Numerical analysis of Thai members of the Eugenia-Syzygium group (Myrtaceae)

29 Pages·1999·1.7 MB·English

by  Parnell, J

BLUMEA 44 (1999) 351-379
Numericalanalysis of Thai membersof the
Eugenia-Syzygium group(Myrtaceae)
J. Parnell
Herbarium,School ofBotany,TrinityCollege,Dublin,Ireland
Summary
Four differentanalyses ofThai Syzygium show, with very small discrepancies, that onesmaller
monophyletic and onelargerpolyphyletic group can be recognised. The smallermonophyletic
group warrants sectional rank asSyzygium section Jambosa and consists ofS.anacardiifolium,
S. aqueum, S. diospyrifolium,S. formosum, S.foxworthianum,S. jambos, S. lakshanakarae,
S.malaccense,S.megacarpum, S.papillosum,S.pseudoformosum,S.pycnanthum,S. samarangense,
S.scortechinii and S.siamense.
Keywords-. Eugenia,Jambosa,Syzygium,cladistics,pheneticanalysis, phylogenetic analysis.
Introduction
TheMyrtaceaearea moderatelysized,mostly southernhemisphere family containing
between 132and 150generaandsomewherebetween3,675and3,900species (Johnson
et al., 1988;Kochummen, 1995;Lemmens, 1995; Mabberley, 1997;Schmid, 1980;
all provide slightly differentestimates). Despite its modest size the family poses a
disproportionately large number ofcomplex taxonomic problems evident at many
levelsinthetaxonomichierarchy. Forexample, McVaugh(1968)describedthespecies
ofAmericanMyrtaceaeas "distressinglyalikeinaspectandinmostindividualcharac-
teristics, making identificationand classificationofbothgeneraandspecies a corre-
spondingly difficultand tediousmatter."
WithintheMyrtaceaetwounequallysizedsubfamilieswererecognised by Niedenzu
(1893): theMyrtoideae andLeptospermoideae. TheMyrtoideae haveonly 60 genera
(Nic Lughadha &Proen§a, 1996)butcontainapproximately two-thirds(2,375) ofthe
species known intheentirefamily (Schmid, 1980).These species occur intheNew
andOldWorldtropics, aremainly shrubs ortrees ofwet-forests, usually haveanin-
feriorovary, andalmostalways possess opposite broadleaves anda fleshy indehis-
centfruit.Theothersubfamily,theLeptospermoideae, containsmore genera(72)than
theMyrtoideae but fewerspecies (1,300). Its species are largely Australasian,have
alternate,spiral or opposite leaves, an inferioror superior ovary and, usually, a dry
dehiscentfruit.
Niedenzu's(1893) subfamilialdivisions are convenientandstill used (e.g. Hora,
1978andNic Lughadha & 1996). However, severalrecent studiesindicate
thatNiedenzu'sclassificationisunsatisfactory(e.g. Johnson& Briggs, 1984orSchmid,
1972,1980). Johnson& Briggs (1984) developedaninformalsystem ofalliancesand
352 BLUMEA Vol. 44, No. 2, 1999
suballiances through cladisticanalysis ofa fairly large and comprehensive dataset
(Briggs&Johnson, 1979;Johnson& Briggs, 1984). Though thealliancesappearwell-
supported their interrelationships and boundaries remain somewhat controversial.
Johnson& Briggs (1984)concludethatNiedenzu's (1893) divisionofthefamily on
the basisoffruitcharacteristics is not phylogenetically supportable: theiralliances
andsuballiances cross traditionalsubfamilialboundaries.
Twoalliancesareofparticular concern inthispaper- theAcmenaand Myrtoideae
s.s. alliances(Johnson &Briggs, 1984)or,morespecifically, theAcmenaandEugenia
alliances(Johnson etal., 1988). Though traditionally placed closetoeachotherinthe
fleshy fruitedMyrtoideae, thesealliancesappearfarapartphylogenetically (Johnson
& Briggs, 1984). Indeedthey could scarcely be much furtherapart in Johnson &
Briggs' cladogram wherein theEugenia alliance(including Jossinia Comm.exDC.)
is ina cladewhichincorporates theLeptospermum alliancewhilsttheAcmenaalliance
forms an altogether separate clade with, amongst others, the Eucalyptus alliance.
However, in alatercompromise classificationboth alliances are placed together in
the subfamily Myrtoideae (Johnson etal., 1988).InthispaperIadheretothis latter
conceptanduse the term Myrtoideae initstraditionalsense.
