KEW BULLETIN VOL. 64: 747–750 (2009)
Arundinella kokutensis (Poaceae, Arundinelleae), a new species
from south-eastern Thailand
Atchara Teerawatananon1,3, Sarawood Sungkaew2 & Trevor R. Hodkinson3
Summary. Arundinella kokutensis Teerawat. & Sungkaew is described and illustrated here as a new species from Kut
Island, Trat Province, Thailand.
Key Words. Arundinella, Gramineae, Poaceae, Thailand.
Introduction
The genus Arundinella was established by Raddi (1823)
based on the type species Arundinella brasiliensis Raddi
collected from Brazil but now recognised as A. hispida
(Willd.) Kuntze. This genus is distinguished by its
paired, 2-flowered spikelets which disarticulate above
the glumes, scabrid upper lemmas, punctiform hilums
and short membranous ligules. Clayton & Renvoize
(1986) reported that there are about 50 species of
Arundinella, distributed chiefly in Asia, an estimate that
has now been raised to approximately 60 species (Sun
& Phillips 2006).
Among the specimens of the genus Arundinella
collected from Thailand, a very distinctive collection,
Charoenphol et al. 5104 from Kut Island, Trat Province,
Southeastern Thailand was previously labelled as Arundinella metzii Hochst. ex Miq. After re-collecting and
critically examining both living and herbarium specimens, from the same locality, their morphology could
not be matched with the species descriptions or type
specimens of A. metzii (Hohenacker 297 (K)), nor any
other Arundinella species. Neither do they fit within the
natural range of morphological variation found within
those other species. Therefore, a new species A.
kokutensis Teerawat. & Sungkaew is described here.
Arundinella kokutensis Teerawat. & Sungkaew sp. nov.
Species A. metziae Hochst. ex Miq. et A. holcoidi (Kunth)
Trin. affinis, sed ab illis ramis et pedicellis fere glabris,
glumis imus glabris, aristis lemmatium superiorium 5 –
6.5 mm longis, staminibus 2 differt. Typus: Charoenphol
et al. 5104 (holotypus K!; isotypi BKF!, C!, E!, NY!).
Annual. Culms slender, 5 – 80 cm tall, erect, shortly
decumbent at base; nodes sparsely pubescent. Leafsheaths 2 – 8 cm long, hispid with tubercle-based hairs
especially along margins. Ligule a ciliate membrane,
0.8 – 1.3 mm long. Leaf-blades oblong-lanceolate, (1 −)
5 – 30 × (0.3 −) 0.6 – 1.3 cm, hispid with tuberclebased hairs on both surfaces, margins sometimes
scaberulous. Panicles open, sometimes drooping,
(3 −) 10 – 25 cm long; racemes (2 –) 4 − 10 cm long,
alternate, rhachis almost glabrous, rarely scabrous.
Spikelets green, ovate-lanceolate, 3 – 4 × 0.6 – 1 mm;
pedicels 0.5 – 6 mm long, glabrous; lower glumes ovatelanceolate, 2 – 2.5 × 0.5 – 1 mm, almost glabrous,
sometimes scabrous at apex, acuminate to aristate, 3 –
5-nerved; upper glumes ovate-lanceolate, 3 – 3.5 (− 4) ×
0.5 – 1 mm, glabrous to sparsely hispid with tuberclebased hairs, caudate, recurved, 5-nerved; lower florets
barren; lower lemmas ovate-lanceolate, 2 – 2.5 mm long,
acute, 5-nerved; lower paleas ovate-oblong to ovatelanceolate, 1.5 – 2 mm long; upper lemmas ovateoblong, 1 – 1.5 mm long, minutely bifid, awned from
the sinus, awns 5 – 6.5 mm long, 3-nerved; upper paleas
ovate-lanceolate, 1.2 – 1.4 mm long, acute; callus hairy,
hairs 0.3 – 0.5 mm long; stamens 2 rarely 3, anthers
yellow, 0.3 – 0.5 mm long; styles 2, stigmas purple, 0.5 –
0.7 mm long. Caryopsis ovoid-elliptic, 1 – 1.2 mm long.
Fig. 1.
DISTRIBUTION. Endemic to Thailand.
