Hedyotis puffii Wangwasit & Chantar., 2015

Wangwasit, Khanit & Chantaranothai, Pranom, 2015, Notes on Hedyotis L. (Rubiaceae) from Thailand, Phytotaxa 206 (1), pp. 47-52 : 49-50

Hedyotis puffii Wangwasit & Chantar. , sp. nov. ( Figs. 1 2 )

Hedyotis puffii has many features in common with H. tavoyensis , especially its capitate inflorescences with long axillary peduncles. It differs most obviously in its angled stems with obtuse edges and the rim of the calyx with (0)1 2 glands.

Type:— THAILAND. Trang: Khao Soi Dao, 700 m, 28 April 1930, A.F.G. Kerr 19285 (holotype K!, isotypes BM!, L!).

Perennial herb or undershrub; stems erect or ascending, 50 100 cm tall, quadrangular, with obtuse angles in young branch and terete in old branch, glabrous. Leaves opposite, ovate to narrowly ovate, 4 12 × 1 4.2 cm, apex acuminate or acute, base attenuate, margin entire, chartaceous to subcoriaceous; both surfaces entirely glabrous; lateral veins 6 8 pairs, distinct on upper surface and indistinct on lower surface; petiole 4 20 mm long, glabrous. Stipules with connate margins above petioles, indistinct, sheath triangular or broadly triangular, apex caudate, 4.5 6 × 3 5.5 mm, glabrous; margins with 11 22 sessile black glands. Inflorescences axillary, capitate, 0.8 1.5 cm in diam.; peduncle 4 10 cm long; primary branches trichotomous, with two ovate to narrowly ovate acute bracts; bracteoles narrowly elliptic to narrowly oblong, apex reaches up to the apex of calyx lobes; usually with 1(2) marginal glands on each side of calyx lobe; pedicel 0.8 2 mm long. Hypanthium 0.7 0.9 mm long, obovoid. Flowers white, narrowly infundibular; heterostylous. Calyx tube 0.1 0.4 mm long; lobes 4, oblong or narrowly oblong, 1.7 2 × 0.4 0.8 mm, apex acute, glabrous, margins usually with 1(2) glands. Corolla tube 3 3.3 mm long, glabrous outside, tomentose inside especially near throat; lobes 4, ovate, 1.7 2.2 mm long, apex acute; glabrous on both sides. Stamens 4. Stigma bilobed. Ovary 2-locular, glabrous. Long-styled flowers: filaments subsessile, glabrous, attached at ¾ from base to top of tube length; anthers oblong, 1 1.2 × 0.15 0.2 mm, inserted; style 4.8 5 mm long; stigma 0.5 0.6 mm long, exserted. Short-styled flowers: filaments ca. 1.0 mm long; anthers oblong, 1.2 1.3 × 0.15 0.2 mm, exserted; style 1.8 2.0 mm long, glabrous; stigma 1 1.3 mm long. Capsules septicidally and loculicidally dehiscent, obovoid or subglobose, 1.3–2.0 mm diam. Seeds 4 7 per locule, dorsiventrally compressed with a longitudinal hilar ridge, 0.5 0.7 × 0.8 1 mm, dorsal face flattened, oblong, elliptic triangular or polyangular, exotesta reticulate, dark brown to black.

Distribution: — Hedyotis puffii is an endemic species, known only from the type locality, Khao Soi Dao, Khao Banthat range, Trang, Thailand.

Habitat: —This species grows in open places by the edge of primary rainforest or in open montane scrubs with a thin sandy soil peat layer, at 700 1240 m.

Phenology: —Flowering in April.

Conservation status:— Hedyotis puffii is considered vulnerable (VU D2) according to the IUCN red list criteria ( IUCN 2001). It was collected from three sites in a sole province in Thailand, occurring in less than 20 km 2 in the Khao Banthat wildlife sanctuary.

Etymology: —The species is dedicated to the late Prof. Christian Puff (1949 2013), an Austrian botanist, who performed much significant work on the Rubiaceae for the Flora of Thailand.

Additional collections studied (paratypes):— THAILAND. Trang: Yan Ta Khao district, Khao Banthat Mountains, trail to summit of Phu Pha Mek , at Nan Mamuang waterfall, primary evergreen forest, at edge of waterfall, on earthy banking, 7° 26.5´N, 99° 50.4´E, ca. 700 m, 6 April 2003, D.J. Middleton, V. Chamchamroon, S. Lindsay, R. Pooma & S. Suwanachat 1920 (BKF) ; the same locality, summit area of Phu Pha Mek , open montane scrub with sandy soil and thin peat layer, 7° 26.4´N, 99° 51.9´E, ca. 1240 m, 7 April 2003, D.J. Middleton, V. Chamchamroon, S. Lindsay, R. Pooma & S. Suwanachat 1998 (BKF) .

Note:— Hedyotis puffii is placed with Hedyotis because of its entire stipules and presence of glandular-serrate margins that conform to Guo et al. (2013), and its septicidally and loculicidally dehiscent capsules and dorsiventrally compressed seeds with a longitudinal hilar ridge congruent with Wikström et al. (2013). Moreover, H. puffii is most similar to H. tavoyensis , which was classified in sect. Diplophragma Wight & Arnott (1834: 406) by Dutta & Deb (2004) and H. bracteosa Hance (1885: 323) , which was placed in Hedyotis s.str. clade ( Guo et al. 2013, Wikström et al. 2013). These three species have axillary pedunculate inflorescences with capitate cymes and heterostylous flowers. Hedyotis puffii is distinguished from H. tavoyensis by having obtusely angled stems, long petioles 4 20 mm and 1 2 glandular appearances on most of the calyx lobe margins. H. tavoyensis has gland tipped subulate teeth at calyx sinus and H. bracteosa has four large, subtending bracts. H. tavoyensis and H. bracteosa do not have glands on the calyx lobe rims ( Table 1).

Figures

FIGURE 1. Line drawing of Hedyotis puffii Wangwasit & Chantar. A. Habit. B. Capitate cymes. C. Detail of open corolla of longistylous flower. D. Detail of open corolla of brevistylous flower. E. Stipules. Drawn by K. Wangwasit from the holotype, A.F.G. Kerr 19285 (K).