Begonia bessangpassensis Calaramo, Rubite, C.W.Lin., 2023

Calaramo, Michael Agbayani, Rubite, Rosario Rivera & Lin, Che-Wei, 2023, Two new endemic Begonia species named after historical landmarks of Ilocos Sur, Philippines, Phytotaxa 613 (2), pp. 171-179 : 175-178

Begonia bessangpassensis Calaramo, Rubite, C.W.Lin. sp. nov.

§ Petermannia ( Figs. 3 & 4 )

Type: — PHILIPPINES. Luzon: Ilocos Sur Province, Cervantes, exposed ridges, wet, mossy environment along pine forest thickets, 1,600 –1,723 meters above sea level, 24 September 2022, Calaramo HNUL0021093 (holotype HNUL) .

Diagnosis: —Allied to B. megalantha Merr. , in being a high-altitude shrubby species, similar in habit and having paired bracteoles subtending the pistillate flowers. However, B. bessangpassensis has leaves measuring 12–15 × 5–7 cm (vs. 5–10 × 1.8–4 cm), adaxial lamina sparsely red or reddish-green hispid (vs. glabrous), with slightly impressed venation (vs. notably impressed), and the tepals of the pistillate flowers are red hirsute (vs. glabrous). This new species also has similarity to Begonia crispipila Elmer due to its entirely pubescent appearance. However, B. bessangpassensis is a larger plant, growing up to 2 m (vs. to 1 m), with ovate leaves (vs. obovate), covered with red or reddish-green hispid hairs (vs. whitish crisply pubescent), and tepals in the staminate flowers being larger, measuring 25 × 30 mm (vs. 6 mm across).

Monoecious, perennial, hairy, vigorous multi-branched herb, becoming shrubby at maturity. Stem erect, up to 2 m or more, green, branched multiple times creating a dense thicket, reddish-olive green to orange in appearance under the sun, internodes 5–10 cm long, hispid or hirsute, nodes slightly swollen. Stipules deciduous, pale green to pinkish-green, ovate to widely ovate, 2–2.5 × 1–1.5 cm, slightly keeled, sparsely pubescent on outer side, margin entire, apex mucronate. Leaves alternate; petioles terete, 10–30 mm long, 2–4 mm in diameter, pale yellowish-green to pinkish-green; blade asymmetric ovate, sometimes slightly falcate, 12–15 × 5–7 cm, base shallow cordate, apex acuminate to attenuate, margin irregularly dentate to denticulate, adaxially bright green, sparsely red to reddish-green hispid; abaxially pale green, hispid on veins; venation pinnate-palmate, with one primary vein extending to the leaf apex, secondary veins ca. 3 on each side, 7 or 8 additional basal nerves radiates towards the entire margin distributed unequally. Inflorescence terminal or axillary on upper parts of the stem, simple to compound dichasium; no scent during observation. Bracts greenish on inner side, reddish with few trichomes on outer side, margin entire, apex apiculate. Staminate flower: pedicel 10–15 mm long, reddish-green, pale red hirsute, tepals 2, whitish, sometimes light pink on outer surface, orbicular to broadly ovate, 25 × 30 mm, adaxially sparsely hirsute, margin entire, apex round; androecium actinomorphic, stamens 50–60, golden yellow; filaments 2 mm long, cylindric terete, anthers obovate or spatulate, ca. 1.5 mm long, apex rounded. Pistillate flower: pedicel 20–30 mm long, pendent, sparse hirsute; bracteoles in pairs, pale reddish-green to pink, glabrous or sparsely puberulous on outer side; tepals 5, white, sometimes tinged pink basally on the outer side, outer 3 obovate, 20–25 × 15–17 mm, inner 2 narrow ovate, 20–25 × 12–15 mm, tepasl incurved, slightly flexuous near the apex, margin entire; ovary olive green, trigonous-globose, 7–10 mm across, wings 3, unequal, 10–13 mm long, lateral wings narrower, 3–5 mm wide, abaxial wing 4–7 mm wide; nearly truncate distally, cuneate to rounded proximally; ovary 3-locular, placentae bilamellate; stigmas compact, golden to yellowish-orange, styles ca. 5 mm long, in three sets with 2 spiral apices. Capsule ovary body trigonous-globose, 15–20 × 25 mm (wings including), unequally 3-winged, green to reddish-green, sparsely hirsute between wings; distally truncate with cuneate base.

Distribution and habitat: — Begonia bessangpassensis grows in pine thickets and in mossy vegetation along slopes, up to subsummit of the Besaang Pass Natural Monument/Landmark, Cervantes, Ilocos Sur, NW Luzon, Philippines, elevation up to 1,600 –1,723 masl.

Phenology: —The species is observed to start flowering during the wet season from June to August.

Etymology: —This species is named to commemorate the Bessang Pass Natural Monument and Landmark, an important historical site where the Battle of Bessang Pass took place during the last stand of the Japanese Imperial Army.

Conservation status: — Begonia bessangpassensis is confined to the summit and subsummit vegetation of Bessang Pass Natural Monument/Landmark with an area of occupancy of 10 km 2, which is highly fragmented due to expanding vegetable farms. Some plants have also been permanently lost due to roadside expansion. There are about 200–250 mature plants found at the last assessment, scattered sporadically along the roadside thickets. It is frequently trimmed down during clearings. Following IUCN Red List Categories and Criteria and Guidelines ( IUCN Standards and Petitions Committee, 2022), the species is provisionally assessed as being Critcially Endangered (CR A1a+2ac; B2ac(i,ii,iii,v)).

Specimen examined (paratype):— PHILIPPINES. Luzon: Ilocos Sur Province, Cervantes, exposed ridges, wet, mossy environment along pine forest thickets, 24 September 2022, Calaramo HNUL0021094 ( HNUL) .

Figures

FIGURE 3. Begonia bessangpassensis Calaramo, Rubite, & C.W.Lin. A, Branch; B, B’, Leaf, adaxial and abaxial surfaces; C, Stipule; D, D’, D’’, Bracts; E, Staminate flower, face and side views; F, F’, Stamens, dorsal and ventral views; G, Pistillate flower, face and side views; H, H’, Style and stigmatic band, dorsal and ventral views; I, Cross section of ovary. All from Calaramo 0021093.

FIGURE 4. Begonia bessangpassensis Calaramo, Rubite, & C.W. Lin. a–e (Pistillate flower), a flower bud, b. capsule bract removed, c. cross section of capsule, d. fully opened flower, e. stamens; f–i (Staminate flower), f. stamens, g. opened flower, h. flower bud, i. sideview of flower; j. pistillate flower with bract removed; k. staminate flower with flower bud bract remove; l. stipules; m. flattened adaxial and abaxial surface; n. leaf petiole; o. bract and young leaf; p. terminal branch with flower; q. plant habit. All from Calaramo HNUL0021093.