A taxonomic and phylogenetic analysis of Rhysotoechia (Sapindaceae)

31 Pages·1994·3.8 MB·English

by  Etman, B

BLUMEA 39 (1994) 41-71
A taxonomic and phylogeneticanalysis of
Rhysotoechia (Sapindaceae)
B.Etman
Rijksherbarium/HortusBotanicus,POBox9514,2300 RALeiden,TheNetherlands
Summary
This study comprises ataxonomic revision ofRhysotoechia (Sapindaceae)preceded by aphylo-
geneticanalysis. Fifteenspecies arerecognisedand three imperfectlyknown speciesare discussed.
Fivenewspecies fromNewGuineaaredescribed. Two speciesfromthePhilippines,Borneo and one
species fromAustraliaarereduced.Thereare noexcluded species. Akey, basedonboth flower and
fruit characteristics,givesaccess tothe species.Thestudy wasrestrictedtothemacromorphological
characters,leadingtoadata matrixwith 25characters. Thecladistic analysis was run withthe com-
puterprogramHENNIG86.Eventuallyonecladogramhasbeenaccepted.
Introduction
Radlkofer(1879) describedthe genusRhysotoechia, choosing thisnamebecauseof
thewrinklingofthe fruitswhen open and dry (rhysos, Gr. =wrinkled, shrivelled).
Inthis new genusheplacedtwo species, R. mortonianaandR.robertsonii, original-
ly described in Cupania (Mueller, 1866). He also describedfive new species, of
whichtwo were includedearlierin Cupania robertsonii(Mueller, 1875): R.flaves-
censandR. bifoliolata.
SixteenyearslaterRadlkofer(1895) describedthe newspecies Rhysotoechia gra-
cilipes. Twelveyears afterthathe describedthenew species R. koordersii(1907).
The latterhadbeenidentifiedearlieras R. mortonianaby Koorders(1898). Maiden
& Betche(1908) describedthenewspecies Cupania dunnii, whichturned outtobea
synonym ofR. bifoliolata.
Merrill(1921) referredto thespecies R. grandifolia,but hemisspelled thename
as R. grandiflora.
Domin(1927) describedthenewspecies R. contermina.
Between 1913and 1933Radlkoferdescribedseveralmorenew species. In 1933
acomplete revisionofRhysotoechia appeared in hisposthumous monograph ofthe
family Sapindaceae.
AfterRadlkofer's death(in 1927) a fewmore species and onesubspecies were
described, viz. R. longipaniculata andR. momiensisby Kanehira& Hatusima(1943),
R.florulenta andR. bifoliolata subsp. nitidaby Reynolds (1991). Reynolds had al-
readypublished arevisionoftheAustralianspecies ofRhysotoechia (1984).
42 BLUMEA Vol. 39, No. 1/2, 1994
As a firstresult ofthepresentstudy fivenewspecies fromNew Guinea are de-
scribed: R. applanata, R. bilocularis, R. congesta, R. multiscapa andR. obtusa.
BothR. acuminataandR. striata arereducedto R. ramiflora; R. conterminaisre-
duced toR. robertsonii. Herbariummaterialwas seen ofall species treated in this
revision,except fortheimperfectly known species nos. 17and 18.
MATERIALS AND METHODS
Thisrevision ofRhysotoechia is basedonherbariumspecimens only. Thematerialis
kept in theRijksherbarium atLeiden(L), unlessstatedotherwise.
Thecriterionusedto distinguish species is thepresenceofatleasttwo characters
inwhichtwo species differ fromeachother. In thisway species arecharacterizedby
amonotheticsetofcharacters.
MORPHOLOGY
Habit
Small tomedium-sizedshrubsor trees. Highest tree: 25 m. The diameterofthe
flowering twigsis measuredjustbelowthelowestinflorescence.
Indumentum
Thevegetativeparts ofRhysotoechia havelittleindumentum.Only inonespecies,
R. robertsonii, simple, solitary, appressed hairsare foundontheleaves.Laxly scat-
teredhairs can beobservedon rachis, petiole, petiolule, pulvinus andboth sidesof
theleaflets.
Young parts are usually densely puberulous in allspecies. Simple appressed hairs
are foundonthescapes, more denselytowards thetopsoftheinflorescences.
