Phyllagathis rubrosetosa 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 : 216-219

6. Phyllagathis rubrosetosa C.W. Lin, C.F. Chen & T.Y.A. Yang , sp. nov. ( Fig. 12 , 13 ).

Type: MALAYSIA. Borneo, Sarawak, Sri Aman Division, Lubok Antu, Batang Ai, ca. 100 m elev. Type specimen pressed from plants cultivated in a nursery in Taiwan, 9 July 2013, C. W. Lin 573 (holotype TAIF)

Diagnosis: Phyllagathis rubrosetosa is similar to P. elliptica , from which it can be distinguished by the sparsely velutinous adaxial leaf surface (vs. with dense bristly hairs); several bracts at the base of the inflorescence (vs. 2 or 3 pairs), the bracts narrowly obovate to oblanceolate, ca. 9 × 3.5 mm (vs. leaf-like, 12–44 × 6–18 mm); white petals (vs. pink or pale yellow), outside puberulous (vs. glabrous); narrowly lanceolate anthers (vs. narrowly ovate) and purplish to bluish (vs. yellow); non-ribbed capsule (vs. 8-ribbed).

Caulescent herb, erect or ascending, terrestrial. Stems unbranched, green to olive, 10–20 cm tall, 0.4–1 cm diam., terete, stout, woody at the base, densely white puberulous and velutinous; internodes 0.5–3(–6) cm long. Leaf blades 2–4, decussate, equal or slightly unequal, thick chartaceous, obovate to widely obovate 9.5–13 × 5.2–8.5 cm; base cordate, slightly auriculate, margins crenulate to repand or inconspicuously denticulate with rows of reddish setae, apex acuminate; venation acrodromous, ca. 5 (–7) veined, 1 primary vein and 1 pair of suprabasal secondary veins, often symmetrical at union with midvein, produced 5 mm from the leaf base, positioned 0.8–1.5 cm in from margin at widest part of blade; secondary and tertiary veins numerous and conspicuous, reticulate or slightly trellis-like; adaxial surface lime green, sparsely erect velutinous, hairs up to 4 mm long; abaxial surface pale green, densely puberulous and velutinous on all veins. Petioles 1–1.8(–3) cm long, slightly grooved and flat terete, densely puberulous and velutinous. Bracts persistent, green, narrowly obovate to oblanceolate, ca. 9 × 3.5 mm at the base of the inflorescence and becoming smaller upwards; margins with rows red hispid trichomes, adaxially sparsely velutinous or glabrous, abaxially puberulous. Inflorescences in the upper leaf axils, umbelliform or congested pleiochasia, peduncle absent or up to 1.5 cm, puberulous. Flowers tetramerous, pedicels ca. 2.5 cm long, densely puberulous and sparsely velutinous. Hypanthium campanulate, 4–5 mm long, 3.5–4 mm diam., puberulous and velutinous outside, with sparse minute glands. Sepals 4, persistent, widely triangular, connate into a rim, each lobe with a triangular keel up to 1 mm long. Petals 4, oblique, ovate to obovate, boat-shaped, ca. 7 × 3–3.8 mm, white, adaxially glabrous, abaxially sparsely puberulous, apex acuminate to apiculate. Stamens 8, isomorphic, subequal, filaments slightly flat, 3.5–4 mm long, purplish to bluish, anthers narrowly lanceolate, apex attenuate, ventrally curved, 2.2–3.5 mm long, pore 1, connective distinct, ventrally with one pair of inconspicuous tuberculate appendages on base of anther sacs, dorsal appendage inconspicuously tuberculate, apex retuse. Style filiform, pale magenta, ca. 8 mm long, glabrous, stigma capitate. Ovary 2/3 as long as the hypanthium, crown lobes large, with connate lobes, margins sparsely denticulate, anther pockets shallow, placentae stalked. Capsules on pedicels up to 4.5 cm long, hypanthium cup-shaped, non-ribbed, ca. 5 × 4.5 mm, placentae disintegrating after seed dehiscence.

Distribution and ecology: Only known from upstream Batang Ai area, Sarawak ( Fig. 3 ). It grows on slope or base of trees in lowland forest at 100 m elevation.

Etymology: “ Rubrosetosa ” refers to the red hairs on the leaf.

Figures

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.

FIGURE 12. Phyllagathis rubrosetosa C.W. Lin, C.F. Chen & T.Y.A. Yang. A. Habit; B.Adaxial leaf surface; C. Abaxial leaf surface; D, D’. Bracts, adaxial view, D’’. Bract, abaxial view; E, E’. flower, face and side views; F. Petal, adaxial view; G, G’, G’’. Stamens, ventral, side and dorsal views; H. Style; I. Hypanthium; J. Vertical section of the ovary, K. The same, showing the crown lobes.All from C.W. Lin 573 (TAIF).

FIGURE 13. Phyllagathis rubrosetosa C.W. Lin, C.F. Chen & T.Y.A. Yang. A, B. Habit and habitat; C, D. Adaxial leaf surface; E. Abaxial leaf surface, showing the hairy petiole; F. Bracts; G. Petal; H. Stamens; I. Style; J. Hypanthium; K. Vertical section of the ovary; L. Old capsules, apical and side views. C–L from C.W. Lin 573 (TAIF).