Rafflesia tiomanensis (Rafflesiaceae), a new species from Pulau Tioman, Pahang, Malaysia

Abstract

Rafflesia tiomanensis (Rafflesiaceae), a new species from Pulau Tioman, Pahang, Malaysia SITI-MUNIRAH MAT YUNOH¹, SALAMAH AHMAD² and RAZELAN MOHD SHAH² Abstract : A new outstanding species of the parasitic plant, Rafflesia tiomanensis, was discovered on Pulau Tioman, Pahang, Malaysia. R. tiomanensis is characterised by small discrete warts on the perigone lobes, the absence of warts on the diaphragm upper surface, lack of processes on the disk, the absence of disk rims, and the irregular shape whose opening aperture is variably lobed. All other species in Peninsular Malaysia have warts on the diaphragm upper surface, processes, and disk rims. This new species is thus entirely unique. The species description, colour plates, and provisional conservation status are provided.

Full text

Rafflesia tiomanensis (Rafflesiaceae),
a new species from Pulau Tioman, Pahang, Malaysia
SITI-MUNIRAH MAT YUNOH¹, SALAMAH AHMAD² and
RAZELAN MOHD SHAH²
Abstract : A new outstanding species of the parasitic plant, Rafflesia tiomanensis, was
discovered on Pulau Tioman, Pahang, Malaysia. R. tiomanensis is characterised by small
discrete warts on the perigone lobes, the absence of warts on the diaphragm upper surface,
lack of processes on the disk, the absence of disk rims, and the irregular shape whose
opening aperture is variably lobed. All other species in Peninsular Malaysia have warts on the
diaphragm upper surface, processes, and disk rims. This new species is thus entirely unique.
The species description, colour plates, and provisional conservation status are provided.
Key words : endemic, morphology, new species, Pulau Tioman, Rafflesia tiomanensis.
INTRODUCTION
Rafflesia R. Br. is a genus of endophytic holoparasites that exclusively infect lianas of the
genus Tetrastigma (Miq.) Planch., which inhabits the tropical rainforests of southern
Thailand, Malaysia, the Philippines, and Indonesia. In Peninsular Malaysia, seven species
of Rafflesia are currently recognised, namely Rafflesia cantleyi Solms-Laubach.
(Solms- Laubach, 1910), R. kerrii Meijer (Meijer, 1984), R. azlanii Latiff & Wong (Latiff
and Wong, 2003), R. su-meiae Wong, Nais & Gan (Wong et al., 2009), R. sharifah-hapsahiae
Adam, Mohamed, Aizat-Juhari & Wan (Adam et al., 2013), R. parvimaculata Sofiyanti,
Mat-Salleh, Khairil, Zuhailah, Mohd Ros & Burslem (Sofiyanti et al., 2016) and
R. tuanku-halimii Adam, Aizat-Juhari, Azilah & Wan (Adam et al., 2016). All of the
aforementioned species are endemic to Peninsular Malaysia except R. kerri, which is
known to inhabit both Peninsular Malaysia and southern Thailand. Although it is found in
four states in Peninsular Malaysia, including Pulau Tioman, Rafflesia has not been reported
in Johor, Melaka, Selangor, Negeri Sembilan, Kedah, and Perlis to date.
Pulau Tioman is the southern island in Pahang and is known as one of the most
beautiful tropical islands in the world. Most part of Pulau Tioman remains covered by
pristine primary tropical rainforests, including the highest point of Gunung Kajang, which
lies about 1038 m above sea level. In the context of ecotourism in the Pulau Tioman forest
area, Bunga pakma or Rafflesia is an iconic flower, and many tourists hike to see it while
visiting the island. Based on the work of Siti Munirah et al. (2020) Rafflesia populations in
Pulau Tioman were identified as Rafflesia cantleyi. The majority of the Rafflesia population
in Pulau Tioman has been well documented (Siti Munirah et al. 2020). While exploring the
Tioman forest area during a routine nature trip in the area of Kg. Juara, the third author,
Mr. Razelan, first encountered this notable new species. It was then reported to the first
author, and after careful examination, the flower was found to have a unique combination
of characteristics that do not match any known species. Hence, it is described here as a new
species (Figure 1).
Malayan Nature Journal 2021, 73(1), 19-26
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¹Forest Research Institute Malaysia, 52109 Kepong, Selangor, Malaysia.
²Kampung Juara, Pulau Tioman, Pahang, Malaysia.
Corresponding author: sitimunirah@frim.gov.my

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Figure 1. Rafflesia tiomanensis Siti-Munirah, Salamah & Razelan sp. nov.
A. Habitat showing flower on its host, Tetrastigma rafflesiae; B. Mr. Razelan with flower;
C. A fully bloomed R. tiomanensis.