Leaves
Theleavesare always paripinnate, withonetofive pairs ofleaflets.Thepetiole is
absentinonly one species, R. congesta,in which thefirst pairofleafletsgrows at
thebaseof therachis.Intheotherspecies thepetiole hasabasalpulvinus. Thepetiole
orrachis may beinconspicuously winged. This is best seennearthe apicalpair of
leaflets, wheretherachis is thethinnest.Thepetiole orrachis is sometimesangular,
i.e., showing a slenderraisedline.
Leaflets
Theleafletsare glossy aboveand dullbelow (the leafletsofR. bifoliolata subsp.
nitida andR.florulenta are vernicoseon theuppersurface), opposite to alternate.
They showawiderange inform,size andthickness. Thebasecanbesymmetric or
slightly oblique, acute or attenuate,seldomrounded. The margin is always entire,
and canberecurvedtoflattened.Theapexshows awiderangefromslightly emargi-
nate to caudateand canbeabruptlynarrowedor not. Onthelowersurfaceoftheleaf-
lets all cells are slightly globular and undera microscope they are visibleas bright
B.Etman: Revision ofRhysotoechia 43
Fig. 1.Venation ofleaflets:(a)looped;(b) opentowards thebase, loopedtowardstheapex;(c)open.
spots. Thisis regarded anapomorphic characterstate forRhysotoechia compared to
Cupaniopsis, thesister group.Thevenation is usuallyslightly raisedaboveandrais-
ed below.Three typesofnervationareobserved:open, loopedandopentowardsthe
base, andlooped towardsthe apex (Fig. 1).The distancebetween thenerves is al-
ways measuredinthemiddleoftheleaflet.Veinsvary fromdensely tolaxly reticu-
late.The lengthoftheleafletincludesthepetiolule andthepulvinus.
Inflorescences
The inflorescencessometimesbranch atthebasewhen two to manyscapes are
fascicled or they are solitary andbranch higher on the scape.Panicles, racemes and
thyrses havebeenfound,andalso thyrses withcymules consisting ofoneflower(in
R. multiscapainsomecases two flowers) instead ofmanyflowers.
Bracts and bracteoles
Thebracteoles, atthebaseofthepedicel, sometimesare somewhatsmallerthan
thebracts, although this differenceis0.5mmatmost.The bracts and bracteolesare
triangular withthemargins strongly incurved, i.e. cymbiform. The abaxialside is
always strigose, especially towardsthemargins. Theadaxialsideis glabrous.
Flowers
All flowersareregularwith azygomorphic calyx. Theplants aremonoeciouswith
flowersunisexual(stamens well developed andstigma not or viceversa) or mayap-
pear hermaphrodite though actually functionally maleor female.The pedicels are
glabrous.
44 BLUMEA Vol. 39, No. 1/2, 1994
Fig. 2.Petal scales:(a)absent;(b)foldedmargins ofpetals; (c) free.
— Sepals: five, dimorphic withtheoutertwo distinctlysmaller thantheinnerthree.
Themargin is(laxly)ciliatetoalmost glabrous.Oftenthey are persistentinthefruit.
— Petals: five, smallerthanthesepals, consisting ofabladeanda claw.Inanumber
ofspecies apairofscalesjustabovetheclawagainsttheblademaysometimesbe
present. Insome they occur as foldedmargins ofthepetal, in othersthey arefree
andwell developed, or they may beabsent(Fig. 2).Inonespecies, R.florulenta,
thescalesare furnishedwithdistinctcrest-likeappendages. Thebladecanhavevar-
iousforms, fromelliptic tobroadly ovate orbroadly obovate.Allthreeparts (blade,
clawand, ifpresent, scales) havein everyspecies theirowntypical indumentum,
whichconsists ofsimpleor pluricellular hairs,pilose, velutinous, orwoolly.
—Disc: complete, slightly lobed, glabrous (except for thehairy discof R. bifolio-
lata).
— Stamens:eight, withthefilamentmoreor lessvelutinousfromthemiddletowards
thebase.Theantherisbasifixed [although Endress & Stumpf (1991) describeit
as dorsifixed]andlatrorsely opening. In somespecies afew simple, solitaryhairs
canbeobservedontheanther.
