinc(Zardini
1975).Theremaininggenerastill needcompletetreatements.Inthecaseof
Chaptalia,Burkart(1944)locusedontheArgentinianspecies,andNesom(1995)
treatedtheNorthandcontinentalCentralAmericanspecies.Inaddition,Nesom
(1983)revisedtheAmericanspeciesol Tcihnitzia,whereasHansen(1988)
treatedtheAsiaticones.Similarly,Hansen(1985a,b,1988)treatedseparately
thedifferentsectionsofGcrhcra,buthedidnotdealwiththegenusasawhole.
Inallthesestudies,theauthorsstatedthedifficultiesincircumscribing
eachgenusduetothesmalldifferencesamongthem.Inmanycasestransfers
weremadefromonegenustoanother,e.g.,speciesfromTrichoclinctoGcrhcra
(Zardini1974),speciesfromC/icq-^itc;/iatoLci/^nit^ia(Nesom1983),speciesfrom
ChaptaliatoGcrhcra(Katinas1998).OnecaulescentspeciesofTrichoclinchad
thenewgenusLulia(Zardini1980)createdforit(whichmaybeexcludedfrom
thecomplex).
Contrastingpotentialsolutionswereproposedtodealwiththeseconflict-
KATINAS.THEGERBERACOMPLEX 937
ingtreatments.SomewouldtreattheentireGerhera-complexasasingle,large
genus(e.g.,Hansen1990),and,thenagam,somewouldsplitthecomplexinto
smallergenera(e.g.,Jeffrey1967).Resolutionoftheproblemwillprobablyonly
beachievedwhentreatmentsofallthetaxaarecompleted.
Whatcharacter?
Nesomreferredtosomemorphologicalcharacterswhendiscussingthetrans-
ferofChaptaliahintoniitoGerhera,andarguingfortheinclusionofthisspe-
ciesinChaptaliasect.Chaptalia.BelowIdiscussthesecharactersinthecon-
textoftheentireGerbera-complex.
VegetativecharactersallowsomedistinctionamonggeneraoftheGerhera-
complex,butreproductiveones,mainlyflorets(numberofseriespercapitulum,
typeofcorollas,stylebranches,staminodes)andfruits(cypselaapex,cypsela
hairs)seemtobemoreusefulforthedelimitationoftaxa.
ApartofGerbera,andthegeneraLu/ia,TrichocH?ic,andL/eclitrit^iahave
theircapitulabiseriate(twotypesofflorets),i.e.,rayfloretsbilabiateanddisc
floretsbilabiate.Leihnitziaalsohastwotypesofflorets,withrayfloretsligu-
lateorbilabiate,sometimeswithaminuteinnerlip(e.g.,L.occimadrensis),and
discfloretstubularorbilabiate.PerdiciumandapartofGerherahavethree
typesofflorets,allbilabiate.Chaptaliaalsohastriseriatecapitula,withthe
outerrayflorets mostlyligulateand insomespecies(e.g.,C. exscapa,C.
tomentosa)aninnerlipisdeveloped.Thecorollaoftheinnerrayfloretsisvery
reduced,filiform,withanarrowtube,andirregularlybilabiate,tubularorligu-
late3-lobed,shorterthanthestyle.Thisshort,reducedcorollaseparatesChaptaIia
fromGerhera.1havefoundonlytwospecies,C.mandon\iandCtomentosa,
wherelongercorollasoftheinnerrayfloretsmayexist,butheretheyaregener-
allymixedwithshortonesinthesamecapitulum.1alsofoundinGerherasome
specimens(e.g.,G.piloselloidesandG.viridijolia)withcorollasthatapproach
thoseofChaptaliainthattheirinnerrayfloretsarereducedandtransitional
betweentheouterrayfloretsandthediscflorets,butheretheyarebilabiate
andaslongasthestyleorlongerThislonger,moredevelopedcorollaispresent
inG.hintoniias1havealreadypointedout(Katinas1998).
ApointconsideredbyNesomisthepresenceandthedegreeofdevelop-
mentofstaminodesinChaptaliaandGerhera.Hansen(1990)showedthatthere
isareductionseriesinthestaminodesoftherayfloretsfromwelldeveloped
staminodesorsterileanthers(Lulia,Trichocline,Uechtritzia,partofGerhera),
vestigial(partofGerhera,partofLeihnitzia,partofPerdicium)toabsent
(Chaptalia). Gerheraparvaistheonlyspeciesinthegenus that lacks
staminodes.ObservationsondifferentspecimensofG.piloselloidesshowthat
staminodescanbepresentorabsent(eveninthesamecapitulum),thesame
situationthatocurrsinG.hintonii.Nesompointedoutthatstaminodesare
foundinspeciesofChaptalia,e.g.,Cestrihensis,Chololeuca,C.incana,andC
938 BRIT.0R6/SIDA21(2)
texana.Thefirsrthreespecies,whichhavestaminodesandlackthetypicalin-
nerray(loretofChaptalia,areincludedinthegroupthat1wouldexcludefrom
thegenus.WithrespecttoC.Lexana,Nesom(1995)reportsthatcertainspeci-
mens(Gentry&Fox11768)havestaminodes.Theapproximately55specmiens
ofthisspeciesthat1haveseenalllackstaminodes.Moreover,thetwosheetsof
Gentry&Fox11768(MEXU,withthenumbers47607and132933)thatIhave
seenlackstaminodesaswell.Chaptaliatexana,inaddition,isaspeciesthat
hasallthetypicalcharactersofChaptalia(e.g.,thecorollasdiscussedabove).
