MINISTRY OF EDUCATION
AND TRAINING
VIETNAM ACADEMY OF
SCIENCE AND TECHNOLOGY
GRADUATE UNIVERSITY SCIENCE AND
TECHNOLOGY
----------------------------
VAN HONG THIEN
BUILDING PHYLOGENETIC TREES FOR THE
ARACEAE IN SOUTHERN VIETNAM BASED ON
MORPHOLOGICAL AND MOLECULAR MARKERS
Major: Ecology
Code: 62 42 01 20
SUMMARY OF BIOLOGY DOCTORAL THESIS
Ho Chi Minh City – 2017
The work was realized in Graduate University of Science and
Technology, Vietnam Academy of Science and Technology.
Advisor 1: Dr. Lưu Hong Truong
Advisor 2: Dr. Nguyen Phi Nga
Examiner 1: Assoc. Dr. Nguyen Van Ket
Examiner 2: Assoc. Dr. Truong Thi Dep
Examiner 3: Dr. Vu Ngoc Long
The thesis will be evaluated by doctoral committee at Graduate
University of Science and Technology, Vietnam Academy of Science
and Technology on …… 2017.
The thesis is available at:
- Library of Graduate University of Science and Technology
- National Library of Vietnam
LIST OF ABBREVIATIONS
CI
:
Consistency index
DNA
:
Deoxyribonucleic acid
HN
:
Herbarium of
Institute of Ecology and Ecological
Resources
HNU
:
Herbarium of University of Science, Vietnam National
University, Ha Noi
IGS
:
Intergenic spacer
ISI
:
International Scientific Indexing
K
:
Herbarium of Kew
MEGA
:
Molecular Evolutionary Genetics Analysis
P
:
Herbarium of Paris
PAUP
:
Phylogenetic Analysis Using Parsimony
PCR
:
Polymerase Chain Reaction
PHH
:
Herbarium of University of Science, Vietnam National
University Ho Chi Minh City
RC
:
Rescaled consistency index
RI
:
Retention index
SGN
:
Herbarium of Southern Institute of Ecology
VNM
:
Herbarium of Institute of Tropical Biology
Sect.
:
Section
1
INTRODUCTION
1. The necesstiy of the thesis
Araceae in Vietnam were first systemerized by the French
botanist Gagnepain in 1942 (Gagnepain, 1942). Pham-Hoang (2000)
in the book "An Illustrated Flora of Vietnam" (Volume III) as well as
Nguyen (2005) in the "Checklist of Plant Species of Vietnam"
(Volume III, edited by Nguyen Tien Ban) provided the brief
information on the taxonomy of species in Araceae. Most recently,
the monograph work on Araceae in Vietnam was conducted by
Nguyen (2006), according to which the author made a list of 116
species belonging to 23 genera in Vietnam. However, much of the
research samples in Nguyen Van Du's work (2006) were collected in
the northern regions of Vietnam. In addition, since 2006, there have
been 13 new species and 4 new records of Araceae in Vietnam
(mostly in the South) which were published by many authors,
thereby, increasing the total number of species of Araceae in
Vietnam up to 133 (Nguyen 2007 & 2008; Hetterscheid, 2006 &
2013; Nguyen & Croat, 2010; Gong et al., 2012; Bruggeman et al.,
2013; Nguyen & Bui, 2013; Nguyen et al., 2013; Luu et al., 2013 &
2014; Hoang et al., 2016; Van et al., 2016). Moreover, many species
and genera in Araceae have currently changed and have not been
unified in the classification (Nguyen, 2006; Gusman & Gusman,
2006; Cusimano et al., 2011; Hetterscheid & Claudel 2012;
Nauheimer et al., 2011; Nauheimer & Boyce, 2013). Thus, the
knowledge of Araceae in Vietnam, especially in the South of
Vietnam, is still incomplete, many species are propably unknown or
unclear in terms of classification. Moreover, in Vietnam, no reseach
has been conducted on the use of morphological characteristics and
especially molecular markers for the purpose of constructing the
phylogenetic tree for systematizing and providing taxonomic
information of Araceae. For the above reason, we decided to
implement the project: “Building phylogenetic trees for the Araceae
2
in southern Vietnam based on morphological and molecular
markers”.
