Phyllagathis wallacei 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 : 222-225

9. Phyllagathis wallacei C.W. Lin, C.F. Chen & T.Y.A. Yang. sp. nov. ( Fig. 17 , 18 ).

Type: MALAYSIA. Borneo, Sarawak, Samarahan Division, Simunjan, near Kampung Sual, ca. 80 m elev. Type specimen pressed from plants cultivated in a nursery in Taiwan, 11 July 2014, C. W. Lin 583 (holotype TAIF)

Diagnosis: Phyllagathis wallacei resembles P. elliptica , but differs from it because P. elliptica has elliptic or obovate leaves (vs. lanceolate to narrowly obovate or rhombic ovate) with a flat surface (vs. slightly bullate); almost glabrous hypanthium (vs. densely hispid); narrowly ovate anthers (vs. narrowly lanceolate), and yellowish (vs. purplish); and absent ovary crown lobes (vs. present).

Caulescent herb, erect or ascending, terrestrial. Stems unbranched or with few branches, green, 10–35 cm tall, 0.2–0.5 cm diam., terete, densely hispid, hairs ca. 2 mm long, glabrescent; internodes 0.7–2(–5) cm long. Leaf blades 4–10, decussate, subequal, thick chartaceous, lanceolate to narrowly obovate or rhombic-ovate, 5.5–20.5 × 1.7–5.8 cm; base cordate, slightly auriculate, margins denticulate, sometimes incised, with rows of dense hispid trichomes up to 4 mm long, apex attenuate; venation acrodromous, ca. 5 veined, 1 primary vein and 1 pair of suprabasal secondary veins, often asymmetrical at union with midvein, produced 2–6 mm from the leaf base, positioned 0.5–1 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, venation impressed, slightly bullate between veins, giving the blade a rugose appearance, each bulla tipped with upstanding hispid-setae up to 4 mm long, abaxial surface pale green, densely hispid on all veins. Petioles 4–20 mm long, slightly grooved and flat terete, densely hispid. Bracts ovate, green, ca. 1.5 mm long at the base of the inflorescence, densely hispid. Inflorescences in the upper leaf axils, umbelliform, peduncle 1–3 cm (up to 7 cm in fruiting), pale green, densely hispid. Flowers tetramerous, pedicels ca. 4–6 mm long, hispid. Hypanthium campanulate, ca. 3 mm long and wide, hispid and with sparse minute glands. Sepals 4, persistent, widely triangular, connate into a rim, each lobe with a triangular keel ca. 0.5 mm long. Petals 4, oblique, ovate to oblong, 3.5–4.5 × 1.5–2 mm, white, glabrous, apex cuspidate to acuminate. Stamens 8, isomorphic, subequal, filaments slightly flat, ca. 3 mm long, white, anthers narrowly lanceolate, apex attenuate, ventrally curved, slightly undulate, 2–2.5 mm long, purplish, pore 1, connective distinct, ventrally with one pair of inconspicuous tuberculate appendages on base of anther sacs, sometimes absent; dorsal appendage absent or inconspicuously tuberculate. Style filiform, ca. 8 mm long, glabrous, stigma capitate. Ovary 3/4 as long as the hypanthium, crown lobes absent, anther pockets shallow, placentae stalked. Capsules pedicels to 9 mm long, hypanthium cup-shaped, non-ribbed, ca. 3 × 3 mm, placentae disintegrating after seed dehiscence.

Distribution and ecology: Endemic to Simunjan, Sarawak, Borneo ( Fig. 3 ). It grows on steep slopes in riparian forest or at the margin of lowland mixed dipterocarp forest at 50 to 150 m elevation.

Etymology: Named in honour of Alfred Russel Wallace, the noted naturalist who explored Simunjan in the19th century, and discovered many wild animals and plants.

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 17. Phyllagathis wallacei C.W. Lin, C.F. Chen & T.Y.A. Yang. A. Habit; B. Adaxial leaf surface; B’. Abaxial leaf surface; C. Flower, face views; D, D’. Petal, both surfaces views; E, E’, E’’. Stamens, ventral, side and dorsal views; F. Style; G. Vertical section of the ovary; H. Capsule, side view. All from C.W. Lin 583 (TAIF).

FIGURE 18. Phyllagathis wallacei C.W. Lin, C.F. Chen & T.Y.A.Yang. A, B. Habit and habitat; C. Adaxial leaf surface; D. Abaxial leaf surface. E. Inflorescence; F. Flower, side view. C–F from C.W. Lin 583 (TAIF).