Finally,unlikeNesom1donotconsiderthatthevestigialstaminodes,present
inG.hmtoniiandothertaxa,shouldbeinterpretedasaplesiomorphicsimilar-
ity.AsIpreviouslypointedout(Katinas1998:381)thereductionofstaminodes
tothreadlike(orvestigial)structuresaswellastheircompleteabsencerepre-
sentapomorphicconditions.
Nesomalsodiscussescypselahairs,inparticularthetwinhairs.According
tohim,thecypselavestiture(togetherwithnoddingbuds)isasynapomorphy
(phylogeneticcoherence)ofChaptalia.Healsosuggeststhatvariationofthe
typeofhairs(togetherwitherectbudsandcleistogamousheads)willallowthe
separationofapartotChaptaliaatgenericrank.Acompleteclassificationof
thesehairscanbeloundinaworkonNassauvimae(Freire&Katinas1995),the
sistersubtribeofMutisiinae,andadiscussionanddescriptionofthecypsela
hairsintheGer/)cra-complexisfoundinmypreviouspaper(Katinas1998:381).
Theanalysisofthecypselatwinhairsinmostspeciesofallgeneraofthecom-
plexledmetothesameconclusionthatHansen(1990)cameto,namelythat
thischaracterismainlyusefulinthedistinctionofUcchtritzia,withverylong,
filiformtwinhairs(ca.1mmlong).Thetypeoftwinhairscandifferentiate
ChaptaliaandGerheratosomedegree,duetosomesectionsofGerherahaving
cypselascoveredbylilitormhairs,atypeofhairthatChaptalialacks.Adis-
tinctioncanalsobemadebetweentheAmericanLcihnitziawithdivergent,
radiate,andcrenatetwinhairsandtheremaininggeneraoftheGerhcra-com-
plex.Gerherahintonii,shareswith manyspeciesofGerhera,Chaptaliaand
othergeneraolthecomplex,thesametypeofhair(basic,rounded).
ThefollowingkeydelimitsthegeneraoftheGerbera-complexusingthe
charactersdiscussedabove,togetherwithsomeothers:
1. Caulescentherbs.Leavesparallel-nerved Lulia
1. Acaulescentherbs.Leavesreticulate-nerved.
2. Pappusbristlesconnateatthebase Perdicium
2. Pappusbristlesfree.
3. Plantsdimorphic:Avernalgenerationwithsmallleaves,sligthlydeveloped,
andchasmogamouscapitula,andanaestivalgenerationwithlargeleaves,
fullydeveloped,andcleistogamouscapitula Leibnitzia
3. PlantsnotdirTiorphic.
4. Cypselastruncateattheapex.
5. Cypselasshaggy,coveredbylonghairs,ca.1mmlong Uechtritzia
KATINASJHEGERBERACOMPLEX 939
5. Cypselaspapillose,coveredbyshorthairs,30-50[jm Trichocline
4. Cypselasrostrateattheapex.
6. Capituladimorphicortrimorphic;whentrimorphic,theinnerrayflorets
withcorollabilabiateorfiliformbilabiate.aslongasthestyleorlonger.
Staminodesgenerallypresent Gerbera
6. Capitulatrimorphic;theinnerrayfloretswithcorollaveryreduced,fili-
form(irregularlytubular,ligulateorbilabiate),shorterthanthestyle.
Staminodesabsent Chaptalia
CONCLUSIONS
Asmentionedabove,theseconclusionsareprovisional,dependingonthe
completionofworkonsomegeneraoftheGerbera-complex.Theexclusionof
ca.15speciescurrentlyincludedinChaptaliawillbecrucialforthere-defini-
tionofthisgenus,asmanyofthemhavecharactersthatapproachthoseofGer-
heraandmayeventuallybetransferredtothatgenus.
Withtheremovalofcertamspecies,thesectionswithinChaptaliamust
beredefined.Thecontroversial C.hintonii,whichhadbeenput insect.
Chaptalia,hasalreadybeenexcluded(Katinasf998).Nowitisnecessaryto
studyallthespeciesofthisgenustore-evaluatethetraditionalsections.For
instance,thecharactersmentionedbyNesomdefiningsectionChaptalia
(monocephalous,ebracteateorfew-bractedscapes,headsnoddinginbud,broad,
creamcolouredrayswithapurplemidstripe,andtuncionallystaminatedisc
flowers)arepresentalsoinspeciesbelongingtoothersectionsestablishedby
Burkart(1944),e.g.,C.denticulatafromBrazil(sect.Archichaptalia),C.meri(iensis
fromVenezuela(sect.Archichaptalia),C.paramensishomColombia.
