Begonia armykapii S.Julia & C.Y.Ling, 2016

Sang, Julia, Kiew, Ruth & Yiing, Ling Chea, 2016, Six new species of Begonia (Begoniaceae) from Central Sarawak, Borneo, Phytotaxa 277 (2), pp. 171-181 : 172-173

1. Begonia armykapii S.Julia & C.Y.Ling , spec. nov. ( Figure 2 )

Section Petermannia

Diagnosis: —Similar to Begonia doloisii Rimi (2015: 9) in its creeping habit and small jagged leaves but it is distinct from B. doloisii in its smaller stipules 1.8–2 × 1–1.2 mm (vs. 6–14 × 2.2–11 mm), smaller glabrous, peltate leaves 1.5–2.8 × 1.3–2.5 cm (vs. hairy, basifixed laminas 3–6.5 × 3–5.4 cm), its deeply laciniate laminas with lobes 5–13 mm long (vs. deeply toothed margin with teeth 2–5 mm long), veins obscure above and inconspicuously raised underneath (vs. impressed above, prominent below), smaller white outer male tepals 3–3.5 × 2–3 mm (vs. pink tepals 6–9 × 4–5.5 mm) and capsules ca. 4 × 8 mm (vs. ca. 6 × 7 mm).

Type: — MALAYSIA. Borneo. Sarawak. Tatau District: Anap Muput Forest Management Unit, Coupe 15, 22 June 2015, Ling et al. SFC 6160 (holotype SAR!, isotype KEP!).

Creeping or climbing herb, to 50 cm long. Stem red brown, little-branched, wiry, slightly succulent, 1–1.5 mm thick, glabrous; internodes 1.2–2 cm long, slightly thicker at nodes. Stipules pale green, ovate, 1.8–2 × 1–1.2 mm, margin entire, apex acute, persistent. Leaves alternate, distant, peltate, not oblique, held horizontally; petioles red brown, very slender, 0.8–1(–2.8) cm long, minutely papillose, terete; lamina plain olive green to dark green above, pale green beneath, in life succulent, matt, asymmetric, ovate, 1.5–2.8 × 1.3–2.5 cm, laciniate with 3 main deeply incised lobes 5–13 mm long corresponding to the 3 main veins with an additional 1–4(–6) minor lobes, broad side 0.8–1.1 cm wide, base rounded, petiole attached ca. 1 mm inside the margin, margin entire; venation palmate, 3 veins radiating from the base of the petiole, obscure above, slightly prominent below. Inflorescences protogynous, erect from the upper leaf axils, paniculate, 2–5.5 cm long. Bracts pale green, linear, 2–3 × 1 mm, margin entire, persistent; bracteoles similar to bracts, pale green, linear, ca. 2 × 1 mm, margin entire, caducous. Male flowers: pedicel white or pale green, 2–3 mm long, glabrous; tepals 4, completely white, glabrous, outer 2 tepals ovate, 3–3.5 × 2–3 mm, margin entire, apex acute; inner 2 tepals lanceolate, 2–2.5 × 0.5–1 mm, margin entire, apex acute; stamens 8–16, cluster conical, subsessile; filaments pale yellow, ca. 0.5 mm long; anthers pale yellow, obovate, 0.8–1 × 0.3 mm, apex emarginate. Female flower not seen. Capsules pale yellow, single on the lower rachis, ca. 4 × 8 mm, glabrous, locules 3, placenta 2 per locule, wings 3, equal, broadly acute distally and almost truncate distally, ca. 2 mm wide, thinly fibrous, dehiscing between locule and wing; pedicel slightly pendent, thread-like, 5–6 mm long.

Etymology: —Named for Army Kapi, Field Assistant at Sarawak Forestry Corporation, who first discovered the species.

Distribution: — MALAYSIA. Borneo. Endemic in Sarawak. Known only from the type locality.

Habitat: —Lowland mixed dipterocarp forest to 340 m elevation. Growing near a cliff on sandstone boulders in shaded areas.

Additional specimens examined: — MALAYSIA. Borneo. Sarawak. Tatau District: Anap Muput Forest Management Unit, Coupe 15, 18 April 2015, Army et al. SFC 2747 (KEP!, SAR!).

Notes: —This species is distinct from all the other species in Borneo, not only in having the smallest leaf of any Begonia species in Borneo but also in being the only laciniate species known so far. In addition, species has peltate leaves, a rare character in sect. Petermannia .

Proposed conservation status: —Critically Endangered. The species is known only from a single locality outside the Totally Protected Area network and it is threatened by habitat disturbance due to logging.

Figures

FIGURE 2. Begonia armykapii. A, Habit; B, Stipule; C, Inflorescence; D, Close-up of leaf; E, Male flower; F, Fruit; G, Cross-section of capsule. All photos from SFC 6160 by C.Y.Ling.