SPECIMENS EXAMINED. THAILAND. Trat: Ko Kut, (12°
35'N 101°31'E), 21 Nov. 1970, Charoenphol et al. 5104
(BKF, C, E, K, NY); loc. cit., 3 April 2006, Teerawatananon & Sungkaew 914 (BKF, TCD, Herbarium of
Accepted for publication September 2009.
1
Natural History Museum Thailand, National Science Museum, Technopolis, Pathum Thani, 12120, Thailand. e-mail: teerawaa@tcd.ie
2
Department of Forest Biology, Faculty of Forestry, Kasetsart University, Bangkhen, Bangkok, 10900, Thailand. e-mail: sarawoodsungkaew@yahoo.com
3
Department of Botany, School of Natural Sciences, Trinity College, University of Dublin, Dublin 2, Ireland. e-mail: hodkinst@tcd.ie
© The Board of Trustees of the Royal Botanic Gardens, Kew, 2010
748
KEW BULLETIN VOL. 64(4)
Fig. 1. Arundinella kokutensis. A habit; B inflorescence; C spikelets; D lower glumes; E upper glumes; F lower lemmas; G lower
paleas; H upper lemmas; J upper paleas. All from Charoenphol et al. 5104. DRAWN BY ATCHARA TEERAWATANANON.
© The Board of Trustees of the Royal Botanic Gardens, Kew, 2010
glabrous or pubescent
up to 50 cm, an open panicle
scabrous
scabrous
c. 1 mm long
0.4 – 0.5 mm long
c. 3 mm long
3
hirsute
3 – 15 (− 20) cm long, a narrow panicle
scabrous and pilose with tubercle-based hairs
glabrous, sometimes sparsely pilose
1 – 1.3 mm long
0.2 – 0.3 mm long
4 – 4.5 mm long
3
sparsely pubescent
(3 −) 10 – 25 cm long, an open panicle, sometimes drooping
almost glabrous, rarely scabrous
glabrous
1 – 1.5 mm long
0.3 – 0.5 mm long
5 – 6.5 mm long
2 (extremely rarely 3)
Nodes
Inflorescence
Rhachis
Pedicels
Upper lemmas
Callus hairs
Awns
Stamens
A. holcoides
A. kokutensis
Species/ Characters
Table 1. Morphological variation in Arundinella kokutensis and its close relatives, A. holcoides and A. metzii.
A. metzii
ARUNDINELLA KOKUTENSIS (POACEAE, ARUNDINELLEAE), A NEW SPECIES FROM SOUTH-EASTERN THAILAND
749
Thailand Natural History Museum, National Science
Museum & 3 April 2006, Teerawatananon & Sungkaew
917 (TCD, Herbarium of Thailand Natural History
Museum, National Science Museum).
HABITAT. Growing on shaded, moist and mossy
granite rocks, along streams in tropical monsoon
rainforest.
ETYMOLOGY. This species is named after the island
(‘Ko’ in Thai) called Kut, Trat Province, southeastern
Thailand, where this plant was collected for the first
time.
CONSERVATION STATUS. Arundinella kokutensis is
extremely restricted in distribution and specific habitat, occurring in small populations. It is very likely an
endemic to Ko Kut. We recommend treating this
species as Vulnerable (VU) D1 D2 until more data are
obtained.
NOTES. Arundinella kokutensis has only two stamens
instead of three as normally found in other species of
the genus (Keng 1936; Bor 1955; Watson & Dallwitz
1992; Clayton et al. 2006; Sun & Phillips 2006).
Occasional florets with three stamens can be found
but the occurrence is extremely rare within an
inflorescence that predominantly contains florets with
two stamens. This species is similar to A. holcoides and
A. metzii but can be distinguished from them by its
almost glabrous rhachis, a glabrous pedicel, an awn of
the upper lemma which is longer (5 – 6.5 mm long),
and its stamen number which is only two. The differences between A. kokutensis, A. holcoides and A. metzii
are summarised in Table 1.
Acknowledgements
The authors are grateful to the curators and the staff
of the following herbaria: BKF, C, E, K, and NY for the
use or loan of specimens. Thanks to Prof. Dr Pranom
Chantaranothai for his kind comments and useful
suggestions, to Prof. John Parnell and Dr Pimwadee
Pornpongrungrueng for their support of the work,
and Prof. Dr Benjamin Øllgaard for help with the
Latin diagnosis. This work was supported by the TRF/
BIOTEC Special Program for Biodiversity Research
and Training Grant T_148026.
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