2. Goal of the subject
Building phylogenetic trees for the Araceae in southern Vietnam
based on morphological and molecular markers, thereby (1)
indicating the evolutionary relationship between taxa in Araceae; (2)
re-classifying and/or confirming the exact identification for
ambiguous species; (3) recording the new species of Araceae for the
flora in Vietnam.
3. The main contents of the study
Collecting plant materials; observation of
specimens in
hebariums; identification and decription of materials; amplification
and sequencing of trnL-trnF IGS and matK chloroplast DNA regions;
data processing methods.
CHAPTER 1: LITERATURE REVIEW
1.1. Introduction to Aracea
Araceae is a family of Monocotyledon of the Magnoliophyta with
about 2824 species of 107 genera (Govaert & Frodin, 2002) and was
first described in 1789 by Jussieu (Jussieu, 1789).
Araceae has very featured morphological characteristics, which
there is a spathe varied in shape, size and color. Spathe is responsible
for protecting spadix and is usually divided into two parts, limb and
tube. Another characteristic of the Araceae is spadix; spadix is
divided into two forms: bisexual and unisexual, unisexual spadix is
the one that carries only famale or male flowers, while bisexual
spadix is a type that carries both male and female flowers. Spadix of
many species in Araceae in general and most of the species in
southern Vietnam in particular have a sterile portion located between
the male and female part or at the end. In addition, flowers of
Araceae are divided into two types, including bisexual and unisexual
flowers. According to many studies, bisexual flowers often appear in
subfamilies of ancient classifications such as Pothoideae,
3
Monsteroideae and Lasioideae; while the unisexual flowers are more
common in the subfamily of higher evolutionary levels, such as
Aroideae (Mayo et al., 1997; Nguyen, 2006; Boyce et al., 2012).
1.2. Research status with taxanomic Araceae
1.2.1. The studies on taxanomic Aracea in the world
Araceae was first described in 1789 by Jussieu, in which he
categorized all climbing species into a group called Pothos L., while
terrestrial species were classified as Arum L. and Dracontium L.
(Jussieu, 1789). Schott (1860) set up the first classification system for
the Araceae. This system was then modified and developed by many
researchers (Hooker, 1883; Engler, 1876b & 1820b; Grayum, 1990;
Bogner & Nicolson, 1991; Mayo et al., 1997).
In the field of molecular marker application research in Araceae,
the first work was done by French et al. (1995). Later, further
research into the construction of the phylogenetic tree for Araceae
were also conducted by several authors, for example, Barabe et al.
(2002) and Cabrera et al. (2008) built the phylogenetic tree for
Araceae based on a combination of two non-coding regions of the
chloroplast DNA. Cusimano et al. (2011) and Nauheimer et al.
(2012) used phylogenetic tree of Cabrera et al. (2008) and some more
genera to form a phylogenetic tree for Araceae based on chloroplast
markers.
1.2.1. Studies on the taxonomic Aracea in Vietnam
Gagnepain (1942) first described Araceae in Vietnam in the
"Flore Général de L'Indochine". Many of the later studies of Araceae
in Vietnam were carried out by a number of authors (Pham-Hoang,
1993 & 2000, Nguyen, 2005). Nguyen (2006) reported that in
Vietnam there were 116 species belonging to 23 genera. From 2006
to date, there have been 13 new species and 4 new records of
Araceae published in Vietnam. Among them, genus Arisaema have
four new species and three new records, followed by genus
Amorphophallus with four new species and one new records,
4
Typhonium and Alocasia with two new species and one new species
for Rhaphidophora (Hetterscheid, 2006; Nguyen, 2008; Nguyen &
croat, 2010; Gong & Li, 2012; Bruggeman et al., 2013; Hetterscheid
& Claudel, 2013; Luu et al., 2013 & 2014; Nguyen et al., 2013;
Nguyen et al., 2015; Nguyen & Quang, 2015; Nguyen et al., 2016;
Van et al., 2016).
