Fimbristylis sunilii, Sanilkumar & Nithya, 2021

Sanilkumar, Malayil Gopalan, Nithya, Vadassery Madhanan, Divya, Periyattu Veedu & Baiju, Edathiruthi Chandran, 2021, Fimbristylis sunilii (Cyperaceae): A new species from Southern Western Ghats, Kerala, India, Phytotaxa 527 (1), pp. 83-88 : 83-87

Fimbristylis sunilii, Sanilkumar & Nithya , sp. nov. ( Fig. 1 and 2 ).

Diagnosis:— Fimbristylis sunilii , superficially similar to F. aphylla Steud. , by the presence of separate sterile and fertile shoot, 5-angled culm, leaves with prominent midvein and 3-sided nuts but differs from it in having horizontally shortly creeping rhizome on which culms are arranged in a row (vs short non-creeping rhizome with tufted culms), small inflorescence with 4–15 spikelets (vs large inflorescence with many spikelets), 6–13-flowered long spikelets (vs many flowered short spikelets), prominently keeled large glume with brown dotted sides and mucronate apex (vs faintly keeled small glume without brownish spotted sides and mucro), presence of 3 stamens with long anthers (vs 1–2 stamens with short anthers) and large smooth nut with 7–11 vertical rows of transversely oblong-linear epidermal cells on each face (vs small densely verruculose nut with transversely linear epidermal cells which are arranged in 4–6 vertical rows in each face). The new species also shows resemblance with F. salbundia (Nees) Kunth in its horizontally creeping rhizome on which culms closely arranged in a row and its pentagonous culms. However, it is quite distinct in having leafy sterile shoots (vs. sterile shoots absent), short simple to compound inflorescence with up to 15 spikelets (vs. large decompounds inflorescence with many spikelets), up to 13-flowered, 5–8 mm long spikelets (vs. many- flowered 3–5 mm long spikelets) and 3–4 mm long glumes with mucronate apex and brown dotted sides (vs. 2–2.5 mm long glumes with muticous apex and without brown spots on sides).

Type:— India, Kerala, Thiruvananthapuram district, Ponmudi , elevation. 1100 m, 12 December 2018, M.G. Sanilkumar & Nithya Madanan 4863 (Holotype: MH! ; isotype: CALI!, SNMH!, CMPR!)

Perennials, 20–59 cm tall. Rhizome horizontal, woody, shortly creeping, 1–7.5 cm long, 2.5–5 mm thick, clothed with pale brown scales; scales 0.8–2.2 × 0.5–0.8 cm, triangular to ovate, acute at apex, imbricate; roots stout, 0.5–1.2 mm thick. Flowering shoots and sterile shoots in a row along the rhizome. Culms smooth, glabrous, 5-angled, 1–2 mm thick. Leaves on culms reduced to bladeless sheaths; sheaths 1.5–6.5 cm long, pale brown. Leaves of sterile shoots well-developed; blades 5–32 cm long, 1.6–4 mm wide, linear, flat to canaliculate with a prominent mid-vein on the lower surface, scabrid along the margins towards apex, acute to subacute or mucronate at apex; ligule absent. Inflorescence simple to compound, corymbose, 2– 4.5 cm long, 1.5–5 cm wide, loosely bearing 4–15 spikelets. Rays 2–5, unequal, 0.8–3.4 cm long, compressed. Involucral bracts 3–7, shorter than inflorescence, 3–12 mm long, 0.3– 1mm wide, linear, scabrid on the margins, acute at apex. Spikelets solitary, 5–8 × 1.6–2.2 mm, ellipsoid, terete, acute at apex, pale brownish, 6–13-flowered; rachilla winged. Glumes spirally imbricated, lowest 2–4 distichous, 3–4 × 2–2.6 mm, ovate-oblong, boat-shaped, mucronate at apex, brown,sides paler but dotted with brownish spots, subcoriaceous with 3-nerved keel; lowest 1 or 2 glumes empty, ovate, long-mucronate, 2.8–3.4 mm long including 1–1.4 mm long scabrid mucro, 1.7–2 mm wide. Stamens 3; anthers 0.9–1.3 mm long, oblong, apiculate at apex, yellow. Ovary ca.0.3 × 0.2 mm, subglobose; style 1–1.4 mm long, glabrous or sparsely hairy at apex; stigmas 3, 1.5–2 mm long, hirsute. Nuts 1–1.3 × 0.9–1.2 mm, obovoid, somewhat asymmetric, 3-sided, whitish or straw coloured, smooth; epidermal cells transversely oblong-linear in 7–11 vertical rows on each face.

Additional specimen examined (Paratype): INDIA, Kerala, Thiruvananthapuram district, Agasthyamala Biosphere Reserve , Pongalappara , 25 February 2018, C.N.Sunil & M.G. Sanilkumar 4967 ( SNMH!) .

Phenology:— Flowering and fruiting from December through April.

Etymology:—The species epithet is named after renowned plant taxonomist from India, Dr. CN Sunil, Professor and Research Guide of Botany, at SNM College, Maliankara, also taught Plant Taxonomy for more than 30 years in Post graduate programme (M.Sc. Botany). Fimbristylis sunilii , is a humble honor offered by his students, in recognition of his immense contribution in plant taxonomy.

Conservation status:—This plant has been provisionally assessed here as Data Deficient (DD) according to IUCN Red List Categories and criteria ( IUCN, 2017). The available information is inadequate to assess the risk factor, though the plant was found in two somewhat close localities. It is currently known only from the type locality. Further explorations are needed in adjacent similar habitats to estimate overall distribution, number of populations, number of subpopulations, number of mature individuals in its overall distributed areas and percentage of population decline during past years.

Habitat, Distribution and Biotic association:— The new species grows in the high altitude grasslands at an elevation of 1100 MSL in association with Arundinella ciliata ( Roxburgh 1820:321) Nees ex Miquel (1851:30) , Isachne setosa Fischer (1932:247) and Hedyotis purpurascens Hook. f. (1880: 50).

Figures

FIGURE 1. A. Habit, B. Rhizome with fertile and sterile shoots, C. Apex and margin of leaf blade, D. C.S. of culm, E. Inflorescence, F. Single spikelet, G. Rachilla showing wings, H-J Fertile glume, H. Abaxial view. I. Adaxial view, J. Side view, K. Adaxial view of sterile glume, L. Single Stamen, M. Pistil, N. Nut.

FIGURE 2. SEM images A. Entire view of nut (inverted), B. Portion of a nut surface, C. Single cell enlarged.