Table Of ContentSelbyana 26(1,2): 347-353. 2005.
SPECIES DELIMITATION IN VANDA SECT. CRISTATAE LINDL.
(ORCHIDACEAE): A MORPHOMETRIC ApPROACH
LAUREN M. GARDlNER*
University of East Anglia, Norwich, Norfolk NR4 7TJ, UK. Royal Botanic Gardens, Kew,
Richmond, Surrey TW9 3DS, UK. Email: [email protected]
JULIE A. HAWKINS
Department of Plant Sciences, University of Reading, Reading, Berkshire RG6 6AS, UK.
DAVID L. ROBERTS
Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3DS, UK.
ABSTRACT. Species are arguably artificial units used for a variet~ o~ purpose~, ~~cluding class.ification,
identification, and conservation, and authors have used different cntena for deluIlltmg new specIes. With
more than 25,000 species already named and described in the Orchidaceae (often based on single or very
few characters) and limited time and funding for conservation, priorities must be set to target resources.
Ideally, observable morphological differences should distinguish genetically meaningful species. A mor
phometric study of five species in Yanda section Cristatae (syn. Trudelia Garay) suggests three morpho
metrically distinct species groups.
Key words: Orchidaceae Yanda, Trudelia, species delimitation, morphometrics
INTRODUCTION V. griffithii, as separate species, a single species,
or a 'complex'. A comparison between morpho
The species limits of the small group of or metric information on vegetative and floral char
chids in John Lindley's Yanda section Cristatae acters in the group was made.
(Lindley 1833), found in the Himalayas and
Southeast Asia, are unclear. The species making
Species Concepts
up Yanda section Cristatae commonly are rec
ognized as Yanda alpina Lindl. (Lindley 1853),
With limited time and funding for conserva
V. chlorosantha (Garay) Christenson (Christen
tion and more than 25,000 orchid species de
son 1992), V. cristata Lindl. (Lindley 1833), V.
scribed, priorities are necessary to target re
griffithii Lindl. (Lindley & Paxton 1851), and V.
sources. The conservation of the widest possible
pumila Hook.f. (Hooker 1890). Yanda griffith ii,
diversity of taxa deserves to be the main target,
however, sometimes is considered a synonym of
but taxonomists must be able to provide quan
V. alpina (M. Motes pers. comm., Roguenant &
titative assessments of this diversity, if they are
Chiron 2001, Senghas 1988). Another member
to provide policymakers with meaningful 'units'
of the section, Vandajainii (A.S. Chauhan), was
for conservation, be they species, populations,
described by Chauhan (1984). Very little mate
or whole ecosystems. Approaches based on a
rial of this species is available, certainly not in
combination of morphological and molecular
western European herbaria. Yanda jainii, de
characters, incorporating an assessment of ge
scribed as closely allied to V. cristata, was not
netic diversity, need to be used in delimiting
mentioned by L.A. Garay (1986), despite being
new species and reassessing existing classifica
described prior to his treatment of the group. It
tions (Schuiteman & de Vogel 2003). The utility
may be that Yanda jainii is a synonym of V.
of the unit of 'species' would be increased, and
cristata. Both V. jainii and also V. chlorosantha
the selection and conservation of the largest
are believed to be extremely rare, with only a
gene pool facilitated.
few herbarium collections of either in existence.
The species concept(s) used by authors when
This study investigates the confused species
describing new species are rarely mentioned or
limits of the section, with particular attention to
discussed (Pridgeon 2003). The species concepts
the status of Yanda alpina, V. chlorosantha, and and criteria used by a taxonomist to distinguish
separate species significantly impact the number
* Corresponding author. of species recognized. Although some taxono-
347
348 SELBYANA Volume 26(1,2) 2005
mists prefer to 'split' a group into different spe within Vanda section Cristatae, we analyzed
cies on the basis of one or a few character dif both vegetative and floral characters using mul
ferences, others prefer to 'lump' on the basis of tivariate statistics. Numerical taxonomy, includ
similarities. For example, the Biological Species ing morphometric techniques, traditionally has
Concept (Mayr 1942, Donoghue 1985) considers been used at or below species level; thus it is
entities that can andlor do interbreed (by 'ordi suited to species delimitation questions. Multi
nary means') to produce fertile progeny and that variate analysis can investigate underlying pat
are reproductively isolated from other such terns and trends that may not be easily detect
groups, as belonging to the same species. Such able to the taxonomist. Such analysis summariz
concepts generally are not used in the Orchida es a range of variation in a relatively easily vi
ceae because of the ability of phylogenetic ally sualized and practical manner.