TheAcmenaandEugenia alliancescontaintwoofthemosttaxonomicallyconfused
generain theMyrtaceae- Eugenia L.and Syzygium Gaertn. anda numberofother
generawhich have, at one time oranother, beencleavedofffromor reunitedwith
them.Schmid(1972)pointed outthattherewereabout35generic nameswhichhave
beenorcouldbereducedtoSyzygium s.l.andatleastanother30assignable toEugenia
s.l.Sincethenthenumberofsegregateshas increasedwith, forexample,thedescription
of WaterhouseaHyland and MonimiastrumJ.Gueho & A.J. Scott. Together these
generaforma"vastarrayofmoreor less closelyalliedspecies" (Ashton, 1981).This
'array', dominatedbyEugenia andSyzygium, is very large- IndexKewensis hasover
3,000species listedunderEugenia andover 1,000underSyzygium. Undoubtedly this
does not reflect thetrue balance in numbersofspecies between thesegenerawhen
they are consideredinthe strict sense as even now many authorsprefer, becauseof
historical precedent, toignore thedifferencesbetweenthem.
Schmid(1972)provides themostcomprehensive reviewofthestatusofSyzygium
s.l.andmakes clearwhyEugenia/Syzygium wereconfused.Schmid'swork summarises
nearlyalloftherelevantreferencesandarguments,andis thereforenot repeated here.
Table 1 summarisestherelevantsections ofSchmid(1972) together withJohnson&
Briggs (1984).
As canbe seen fromTable 1:
1)thereis someoverlapinallofthemosteasily observabledifferentialmorpholo-
gical charactersbetweenEugenia andSyzygium (e.g. pubescence of vegetative and/
orreproductive parts,fugacity ofbractsandbracteoles,presenceorabsenceofapseu-
dostipeandfusionofthecotyledons);
2) thereare ± nomeristiccharactersinthistable.Thisreflects thefact that,as far
asIknow, therehavebeennopublished studiesdealing withmorphometric variation
withinthegroup;
3) thereappeartobe sometruly diagnosticcharacteristics(e.g. pathwayofvascular
supply to theovules, presence of siliceousrays, elongation ofvessel-ray pits, carpel
number), howevernoneofthese, withthepossible exception ofthe latter, are easily
J.Parnell: Numerical analysis ofThai Eugenia-Syzygium 353
Table 1.Majordifferential and diagnosticcharacteristics ofEugeniaandSyzygium. Datafrom
Schmid (1972),Johnson & Briggs (1984)andpersonal observation.The percentageofspe-
ciesestimatedtohave atraitare shown and are largelytakenfromSchmid(1972).
CChhaarraacctteerr EEuuggeenniiaass..ss.. SSyyzzyyggiiuumm ss..ll..
PPuubbeesscceennccee ooffvveeggeettaattiivvee UUssuuaallllyypprreesseenntt((9900%%)) RRaarreellyy pprreesseenntt((55%%))
aanndd//oorr rreepprroodduuccttiivveeppaarrttss
BBrraaccttssaanndd bbrraacctteeoolleess PPrreesseenntt aanndd ccoonnssppiiccuuoouuss FFuuggaaccoouussaanndd iinnccoonnssppiiccuuoouuss
((8800%%)) ((9955%%))
PPsseeuuddoossttiippee11 AAbbsseenntt ((9999%%)) PPrreesseenntt ((9922%%))
CCoottyylleeddoonnss UUssuuaallllyy ffuusseedd UUssuuaallllyyffuussiioonn aabbsseenntt
DDeeggrreeeeoofffflloorraall ttuubbee pprroolloonn-- ++NNoottpprroolloonnggeedd PPrroolloonnggeedd
ggaattiioonn aabboovvee tthheeoovvaarryy
PPeerriiaanntthh UUssuuaallllyy llaarrggee aanndd ccoonnssppicic-- UUssuuaallllyyssmmaallllaannddiinnccoonnssppicic--
uuoouuss uuoouuss
SSuurrffaacceeooffsseeeedd--ccooaatt SSmmooootthh RRoouugghh
PPaatthhwwaayy ooffvvaassccuullaarr TTrraannsseeppttaall AAxxiillee
ssuuppppllyyttoooovvuulleess
VVeesssseellss MMoossttllyy ggrroouuppeedd MMoossttllyy ssoolliittaarryy
EElloonnggaattiioonnooffvveesssseell--rraayy ppiittss CCoonnssiiddeerraabbllyyeelloonnggaatteedd IIssooddiiaammeettrriicc oorr mmooddeerraatteellyy
eelloonnggaatteedd
BBoorrddeerreeddppiittssffrroommffiibbrreess AAbbsseenntt PPrreesseenntt
AAppoottrraacchheeaallppaarreenncchhyymmaa AAbbsseenntt PPrreesseenntt
PPaarraattrraacchheeaall ppaarreenncchhyymmaa CCoonnfflluueenntt oorrbbaannddeedd SSccaannttyy
SSiilliicceeoouuss iinncclluussiioonnssiinn rraayyss PPrreesseenntt AAbbsseenntt
NNuummbbeerr ooffccaarrppeellss 22 44--55
NNuummbbeerr ooffsseeeeddssffoorrmmiinngg SSeeeeddss rreedduucceedd ttoo 11 oorr22 MMoossttoovvuulleess ffoorrmmiinnggsseeeeddss
ffrroommoovvuulleess
1) Pseudostipeasdefined byWilson (1957)=pseudostalkofHenderson (1949).