—Pistil:theovary isovoid andin mostspecies 3-lobed,3-locular, andmostly den-
sely coveredwithlong appressed hairs.Thestyle is glabrous, elongating in fruit.
InR. flavescens andR. bilocularis the ovary is 2-lobed, 2-locular. Thereis al-
ways oneovuleperlocule.
Fruit
Thefruitis always acapsule, obcordatetoreniformand2- or3-lobed, butnotall
lobes always develop. The driedfruits areoftenrugoseto ribbed. They are some-
timeslaxly pubescent, butpresumably glabrescent. Inside, thefruitwallis setwith
papillae, except in onespecies, R.flavescens. Rhysotoechia elongata has fruitswith
sutures densely setose inside. The length ofthe stipe ofthe fruitsvariesconspicu-
ously. Thelength ofthefruits includesthe stipe(Fig. 3).
Seed
The seedsareobovoid or ellipsoid, usually black, smoothand shiny whendry.
Atthebase theyare coveredbyacup-shaped arillode,exceptforR. applanata, where
asarcotesta isfound.Thepseudohilum andhilumareorbicularandthediameterwas
measured.Thelength oftheseed doesnot includethe arillodewhenthe latterisex-
panded downwards.
B. Etman: Revision ofRhysotoechia 45
Fig. 3.Measurements ofthe fruitsweretakenas shown bythe arrows: 1 =widthoffruit;2=length
offruit;3=widthoflobe;4=lengthoflobe.
PHYLOGENETIC ANALYSIS
Rhysotoechia: a monophyletic group?
MullerandLeenhouts(1976: 424) placed Rhysotoechia among themostprimi-
tive generain Sapindaceae-Cupanieae, closely relatedto Cupaniopsis. BothRhyso-
toechiaandCupaniopsis arethought tobe derivedfrom Cupania. Itseemedtothese
authors thatDictyoneura is derivedfromRhysotoechia, withatendency towardsre-
ductionofthe flowerparts, especially ofthepetals. Ifthisis trueandthe derivation
is from anancestralspecies withinRhysotoechia, then the genuswillbeparaphyletic;
however,when Dictyoneura shares anancestralspecies withRhysotoechia, thelatter
maybe monophyletic.
Thereare severalindicationsthatRhysotoechia is amonophyletic group.Thegenus
is very homogeneous inthefollowing characterstates.
1) leaves glabrous orsubglabrous; uppersurface glossy, lowersurface dull(also in
driedleaves), cells domed;
2) domatiaabsent;
3) bracts andbracteolestriangular, adaxially glabrous, abaxially strigose;
4) flowerswith unequal sepals;sepals glabrous except forthemargins, innerthree
withpetaloid margin;
5) crestabsentonpetal scales (except forR.florulenta);
6) disc complete, slightly lobed;
7) stamens 8; filamentvelutinousfromthemiddletowardsthe base;anthers basi-
fixed, latrorsely opening;
8) fruit a capsule, outsidewrinkled, insidepapillose (except for R.flavescens);
9) seedsblack, shiny, glabrous;
10) arillodeyellow, cup-shaped;
11) cotyledons secondarily besideeachother.
46 BLUMEA Vol. 39, No. 1/2, 1994
Table 1. Charactersand data matrix ofthe analysis.