distant species to hybridize to produce fertile Classifications made using phenetic theory
offspring. group entities are based on phenetic similarity,
A phylogenetic species concept, with all and the methods adhere to a series of neo-Adan
monophyletic, geographically distinct lineages sonian principJes, as described by Sneath and
regarded as distinct species (Brasier 1997, Don
Sokal (1973). The more characters included, the
oghue 1985, Luckow 1995), cannot be applied
more rigorous is the classification produced; and
to Vanda and its related genera, as a full molec
the greater the reduction in subjectivity, the
ular analysis of the group has yet to be under
greater is the increase in reproducibility of re
taken.
sults. Characters, scored for individual opera
More 'practical' species concepts applicable
tional taxonomic units (OTUs), are equally
to groups not yet subject to molecular study in
weighted and non-directional (i.e., no inference
clude morphological species concepts, phenetic
as to the probable direction of character evolu
species concepts, and taxonomic species con
tion).
cepts; as well as more specifically, the Autapo
Morphometric methods have not been used
morphic Species Concept (Mishler & Brandon
extensively in the Orchidaceae, but a study by
1987) and the Phylogenetic Species Concept
Bateman and Denholm (1983) used the multi
sensu Nelson and Platnick (1981).
variate technique to classify British and Irish
Taxonomic and morphological species con
marsh-orchids and recommended that the group
cepts (Mayden 1997, Cronquist 1978) are in
be reduced to a single species with four subspe
tended to be practical, morphological concepts
cies. A study by Clifford and Lavarack (1974)
useable with all groups of organisms. Propo
compared the use of vegetative and reproductive
nents of these concepts theorize that if an indi
attributes of 93 Orchidaceae taxa by means of
vidual or a population of individuals can be re
peatedly and consistently distinguished from group-average clustering and found both types
others by a taxonomist using 'ordinary means', of character "equally efficient predictors of the
then it can be recognized as a distinct species. classification. "
The diagnosis of a species may be based on only The most common multivariate statistical
a few characters or even on a single character, methods used in taxonomic processes are Clus
such as flower color. Phenetic species concepts ter Analysis and the ordination techniques,
recognize species on the basis of overall simi which include the Principal Components Anal
larity uniting taxa, in conjunction with their dis ysis (PCA) and its equivalent for handling con
continuity from related taxa (Gornall 1997). tinuous and discontinuous data-the Principal
Such concepts may involve only one or a few Coordinates Analysis (PCO or PCoA). The or
key diagnostic characters or a range of attributes dination techniques represent all data collected
may be taken into account. Concepts based on in multidimensional space and summarize it in
numerical taxonomy, such as the Phenetic Spe 2- or 3-dimensional graphical plots.
cies Concept sensu Sneath and Sokal (1973), use
a range of attributes, attempting to take all avail
MATERIALS AND METHODS
able characters into consideration to detect un
derlying patterns of similarity and discontinuity. A total of 30 spirit collections of flowers from
Proponents of the concept find the species level Vanda section Cristatae from the University of
is that at which distinct phenetic clusters can be Copenhagen (C), Royal Botanic Gardens Kew
observed. The Phenetic Species Concept is used (K), and Royal Botanic Gardens Edinburgh (E)
in this study to examine species delimitation were scored for 39 floral characters (see TABLE
within Vanda section Cristatae. 1). Flowers stored in preservative spirits unfor
tunately lose color characters, which therefore
Morphometric Analysis
could not be scored. In all, 118 herbarium sheet
Employing a morphometric approach to de specimens from Natural History Museum (BM),
termine the species limits and number of species K, E, National Herbarium Nederland Leiden (L),
SECOND IOCC PROCEEDINGS 349
TABLE 1. Floral character list for a morphometric study of five species in Yanda section Cristatae.