observed.In generaltheworkofSchmid(1972), Johnson& Briggs (1984)andothers
isbasedonasmallfractionoftheEugenia/Syzygium complex; thereforetheirconclu-
sionsmay beoflimitedapplication. On theother handthesheer numberofspecies
involvedmakeitunrealistictoexpecttheassemblage ofatrulycomprehensive dataset
whichwillallow foranall-inclusivephylogenetic analysis andinarguableresolution
ofthe controversy. Assemblage of data ona regional basis in the hope ofeventual
amalgamation offers the only potential solution.An additionaldifferencebetween
Eugenia andSyzygium not showninTable1 is thatEugenia is alargely tropical New
Worldgenus(though EugeniaahernianaC.B.Rob.isfoundinthePhilippines), whilst
Syzygium is astrictly tropical OldWorldgenus.
Although phenetic analysis ofa partial dataset is not problematic - phylogenetic
analysis ofsuch datacanonly bejustified if:
1) representatives cover thecomplete rangeofvariabilityofthegenus;
2) theapomorphies usedareunique on aworld-widescaleandnotjusttothestudy
area in question (Esser etal., 1998);
3) aconservativeapproach to monophyletic groupdelimitationfromanyresulting
cladogram is taken.
Thesecriteriaaremet inthispaper.
354 BLUMEA Vol. 44, No. 2, 1999
In the absence ofcontradictory evidence on monophyly, Syzygium, the more geo-
graphicallyconfinedandsmallerofthetwo genera,appearsthe bettergenus to start
analysis withandis theone dealtwithhere.
THECONCEPT OF SYZYGIUMADOPTED IN RECENT
SOUTH-EASTASIANFLORAS
Historical precedent is a particular problem in South-EastAsia where the genus
Syzygium is centred.Ashton (1981)points out that"through thelatterpartofthe 19th
century a broad generic definitionoperated inAsiatic floras with all species being
consideredaspartofEugenia.” Even nowadays some authors continuetoutiliseone
orothergeneric namefortheentireconstellationofspecies (e.g. Kochummen,1995)
whilstothersacknowledge thatnew combinationsareneededbutrefusetomakethem
(Lemmens, 1995).Whilst such procedures promote nomenclaturalstability they
perpetuatetheuseofinaccuratenamesandmakeitpsychologically more difficultto
introducethenecessary new combinations.
Despite the strength ofhistorical precedent there have been three concepts ofthe
Syzygium/Eugenia complex adopted inrecent South-EastAsianfloras.
Concept 1 — The simplest concept,andthat whichcurrent evidenceindicates is
themostinaccurate,is theall-inclusiveoneusedby Henderson(1949),Kochummen
(1995)andLemmens(1995) whereinasingle enormous genus- Eugenia - is recog-
nised.However,itisobviousfrom Schmid(1972) and Johnson&Briggs (1984) that
thisconceptisanuninformativeoption, thatEugenia andSyzygium aredistinguishable
andthereforethisconcepthas latterlybeenadoptedmerely forthesakeofconvenience.
Henderson(1949)acceptsconvenienceasavaliddeterminantofaclassificatory struc-
ture andproduces furtherevidence to suggestthatEugenia andSyzygium are notin
reality distinct fromeachother. Healso points out that such a single large genus is
unwieldy andthat "attempts to split itup have not met with conspicuous success";
hethenproceeds tosplitEugenia intofivesections basedon featuresofthecalyx and
androecium(Table 2).