1agreewithNesomthatChaptaliaisanaturalgroup,althoughIdisagree
thatthecypselavestitureandnoddingbudsgivecoherencetothegenus.The
basictwinhairsdifferentiateChaptaliaandothertaxaoftheGerhera-com-
plexonlytosomedegree,whereasnoddingbudsarenotpresentinmanyspe-
ciesoi Chaptalia(e.g.,Cdentata,C.exscapa,C.mandonii,C.piloselloides,C.
runcinata).Thecorollamorphologyoftheinnerrayflorets,ontheotherhand,
seemtobethemostconsistent,apomorphiccharacterforcircumscribingthe
genus.Thelackofstaminodes,aconditionfoundalso(thoughuncommonly)
mGerbera,canalsohelptocircumscribeChaptalia.
Incontrast,Gerberahasprovedtobeanonmonophyleticgenus(Hansen
1990).ThissituationandthepotentialadditionofspeciesfromChaptaliamakes
itnecessarytocompletelyrevisethegenus.Forthisreason,itisprematureto
considerifGerberacouldbesplitedinnew,small,genera.1believethatatleast
somegeneraof theGerbera-complexhavecharactersthatallowthemtobe
mantainedasindependenttaxawithinthecomplex,i.e.,theparallel-nerved
leavesofLulia,thelong,filiformtwinhairsonthecypselasofUcchtritzia,the
alternatingplantphasesofLeibnitzia,andthemorphologyof theinnerray
corollasofChaptalia.
940 BRIT.ORG/SIDA21(2)
Finally,IconcludethatthecharactersexhibitedbyGcrhcrahintonii,i.e.,
bilabiateinnerrayFloretswithcorollassurpassingthestyle,andvestigialstami-
nodcsprovidegoodsupportforpositioningitinGcrhcraratherthaninChaptalia.
acknowi>:dgmhnts
IthankGuyL.Nesomforaccesstohismanuscriptandlorinsightlulcomments
duringmyworkinthisgroupol plants.1alsothankJorgeV.CrisciandBob
Kowalforcriticalreadmgotthisresponse.ConsejoNacionaldeInvestigaciones
CientificasyTecnicas(CONICET)andtheNationalGeographicSociety(Grant
n.5776-96)arealsoacknowledged.
REFERTiNCHS
BuRKART,A.1944.EstudiodelgenerodcCompuestasChaptaliaconespecialreferendaa
lasespeciesargentinas,Darwiniana6:505-594.
Freiri,S.E.and L.Kaunas.1995.Morphologyandontogenyofthecypsela hairsof
Nassauviinae(Asteraceae,Mutisieae).In:D.J.Hind,C-Jeffrey,andG.V.Pope,eds.Advances
inCompositaesystematics.Roya!BotanicGardens,Kew.Pp.107 143.
hiANSEN,H.V.1985a.AtaxonomicrevisionofthegenusGerbera(Compositae-Mutisieae)
sectionsGerbera,Parva,Piloselloides(inAfrica)andLa5iopus.OperaBot.78:5-36.
Hansen,hH.V.1985b.NotesonGerberasect.Pseudoseris(Compositae-Mutisieae).NordicJ.
Bot.5:451-453.
Hansin.H.V.1988.ataxonomicrevisionofthegeneraGerberasect.Isanthus.Lelbnit/ia(in
Asia),andUechtritzia(Compositae,Mutisieae).NordicJ.Bot.8:61-76.
Hansen,H.V.1990.Phylogeneticstudies in theGerbera-complex(Compositae,tribe
Mutisieae,subtribeMulisiinae).NordicJ.Bot.9:469 485.
Hind,D.J.N.2001.AnewcombinationinAmb/yspermo(Compositae:Mutisieae).KewBull.
56:711 713.
Jeffriy,C.1967.NotesonCompositaeII.TheMutisieaeincasttropicalAfrica.KewBull.
21:177-223.
Kaunas,L1998.TheMexicanChaptaliahintoniiisaGerbera(Asteraceae,Mutisieae).Novon
8:380-385.
Kaunas,L.2004.4/77b/yspermashouldberetainedunderTr/c/"ioc7;ne(Asteraceae,Mutisieae).
Taxon53:108-112.
Nesom,G.L.1983.BiologyandtaxonomyofAmericanLeibaitzia(Asteraceae:Mutisieae).
Brittonia35:126-139.
Nesom,G.L.1995.RevisionofChapta//o(Asteraceae:Mutisieae)fromNorthAmericaand
continentalCentralAmerica.Phytologia78:153-188.
Zari)ini,E.M.1974.SobrelapresenciadelgeneroGerberaenAmerica.Bol.Soc.Argent.Bot.
16:103-108,
Zardini,E.M.1975.RevisiondelgeneroPrichocline(Compositae).Darwiniana19:618-733.
Zarluni,E.M.1980.Lulia:un nuevogenerodeCompuestas.Bol.Soc.Argent.Bot.19:
255-258.