A new species of Arundinella (Poaceae) from Kerala, India
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Abstract
A new species of Arundinella is described from the state of Kerala in India. It resembles A. metzii Hochst. ex Miq. in having an effuse panicle and awned spikelets but differs from the latter due to its perennial habit, the presence of ovoid silky basal buds and stolons, its pilose culm internode, its broad leaf blade, culms that are pilose below the panicles, short pedicels of spikelets, and its scaberulous upper lemma with a short awn.
INTRODUCTION
The genus Arundinella Raddi (Poaceae, subfamily Panicoideae, tribe Arundinelleae) was described by Raddi (1823: 58) and Arundinella brasiliensis Raddi was selected as type species. Sun and Philips (2006: 563) estimated Arundinella Raddi to have about 60 species distributed in the tropical regions of the world, mainly in Asia. According to Veldkamp (2015: 167) there are 50 species of Arundinella. In India, the genus is represented by 28 species (Hooker, 1896; Fischer, 1934; Bor, 1960; Sreekumar and Nair, 1991; Shaju and Mohanan, 2004; Clayton et al., 2006; Kabeer and Nair, 2009; Govaerts, 2011; Sunil and Naveen Kumar, 2014; Sunil et al., 2014, 2017; Jaiswal et al., 2021; Kellogg et al., 2020; Murugesan et al., 2022), of which 13 species are endemic. According to Sasidharan (2013) the genus represented by 16 species in Kerala. The genus is characterized by panicled inflorescence with 2-flowered spikelets disarticulated above the glumes, entire or 2-lobed or 2-aristate scabrid upper lemmas, punctiform hilums, and short membranous ligules.
Among infrageneric classification of Arundinella Keng (1936: 1) and Phipps (1967: 1047) are two main taxonomic systems. Keng (1936: 1) in a study of Asian species recognized four subgenera and 39 species in Asia, while Phipps (1967: 1047) separated the genus into 15 series and recognized 47 species in the world.
While carrying out an inventory of the floristic diversity of the north Malabar region of Kerala, the authors came across an interesting species of Arundinella in the laterite hills of Kayyur. Critical studies revealed that the species is similar to A. metzii Hochst. ex Miq. but differs in many characteristics (Table 1). Detailed taxonomic studies and perusal of relevant literature proved this to be a new species hitherto unknown to science, which is described and illustrated here.
Comparison of key features of A. metzii and A. bulbifera
TAXONOMIC TREATMENT
Arundinella bulbifera Shaju, Ratheesh Narayanan, Sunil, Rijuraj, & Rajendraprasad sp. nov. (Figs. 1, 2). —TYPE: INDIA. Kerala, Kasaragod District, Chuttupara, Kayyur, 12o15′47.75″N, 75o11′02.79″E, elevation ca. 80 m, 9 Dec 2022, Shaju, Sunil & Rajendraprasad 97553 (holotype: TBGT! isotypes: MH, SNMH).
Arundinella bulbifera sp. nov. a. Habitat. b. Habit. c, d. Basal portion showing basal buds and stolons. e. Leaf sheath. f. Nodal and intermodal portion. g. Ligule. h, h1. Leaf - abaxial and adaxial. i, j. Portions of inflorescence. k. Single spikelet. l, l1. Lower glume - abaxial and adaxial. m, m1. Lower lemma - abaxial and adaxial. n, n1. Lower palea - abaxial and adaxial. o. Upper floret. p, p1. Upper glume - abaxial and adaxial. q, q1. Upper lemma - adaxial and abaxial. r, r1. Upper palea - abaxial and adaxial. S. Stamens and carpel. t. Lodicules.
Arundinella bulbifera sp. nov. a. Habit. b. Bulbous base. c. Single spikelet. d. Single spikelet side view. e. Lower gume adaxial. f. Lower lemma abaxial. g. Lower palaea adaxial. h. Upper glume adaxial. i. Upper lemma adaxial. j. Upper palaea. k. Single stamen
Diagnosis: Arundinella bulbifera related to A. metzii Hochst. ex Miq. by the effuse panicle, awned spikelets but differs in its perennial habit, presence of ovoid silky basal buds and stolons, pilose culm internode, broad leaf blade, culms pilose below the panicles, short pedicel of spikelets and scaberulous upper lemma with short awn.