Henderson's section Fissicalyx contains only two rare species, both endemic to
Malaysia, andbothofwhichhave the sameapomorphic characteristics - that their
stamens are not attachedtotherimofthe calyx-tubebut occur scatteredover its sur-
Table2. Sectionaldifferences within Eugenias.l.according toHenderson (1949). § =section.
CChhaarraacctteerr §§ CClleeiissttooccaallyyxx §§ SSyyzzyyggiiuumm §§ AAccmmeennaa §§ FFiissssiiccaallyyxx §§EEuu--eeuuggeenniiaa
CCaallyyxx--ttuubbeepprroodduucceedd YYeess YYeess YYeess YYeess NNoo
aabboovveeoovvaarryy
SSttaammeennssmmaarrggiinnaall YYeess YYeess YYeess NNoo YYeess
oonnddiisscc lliinniinngg
ccaallyyxx--ttuubbee
AAnntthheerr--cceellllss ddiivvaarr-- NNoo NNoo YYeess NNoo NNoo
iiccaattee
CCaallyyxx ccaallyyppttrraattee YYeess NNoo NNoo NNoo NNoo
J.Parnell: Numerical analysis ofThai Eugenia-Syzygium 355
Table 3.Henderson’s (1949)division ofhis sectionSyzygium intogroups. Henderson’s calyx-
tube charactersinclude thepseudostipe:acharacter described in detail by Chantaranothai &
Parnell (1994a).
Character Group 1 Group2 Group 3 Group 4 Group5
Calyx-tube atleast 1 cm Yes Yes No No Yes
long
Calyx-tubecampanulate, 1 1 1 1 2
funnel-shaped,urceo-
late orsubglobose(1)
orCalyx-tube fusi-
form,peg-shaped,
clavateorgradually
narrowed (2)
Inflorescence short Yes No No Usuallyno Varied
Inflorescencesfew- Yes No No No Usuallyno
flowered
faceandthatthecalyx-tube splitsafteranthesisintosix or seven irregular segments.
Thesedifferencesare sufficientlygreattosuggestthatHendersonwasunduly conserva-
tiveandthatthesespecies should, probably, besegregated intoaseparate genus.As
Henderson'sotherfoursections occurinThailandphylogenetic analysis, as undertaken
herein,is stilljustifiable. SectionsCleistocalyxandAcmenacontainonlytheirepithet
bestowing generaandare separated by autapomorphies fromthe othersections (viz.
calyx calyptrate andanthersdivaricate,respectively). Section Syzygium containsthe
vast majority ofspecies andwas furthersubdividedby Henderson(1949) into five
groupsonthebasis ofcalyx andinflorescencecharacters(Table3).
Henderson'sgroups are entirely novel anddo not correspond topreviously recog-
nised genera.Henderson was also the first author touse a biometriccharacter(the
lengthof thecalyx-tube)tosubdividethiscomplex. Otherauthors, forexample Hung-
ta& Ru-hwai(1982), dividethegenusSyzygium intosections andseriesonthebasis
of differencesin characters such as flower length, petals eitherfree or fused, and
inflorescencetype.Unfortunately manyspecies aretoo littleknown toallowthemto
beeasily accommodatedin theirsystem.
Concept 2— Thissecondconceptallowsforseparation ofSyzygium fromEugenia
but givesnorecognition toanyothergeneric segregates.It conformstothatofAlston
(1931) (who,in hisrevisionofSriLankanmaterial, reduced Jambosato synonymy
withSyzygium whilstmaintainingthesplitbetweenSyzygium andEugenia) andmore
orless tothose ofAshton (1981), Hartley & Perry (1973), andAiry Shaw (1949).
Concept 3— The third concept of the complex is themost divisive. In itsmost
fissibleformit was adopted by Merrill& Perry (1938, 1939) whoaccepted a large
seriesofgeneric segregatesincludingAcmenaand Cleistocalyx. However,Merrill&
Perry didnot acceptJambosa:: a genus or subgenus definedina varietyofways [on
thebasis ofitslarge leaves, flowers andfruits(Ridley, 1922)]or differingonly inits
centrifugal inflorescence (Bentham& Hooker, 1865). Similarconcepts have been
utilisedby Kostermans (1981)and Hyland (1983). In addition, Merrill(1950a, b),
356 BLUMEA Vol. 44, No. 2, 1999
though not Perry (pers. comm. inSchmid, 1972), also accepted thefurthersegregate
Jossinia:agenusorsubgenus distinguished fromEugenia largelyby itsbroadstamini-
ferousdisc (Bentham& Hooker, 1865)as wellas manyseededfruitsandlongradicle
according to DeCandolle(1828). Ho (1992) accepted aspects ofMerrill& Perry's
conceptandrecognised Acmena,Cleistocalyx, Syzygium, andEugenia. Noneofthese
segregates were supported by Schmid(1972) whowas unableto distinguish any of
them.