CHAPTER 2. CONDITION AND METHOD
2.1. Research subject
The species of Araceae is distributed in southern Vietnam, from
Da Nang City.
2.2. Research Method
2.2.1. Field survey method
The field survey method is implemented in the following steps:
(1) Listing the number of species available in southern Vietnam; (2)
selecting sample location; (3) recording the distribution of species;
(4) documentary photography; (5) collecting samples for dried
specimens; (6) DNA sample collection.
2.2.2. Method in the laboratory
2.2.2.1. Method of morphological characterization includes
steps: (1) observation of specimens in hebariums (HN, VNM, HNU,
SGN, PHH, P and K); (2) species identification by morphological
comparison method; (3) building morphological characteristics of
species in southern Vietnam.
2.2.2.2. Molecular method includes the steps: (1) selection of
molecular markers in research of building phylogenetic tree; (2) total
DNA extraction; (3) PCR reaction; (4) Purification of PCR products
and sequencing.
2.2.3. Data processing methods
2.2.3.1.Phylogenetic
tree
based
on
morphological
characteristics: building phylogenetic tree for 103 taxa, including
101 species, 1 subspecies and 1 form in southern Vietnam based on
33 morphological characteristics by PAUP software (Swofford,
5
2002), according to the Maximum Parsimony method
with 1000 bootstrap replicates (Felsenstein, 1985).
2.2.3.2. Phylogenetic tree based on molecular markers: building
phylogenetic tree for 70 taxa, including 64 species, 1 subspecies and
1 form which were collected in southern Vietnam and 4 taxa from
Genbank data by PAUP * software (Swofford, 2002) and MEGA6
(Tamura et al., 2013) by Maximum parsimony, Neighbor joining and
Maximum likelihood methods.
CHAPTER 3. RESULT AND DISCUSSION
3.1. Results of the construction of the Phylogenetic tree based on
morphological characteristics
The results on the phylogenetic tree in Figure 3.1 showed that the
resolution was not high because the branches tended to start from the
same root. The morphological relationships of 101 species, 1
subspecies and 1 form were basically divided into 4 subfamilies:
Pothoideae (I), Monsteroideae (II), Lasioideae (III) and Aroideae
(IV).
3.1.1. Subfamily Pothoideae and Monsteroideae
The phylogenetic tree in Fig. 3.1 showed that the two subfamily
of Pothoideae and Monsteroideae with bisexual flower (3-tribe
Potheae, Anadendreae and Monstereae) grouped together with
bootstrap as 83% and were separated from subfamily Aroideae with
unisexual flower . This result was consistent with the view of the
classification system established by Mayo et al. (1997).
3.1.2. Subfamily Lasioideae
In contrast to the subfamily Pothoideae and Monsteroideae,
another subfamily with bisexual flower, Lasioideae, had no
distinction with the Aroideae subfamily in the phylogenetic tree in
Figure 3.1. Accordingly, despite belonging to the group with bisexual
flower, subfamily Lasioideae has terrestrial or aquatic living form
similar to most of tribe of the subfamily Aroideae (Mayo et al., 1997;
Li et al., 2010; Boyce et al., 2012); thus, in the phylogenetic tree in
6
Figure 3.1, the subfamily Lasioideae was the intermediate group
between the group with bisexual flower (Pothoideae and
Monsteroideae) and the subfamily with unisexual flower (Aroideae).
