Phyllagathis millelunata 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 : 206-211

3. Phyllagathis millelunata C.W. Lin, C.F. Chen & T.Y.A. Yang , sp. nov. ( Fig. 6 , 7 ).

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 Hong Kong, 9 July 2014, C. W. Lin 582 (holotype TAIF)

Diagnosis: Phyllagathis millelunata bears a superficial resemblance to P. elliptica . They are similar in having an erect stem, ovate leaves, umbelliform inflorescences and tetramerous flowers. However, P. millelunata differs from the latter in the densely appressed puberulous indument on the stem (vs. erect velutinous); leaf adaxial surface glabrous (vs. covered with bristly hairs); inflorescence peduncle 4–7 cm long (vs. subsessile or peduncle up to 1 cm long); and ovary crown lobes margins erose to denticulate (vs. entire).

Caulescent herbs, erect or ascending, terrestrial. Stems unbranched, olive to brown, 10–20(–28) cm tall, 0.3–0.5 cm diam., terete, woody at base, densely appressed puberulous; internodes 1.5–3.5(–5) cm long. Leaf blades 4–8, decussate, equal or sometimes unequal, elliptic to ovate, sometimes obovate or widely panduriform-obovate, 6.5–14 × 3–6.5 cm, base cordate to slightly auriculate, margins entire with rows of appressed puberulous trichomes, apex attenuate to acuminate; thick chartaceous; venation acrodromous, ca. 7 veined, 1 primary vein and 1 pair of suprabasal secondary veins, often symmetrical at union with midvein, produced 3–12 mm from the leaf base, positioned 0.7–1.5 cm in from margin at widest part of blade; veins slightly depressed on the adaxial surface and prominent on the abaxial surface, secondary and tertiary veins numerous and conspicuous, reticulate or slightly trellis-like; both surfaces with translucent vesiculate trichomes; adaxially chartreuse to emerald green, appressed puberulous on main veins, densely towards the base; abaxially pale green, densely appressed brown puberulous on all veins. Petioles 0.5–1.5(–4) cm long, slightly grooved or flat, densely appressed brown puberulous. Bracts persistent, green, oblanceolate to linear,4–8 × 1–2 mm at the base of the inflorescence and becoming smaller upwards; margins with rows of appressed brown puberulous trichomes, adaxial surface glabrous or with sparse minute hairs, abaxial surface puberulous. Inflorescences in the upper leaf axils, umbelliform, peduncle 4–7 cm long, pale green, densely appressed brown puberulous. Flowers not seen fresh; tetramerous, pedicels 5–8 mm, densely puberulous; ovary crown lobes large, with connate lobes, margins erose to denticulate. Hypanthium campanulate, 3–4 mm long, ca. 4 mm diam., shortly appressed puberulous and velutinous outside. Sepals 4, persistent, widely triangular, connate into a rim, each lobe with a triangular keel, sparsely velutinous outside. Petals 4, oblique, ovate to obovate, white. Stamens 8, isomorphic, subequal, filaments slightly flat, purplish, anthers narrowly lanceolate, attenuate, ventrally curved. Capsules on pedicels to 1 cm long, hypanthium cup-shaped, subquadrangular, 8-ribbed, 3.5–4.5 × 3–4.5 mm, brown appressed puberulous, placentae disintegrating after seed dehiscence.

Distribution and ecology: Endemic to Batang Ai area, Sarawak ( Fig. 3 ). It grows on steep slopes along a stream, in a deep, shaded gorge in lowland mixed dipterocarp forest with thin vegetation, at 100 m elevation.

Etymology: Latin, mille =thousand, luna =moon, referring to the vesiculate translucent (and scintillating in the sunshine) trichomes on both leaf surfaces, resembling numberless moons.

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 6. Phyllagathis millelunata C.W. Lin, C.F. Chen & T.Y.A. Yang. A. Habit; B. Adaxial leaf surface; B’. Abaxial leaf surface; C. Adaxial leaf surface, showing translucent vesiculate trichomes; D, D’. Bracts, adaxial view; E. Hypanthium; F. Vertical section of the ovary; G. Old capsule.All from C.W. Lin 582 (TAIF).

FIGURE 7. Phyllagathis millelunata C.W. Lin, C.F. Chen & T.Y.A.Yang. A, B. Habit and habitat; C. Stem and petioles; D. Leaf, adaxial view; E. Adaxial leaf surface; F. Immature capsules; G. Mature infructescence. B–G from C.W. Lin 582 (TAIF).