Previous analyses ofthe Eugenia/Syzygium controversy have relied on alpha-
taxonomic methods- littlephenetic or phylogenetic analysis has been undertaken.
Thispaperuses regional datafullyrepresentative oftheSyzygium complex inaphenetic
and phylogenetic analysis, with particular emphasis placed on theuse ofbiometric
characteristicsandthe question ofhomogeneity ofSyzygium.
MATERIALS AND METHODS
Datawere in part drawnfromChantaranothai(1989): furtherdatawere collectedby
re-examinationofherbariummaterialcitedinthisworkandof newmaterial(Simpson
etal., 1995,provides furtherdetailsofthesecollections). Thedatausedinthispaper
arebasedonexaminationofallthe availablematerial(c. 4,000specimens) ofthese
taxa from A, AAU, ABD, BK, BKF, BM, C, E, K, L, MEL, OXF, P, PDA, PSU,
SING, TCD,Uandonthebasisoffield-collections.Thereare89species intheAcmena
andEugenia alliancespresentinThailand(Chantaranothai &Parnell, 1994a). Chan-
taranothai& Parnell (1994a), Parnell(1995), Parnell & Nic Lughadha (1992) and
Parnell& Chantaranothai(1996)provide detailsofallofthetaxa ofSyzygium s.l.in
Thailandandfurtherdetailsofthecharacters recordedforthesespecies. A very few
(5) species ofSyzygium s.l., includedin Chantaranothai& Parnell(1994a), are not
dealtwithbecausetheavailablematerialwas inadequate toallowthem tobe scored.
Normally,forphylogenetic analysis suchaprocedure wouldbeunacceptable, itbeing
bettertohave representation ofall taxa thanall characters. However,as previously
stated, thisanalysis uses arepresentative selectionofspecies in thegenusSyzygium
whichrepresentation is not diminishedby theaboveprocedure. Alist ofthetaxa in-
cludedin thispaperis given inAppendix Table 1.
Chantaranothai& Parnell(1994a) assigned these84 species togeneraas follows:
81 species toSyzygium s.s., 1 species toAcmena (autapomorphy, anthers divaricate),
4toCleistocalyx (autapomorphy, calyx calyptrate) and3to Eugenia (autapomorphy,
inflorescenceand/orvegetative parts hairy).
Ofthesegeneraonlyone, themostdistinctive,,-Acmena,wasdefinedas anoutgroup
forphylogenetic analysis, though representatives of,Eugenia and Cleistocalyx were
addedas possible outgroups too.
ANALYSES UNDERTAKEN
Anumberofdifferenttypesofanalysis wereundertaken.For morphometricphenetic
analysis two fundamentally differenttechniques were used. Firstly the datawere
ordinated.
J.Parnell: Numerical analysis ofThai Eugenia-Syzygium 357
PrincipalComponents Analysis (PCA)isdesignedforcontinuously varying orquantita-
tive dataormultistatedataexpressed onascaleofreasonablelength. Withmostbiolo-
gical datasetsPCA willextractas manysummaryaxes as thereareoriginal variables
in the data.However, only the first few axes represent effective summariesofthe
data.OnthebasisofParnell&Needham(1998)only thosecomponentswhichsatisfied
Frontier's (1976)criterionas well as the firstcomponentwhichhis scheme signals
maybetrivialbutwhichstillmeets theheuristicKaiser-Guttmanncriterionwereused.
TheprogrammeusedwasDatadesk5.0.1(cf.DataDescription Inc.,Ithaca,NewYork).
DiscriminantAnalysis (DSC),was usedtotestwhetherpre-defined groupsofspecies
visualised on PCA were or were not statistically distinguishable. This multivariate
extension ofanalysis ofvariance (Marriott, 1974) was performed in both stepwise
and non-stepwise ways. Stepwise analysis was performed using all defaultoptions
[minimisation ofWilks lambda, auto F-to-enterand F-to-remove in SPSS 6.1 (cf.
Norusis & SPSS Inc., 1993)].
