Phyllagathis rajah, Lin, Che-Wei, Chen, Chien-Fan, T. - Y & Yang, Aleck, 2015

Lin, Che-Wei, Chen, Chien-Fan, T. - Y & Yang, Aleck, 2015, Two new taxa of Melastomataceae Trib. Sonerileae: Phyllagathis rajah and Sonerila metallica from Batang Ai, Sarawak, Borneo, Phytotaxa 201 (2), pp. 122-130 : 123-126

1. Phyllagathis rajah C.-W. Lin, C.-F. Chen & T.-Y.A. Yang sp. nov. ( Figures 2 , 3 ).

Diagnosis: Phyllagathis rajah resembles P. subacaulis (Cogn.) Cellin. (2003: 93) in having a pleiochasium, but the latter has ventral appendages bending upward and a slightly bifid dorsal spur pointing downward at the base of the anthers (vs. ventral bifid appendages at the base and a slightly prominent and undulating dorsal spur). Phyllagathis rajah is also similar to P. guttata (Stapf) Cellin. (2003: 83) , but differs in having a pleiochasium instead of an umbelliform inflorescence ( Table 1).

pollen grain (SEM); L. Polar view of pollen grain (LM); M: Equatorial view of pollen grain ( I – M from the type C.- W. Lin 550) .

Type:— MALAYSIA. Borneo, Sarawak, Lubok Antu , Batang Ai District , in shade along humid riverside, 1°16’ N, 112°02’ E, elev. 130–200 m, 5 July 2013, C.- W. Lin 550 (holotype TAIF; isotype TNM) .

Herbs, subacaulescent, prostrate. Stems 3–8 cm long, 0.8–1.2 cm thick, terete, pale green or reddish, with sparse bristles; nodes congested, slightly succulent, strigose, hairs ca. 8 mm long, red; internodes 0.8–2 cm long. Leaves 4 or 6, opposite; thick, chartaceous to slightly succulent, equal or sometime slightly unequal, suborbicular to very broadly ovate, 20–29 cm long, 18.5–25 cm wide; venation basal, palmate, veins 7 or 9, secondary and tertiary nerves conspicuous, connected, reticulate; base broadly cordate, basal lobes often imbricate, margin crenate to crenulate, ciliate, cilia ca. 1 mm long, apex obtuse to obtuse-acuminate; adaxial surface rugose, dark green, with silvery gray patches between main veins, upper half sparsely setose; hairs red, ca. 2.5 mm long; abaxial surface pale green or reddish, veins prominent and reticulate, bristly; bristles dense red, multiseriate. Petioles 3.5–4(–10) cm long, slightly grooved or flat, margin villous. Bracts broadly ovate to orbicular, ca. 0.5 mm long, becoming smaller upward, pale green or red, membranaceous, translucent, apex setaceous, red. Inflorescence terminal, a pleiochasium, branches scorpioid; peduncle 3.5–7 cm long, with appressed glandular hairs; hairs minute, inconspicuous, pink or carmine. Flowers 5-merous, pedicel ca. 5 mm long, with minute, glandular hairs. Hypanthium campanulate, ca. 3 mm long, 4 mm wide, 10 ribbed, hairy and glandular; hairs sparse, minute, uniseriate, appressed, glands white. Sepals 5, narrowly triangular, ca. 3 mm long, strongly keeled with a pointed extension exceeding the apex and falcately curved inward, entire or 1 or 2-denticulate. Petals 5, oblique, oblong to obovate, 9–11 mm long, 3–4 mm wide, white, glabrous, apex truncate, oblique, apiculate. Stamens 10, isomorphic, equal; filaments slightly flattened, 4–5 mm long, magenta; anthers narrowly lanceolate, attenuate, curved ventrally, 2.5–3 mm long, yellow, pore 1, base ventrally bifid, tuberculate, dorsally slightly prominent, somewhat undulate. Styles filiform, 8–9 mm long, glabrous; ovary half as long as hypanthium, crown denticulate, fully connate; placenta axile. Pollen grains tricolporate, spheroidal; 10.7±0.6 × 11.9±0.7 μm (measured by LM); furrow thicken, ca. 2 μm long; exine 1 μm thick, ornamentation muricate ( Figure 3 , I–M). Fruit widely campanulate, 10 ribbed, up to 8 mm long × 6.5 mm wide (calyx include), placentae disintegrating after seed dehiscence.

Distribution and ecology:— Phyllagathis rajah occurs in a few ravines in Batang Ai Dist., Sarawak, Borneo (Figure 1). It grows on humid, steep slopes beside streams in deeply shaded tropical rainforests. Elev. 130– 200 m.

Vernacular name:—Malay King Phyllagathis .

Etymology:—The specific epithet derives from the Sanskrit ‘rajah’, meaning ‘King’ in the Malay language. Phyllagathis rajah has larger and more magnificent leaves than other species of Phyllagathis in Borneo, with conspicuous stripes and patches on the adaxial surface. In addition, the habitat where it grows is difficult to access. The name ‘rajah’ indicates its rarity and magnificence.

Figures

FIGURE 2. Phyllagathis rajah A. Habit; B,B’. Portion of leaf adaxial and abaxial surfaces, also showing leaf margin; C. Inflorescence; D. Bract; E,E’. Flower, front view and side view; F. Petal; G. Stamen and filament, ventral view, G’. Dorsal view, G’’. Side view; H. Style; I. Hypanthium and calyx; J. Cross section of ovary (all from the type, C.-W. Lin 550, TAIF).

FIGURE 3. Phyllagathis rajah A. Habit and habitat; B. Leaf abaxial surface; C. Leaf adaxial surface; D & E. Inflorescence; F. Flower, top view; G. Flower, side view; H. Cross section of ovary, showing crown; I. & J. Equatorial view of pollen grain (SEM); K. Polar view of