Begonia argentii Kiew & S.Julia, 2018

Sang, Julia, Kiew, Ruth & Yiing, Ling Chea, 2018, The Begonia flora of Gunung Mulu and Gunung Buda National Parks, Sarawak, Borneo, including five new species, Phytotaxa 381 (1), pp. 58-79 : 61-63

2. Begonia argentii Kiew & S.Julia , spec. nov. ( Figure 3 )

Sect. Petermannia

It is most similar to Begonia punchak Kiew & S.Julia (2007: 223) in its habit and leaf characters; but B. argentii is different in its smaller stipules 9–16 × 4–5 mm (vs. ca. 22 × 8 mm), 2-tepaled male flower (vs. 4-tepaled), and larger capsules, 19–20 × 18–22 mm (vs. 10–13 × 9–15 mm).

Type: — MALAYSIA. Borneo, Sarawak, Marudi District: Gunung Mulu National Park , Gunung Api , 14 April 1978, Argent & Jermy 981 (holotype KEP!; isotype K!) .

Erect herb, whole plant glabrous. Stem little branched, quite woody, 3–4 mm diameter, internodes 0.8–1.6 cm long. Stipules lanceolate, 9–16 × 4–5 mm, margin entire, apex acute, caducous. Leaves alternate, distant. Petiole 1.4–2 cm long on lower leaves, 0.8–1.2 cm long on upper leaves, slightly grooved. Laminas plain green, stiff, thickly coriaceous when dried, oblique, ovate, 4–5.2 × 2.5–2.7 cm, asymmetric, broad side 1.7–1.9 cm, base cordate but not overlapping, basal lobes 0.8–1.2 cm, margin slightly dentate, apex sharply acute; veins palmate-pinnate, palmate ones, branching once or twice about halfway to margin, 3 veins on either side of midrib, 2 veins in basal lobes, prominent and slightly raised on both sides. Inflorescences protogynous, paniculate, axillary from the upper leaf axils, to 2.2 cm long, ca. 2 female flowers below, much branched with many male flowers above. Bracts lanceolate, ca. 12 × 4 mm, margin entire. Male flower: pedicel ca. 5 mm long; tepals 2, pink, broadly oval, 3.5–4 × 4 mm, margin entire, apex rounded; stamens ca. 25, cluster globose, sessile; filament ca. 0.5 mm long; anthers oblong, ca. 0.8 × 0.5 mm, apex emarginate. Female flower: pedicel 6–8 mm long, pinkish; ovary broadly ellipsoid, ca. 5 × 6 mm, wings 3, equal, locules 3, placentas 2 per locule; tepals 5, pink, broadly elliptic; outer 4 tepals 6–7 × 5.5 mm; inner tepal elliptic, ca. 6 × 4 mm, margin entire, apex broadly acute; styles 3, to 0.5 mm long, bifurcating; stigma anchor-shaped, papillose forming a continuous twisted band. Fruits obovate, 19–20 × 18–22 mm, glabrous, locules 3, wings equal, truncate or rounded distally, broadly acute proximally, 5–9 mm wide, dehiscing between the wings and locules; pendent, pedicel 1.5–2.2 cm long.

Distribution: — MALAYSIA. Borneo. Endemic in Sarawak. Known only from Gunung Api.

Habitat: —Limestone forest at 1300 m elevation, growing on a ridge that has been burned within living memory and is now covered by Pandanus calcinactus St.John ex B.C.Stone and P. lepatophilus B.C.Stone , both endemic to Gunung Api.

Etymology: —Named for Dr G. C. George Argent, b. 1941, who collected widely in Malesia including this new species and is an expert in Ericaceae and Musaceae .

Notes: —Measurements in the above description are based on dried herbarium specimens. Among the Borneo begonias, it is similar to B. subisensis K.G.Pearce (2003:82) in its habit but is generally less robust and has shorter internodes and smaller lamina.

Although it is known from a single collection, it may not be rare but is under-collected because it grows on a ridge that is dangerous to explore.

Figures

FIGURE 3. Begonia argentii Kiew & S.Julia. A. Habit; B. Portion of male inflorescence; C. Male flower; D. Stamen; E & F. Female flower; G. Outer tepal; H. Inner tepal; I. Stigma; J. Fruit; K. Transverse section of fruit.All from Argent & Jermy 981.