Thefollowingcharacterswere measuredformorphometryphenetic analysis (Table
4). In virtually allcases thecharacterswere measuredon frombetweenoneandfour
leavesandflowersfromeachoffourseparatespecimens ofthetaxon (alistofmostof
the specimens measuredis given inChantaranothai, 1989).The valuesobtainedper
specimen were firstaveraged andthenthe averagevaluesper taxonwerecalculated:
theselattervalueswerethenusedinPCAandDSC.Allleafmeasurements weremade
on driedmaterialand allflowermeasurements on flowers whichhadbeen soakedin
water overnightorboiledfor10-15minutes.Itprovedimpossible toobtainacomplete
datamatrixwhich covered all Thai Syzygium species andbecause I do not like to
interpolate dataI decidedtoeliminatethe taxa for whichIhadincomplete datafrom
the analysis. Theproblems raisedby this procedure for phylogenetic analysis have
beendiscussedearlier.Theremaining taxa are listedinAppendix Table1.
AppendixTable 1.
Taxaincluded inthis analysis.A.acumenatissima,C.khaoaienensis,C.nigrans,C.operculatus,
C. operculatus subsp.paniala, C.phengklaii, E. bracteata, E. xanthocarpa, S. abortivum,
S.aksornii, S. albiflorum,S.anacardiifolium,S. angkai,S.angkaesubsp.spissum, S.aqueum,
S.aromaticum,S. attenuatum, S.attenuatumsubsp.montanum,S.attenuatumsubsp.circumcis-
sum,S.balsameum,S.boiseanum subsp.longifolium,S.borneense subsp.myrtillus, S.borneense
subsp.myrtillus, S. cacuminis,S.cacuminissubsp.inthanonense,S.cerasiforme,S. chavaran,
S.cinereum,S.claviflorum, S. craibii,S. cuminii,S. diospyrifolium,S. duthieanum,S. dyerianum,
S.fastigiatum, S. filiforme, S. formosum, S. foxworthianum,S. fruticosum, S. fuscescens,
S. glaucum, S. globiflorum, S. grande, S. grandesubsp.parviflorum, S. gratum, S. gratum
subsp.confertum,S. helferi,S.hemsleyanum,S.hemsleyanumsubsp.paucinervum,S.hulletia-
num, S. ixoroides,S.jambos, S.jasminifolium, S. kerrii,S.kurzii, S.laetumsubsp.jugorum,
S. laetum subsp. sublaetum, S. lakshanakarae, S. leptostemon, S. lineatum, S. maingayi,
S. malaccense, S. megacarpum, S. mekongense, S. muelleri,S. nitrasarirakii,S. oblatum,
S.oblatumsubsp.laevicaule,S. pachyphyllum, S.pachysarcum, S.papillosum,S. pergmanta-
ceum,S.polyanthum, S.praecox, S.praineanumsubsp. minor,S.pseudoformosum,S.puttii,
S.pycnanthum,S.pyrifolium, S. refertum,S. ridleyi, S. rigens,S. ripicola, S. samarangense,
S.samarangense subsp.parviflorum, S. scortechinii,S.siamense, S.skiophilum, S. subrufum,
S. subrufum subsp. smalianum, S. syzygiodes, S. tetragonum,S. thumra, S. thumra subsp.
punctifolium, S. toddalioides,S. urophyllum, S. winitii,S. zeylanicum, S. zimmermannii.
358 BLUMEA Vol. 44, No. 2, 1999
Table4.Morphologicalcharactersmeasured forphenetic,morphometricanalysis.
