Phyllagathis bicolor C.W. Lin, C.F. Chen & T.Y.A. Yang, 2017

Lin, Che-Wei, Chen, Chien-Fan & Yang, T. Y. Aleck, 2017, Ten new species of Phyllagathis (Trib. Sonerileae, Melastomataceae) from Sarawak, Borneo, Phytotaxa 302 (3), pp. 201-228 : 202-205

1. Phyllagathis bicolor C.W. Lin, C.F. Chen & T.Y.A. Yang , sp. nov. ( Fig. 1 , 2 ).

Type: MALAYSIA. Borneo, Sarawak, Limbang Division, ca. 100 m elev. Type specimen pressed from plants cultivated in a nursery in Singapore, 11 July 2014, C. W. Lin 583 (holotype TAIF).

Diagnosis: Phyllagathis bicolor resembles P. elliptica Stapf (1894: p1 . 2279) in having an erect stem, umbelliform inflorescences and tetramerous flowers. However, it differs in the leaves adaxially dark maroon with green margins (vs. uniformly green or dark olive), and densely bullate (vs. flat); densely hispid hypanthium (vs. glabrous), narrowly lanceolate anthers (vs. narrowly ovate), purplish to bluish (vs. yellow), with two inconspicuous, ventral-basal tuberculate appendages (vs. absent); cross section of capsule orbicular (vs. quadrangular), and non-ribbed (vs. 8-ribbed).

Caulescent herbs, erect or ascending, terrestrial. Stems usually unbranched, green to olive, 10–15(–25) cm tall, 0.3–0.8 cm diam., terete, stout, slightly woody at base, with densely magenta hispid hairs up to 3 mm long; internodes 0.6– 2(–4) cm long. Leaf blades 4–8, decussate, equal or sometimes unequal, narrowly elliptic to lanceolate, sometimes oblanceolate to obovate-elliptic, 8–15 × 2.5–5 cm, base cordate, margins crenulate to denticulate, apex acute to obtuse; thick chartaceous; venation acrodromous, ca. 5 (–7) veined, 1 primary vein and 1 pair of suprabasal secondary veins, often symmetrical at union with midvein, distant 2–8 mm from the leaf base, positioned 0.5–1.2 cm from margin at widest part of blade; veins depressed on the adaxial surface and prominent on the abaxial surface, secondary and tertiary veins numerous and conspicuous, reticulate or slightly trellis-like; adaxially dark maroon to purplish-brown (sometimes dark green) with a broad emerald green border, densely bullate between veins, each bulla tipped by erect magenta hispid curved hairs up to 3 mm long, giving blade a rugose appearance, abaxially magenta with a pale green border, densely magenta hispid on all veins. Petioles 4–10(–18) mm long, slightly grooved or flat, densely hispid, with curved, magenta trichomes. Bracts persistent, green, oblanceolate to linear, ca. 7 mm × 1–2 mm at the base of the inflorescence and becoming smaller upwards; margins ciliate, adaxially usually glabrous, abaxially sparsely hispid. Inflorescences in the upper leaf axils, umbelliform, peduncle 4–15 mm long, pale green, hispid, with magenta trichomes. Flowers tetramerous, pedicels 1.5–3 cm long, sparsely to densely hispid, with magenta trichomes. Hypanthium campanulate, ca. 4 mm long, 3–4 mm diam., hispid, with magenta trichomes. Sepals 4, persistent, widely triangular, connate into a rim, each lobe with an acute-angled, triangular keel, ca. 0.5 mm long. Petals 4, oblique, boat-shaped, ovate to widely ovate, 4.5–6.5 mm × 3.5–4.5 mm, white, adaxially glabrous, abaxially with sparse short magenta hispid trichomes at upper half, apex mucronate-apiculate. Stamens 8 isomorphic, subequal, filaments slightly flat, 3–5 mm long, white, anthers narrowly lanceolate, apex attenuate, ventrally curved, 3–4 mm long, purplish to bluish, pore 1, connective distinct, ventrally with one pair of inconspicuous tuberculate appendages on base of anther sacs, dorsal appendage a ca. 0.3 mm long. Style filiform, 8–10 mm long, glabrous, stigma capitate. Ovary ca. 3/4 as long as the hypanthium, crown lobes small or inconspicuous, with connate lobes, densely covered with minute uniseriate or glandular trichomes, anther pockets shallow, placentae stalked. Capsules on pedicels up to 4 cm long, hypanthium cup-shaped, non-ribbed, ca. 5.5 × 5 mm, placentae disintegrating after seed dehiscence.

Distribution and ecology: Endemic to Limbang Division, Sarawak ( Fig. 3 ). It grows on steep banks along streams, in lowland dipterocarp forest.

Etymology: “ Bicolor ” refers to the color of the leaves, with dark maroon background surrounded by an emerald green periphery.

Figures

FIGURE 1. Phyllagathis bicolor C.W. Lin, C.F. Chen & T.Y.A. Yang. A. Habit; B. Adaxial leaf surface; C. Abaxial leaf surface; D. Bracts, adaxial view, at lowermost and uppermost parts of inflorescence; E. Bracts, abaxial view; F, F’. Flower, face and side views; G. Petal, abaxial view; H, H’. Stamens, ventral view, H’’, H’’’. Stamen, side and dorsal view; I. Style; J. Vertical section of ovary; K. Ovary, showing uniseriate hairs; L. Capsule, side view. All from C.W. Lin 583 (TAIF).

FIGURE 2. Phyllagathis bicolor C.W. Lin, C.F. Chen & T.Y.A. Yang. A. Habit; B. Adaxial leaf surface; C. Adaxial leaf surface; D. Abaxial leaf surface; E. Bracts; F, G. Flower, face and side views; H. Capsule, apical view; I. Vertical section of an immature capsule. All from C.W. Lin 583 (TAIF).

FIGURE 3. Distribution maps of Phyllagathis lii, P. millelunata, P. rivularis, P. rubrosetosa, P. ulu, (stars); P. phyllioides, P. violinifolia, P. yodae (solid circles); P. bicolor (solid triangles); P. wallacei (solid squares) in Sarawak, Borneo.