3.1.3. Subfamily Aroideae
Figure 3.1 showed that taxa of the subfamily Aroideae tended to
be grouped into one group and could be distinguished from the
bisexual group, especially the two subfamily Pothoideae and
Monsteroideae. Accordingly, the subfamily Aroideae shared many
morphological characteristics and could be distinguished from the
subfamilies Pothoideae, Monsteroideae and Lasioideae in the
characteristics of unisexual flowers, absent perigone, tuber or
rhizome, their often appearrance on terrestrial, swamps or streams
(Mayo et al., 1997; Pham-Hoang, 2000; Nguyen, 2006; Li et al.,
2010; Boyce et al., 2012). In addition, the results of the
categorization of taxa in subfamily Aroideae on the phylogenetic tree
(Figure 3.1) basically showed that there was a division between the
tribe and genus, whereby the arrangement of each case in the
subfamily Aroideae is as follows:
- Tribe Homalomeneae
In the south, Homalomeneae has one genus Homalomena. In the
phylogenetic tree in figure 3.1, species belonging to the genus
Homalomena were grouped together on a branch with a bootstrap
value of 79%. However, taxa belonging to the genus Homalomena
originated from the same branch (Fig. 3.1), which did not show the
difference between taxa in the genus. Therefore, this issue will be
clarified in the analysis of the phylogenetic tree based on the
molecular markers (see page 15 for details).
7
Figure 3.1. One of most-parsimonious tree obtained based on 33
morphological characteristics of 101 species, 1 subspecies and 1 form
in in southern Vietnam with Acorus verus (Acoraceae) as outgroup.
The bootstrap values of 50% or more than from 1000 replicates are
shown above the nodes. Note: I. Subfam. Pothoideae, II. Subfam.
Monsteroideae, III. Subfam. Lasioideae, IV. Subfam. Aroideae.
8
- Tribe Aglaonemateae
In the history of research on Aglaonemateae, there were different
opinions on the genus Aglaodorum (with the only species
Aglaodorum griffithii). Some said that Aglaodorum griffithii had
many morphological characteristics similar to Aglaonema such as
flower structure, morphology of leaf and petiole, etc., and it was thus
placed in genus Aglaonema (Schot, 1856; Hooker, 1883; Ridley,
1925). However, many authors said that there were some differences
between these two genera and suggested that Aglaodorum griffithii
was independent of the Aglaonema species Schot, 1856; Mayo et al.,
1997; Pham-Hoang, 2000; Nguyen, 2005 & 2006; Boyce et al.,
2012). Based on the phylogenetic tree in Figure 3.1, Aglaodorum
griffithii was not on the same branch with the Aglaonema species.
This result supported the view of many researchers who have recently
said that Aglaodorum and Aglaonema were the two separate genera.
- Tribe Thomsonieae
Previously, Tribe Thomsonieae had two genera, Amorphophallus
and Pseudodracontium (Serebryanyi, 1995; Mayo et al., 1997; PhamHoang, 2000; Nguyen, 2006). However, Hetterscheid & Claudel
(2012) said that characteristic features of genus Pseudodracontium
were present in species belonging to genus Amorphophallus. In
addition, many molecular evidences also showed a very close genetic
relationship between the two genera này (Cabrera et al., 2008; Grob
et al., 2002 & 2004; Nauheimer et al., 2012); Hetterscheid & Claudel
(2012) thus removed the genus Pseudodracontium and transferred all
of taxa of genus Pseudodracontium to Amorphophallus. The results
in the pedigree tree of Figure 3.1 showed that the species of genus
Pseudodracontium, including A. fallax, A. macrophyllus, A. lacourii,
A. lanceolatus, A. pseudoharmandii and A. sp3. were previously
grouped together but their relationship with Amorphophallus species
was unclear. In addition, the resolution of the species in tribe
Thomsonieae in phylogenetic tree (Figure 3.1) was not high, so it was
9
difficult to see the species classification clearly. Therefore, this issue
will be clarified in the analysis of phylogenetic tree based on
molecular markers (see page 15 for details).
- Tribe Arisaemateae
Genus Arisaema was first described in 1831 (Martius, 1831).