1. Maximum thicknessoffloweringtwig 12. Lateralnerves
1. 5mm 1. atmost2.5cmapartalong themidrib
2. 10mm 2. atmost 5cm apartalongthemidrib
3. 15 mm 13. Nervation
1. looped
2. Number ofjugae
1. 1-3 2. open towardsthebase, loopedtowards
2. 1-5 theapex
3. open
3. Rachis lengthofleaf 14. Veins
1. < 20 cm 1. verylaxly reticulate
2. > 20 cm 2. reticulate
4. Maximum lengthofleaflet 3. very denselyreticulate
1. 10cm 15. Minimum lengthofpetiolule
2. 20cm 1. < 3 mm
3. 35cm 2. > 3 mm
16. Maximumlength ofpetiolule
5. Maximum width ofleaflet 1. 1 cm
1. 5cm 2. 2 cm
2. 10cm
17. Inflorescence
3. 15cm
1. atleast sometimesramiflorous
6. Index ofleaflet 2. neverramiflorous
1. <3.4 18. Branching ofinflorescence
2. > 3.5 1. notatthe base
2. sometimesatthebase
7. Shapeofleaflet
3. alwaysatthebase
1. usuallyobovate
2. usuallyovate 19. Inflorescence
3. usuallyelliptic 1. paniclesor thyrses
2. thyrses withcymule of 1 flower
8. Apexofleaflet 20. Marginofinner 3sepals
1. notabruptly narrowed 1. laxlyciliate
2. abruptlynarrowed 2. ciliate
9. Marginofleaflet 21. Petal
1. outsidepilose,inside glabrous
1. recurved
2. insidepilose,outside glabrous
2. recurved orflattened
3. flattened 3. bothsidespilose
4. both sides glabrous
10. Base ofleaflet,symmetry 22. Scalesofpetal
1. slightlyto distinctly oblique 1. absentorasfoldedmarginsofpetal
2. symmetric 2. free
3. usuallyslightly oblique, 23. Anther
sometimes symmetric 1. glabrous
4. usually symmetric, 2. pilose
sometimes slightlyoblique
24. Number oflocules offruit
11. Base ofleaflet,shape 1. 3
1. attenuate 2. 2
2. acute orattenuate 25. Stipe offruit
3. rounded toobtuse 1. <3mm
4. acute 2. > 3mm
B. Etman: Revision ofRhysotoechia 47
TTaaxxoonn//CChhaarraacctteerrss 11 22 33 44 55 66 77 88 99 1100 1111 1122 1133
CCuuppaanniiooppssiissaannaaccaarrddiiooiiddeess 11 2211 22 22 11 11 11 33 44 11 11 11
RRhhyyssoottooeecchhiiaaaappppllaannaattaa 22 11 11 22 22 11 33111122424 32 3
bbiiffoolliioollaattaa 11 11 11 11 11 22 33 11 11 11 22 11 11
bbiillooccuullaarriiss 22 22 11 22 221122111 41 14 1 11 11
ccoonnggeessttaa 33 11 22 33 33 11 33 11 11 11 33 22 22
eelloonnggaattaa 22 22 22 33 11 22 22 22 11 33 22 11 11
ffllaavveesscceennss 22 22 11 33 22 22 33 22 11 33 11 11 11
fflloorruulleennttaa 11 22 11 22 22 11 33 11 22 11 11 11 22
ggrraacciilliippeess 11 2211 22 22 22 22 22 33 22 11 11 11
ggrraannddiiffoolliiaa 22 22 22 33 22 11 33 22 22 44 11 22 22
kkoooorrddeerrssiiii 22 22 22 33 33 22 11 22 22 44 22 22 22
mmoorrttoonniiaannaa 11 11 11 22 221122111 11 1 11 11 11
mmuullttiissccaappaa 22 11 11 22 11 2233112222111 21 2
oobbttuussaa 22 22 11 22 22 11 33111144111 21 2
rraammiifflloorraa 33 22 22 33 33 11 33222244121 22 2
rroobbeerrttssoonniiii 22 22 11 22 22 2233111133212 21 2
TTaaxxoonn//CChhaarraacctteerrss 1144 1155 1166 1177 1188 1199 2200 2211 2222 2233 2244 2255
CCuuppaanniiooppssiissaannaaccaarrddiiooiiddeess 11 11 11 22 11 11 224422212 11 1
RRhhyyssoottooeecchhiiaaaappppllaannaattaa 2211 11 22 33 221133121 12 11 1
bbiiffoolliioollaattaa 11 11 1122 11 11 22 11 11 11 11 11
bbiillooccuullaarriiss 33 22 22 22 33 11112211222?2 ?
ccoonnggeessttaa I1 l1 l1 11 33 11 ?? ?7 ?7 ?7 11 22
eelloonnggaattaa 33 22 22 22 11 111111121 12 11 1
ffllaavveesscceennss 33 11 22 22 11 11 11 22 11 22 22 22
fflloorruulleennttaa 33 22 22 22 1111141 24 12 1 11 ??