No. Floral diagnostic character No. Floral diagnostic character
Maximum breadth of flower (tip of tepal to 20 Labellum epichile length (straight line along
tip of tepal) underside of labellum, from where epichile
2 Maximum height of flower (tip of dorsal se joins labellum midsection to end of label
pal to tip of lowest lateral sepal) lum, excluding length of any apical projec
3 Maximum distance from top of corolla tube tions)
to furthest tip of tepals 21 Labellum hypochile midpoint width
4 Positioning of tepals around labellum and col- 22 Labellum epichile midpoint width
umn: open (0), cupped (1), strongly cupped 23 Labellum lateral lobes on hypochile: small
(2) (0), large (I)
5 Dorsal sepal-length 24 Labellum apical lip thickness
6 Dorsal sepal-midpoint width (perpendicular 25 Labellum callus beneath epichile apex: nonel
to sepal midline) indistinct (0), distinct (l)
7 Dorsal sepal-apical width (measured 1 mm 26 Labellum callus length
from tip of sepal along midline) 27 Labellum callus width
8 Dorsal sepal-basal width (measured I mm 28 Type of labellum apical projections: none (0),
along midline of sepal from point of at small bumps (l), large bumps (2), distinct
tachment) hornsllobes (3)
9 Lateral petal-length 29 Number of labellum apical projections
10 Lateral petal-midpoint width 30 Maximum length of labellum apical projec
11 Lateral petal-apical width tions
12 Lateral petal-basal width 31 Ribbing on labellum upper surface shallow
13 Lateral sepal-length (0), intermediate (1), deep (2)
14 Lateral sepal-midpoint width 32 Presence and type of spur on labellurn hypo
15 Lateral sepal-apical width chile: none/indistinct bowl-shape (0), pro
16 Lateral sepal-basal width nounced deep hollow (1)
17 Total labellum length (straight line measured 33 Depth of labellum spur (from base of sinuses
from point of attachment to furthest tip of of hypochilar lateral lobes to spur apex)
labellum) 34 Midpoint width of labellum spur (side view)
18 Labellum hypochile length (straight line along 35 Column length
underside of labellum, from point of attach- 36 Column midpoint width
ment to rest of floral organs, to apex of 37 Angle between midline of dorsal sepal to that
'spur') of right- hand lateral petal
19 Labellum midsection length (straight line 38 Angle between dorsal sepal and lateral sepal
along underside of labellum, from apex of 39 Angle between line straight through column
'spur' to angled point where epichile starts) and central line of labellum
and Universitiit Wien (WU) were scored for 25 responding to all specimens previously identi
vegetative characters (see TABLE 2). Each indi fied as Yanda cristata, all V. pumila specimens,
vidual plant (1 OTU) was assigned an identifi and a group of the V. alpina, V. griffithii, and V.
cation code, and measurements were made using chlorosantha specimens (see FIGURE 1). This
a metal ruler with 0.5 mm divisions, cotton pattern was repeated when labellum characters
thread for measuring curved structures, a grid of were excluded from analysis and when tepal
1 X 1 mm squares, and a protractor for measur characters alone were analyzed. Cluster Analysis
ing angles. of the floral data shows the OTUs split accord
The floral and vegetative data sets were ana ing to the same pattern, with V. cristata and V.
lyzed with PCO (Principal Coordinates Analy pumila specimens dividing into two distinct
sis) in the statistical program MVSP (Kovach clusters, similar more to each other than to the
Computing Services 2002a). Analyses employed third cluster, composed of V. alpina, V. griffith ii,
Gower's General Similarity Coefficient (Kovach and V. chlorosantha with no further intra-cluster
Computing Services 2002b) and 10glO trans groupings (see FIGURE 2). Analysis of the veg
formed the data. Cluster analyses were per etative morphometric data showed no groupings
formed on the floral data, using UPGMA as the at all (see FIGURE 3).
clustering method, Gower's General Similarity
Coefficient, and 10glO transformation of the data.
DISCUSSION
RESULTS This study shows that the five currently rec
Analyses of the floral morphometric data con ognized species of this section are not distin
sistently showed three floral morphotypes, cor- guishable on the basis of vegetative morpholo-
350 SELBYANA Volume 26(1,2) 2005
TABLE 2. Vegetative character list for a morphometric study of five species in Yanda section Cristatae.
No. Vegetable diagnostic character No. Vegetative diagnostic character
Height of plant measured from base of stem 15 Leaf lobe height difference
(not incorporating roots) up to furthest 16 Average leaf length divided by average lobe
point (usually tip of a leaf) height
2 Average root width measured 2 cm from 17 Leaves: lobes acutely ended (0), roundly end
emergence from stem ed (1), blunt (2), mixed (3), acute and blunt
3 Stem length (4), rounded and blunt (5)
4 Stem width below first leaf 18 Leaves mucrone: absent (0), present narrowed
5 Stem midpoint width (l), present expanded (2)
6 Stem width below 4 youngest leaves 19 Leaves: number attached to plant
7 Average leaf length 20 Number of leaves excised from plant
8 Average midpoint leaf width 21 Number of excised leaves divided by number
9 Leaves: average apical leaf width measured 5 attached leaves
mm back from apex of shortest leaf lobe 22 Total number of leaves
10 Length of longest leaf 23 Height of leaf sheath bases
11 Midpoint width of longest leaf 24 Height of stem (sheath bases without leaves)
12 Midpoint width of widest leaf 25 Total stem height divided by height of stem
13 Leaf length divided by midpoint width (sheath bases without leaves)
14 Leaf tapering: midpoint width divided by api
cal width
gy; however, three distinct floral morphotypes, U sing the Phenetic Species Concept sensu
based on multiple characters, are Yanda pumila, Sneath and Sokal (1973), three species can be
V. cristata, and the V. alpina groups. recognized. They are Yanda a/pina, V. cristata,
The floral study broadly supports the currently and V. pumila, distinguishable on their floral
accepted classification of section Cristatae, with morphologies. Intraspecific levels of variation
a few changes at the ranking level of the taxa. occur within the species, corresponding to the
i pumila
0.2
\' cristata
.