Character
number Character Comments
1 Petiole length The lengthofthe petiole fromthe base of
thepetioletothe baseofthe lamina
2 Lamina width Measured atright-angles totheaxis at the
pointofmaximum width
3 Lamina length The lengthasmeasured alongthe midrib
4 Basal angle The angleformedatthebaseoftheleaves
5 Apicalangle The angleformedattheapexoftheleaves
6 Midrib width Measured atthepointmidwaybetween the
apex and base oftheleaf
7 Number ofsecondary veins Counted upwards fromthe secondpairof
veins atthe base ofthe lamina
8 Distancebetween the secondary Measured atthepointmidwaybetween the
veins midribandthemarginina lineparallelto
the midrib
9 Number ofintramarginalveins Counted atthebase ofthe lamina
10 Distance between the intramar- Measured atrightanglestothe marginata
ginalveins and the margin point midway between the leafbaseand
leaf apex. Ifthe leaf had 2 or 3 intra-
marginalveinsthenthe innermost distance
wasmeasured. Ifthe species hadnointra-
marginal veins thenthe distancebetween
the secondary veins and the margin was
measured instead
11 Calyx-tube length Measured fromthe base ofthe calyx-lobes
tothebase ofthecalyx-tube
12 Number ofcalyx-lobes
13 Lengthofcalyx-lobes Measuredalongthe mid-axis ofthecalyx-
lobe
14 Number ofpetals
15 Petal length Measuredalongthelongaxisofthepetalat
its longestpoint
16 Outer stamenlength Measured from the junction of the calyx-
tube tothe tipofthe anther
17 Number of glands ontheback
ofthe anther
18 Style length Measured fromitsjunctionwith the calyx-
tube tothetipofthe stigma
19 Numberoflocules
20 Number ofovulesper locule
21 Numberofgland-dotsperpetal
Initialanalysis showedthatcharacters 17and 19(Table 4)wereinsufficiently variable
toallowforinclusioninaPCA orDCA;they were thereforenot directlyincludedin
theseanalyses. Initialanalysisalso showedthatcharacters4, 8,10, 13, 15, 16,18,20
and21 were not normally distributedon anindividualbasis. (These variables were
eithermarkedly skewed, hadabnormalkurtosis or didnot fallalong astraight lineon
a normalprobability plot.) Transformationofthe above characters was undertaken
J.Parnell: Numerical analysis ofThai Eugenia-Syzygium 359
following Manly (1986) andMarriott(1974). Bytrialanderror themostappropriate
transformationforallthesecharacters,exceptforcharacter8,was foundtobeLogt0:
character 8required areciprocal squareroot transformation.Thesetransformations
contractedtherangeofthetransformedvariables,bunching themclosertogetherthan
intheiruntransformedstate.(Initialanalysis showedthatPCAandDSC analyses run
on an untransformeddatasetproduced analmost identical pattern ofresults as that
run withthe abovetransformationsincluded, though thegapbetweenGroup 1 and2
appeared muchlarger).
PCA(andDSC) require datawhichareapproximately multivariatenormalandare
thereforeinappropriate forcategorical data(Manly, 1986).Suitableordinationmethods
are detailedin Causton (1988) and their advantages and disadvantages outlinedin
Kent & Coker(1992) who indicatethatDetrendedCorrespondence Analysis (DCA)
is probably themost widely usedtechnique. Its derivation,application andpossible
flawsarefurtherdetailedinTerBraak(1988),Hill(1973,1979),Hill& Smith(1976),
Minchin(1987), Oksanen & Minchin(1997) andParnell& Waldren (1996). Parnell
& Waldren(1996) show that DCA has wide application to taxonomicbistate data
providingsimple, clearplots ofeasyinterpretabilitywherebothobjectsandcharacters
are plotted to the same scale andare overlayable. FurthermoreDCA can be used
where the groupunderconsideration does not form a complete phylogenetic unit.
DCA wasperformedusing theDCAoption ofCANOCO(TerBraak, 1988).Although
DCA canutilisemixeddatasets, wheresomedataare recordedononescaleandother
dataarerecordedon another, itis clearthatthispractice results in ordinationswhich
are very difficultto interpret. Itis muchpreferable toutilise datamatriceswherethe
dataareallscored tothesamescale.AlsoDCA isderivedfromCA: thelattertechnique
preserves theX2 distancesbetweenobjects, andhence ignores comparisons between
valueswithdouble0ranks (Legendre &Legendre, 1983).Soif0was offrequent oc-
currenceplots couldresultwiththeintertaxonor intercharacterdifferencesincorrectly
scaled, i.e. characters should not beara 0 code ifit is avoidable.Characterswere
codedas possessing oneoftwoalternativestates(1) or(39), thelattercorresponding
totherangeofthenumberofcharactersinput (Parnell &Waldren, 1996).Table5 lists
thecharactersandtheircoding forthisanalysis.Thesametaxa were surveyed forthis
analysis as forPCA (Appendix Table 1). Very few morphometric characters were
used in DCA. Those thatwere includedwere decomposed into naturally occurring
groups: forexample itwasclearfromexaminationofhistograms oftheraw datathat
a naturally occurring break interms ofstamen length is that betweenthose flowers
withouter stamens less than 15mm andthose withouter stamens 15 mmor morein
length: this break thenallowedthesetwo states tobe coded forDCA.