Schott (1860) divided into four groups: Trisecta, Pedatisecta,
Radiatisecta and Peltatisecta. Many classification systems of genus
Arisaema have later proposed by several authors (Nakai et al., 1950;
Hara, 1971; Murata 1984 & 1991; Murata et al., 2013). Gusman &
Gusman (2002) introduced a new classification system for the genus
including 14 sections and 15 sections in the second edition in 2006.
Murata et al. (2013) introduced a new classification system by
merging sect. Fimbriata and Lobata into the sect. Attenuata and
Pistillata, respectively; in addition, the author added a new section
Odorata to form a classification system of 14 sections for genus
Arisaema. Recently, Ohi-Toma et al. (2016) split sect. Fimbriata out
of sect. Attenuata based on molecular markers and thereby
introducing the classification system for Arisaema with 15 sections.
In Southern Vietnam, Arisaema has three sections: Anomala,
Fimbriata and Sinarisaema. Based on the phylogenetic tree in Figure
3.1, Arisaema species tended to rank together. Of which, 2 species of
A. consanguineum subsp. consanguineum and A. kerrii from sect.
Sinarisaema were grouped into one group with a bootstrap value of
87%. However, the taxa of the two sections of Anomala and
Fimbriata were not completely separated into two groups, so the
division of Arisaema into three sections in the south was not yet
evident in the phylogenetic tree, which will be clarified in the
analysis of phylogenetic tree based on molecular markers (see page
18 for details).
- Tribe Colocasieae
In southern Vietnam, Colocasieae consisted of four genera:
Alocasia, Colocasia, Remusatia and Leucocasia (Mayo et al., 1997;
10
Nauheimer et al., 2011). The phylogenetic tree of Figure 3.1 showed
a partial relationship between taxa in tribe Colocasieae, whereby
Alocasia evrardii (which was moved to genus Colocasia in this
study) had intermediate characteristics between genus Alocasia and
Colocasia in which the ovule was parietal and basal placentation but
they were close to the genus Colocasia because it had the
characteristic of having a lot of ovules, so it tended to be closer to C.
esculenta in the phylogenetic tree (Figure 3.1). In addition,
Remusatia vivipara had other important characteristics compared to
Alocasia and Colocasia in which spadix without appendix, hence, the
species is also classified as a branch.
The phylogenetic tree based on morphological characteristics in
Figure 3.1 partly reflected the relationship between the levels of
classification in Araceae in southern Vietnam. However, the
resolution shown on the phylogenetic tree was low, leading to less
clustering if the bootstrap value was significant (over 50%) (Salemi
& Vandamme, 2003). For example, Figure 3.1 showed that some
species of the genus Amorphophallus did not have clear clustering
with species of genus Sauromatum and Typhonium (tribe Areae).
Similarly, tribe Anadendreae and Monstereae tended to group
together. In addition, among species in many genera, the resolution
was not high and therefore, there was no relationship between species
in the genus. This result was similar to the phylogenetic tree of
Cusimano et al. (2011) whose study also showed that the
phylogenetic tree also had the branch with low significance level
(bootstrap >50%).
Therefore, most of the recent researches on phylogenetic systems
in plants in general and Araceae in particular were based on
molecular markers (Grob et al., 2002 & 2004; Jung et al., 2004;
Renner & Zhang, 2004; Renner et al., 2004; Cabrera et al., 2008;
Sedayu et al., 2010; Wong et al., 2010; Cusimano et al., 2011;
Nauheimer et al., 2011 & 2012; Nauheimer & Boyce, 2013; Ohi-
11
Toma et al., 2016). Therefore, in this study, we constructed the
phylogenetic tree based on molecular markers (Figure 3.2) to solve
many problems in Araceae which could not be clarified on the basis
of morphologial characteristics.
3.2. Results of the construction of the phylogenetic tree based on
melecular markers.
