Fimbristylis fusiformis Wangwasit & D.A.Simpson, 2017

Wangwasit, K., Muasya, A. M., Chantaranothai, P. & Simpson, D. A., 2017, Taxonomy and phylogenetic position of Fimbristylis fusiformis, a new species of Cyperaceae from Thailand, Blumea 62 (1), pp. 47-52 : 49-52

Fimbristylis fusiformis Wangwasit & D.A.Simpson , sp. nov. — Fig. 1–3; Map 1

Superficially similar to F. pauciflora R.Br. but distinguished by the glumes 6.5–8.5 mm long (vs 2.5–3 mm long in F. pauciflora ), nutlets fusiform, fimbriate at apex and base,with 3 longitudinal costae (vs nutlets obovate and glabrous in F.pauciflora ). — Type: K. Wangwasit 080927-17 (holo K; iso BK, KKU), Thailand, Ubon Ratchathani, Pha Taem National Park , 27 Sept.2008 .

Etymology. Named after the shape of the nutlets.

Rhizomatous perennial. Culms densely tufted, 12–23 cm by 0.1–0.4 mm, trigonous, glabrous. Leaves basal; blade narrowly linear, 4–5 cm by 0.5 mm, obtuse, thickly crescentiform in cross-section, laterally flattened, glabrous; sheath 1–1.5 cm long, stramineous, sides membranous; ligule absent. Involucral bracts glume-like. Inflorescence a single terminal spikelet. Spikelet linear-cylindric, terete, 1 cm by 1.2–1.5 mm. Glumes 9 per spikelet, spirally arranged, lower glume glabrous, uppermost strigose, oblong elliptic, 6.5–8.5 by 1.5–2.3 mm, acuminate, sides membranous, stramineous, reddish brown tinged, keel obtuse, 1-nerved. Stamens 3; anthers 2–2.5 by 0.1–0.2 mm. Stigma branches 3; style persistent; style base rather indistinct, somewhat elongate, gradually widening into the nutlet, scabrous. Nutlets fusiform, trigonous, fimbriate, especially at apex and base, 2.5–3.8 by 0.5–0.85 mm, apex brown to dark brown, with minute hexagonal epidermal cells, longitudinal costae present.

Distribution — Endemic to eastern Thailand. Mostly seen in Pha Taem National Park but also observed in Phu Chong Na Yoi National Park, both in Ubon Ratchathani.

Habitat & Ecology — Open, stony places with scattered tree cover on seasonally wet, sandy soils. Altitude 227 m ( Google Earth 2016).

Conservation status — Least Concern (LC; IUCN 2012). The species occurs in protected areas and is locally abundant in these localities.

Additional specimens examined. THAILAND, Ubon Ratchathani: Khong Chiam, Pha Taem National Park, Khua Nangnee Falls (N15°24'11" E105°31'02"), Pooma, De Wilde & Duyfjes 2270 (BKF); Sribunreung District , 27 Sept.2008, K. Wangwasit 080927-6 (KKU) .

Note — Fimbristylis fusiformis is superficially similar to F. pauciflora , in having an inflorescence with a single terminal linear-cylindric spikelet bearing a glume-like bract. We interpret these similarities to be due to morphological convergence, as the two taxa are not sister in our phylogeny.

Figures

Map 1 Distribution of Fimbristylis fusiformis Wangwasit & D.A.Simpson.