Itis obviously impossible toexpress characters wheremorethan asingle natural
break occurs in asingle pair ofdichotomousvalues.There is no perfect solutionto
this problem, though there are three potential approaches. Firstly, to introducesub-
divisions withinthe codedrange foreach character(i.e., for afour statecharacter,
codes wouldbe 1, 11, 22 and 34). Unfortunately, this procedure is inadvisableas
implementations ofDCAappearnot tobeabsolutely scale independent. Secondly, to
treateachpotentially multistatecharacteras anumberofindependent dichotomous
characters-thereforeafourstatecharacteris codedasfourseparatebistatecharacters.
360 BLUMEA Vol. 44, No. 2, 1999
Table5.Charactersrecorded forweightedDetrendedCorrespondenceAnalysis(DCA).Charac-
ters were scored as oneoftwo states, and coded as(1) or (39) and are given in that order
below;the slash (/)is used todivide the differentcharacter states.
Character
number Character states
1 Trees /Shrubs
2 Plant without hairs/planthairy
3 Midvein impressedorsunken/midveinnotimpressedorsunken
4 Midvein notraised with achannel inthemiddle ofthe vein/midvein raisedwith achannel
inthemiddleofthevein
5 Midrib notkeeled /midribkeeled
6 Intramarginalveins 0/intramarginalveins not0
7 Intramarginalveins 1/intramarginalveins not 1
8 Intramarginalveins 2/intramarginalveinsnot 2
9 Intramarginalveins 3/intramarginalveinsnot 3
10 Midvein less than 1mmwide/midveinmorethan 1mm wide
11 Number ofsecondaryveins5-10/numberofsecondaryveinsnot5-10
12 Number ofsecondaryveins 11-15/numberofsecondaryveins not 11-15
13 Number ofsecondaryveins 16-20 /number ofsecondaryveinsnot 16-20
14 Number ofsecondaryveins21-25 /number ofsecondaryveins not21-25
15 Number ofsecondaryveins26-30/numberofsecondaryveinsnot 26-30
16 Calyx-tubenarrowlyfunnel-shapedandcontracted intoadistinctpseudostipe/ calyx-tube
notnarrowlyfunnel-shapedand contractedintoadistinctpseudostipe
17 Calyx-tubebroadlyfunnel-shapedandnarrowedintoapseudostipe/calyx-tubenotbroadly
funnel-shapedand narrowed into apseudostipe
18 Calyx-tubeclavateornarrowlyfunnel-shapedandnarrowed intoalongpseudostipe/calyx-
tubenotclavateornarrowlyfunnel-shapedand narrowed into alongpseudostipe
19 Calyx-tube cylindrical/calyx-tubenot cylindrical
20 Calyx-tubebroadlyfunnel-shapedandmorethan10mmlong/calyx-tubenotbroadlyfunnel-
shapedand morethan10mmlong
21 Calyx-tubefunnel-shapedand less than 10mm long/ calyx-tubenotfunnel-shapedand
lessthan 10mm long
22 Calyx-tubefunnel-shapedwithoutadefinitepseudostipeorwith apseudostipeless than
1mmlong/calyx-tubenotfunnel-shapedwithoutadefinitepseudostipeorwith apseudo-
stipelessthan 1mm long
23 Pseudostipeabsent/pseudostipepresent
24 Number ofgland-dotsonapetal0-50 /numberofgland-dotsonapetalnot0-50
25 Number ofgland-dotsonapetal51-100/number ofgland-dotsonapetalnot 51-100
26 Number ofgland-dotsonapetal 101-150/number ofgland-dotsonapetalnot 101-150
27 Number ofgland-dotsonapetal 151-200 /number ofgland-dotsonapetalnot 151-200
28 Numberofgland-dotsonapetal>200/number ofgland-dotsonapetalnot> 200
29 Number ofcalyx-lobes0 or4/number ofcalyx-lobes5ormore
30 Numberofpetal-lobes4/number ofpetal-lobes5ormore
31 Petalcolournotpolymorphic(always yellow)/petal colour polymorphismpresent (not
alwaysyellow)
32 Stamenlength0-14.9 mm /stamenlength15mmormore
33 Stylelengthapproximatelyequaltoouterstamenlength/style lengthlessthan outerstamen
length
34 Bracts absent ornarrow,oblongorspathulateorlinear orsheathing/bracts triangularor
OV3tC
35 Twolocules perovary/sometimesmorethantwolocules per ovary
36 Numberofovulesper locule 5-10/numberofovulesperlocule not5-10
37 Numberofovules perlocule 11—15/number ofovules perloculenot 11-15
38 Numberofovulesper locule 16-20/numberofovulesper locule not16-20
39 Numberofovulesperlocule > 20/number ofovulesper loculenot>20