Based on the classification in the phylogenetic tree in Figure 3.2,
we provided the case-by-case observations as belows:
Subfamily Pothoideae, Monsteroideae and Lasioideae
Figure 3.2 showed that the subfamily Lasioideae, Pothoideae and
Monsteroideae were located closely together on the phylogenetic tree.
This result was consistent with many previous studies on the
phylogenetic system based on molecular markers for Araceae
(Cabrera et al., 2008; Cusimano et al., 2011; Nauheimer et al., 2012).
Accordingly, these three subfamily (6 genera Pothos, Anadendrum,
Raphidophora, Epipremnum, Scidapsus and Lasia) were located
close to each other and placed outside in comparison with the
subfamily Aroideae because they shared the same important
morphological chacteristic of bisexual flower. Therefore, this result
was consistent with the evolutionary view of Mayo et al. (1997) that
taxa of bisexual flower were an ancient group while the taxa of
unisexual flower were the later evolutionary groups. In this group, the
subfamily Lasioideae (Lasia and Pycnospatha genus) were
individually classified as a branch due to the characteristic of a
habitat on marsh or soil, while the other branch was the group of tribe
Potheae, Monstereae and Anadendreae which live on plant or stone
(Mayo et al., 1997; Pham-Hoang, 2000; Nguyen, 2006; Li et al.,
2010; Boyce et al., 2012).
Subfamily Aroideae
* Tribe Aglaonemateae
- Aglaonema was founded by Schott in 1829 (Schott, 1829).
Nicolson (1969) first divided the genus into two sections based on
12
morphological characteristics. Nguyen (2006) and Boyce et al.
(2012) accepted Nicolson's view of division. At present, no research
has yet been done on the use of molecular markers for the purpose of
constructing the phylogenetic tree for Aglaonema. Most studies
focussed on building the phylogenetic system for the whole family at
the level of genus, not going to the details of species of the genus
(Cabrera et al., 2008; Cusimano et al., 2011; Nauheimer et al., 2012).
The results of the arrangement of the Aglaonema species shown in
the phylogenetic tree (Figure 3.2) showed that there was no clear
separation between species of the two sections. Therefore, in this
study, we did not use the Nicolson sectioning system (1969).
- Aglaonema griffithii was first described by Schott (1856).
However, Schott (1858) found that, there were some differences
between Aglaonema griffithii and Aglaonema species, so he founded
the genus Aglaodorum and transferred the Aglaonema griffithii to this
genus with its scientific name of Aglaodorum griffithii. Hooker
(1883) and Ridley (1925) put Aglaodorum griffithii into genus
Aglaonema. At present, Aglaodorum griffithii was still accepted by
many authors as the only Aglaodorum species (Mayo et al., 1997;
Pham-Hoang, 2000; Nguyen, 2005 & 2006; Boyce et al., 2012).
Recently, studies on the construction of phylogenetic tree by
molecular markers also showed that Aglaonema and Aglaodorum
were always grouped together in the phylogenetic tree and were
termed as “sister group" (Cabrera et al., 2008; Cusimano et al., 2011;
Nauheimer et al., 2012).
The phylogenetic tree in Figure 3.2 showed that the Aglaodrum
griffithii, Aglaonema simplex, and A. costatum f. immaculatum are
grouped together (bootstrap values = 88%) and nested in Aglaonema
clade with Aglaonema cochinchinense as sister (bootstrap values =
100%). Thus, based on similarities in morphological and genetic
characteristics, in this study we classified Aglaodorum griffithii into
Aglaonema as suggested by Schott (1856).
13
Figure 3.2. One of most-parsimonious tree obtained based on
combined data set of trnL-trnF IGS and matK of 70 taxa (Araceae) in
southern Vietnam with Acorus verus (Acoraceae) as outgroup. The
bootstrap values of 50% or more than from 1000 replicates are shown
above the nodes. CI= 0.72, RI= 0.87, and RC= 0.63. Note: taxa(*) are
referenced from the GenBank database; I. Subfam. Pothoideae, II.