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MATERIALS AND METHODS
This study is based on material documented in 2020 from Pulau Tioman (Figure 2). The
specimens were preserved as herbarium specimens in the KEP herbarium collections.
Morphological characters were studied using an image from high-resolution macro
photography. Measurements were taken from the living and dry-preserved material. The
specimen details were thoroughly compared with original drawings and descriptions given in
the worldwide protologues of the genus Rafflesia.
Figure 2. Type locality of Rafflesia tiomanensis (●).
Taxonomy
Rafflesia tiomanensis M.Y. Siti-Munirah, A. Salamah & M.S. Razelan sp. nov.
(Figures 1 and 3-4)
Type: MALAYSIA. Peninsular Malaysia: Pahang, Rompin District, Pulau Tioman, lowland
dipterocarp forest, 320 m altitude, 9 November 2020, Salamah & Razelan FRI 94892 (Male
flower). (holotype KEP!).
Rafflesia tiomanensis is unique in that it has perianth lobes that are variable in size and shape
(other species typically have rounded or suborbicular lobes that are similar in size); warts on
its perianth lobes, which range in size from very tiny to 1 cm and are distributed across the
upper surface in a variable pattern (other species warts are consistent in size and distribution
pattern); an absence of warts on the upper surface of the diaphragm (other species show warts
on the upper surface of the diaphragm); an irregular opening that is unequal and variably lobed
(other species have rounded or irregular lobes); a lack or near-lack of processes (other species
are present and noticeable); a disk rim absent (others species are always present). Other
species herein refer to those in Peninsular Malaysia, namely R. cantleyi, R. kerri, R. azlanii,
R. su-meiae, R. sharifah-hapsahiae, R. parvimaculata and R. tuanku-halimii.
Holoparasite. Buds mature ca. 72 cm (circumference). Flower ca. 40-42 cm diameter when
fully open. Perigone lobes (petals) valvate, 5, sub-irregular, size varies, ca. 9-16 cm long,
13-21 cm wide, reddish, margins entirely to irregularly, wavy; upper surface covered with
powdery white warts that are remarkably sparse, variously shaped; outer surface contains

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numerous white moles. Diaphragm ca. 21-25 cm diameter, rounded; upper surface
glabrous, warts are absent; lower surface (windows) dark reddish and cover with sparse
small rounded white warts; aperture (diaphragm opening) ca. 10-14 cm diameter, irregular
shape, variable lobe size, margin rim dark red band c. 1 cm. Tube perigone ca. 17 cm
height; (inner) maroon-red cover with ramenta; upper ramenta dark simple, slender, thin,
some with thick stalks, maroon-reddish, swollen white apex, unbranched, lower ramenta
slender, thin, completely unbranched and fully maroon. Disk 8 cm diam., flat with a rim’s
margin absent, not raised; disk fully visible through the aperture, pale yellowish darker at
the margin. Processes lack and almost absent; undeveloped processes about 8, very short
each with trichomes. Anthers 26; pollen yellow.
Distribution. Endemic to Pulau Tioman, Pahang, Peninsular Malaysia. Currently known
only from the type locality (Figure 2).
Ecology. Insular lowland dipterocarp forest, under shade, at 320 m altitude. Flowering in
November. R. tiomanensis was encountered growing on its host plant Tetrastigma rafflesiae.
The host plant was found near the walking trail. The habitat is near to a population of
R. cantleyi.
Etymology. The species is named after Pulau Tioman, the type locality of this species.
Provisional conservation status. Vulnerable VU D2. Following the IUCN Standards and
Petitions Committee (2019), this species is assessed as vulnerable because it is only known
from the type locality and is certainly an endemic and very rare species. Less than ten
individuals were observed, including both flowering and growing (buds) individuals. The
site where R. tiomanensis were found is currently a tourist area within Pulau Tioman. Any
guide can freely bring tourists to the area without special permission from the Lembaga
Pembangunan Tioman or PERHILITAN. Although the locality is within the wildlife forest
reserve, which is a protected area, the area is located not far from the main road Tekek-Juara
and close to the walking trail, which are used by most of the tourists visiting the Kampung
Juara forest area.
Due to the fact that it relies on its host for safety, the plant can be threatened by
irresponsible individuals, and it is highly possible that it will be disturbed. Without proper
guidance or legal protections, the existence of R. tiomanensis might be threatened.
R. tiomanensis qualifies for VU D2 because of its minute and restricted population; only
one host has been recorded thus far. Given the species’ regular exposure to tourists, a
population reduction is certainly possible, and due to its small population, the species could
become Endangered or Critically Endangered in the future.
DISCUSSION
Typically, the taxonomy of Rafflesia is entirely based on floral morphology (form and
structure), with an emphasis on outer appearance. The current species delimitation of
Rafflesia is based on eight major characters, which are listed by Nais (2001). Based on a
comparison of the specimen with the protologue specimen and type images, significant
differences are apparent in most morphological features, with few remaining similarities.
This is the first report of a notable newly-described, very rare plant R. tiomanensis
which inhabits Pulau Tioman itself and is significantly different from other Rafflesia
individual “bunga pakma” species found on Pulau Tioman, Malaysia or elsewhere in the
world. Morphologically, this new species is quite remarkable and its diagnostic
characteristics stand on their own.