ggrraacciilliippeess 22 22 22 221111 ?? ?7 ?? ?7 11 11
ggrraannddiiffoolliiaa 22 2222 ?? ?? ?? ?? ?? ?? ?7 11 ??
kkoooorrddeerrssiiii 22 11 11 22 33 22 2233121 12 21 2
mmoorrttoonniiaannaa 11 11 22 22 22 1111121 12 1 11 22
mmuullttiissccaappaa 22 11 11 22 33 22 11 33 11 22 11 ??
oobbttuussaa 22 11 22 22 33 11 ?7 ?? ?? ?7 11 11
rraammiifflloorraa 22 22 22 11 22 22 22 11 11 22 11 22
rroobbeerrttssoonniiii 22 11 11 22 11 11 22 33 11 22 11 11
Although mostofthesecharacterstates also occur in closely related genera(e.g.,
Cupaniopsis, Guioa)andarethereforeplesiomorphic, afew are apomorphic, i.e., the
leavesbeing glossy aboveand dullbelow,cellsdomed,andthefruitsbeing papillose
inside.
48 BLUMEA Vol. 39, No. 1/2, 1994
Phylogenetic analysis
The phylogenetic analysis was carriedout with HENNIG86. To select themost
parsimonious tree(s) the 'branch-and-bound'option was chosen.
Following Muller&Leenhouts(1976), Cupaniopsis was selected astheoutgroup.
Ithasbeenrepresented intheanalysis by C. anacardioides, since thisspecies is re-
gardedto containthelargestnumberofplesiomorphies and thefewestapomorphies
(Adema, 1991).
Data matrix
A multistate-eoding is usedforthecharacterstates inthedatamatrix.Missing data
areindicatedwitha question mark. HENNIG86 was run using theunorderedoption
forallcharacters.
Cladistic analysis
WiththedatamatrixofTable1,fourequally parsimonious cladograms wereob-
tainedbyusing theoptions 'mhennig', followedby 'bb*'inHENNIG86.
Thisresultedin fourtrees(length 89,CI0.43, RI0.53),but afteriterativecharac-
terweighting only oneoftheseremainedwithlength 159,CI0.51andRI0.67.This
cladogram hasbeen accepted here(Fig. 4).
Discussion of the results
Thenumberofhomoplasies is very high intheaccepted cladogram; however,the
subtreesarebasedonreliablecharacteristicsandcan befairlywellrecognised. Most
ofthehomoplasies werecausedby parallelisms.
Withinthetree, threemaingroupscanbe distinguished. Thefirst groupconsists
of three Australian species, R. bifoliolata, R. mortoniana and R.florulenta. This
groupis supported byoneapomorphy andthreeparallelisms, anthersglabrous (231),
petals outside pilose, inside glabrous (211), numberofjugae 1-3 (2i),and baseof
leaflets slightly to distinctly oblique (10i). The second groupis a geographically
rathermixedgroupwithspecies fromBorneo,Philippines, Sulawesi,Moluccasand
NewGuinea. Here, thereis supportfrom six characters, two apomorphies andfour
parallelisms, maximumwidthofleaflet 15 cm(53), inflorescences atleastsometimes
ramiflorous(170, stipe> 3mm (252), rachisofleaf>20 cm(32), lateralnervesal-
most 5 cm apart(122), leaflet<35cm (43).The thirdandlast groupmainly occurs
in New Guinea. Italso includes onespecies from Australia. They are definedby a
homoplasy thatoccurs also in R. mortonianaandR. florulenta, i.e., hairiness of
margin ofinner threesepals laxly ciliate(20i). Itis obvious thatthis groupis only
weakly supported. Two nodes lower, there is support from fivecharacters, two
apomorphies, twoparallelisms andonereversal: veinsvery densely reticulate(143),
petals insidepilose, outsideglabrous (212),leafletusually ovate(12), minimallength
ofpetiolule >3 mm(152), nervationlooped (13i). Allthenodesthatfollowarebased
on reversals andparallelisms.
One species, R. robertsonii, is not connectedwithany ofthese groups.It splits
offtogether withgroupstwo andthreeandformsthe intermediatebetweenthe'prim-
itive' Australianspecies andthe'newer' species ine.g. New Guinea,something that
was alreadyexpected intuitively.