Subfam. Monsteroideae, III. Subfam. Lasioideae, IV. Subfam.
Aroideae.
14
* Tribe Homalomeneae
Currently, two species of H. cochinchinesis and H. occulta still
have different opinions from botanists, for example, Hu (1968) and
Li (1979) identified that H. cochinchinesis was a synonym of H.
occulta, Nguyen (2006) had the same view as the two authors.
However, Pham-Hoang (2000) and Govaerts et al. (2002), H.
cochinchinesis and H. occulta were the two distinct species. Based on
the type specimens and specimens of these two species stored in
herbariums (HN, VNM, HNU and P), especially fresh specimens
collected, we found that H. cochinchinensis can be distinguished
from H. occulta in having: spadix being 2/3 shorter than spathe, long
stipitate; density flowers with many staminodes in female part; oval
male part, diameter larger than female part. In addition, The results of
the phylogenetic tree shown in Figure 3.2 showed that H.
cochinchinesis and H. occulta did not group together, but grouped
with H. pierreanum. Therefore, based on morphological and genetic
differences, we agree with the views of Pham-Hoang (2000) and
Govaerts et al. (2002) that H. cochinchinesis is a good species and
obviously distinct from H. occulta.
* Tribe Thomsonieae
Amorphophallus genus were grouped together with a bootstrap
value of 100%, especially, group included A. coudercii, A. fallax, A.
lacourii, A. lanceolatus, A. macrophyllus, A. pseudoharmandii, A.
tenuistylis, A. sp1., A. sp2. and A. sp3., of which A. tenuistylis were
ranked separately, followed by three species A. coudercii, A. sp1. and
A. sp2. which were grouped together, the rest was the group of six
species of the previous genus Pseudodracontium. This result was in
accordance with the views of Hetterscheid & Claudel (2012) and
Bogner et al. (1985) suggesting that species of the genus
Pseudodracontium have most relative to some species in genus
Amorphophallus, including A. coudercii and A. tenuistylis.
15
In addition, A. fallax, A. macrophyllus, A. lacourii, A.
lanceolatus, A. pseudoharmandii and A. sp3. had the morphological
characteristics belonging to the genus Pseudodracontium. This genus
was established by Brown (1882) with a new species, P. anomalum
and a species from Amorphophallus, P. lacouri. Serebryanyi (1995)
reported the number of species of the genus Pseudodracontium to be
7 and suggested that Pseudodracontium had the morphological
characteristics that Amorphophallus species did not have or rarely
had. Many researchers later identified that Pseudodracontium and
Amorphophallus were the two separate genera of tribe Thomsonieae
(Mayo et al., 1997; Pham-Hoang, 2000; Nguyen, 2005 & 2006).
However, Hetterscheid & Claudel (2012) disagreed with the view of
Serebryanyi (1995) and suggested that many Amorphophallus species
also have morphological characteristics that Serebryanyi (1995)
attributes to Pseudodracontium. Therefore, Hetterscheid & Claudel
(2012) removed Pseudodracontium and moved all species of this
genus to Amorphophallus. Boyce et al. (2012) also accepted the view
of Hetterscheid & Claudel (2012).
Recently, studies on the development of phylogenetic systems
using molecular and morphological markers for Araceae have shown
that Amorphophallus and Pseudodracontium are very close together,
which are termed as "sister group" (Cabrera et al., 2008; Cusimano et
al., 2011; Nauheimer et al., 2012). More specifically, Grob et al.
(2002 & 2004) or Sedayu et al. (2010) constructed the phylogenetic
tree for tribe Thomsonieae using molecular markers which showed
that Pseudodracontium harmandii and P. lanceolatum were nested
within the group of species in genus Amorphophallus and Grob et al.
(2002) also suggested that Pseudodracontium should be transferred to
genus Amorphophallus (because Amorphophallus was the genus
formly established and had more species).