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Following most revisions and all protologues (Meijer, 1984, 1997; Nais, 2001; Abdul
Wahab et al. 2018), the species does not resemble any previously described species. The
morphological characteristics of R. tiomanensis represent interesting findings, as the warts on
the perigone lobes are completely discrete and well-spaced and the pattern is not consistent
between each perigone lobe. These small and discrete characters most closely resemble
those of R. kerri, a large highland species that grows up to 110 cm diameter, but even this
species remains largely dissimilar from R. tiomanensis. Furthermore, unlike other species,
R. tiomanensis flower does not possess any warts on the diaphragm upper surface. Its opening
aperture is also notable, as it has an irregular shape with variably sized lobes.
Moreover, its disk does not have a raised rim, a character which is different from any
other species in Malaysia. The other species that does not have a raised or slightly raised
margin is R. rochussenii (Meijer, 1997) of Java and R. leonardii (Barcelona and Pelser, 2008),
from the Philippine. R. tiomanensis also shows a lack of processes while most other species
have a well-developed process. Again, this character was also found in certain species like
R. rochussenii. These diagnostic characteristics are undoubtedly different from the morphological
variations that have been documented previously by Siti Munirah et al. (2020) (Figure 3). All
these significant differences, the warts pattern, the diaphragm form, the disk structure, the lack
of a raised rim and lack of processes, set R. tiomanensis apart from other Rafflesia species
around the world and strongly support the recognition of this outstanding new species.
Acknowledgements: This research was carried out as part of the Flora of Peninsular Malaysia
Project (FPM) at the Forest Research Institute Malaysia (FRIM), Kepong, funded by the Ministry
of Energy and Natural Resources (KeTSA) of Malaysia under the 11th Malaysian Plans
(SPPII No. P23085100018003). We would like to thank Lembaga PembangunanTioman and
PERHILITAN for their continuing support of research activities. We also thank Mohd. Faizal
Mat Tahir for the courage and significant help during the preparation of the manuscript.
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Figure 3. Rafflesia tiomanensis.
A. Flower in full bloom; B. Side view of a flower attached to the host plant;
C-E. Perigone lobes (petals); F. Top view of the diaphragm; G. Disk.

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Figure 4. Inner part of perigone tube of Rafflesia tiomanensis.
H. Inner surface from the top to the base; I. Lower surface of the diaphragm; J. Upper ramenta;
K. Lower ramenta; L. Disk and annulus; M. Lack or very short processes with trichomes;
N. Surface below the disk showing a pollen ring.

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Figure 5. Rafflesia flowers from various populations.
A-I. R. cantleyi from Pulau Tioman J. R. cantleyi from Perak.
K. R. kerri from Kelantan.