Perennial herbs. Stolons 2–6 cm long. Basal buds 2–4 × 2–3 mm, ovoid, silky. Culms tufted, erect to geniculate at base, 40–70 cm tall; nodes glabrous to pubescent; internodes pilose with bulbose-based patent hairs. Leaves linear to linear-lanceolate, 8–38 × 0.5–2.3 cm, base truncate to shallowly cordate, apex acuminate, both surfaces pilose with bulbose-based hairs; ligule a hyaline membrane, 0.5–1 mm long, lacerate at apex; sheaths 4– 10 cm long, densely pilose with bulbose-based patent hairs; the hairs 1.6–3 mm long. Inflorescence panicles of racemes, terminal, open, 12–18 × 6–12 cm; main rachis 3-angled, bristly at nodes; racemes 14–18, alternate, 2–8 cm long, 3-angled, scabrid. Spikelets ovate-lanceolate, 2.8–3.2 × 1–1.2 mm, whitish with green nerves, in unequally pedicelled pairs, one short pedicelled and the other long pedicelled; pedicels scabrid, 0.3–0.5 mm long in shorter pedicelled spikelets and 1.5–3 mm long in longer pedicelled spikelets. Lower glume ovate or ovate– lanceolate, 1.8–2 × 1 mm, acuminate at apex, chartaceous, 3-nerved, setose along margins and nerves. Upper glume ovate–lanceolate, 2.8–3.2 × 1–1.2 mm, caudate-acuminate at apex, chartaceous, whitish with 5 green nerves, setose along the nerves. Lower lemma male or bisexual, ovate-lanceolate, 1.9–2.1 × 1–1.2 mm, acute to mucronate at apex, 3-nerved. Lower palea ovate-lanceolate, 1–1.2 × 0.5–0.7 mm, acute at apex, hyaline, 2-nerved, 2-keeled, scabrid on nerves. Upper lemma bisexual, hyaline, ovate or ovate-oblong, 1–1.2 × 0.8–1 mm, apex notched and awned from the sinus, microscopically scaberulous, nerveless; callus sparsely hairy, hairs ca. 0.2 mm long; awns geniculate, 2.7–3 mm long, column ca. 1 mm long, purple, bristle ca. 2 mm long, hyaline. Upper palea oblong, 1–1.2 × 0.4–0.6 mm, obtuse at apex, hyaline, 2-nerved, 2-keeled, microscopically scaberulous. Stamens 2–3; filaments ca. 2 mm long; anthers oblong, 1–1.4 mm long, purple. Ovary ovoid, ca. 0.4 × 0.4 mm; styles 2, ca. 1.2 mm long; stigmas ca. 1 mm long, purple.
Flowering and fruiting: December–February.
Distribution: So far known only from the type locality (Kerala, Kasaragod District, Kayyur: Chuttupara).
Habitat and ecology: Arundinella bulbifera has been collected from Chuttupara, a wetland area among the lateritic plain in Kayyur, Kasaragod district of Kerala, India. This taxon was found with restricted distribution on the habitat in association with Axonopus compressus (Sw.) P. Beauv., Merremia umbellata (L.) Hallier f., Ixora coccinea L., Smilax zeylanica L., Leea indica (Burm. f.) Merr., Syzygium caryophyllatum (L.) Alston, Aporosa sp., Acacia auriciliformis A. Cunn. ex Benth. etc.
Etymology: The specific epithet of the new taxon refers to its prominent basal bulbs.
Conservation status: Arundinella bulbifera has been collected from only one locality with very few individuals. More explorations are essential to understand its distribution and assess its conservation status according to the guidelines and criteria of IUCN Standards and Petitions Committee (2022). Based on the available data, the species should be treated as belonging to the category ‘Data Deficient’ (DD).
