Kew Bulletin

, Volume 64, Issue 4, pp 747–750

Arundinella kokutensis (Poaceae, Arundinelleae), a new species from south-eastern Thailand

Authors

    • Natural History Museum ThailandNational Science Museum
    • Department of Botany, School of Natural Sciences, Trinity CollegeUniversity of Dublin
  • Sarawood Sungkaew
    • Department of Forest Biology, Faculty of ForestryKasetsart University
  • Trevor R. Hodkinson
    • Department of Botany, School of Natural Sciences, Trinity CollegeUniversity of Dublin
Article

DOI: 10.1007/s12225-009-9168-5

Cite this article as:
Teerawatananon, A., Sungkaew, S. & Hodkinson, T.R. Kew Bull (2009) 64: 747. doi:10.1007/s12225-009-9168-5
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Summary

Arundinella kokutensis Teerawat. & Sungkaew is described and illustrated here as a new species from Kut Island, Trat Province, Thailand.

Keywords

ArundinellaGramineaePoaceaeThailand

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 kokutensisTeerawat. & Sungkaewsp. 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 56.5 mm longis, staminibus 2 differt. Typus: Charoenphol et al. 5104 (holotypus K!; isotypi BKF!, C!, E!, NY!).

Annual. Culms slender, 580 cm tall, erect, shortly decumbent at base; nodes sparsely pubescent. Leaf-sheaths 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 ) 530 × (0.3 ) 0.6 1.3 cm, hispid with tubercle-based 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, 34 × 0.6 1 mm; pedicels 0.56 mm long, glabrous; lower glumes ovate-lanceolate, 2 2.5 × 0.5 1 mm, almost glabrous, sometimes scabrous at apex, acuminate to aristate, 35-nerved; upper glumes ovate-lanceolate, 33.5 ( 4) × 0.5 1 mm, glabrous to sparsely hispid with tubercle-based 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 ovate-lanceolate, 1.5 2 mm long; upper lemmas ovate-oblong, 1 1.5 mm long, minutely bifid, awned from the sinus, awns 56.5 mm long, 3-nerved; upper paleas ovate-lanceolate, 1.2 1.4 mm long, acute; callus hairy, hairs 0.30.5 mm long; stamens 2 rarely 3, anthers yellow, 0.3 0.5 mm long; styles 2, stigmas purple, 0.50.7 mm long. Caryopsis ovoid-elliptic, 1 1.2 mm long. Fig. 1.
https://static-content.springer.com/image/art%3A10.1007%2Fs12225-009-9168-5/MediaObjects/12225_2009_9168_Fig1_HTML.gif
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.

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 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.
Table 1.

Morphological variation in Arundinella kokutensis and its close relatives, A. holcoides and A. metzii.

Species/ Characters

A. kokutensis

A. holcoides

A. metzii

Nodes

sparsely pubescent

hirsute

glabrous or pubescent

Inflorescence

(3 −) 10 – 25 cm long, an open panicle, sometimes drooping

3 – 15 (− 20) cm long, a narrow panicle

up to 50 cm, an open panicle

Rhachis

almost glabrous, rarely scabrous

scabrous and pilose with tubercle-based hairs

scabrous

Pedicels

glabrous

glabrous, sometimes sparsely pilose

scabrous

Upper lemmas

1 – 1.5 mm long

1 – 1.3 mm long

c. 1 mm long

Callus hairs

0.3 – 0.5 mm long

0.2 – 0.3 mm long

0.4 – 0.5 mm long

Awns

5 – 6.5 mm long

4 – 4.5 mm long

c. 3 mm long

Stamens

2 (extremely rarely 3)

3

3

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.

Copyright information

© The Board of Trustees of the Royal Botanic Gardens, Kew 2009