B. Etman: Revision ofRhysotoechia
49
Cupaniopsis
anacardioides
Rhysotoechia
bifoliolata
mortoniana
florulenta
robertsonii
grandifolia
ramiflora
koordersii
congesta
multiscapa
applanata
obtusa
bilocularis
gracilipes
elongata
flavescens
Fig. 4.CladogramofRhysotoechia.
The accepted cladogram is the best hypothesis about the phylogenetic relations
among thespecies, withthe datamatrixathand. However, thisshouldbe testedby
studying moreandbettermaterial, andothercharactercomplexes.
Note on distributionpatterns
For a detailedbiogeographical analysis itwouldbe best tosplit upNewGuinea
and Australiainto smaller areas. However, the problem is thatmostof the species
50 BLUMEA Vol. 39, No. 1/2, 1994
from NewGuinea are based on two or even one collectiononly. The uncertainty
whether thesespecies really arerestrictedto smallareas, orthatthey areoverlooked
in otherareasmakes thebiogeographical analysis very unreliable.
Bylooking carefully atthecladogram, someremarks can still bemadeaboutthe
distributionpatterns.
Theancestralspecies ofRhysotoechia occurred inAustralia, andpossibly inNew
Guineatoo. A vicarianceevent,maybe preceded by dispersion, ledto separation of
the populations in Australia (group 1) and New Guinea(groups 2 and 3).Rhyso-
toechiarobertsonii, as intermediatebetweenthetwo clades,stilloccurs inbothareas.
VanWelzen(1989) foundthatGuioaspecies occupy threedifferentgeographical
areas in eastern Australia, dividedby vicarianceboundaries.Thespecies ofgroup 1
occupy thesame areas, possibly as aresult ofthe same historicalbiogeographical
mechanisms: Cape York Peninsula (.R. bifoliolata subsp. nitida),AthertonPlateau
(R. florulenta andR. mortoniana), SE Queensland and NE New SouthWales(R.
bifoliolata subsp. bifoliolata andR. mortoniana). InNew Guinea,probably as are-
sultofdispersion, manyspecies originated, all occupying smallareas.
Subsequently, dispersion occurred to Sulawesi, Borneo, thePhilippines and the
Moluccas, followedbyspeciation. Finally, travelling intheopposite directionfrom
its ancestors, the ancestorofR.flavescens andR. elongata dispersed back to Aus-
tralia, giving rise tothepresentspecies.
INFRAGENERIC CLASSIFICATION
Theinfrageneric classification of Radlkofer(1933) isrejected, mainly because pres-
entlymoreherbariummaterialisavailable.Forexample his character'laxly/densely
flowering' is very questionable, sinceit depends onthe qualityofthematerial.
In my opinion, infrageneric classification is only useful in generalarger than
Rhysotoechia or inthosecases where itmakestherecognition ofspecies orgroups
ofspecies easier.
Although fourdistinctgroupsoccur inthe cladogram givenhere,I donot presenta
subgeneric classification.Theapomorphies andhomoplasies thatdefinethesegroups
do not make therecognition ofspecies or groupsofspecies easier. Mostofthese
characters are useful forphylogenetic analysis, but are not distinctiveenough for
taxonomicdelimitation.
REFERENCES
Adema,F. 1991. CupaniopsisRadlk. (Sapindaceae):amonograph.Leiden Bot. Series 15: 1-190.
Domin,K. 1927.BeitragezurFloraund PflanzengeographieAustraliens. Bibl.Bot. 89,IV:287-382
Endress,P.K.,& S.Stumpf. 1991.The diversityofstamenstructures in 'Lower'Rosidae (Rosales,
Fabales,Proteales,Sapindales).Bot. J.Linn. Soc. 107:217-293.
Kanehira,R., & S. Hatusima. 1943. 1940collection ofNewGuineaplants. Bot.Mag. Tokyo57:
79-82.
Koorders,S.H. 1898.Verslageenerbotanische dienstreisdoor deMinahasa,tevenseerste overzicht
derfloravanN-O.Celebes. Meded. 's-Lands Plantentuin 19:407.
Maiden, J.M.,& E.Betche. 1908.Notes from the botanic gardens. Proc.Linn. Soc. New South
Wales 33: 305.