Xyris thailandica Phonsena & Chantar., 2012

4. Xyris thailandica Phonsena & Chantar. View in CoL , sp. nov. — Fig. 4 View Fig ; Plate 1h, i View Plate 1 , 2g, h View Plate 2 ; Map 1 View Map 1

Xyridi linifoliae similis habitu cormo subterraneo, sed foliis linearibus (versus teretis), folii marginibus papillosis (versus laevibus) differt. — Typus: Phonsena 6444 (holo KKU; iso BK, BKF, L), Thailand, Loei, Phu Kradueng National Park, trail from Lang Pae to Pha Mak Duk , 1280 m, 28 Oct. 2009 .

Solitary perennial herb, 25 –50(–70) cm tall, base abruptly dilated and bulbous. Bulb ovoid, 1.6 – 2.5 by 0.9 –1.8 cm. Leave s (2–)3 per plant, linear, flattened, twisted, 20–50 cm by 1.5 – 2.2 mm, without a ligule; blade smooth, margin papillose or finely serrate, apex bluntly oblique to acute. Scape terete, 1.6 –2 mm thick. Spike ovoid to ellipsoid, 1.1–1.6 by 0.7–1 cm. Sterile bracts 4 –7, reddish- to blackish brown, obovate to circular, 4 –6 by 3 –6 mm, margin entire, apex lacerate or entire. Fertile bracts reddish- to blackish brown, ovate, 5 – 6 by 4 – 5 mm, margin entire, apex lacerate or entire; stomate field triangular, 1.4–1.6 by 0.9–1.2 mm. Lateral s epals hyaline or brown, 5 –7 by c. 1 mm, crest entire. Petal limbs yellow, obovate, 10–13 by 8 –9 mm, margin distally lacerate. Staminodia bibrachiate, branches elongate-penicillate, 3.5– 4 mm long. Anthers oblong, c. 2.5 mm long, shallowly bifid, deeply sagittate, filaments 1.5–2 mm long. Style terete, 6.5–7 mm long, distally 3-branched, branches c. 3 mm long. Capsules brown, obovoid, 4 – 5 by 2 –3 mm. Seeds reddish brown, translucent, narrowly ellipsoid, 0.9 –1.1 mm long, 0.3– 0.4 mm diam, with 14–15 longitudinal ridges and with 1–4 transverse ridges between the longitudinal ridges.

Distribution — Endemic to North-Eastern Thailand, known only from a restricted area in Phu Kradueng National Park and Phu Ruea National Park.

Habitat & Ecology — On open places, among grasses in lower montane pine-oak forest at 1187–1280 m altitude.

Phenology — Flowering: September to November, between the late rainy season and the beginning of the dry season. The flowers open in the afternoon at 2.00 p.m. and persist until 5.00 p.m.

Vernacular name — Kathin phu.

Specimens examined. Loei ( Phu Kradueng National Park, trail from Lang Pae to Pha Mak Duk , 1280 m alt., 16°53'N, 101°49'E): Phonsena 6444 ( BK, BKF, KKU, L), 28 Oct. 2009 GoogleMaps ; Phonsena 6588 ( BK, BKF, K, QBG), 13 Nov. 2010 . Loei ( Phu Ruea National Park, Phu Son Camping Ground , 1187 m alt., 17°30'N, 101°20'E): Phonsena & Sutthisaksopon 6759 ( BKF, KKU), 1 Oct. 2011 GoogleMaps .

Conservation status — Xyris thailandica is endemic to Thailand, recorded only from Phu Kradueng National Park and Phu Ruea National Park. Its extent of occurrence is estimated to be less than 50 km 2, but the population in these national parks are well protected. A rating of Endangered (EN, IUCN 2001) is merited.

Note — Xyris thailandica is similar to X. linifolia by having a bulbous underground stem, but differs in its flat, linear leaves (terete in X. linifolia ) and in its papillose margin of the leaves (entire in X. linifolia ). Xyris thailandica is a montane species, occurring above 1 000 m altitude whereas X. linifolia occurs in the lowland, between 180 –200 m altitude.