.
N O.1 • .
~-~----------------------+-----------------------------
: • alpina
• I
:
I
ii • chlorosantha
ii
i
i
-0.4
• griffithi i
-0.5+---,--...,.----,--.----'-----,---,----,-----,----,
-0.5 -0.4 ..Q.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5
Axis 1
FIGURE 1. Analysis of floral characters: PCO axes 1 and 2 (Gower's General Similarity Coefficient used,
data 10glO transformed).
SECOND IOCC PROCEEDINGS 351
tially could remain at the species level, as they
are all distinguishable by a few unique charac
ters.
Vanda jainii may be recognized as a subspe
cies of V. cristata, which shows an extremely
high level of floral morphological variation,
from the number and length of the apical pro
jections on the labellum, to the color and num
ber of striations on the labellum upper surface,
even on the same plant (M. Motes pers. comm.).
Vanda jainii, only collected once from the wild,
may be part of the natural phenotypic variation
of the species.
Where geographic distributions of species are
very similar, where their distributions overlap,
and where they share pollinators, we may not be
looking at genetically distinct species. Instead
we could be observing a complex of hybridizing
entities with a shared gene pool. The taxa within
the Vanda alpina complex may be interbreeding
or, alternatively, may be gradually diverging.
If Vanda section Cristatae has speciated rel
atively recently to give the currently recognized
species, and if few significant environmental dif
ferences exist between habitats, then the vege
tative parts of the plants may not have diversi
fied sufficiently to be discriminating at the spe
cies level by morphometric techniques. If recent
speciation has been the result of isolation, per
haps because of a change in pollinator/pollinator
behavior, radiation in floral structures would pre
cede radiation in the vegetative parts.
The analyses presented here may suggest that
Vanda alpina, V. griffith ii, and V. chlorosantha
are indistinguishable and therefore closely relat
ed, and it is not a priority to conserve all three.
The three currently recognized species, however,
are distinguished one from another by a few au
tapomorphies each-mostly characters related to
the labellum and flower color. Since these are
only a small number of characters out of the
large number measured in this study, especially
since color characters were not included because
of the nature of the material studied, these dif
ferences among the taxa are not seen in the anal
yses performed. The species could be genetical
ly closely related and in the process of diverging
into three separate lineages, in which case, they
FIGURE 2. Analysis of floral characters: clustering may constitute relatively low priority for con
analysis (UPGMA clustering method, Gower's General servation. Alternatively, they could be distantly
Similarity Coefficient used, data loglO transformed). related, but morphologically similar either be
cause of convergence or retention of the ances
currently recognized species V. griffithii and V. tral morphology of the group, in either case,
chlorosantha, as subspecies of V. alpina divisi constituting a higher priority for conservation.
ble on the basis of one or a few floral characters Phylogenetic study with wide sampling and sur
(mostly related to flower color). If either the tax veys of distribution and pollinators-whether
onomic or autapomorphic species concept was the species are sympatric or allopatric and
applied to the section, then all the taxa poten- whether gene flow is likely to occur between
352 SELBYANA Volume 26(1,2) 2005
0.35
"
'I
'I( 'I II!
0.28 " cristata
,
': v
'I( 1\
0.21 , Ii)
, If cristata?
A ~
"
~ ~
II
@ alpina
~---~------ A pumila
indet
-0.14
+ griffithii
'In:
-0.21-+----,----,----,--L-~--__r--___,__--__,__--__,__--,
-0.36 -0.27 -0.18 -0.09 0.00 0.Q9 0.18 0.27 0.36 0.45
Axis 1
FIGURE 3. Analysis of vegetative characters: pca axes 1 and 2 (Gower's General Similarity Coefficient used,
data log,o transformed).
them-would provide greater insight into the re IDENTIFICATION KEY OF VANDA
lationships and dynamics of the group. SECTION CRISTATAE
For Yanda section Cristatae, a morphological
L Labellum base open saccate hollow. Labellum
species concept based on floral characters ap
equal in length or shorter than tepals. Small flowers,
pears to be an appropriate concept to distinguish
less than 2.5 cm diameter. . ............. .