In this study, six Pseudodracontium species’s molecular data
were most analyzed for the first time. Accordingly, the results shown
16
in Figure 3.2 showed that six species of Pseudodracontium were
nested within Amorphophallus species with an maximum bootstrap
value (100%). In addition, the genetic distance between these species
and some Amorphophallus species were lower than the genetic
distance between Amorphophallus species, for example, the genetic
distance between Pseudodracontium species and A. coudercii ranged
from 0.011 to 0.013 or with A. tenuistylis from 0.015 to 0.016.
Meanwhile, the genetic distance between A. longicomus and A.
tenuistylis, A. coudercii was 0.027 and 0.025, respectively.
Accordingly, based on the study results shown in the phylogenetic
tree (Figure 3.2), all species of genus Pseudodracontium were
transferred to genus Amorphophallus with the scientific names
proposed by Hetterscheid & Claudel (2012).
* Tribe Colocasieae
The results shown in the phylogenetic tree (Figure 3.2) showed
that there has been some confusion in the taxonomy of some taxa of
tribe Colocasieae in Southern Vietnam. For example, Alocasia
evrardii was not grouped with Alocasia species but tended to be
classified as Colocasia species. Alocasia evrardii was first described
by Gagnepain (1942) based on specimens collected by Francois
Evrard in Dalat, Lam Dong province. This species was also recorded
by Pham-Hoang (2000) in the book "An Illustrated Flora of
Vietnam". However, the description of Gagnepain (1942) was not
valid under the international nomenclature of algae, fungi and plants
(Turland, 2013). Nguyen et al. (2013) described Alocasia evrardii for
the first time and classified species into genus Alocasia because of
the characteristics of ovule with basal placentation. However, through
the detailed morphological study, we found that A. evrardii has
ovules with parietal and basal placentation. Therefore, that fact that
Nguyen et al. (2013) classified this species into genus Alocasia was
unstable. In addition, the results shown in the phylogenetic tree
(Figure 3.2) showed that A. evrardii was not completely grouped
17
together with Alocasia species, but tended to be close to Colocasia
species. Therefore, A. evrardii differed in morphological and genetic
characteristics compared to Alocasia species and in our opinion, this
species has been confused during classification. Therefore, in this
study, we have transferred Alocasia evrardii to Colocasia with the
scientific name of Colocasia evrardii.
* Tribe Arisaemateae
In this group, asside from A. roxburghii, the species which was
widespread in the whole Indochinese, Malayan Peninsula and
Vietnam (Pham-Hoang, 2000, Nguyen, 2005 & 2006, Gusman &
Gusman, 2006, Boyce et al. 2012), there have been five other
species, including A. chauvanminhii, A. condaoense, A. honbaense,
A. pierreanum and Arisaema sp2, recently discovered in southernern
Vietnam, so they have never been included in any of the phylogenetic
systems. Of those species, two species of A. condaoense and A.
pierreanum have been currently suspected as a synonym of A.
roxburghii (Gusman & Gusman, 2006). Based on results obtained
from the detailed morphological and molecular characterization, we
made the two observations as belows:
- A. condaoense was first described by Nguyen Van Du as a new
species for science in 2000. In this publication, the author suggested
that A. condaoense could be distinguished from A. roxburghii in
having appendix very long exserted from spathe tube (about 4 cm)
(Nguyen, 2000). However, the description of A. condaoense by
Nguyen (2000) was based on based on only dried specimens with
male inflorescences only (N.T. Bân & Averyanov 385, HN!, 20 June
1989) so the descriptive information lacked color information of plant
parts and characteristics of female inflorescences. Thus, Gusman &
Gusman (2006) suspected that A. condaoense might be a synonym of
A. roxburghii and that "it is necessary to study living material to
identify the status of A. condaoense". To ascertain its identity, we reexamined the questioned taxon. New fresh material (male and female
- Xem thêm -