Additional specimen examined: INDIA. Kerala, Kasaragod District, Kayyur: Chuttupara, 12o 15′47.75″N, 75o11′02.79″E, ±80 m, Feb 2022, Rijuraj, Shaju & Ratheesh Narayanan, 99140.
Key to the species of Arundinella in Kerala
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1. Upper lemma with two setae, one on each side of the awn at the tip.
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2. Spikelets tubercle-based hairy.
3. Annuals; spikelets 7.5–9.5 mm long; lower lemma 4–4.5 mm long; awn on upper lemma 13–15 mm long ·· A. tuberculata
3. Perennials; spikelets 4–7 mm long; lower lemma 2–3 mm long; awn on upper lemma 5–8 mm long ··· A. mesophylla
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2. Spikelets glabrous to scabrellate, not tubercle-based hairy.
4. Annuals; upper glume caudate at apex ··················································································· A. nervosa
4. Perennials; upper glume acuminate at apex ················································································ A. setosa
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1. Upper lemma with a single awn or awn absent.
5. Spikelets awnless ··············································································································· A. leptochloa
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5. Spikelets distinctly awned.
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6. Spikelets 1–2 mm long.
7. Lower glume 3-nerved; upper glume 5-nerved; upper lemma notched at apex without arista ·············· A. pumila
7. Lower and upper glumes 1-nerved; upper lemma deeply bifid at apex, aristate ·································· A. ravii
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6. Spikelets well over 2 mm long, if 2 mm long then spikelets densely covered with tubercle-based bristles.
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8. Spikelets densely hairy with tubercle-based bristles; panicles generally narrow, spiciform.
9. Leaves elliptic-lanceolate or lanceolate, up to 16 cm long; panicles loosely speculate; spikelets 2–4 mm long; lower glume much longer than the lower lemma ································································· A. ciliata
9. Leaves linear-lanceolate, up to 40 cm long; panicle densely speculate; spikelets 5–8 mm long; lower glume as long as the lower lemma ···························································································· A. vaginata
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8. Spikelets glabrous or sparsely hairy; panicles effuse, if contracted then the spikelets glabrous.
10. Rheophytic perennial grasses; column of awn distinctly flat ········································· A. thirunelliensis
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10. Terrestrial annual or perennial grasses; column of awn terete.
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11. Plants annual.
12. Spikelets 2.5–3 mm long; nodes of panicle glabrous; upper lemma greenish yellow when meatured ·· A. metzii
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12. Spikelets 4–6 mm long; nodes of panicle bearded with long hairs; upper lemma brown when matured.
13. Leaves up to 6 cm long, mostly collected at base of the plant, glabrous or sparsely hairy; branches of panicles ascending; spikelets 5–6 mm long; awns 8–10 mm long ················ A. cannanorica
13. Leaves 10–35 cm long, not collected at base, densely tubercle-based hairy; branches of panicle not ascending; spikelets 4–4.5 mm long; awns 5–7 mm long ······························ A. pradeepiana
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11. Plants perennial.
14. Plants with silky basal buds and stolons ····························································· A. bulbifera
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14. Plants without basal buds and stolons.
15. Panicles often contracted; leaves collected at the base of the plant, bluish-green turning yellowish-green when dry at maturity ········································································ A. purpurea
15. Panicles very effuse; leaves not as above ····················································· A. nepalensis
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Notes
ACKNOWLEDGMENTS
The authors are grateful to the Director, Jawaharlal Nehru Tropical Botanic Garden and Research Institute (KSCSTEJNTBGRI), Palode, Thiruvananthapuram for providing constant help and encouragement in research activities. The second author is grateful to the Principal, Payyanur College, Edat, Kannur for providing necessary support for the work. Third author acknowledge the encouragement and support extended by the Manager, S.N.M. College, Maliankara, Ernakulam. Fourth author is thankful to University of Kerala, Thiruvananthapuram.
CONFLICTS OF INTEREST
The authors declare that there are no conflicts of interest.