species, with floral autapomorphies used to rec ................... Vanda alpina complex
ognize intraspecific levels of variation. If such 2. Strongly cupped flowers (tepals held closely
autapomorphic individuals consistently and per around Jabellum). ... . . . . . . .. "V. alpina"
sistently are identified and seen to form isolated 2. More open flowers (tepals cupped slightly for
ward but not held closely around labellum).
populations with different distributions from the
3. Flower pale yellowish green tepals, all same
rest of the species, then grounds for the eleva
color. Labellum unstriped ........... .
tion of such taxa to specific level may be justi
.................. "V. chlorosantha"
fied. Yanda chlorosantha, for example, may 3. Flower bright greenish. Labellum with purple
warrant remaining as a separate species from V. striations. ............. "v. griffithii"
alpina, if it meets such criteria. In combination 1. Labellum base with distinct spur. Labellum longer
with genetic and biogeographic distribution than tepals. Large flowers, greater than 2.5 cm di
ameter.
studies, a revision of the section will be pro
4. Strongly cupped flowers (tepals held
duced.
closely around labellum). Thick, fleshy la
The whole genus Yanda needs considerable
bellum without distinct callus below apex
work in order to produce a phylogenetic frame of labellum, slight apical swellings of
work around which to base a more meaningful varying size on edge of labellum. White
classification of the group. flowers with reddish striations on label-
A simple identification key is presented, dis lum. ........ Vanda pumila complex
4. More open flowers (tepals cupped slightly
tinguishing the three floral morphotypes, Yanda
forward but not held closely around la
alpina, V. cristata, and V. pumila, and the sub
bellum). Distinct callus below apex of la
morphotypes corresponding to the currently rec
bellum and distinct apical projections of
ognized species epithets, 'alpina', 'cristata', varying size on edge of labellum. .....
'griffithii', 'pumila', and also 'jainii'. . . . . . . . . . . .. Vanda cristata complex
SECOND IOCC PROCEEDINGS 353
5. Apical projections very distinct hom Garay, L.A. 1986. Trudelia, a new name for Vanda
shaped lobes, commonly 2-3, often di alpina. Orchid Digest 50(2): 73-77.
varicating. Labellum longer than lateral Gornall, RJ. 1997. Practical aspects of the species
sepals, 5-6 carunculate ridges on upper concept in plants. Pp. 171-190 in M.P. Claridge,
surface of labellum. Distinct, deep H.A. Dawah and M.R Wilson, eds. Species: The
spur. .............. "V. cristata" Units of Biodiversity. The Systematics Associa
5. Two erect lobules at apex of labellum. tion Special Volume Series 54, Chapman & Hall,
Labellum shorter than lateral sepals. 8- London.
9 shallow purple ridges on upper sur Hooker, J.D. 1890. The Flora of British India 5(17):
face of labellum. Spur obtuse and shal 49-54.
lower. . . . . . . . . . . . . .. "v. jainii" Kovach Computing Services. 2000a. MVSP: Multi
Variate Statistical Package. KCS, Anglesey,
Wales.
ACKNOWLEDGMENTS
---. 2000b. Gower's General Similarity Coeffi
cient, KCS, Anglesey, Wales.
We thank Dave Simpson at Royal Botanic
Lindley, J. 1833. Genera and Species of Orchidaceous
Gardens Kew for help with multivariate analy Plants. pp. 215-217.
sis, also Martin Motes, of Motes Orchids, Flor
---. 1853. Folia Orchidacea 4(10): 1-11. J. Mat
ida, and Phillip Cribb at RBG Kew for advice thews, London.
on this study. Claire Moyle at RBG Kew assist Lindley, J. and J. Paxton. 1851. Paxton's Flower Gar
ed with loans and digitized type images; and den 2: 22. Cassell, Petter, Galpin & Co., London.
herbaria staff at BM, C, E, K, L, P, and WU Luckow, M. 1995. Species concepts: assumptions,
loaned preserved plant material. We thank Brent methods and applications. Syst. Bot. 20(4): 589-
Emerson at University of East Anglia (UBA) for 605.
Mayden, RL. 1997. A hierarchy of species concepts:
advice with the writing of this article and Sue
the denouement in the saga of the species prob
Mott and Sue Rumsey at Reading University for
lem. Pp. 381-424 in M.P. Claridge, H.A. Dawah
assistance with plant material loans and equip and M.R Wilson, eds. Species: The Units of Bio
ment. diversity. The Systematics Association Special
Volume Series 54, Chapman & Hall, London.
Mayr, E. 1942. Systematics and the Origin of Species.
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