Begonia

Nakamura, Koh, Rubite, Rosario Rivera, Kono, Yoshiko, Macabasco, Jelene V., Talaña, Arlene D., Alejandro, Grecebio J. D., Ho, Meng-Jung, Yang, Hsun-An, Chung, Kuo- Fang & Peng, Ching-I, 2021, Begonia × dinglensis, a natural hybrid of Philippine Begonia section Baryandra, as evidenced by morphological, phylogenetic and cytological data, Phytotaxa 494 (1), pp. 151-164 : 158-159

Begonia × dinglensis Rubite, C.-I Peng, Koh Nakam. & K.F.Chung, nothosp. nov. ( Begonia camiguinensis Elmer ×

Begonia nigritarum (Kamel) Steud.

sect. Baryandra

Type: — PHILIPPINES. Panay Island, Iloilo Province, Dingle, Bulabog Puti-an National Park , elev. ca. 200 m, E122°40’02”, N11°02’01”, 24 June 2012, Peng 23859 (holotype PNH, isotype HAST 13390 ). Fig. 4 .

Monoecious perennial herbs. Stem dark green to brown, glabrous, prostrate, 8–10 mm in diameter, internodes 8– 10 mm. Stipules pink to maroon, glabrous, ovate-triangular 9–14 × 6–9 mm, keel present, apex fimbriate. Leaves alternate; petiole, 9–26 cm long and 3–6 mm in diameter, erect, terete, succulent, pinkish green to brown, sparsely associated with maroon to brown diagonal to erect hairs (2–4 mm); blade obliquely ovate, 10–14 × 9–11 cm, adaxial surface green with darker green veins, glabrous, abaxial surface light maroon, densely associated with maroon hairs (1–2 mm) at the veins, base cordate, lobes rounded, apex acuminate, margin shallowly undulate and shallowly dentate with maroon hairs (1 mm), primary veins 6–8. Inflorescence 35–46 cm long axillary, arising directly from the rhizome, dichotomously branching 4 to 5 times; peduncle light maroon from the base becoming pink towards the apex, erect, glabrous, 17–37 cm long, 2–4 mm in diameter; pedicels 10–15 mm long, erect to ascending in staminate flowers, horizontal in pistillate flowers. Staminate flowers 1.7–2.0 × 1.3–1.7 cm; tepals 2+2 glabrous, outer pair orbicular abaxial surface pinkish to greenish, base of the bud prominently red; adaxial side white to pink, 8–10 × 8–10 mm, inner pair obovate, retuse, white 6–8 × 4–5 mm; stamens 20–30; filaments 1 mm long, free; anthers yellow, oblong 1 mm long. Pistillate flowers 1.6 –1.9 × 1.6–2.0 cm; tepals 2+2 white glabrous, outer pair orbicular, abaxial surface pink, adaxial surface white, 8–9 × 8–10 mm; inner pair obovate, retuse, white, 8–10 × 4–5 mm; ovary elliptic, green with red outline 6–8 × 4–5 mm, wings unequal, abaxial wing rounded 9–12 × 4–6 mm, lateral wings triangular or rounded 9–12 × 5–9 mm, three-locular, placentae axile, bifid; styles three, 7–9 mm long, stigma yellow coiled twice. Capsule sub-rhomboid in outline, glabrous, nodding, 10–13 × 15–22 mm. Somatic chromosome number, 2 n = 29 ( Fig 6A ).

Diagnostic characters:— The natural hybrid B. × dinglensis is an intermediate between B. camiguinensis and B. nigritarum in its morphology ( Table 1). Begonia × dinglensis is similar to B. nigritarum by the keeled stipules, color and pubescence of lamina, peduncle color, tepal colors, the retuse inner tepals and the green ovary with red outline; however, it is distinguished from B. nigritarum in its larger vegetative parts including stem, petiole, lamina, stipule peduncle and pedicel; dark green veins of adaxial leaf surface (vs. veins same color as lamina), shallowly undulate and shallowly dentate leaf margin (vs. almost entire), inflorescence branching 4–5 times (vs. 2–3) and ovary with unequal wings (vs. almost equal). Moreover, B. × dinglensis is similar to B. camiguinensis in having large leaves, long petioles, long peduncles and pedicels, shallowly undulate and shallowly dentate leaf margin, ovary with unequal wings, but it is different from B. camiguinensis in its pubescent petiole (vs. glabrous), lamina dark green with darker green veins (vs. veins green and same color as lamina), abaxial leaf surface maroon and pubescent (vs. light green and glabrous), pink to maroon stipule with keel (reddish green without keel), inflorescence branching 4–5 times (7–8) and ovary green with red outline (vs. green).

Distribution, habitat and ecology: —The species is currently known only from the type locality. Moist ground or rock faces on coralline rock slopes at 200 m elevation. Flowering and fruiting in June.

Etymology: —The plant is named after Dingle, the municipality in which it was discovered, situated in the province of Iloilo in the Island of Panay, Philippines.

Note: —Morphological, molecular, and cytological evidences proved its origin from natural hybridization between Philippine endemics B. camiguinensis and B. nigritarum .

Proposed IUCN Red list category: —Vulnerable ( VU D2 ) . Begonia × dinglensis is known only from the type locality in Dingle, Iloilo. Although the area is under protection as a national park, habitat disturbance brought about by human activities such as tourism and maintenance/building of roads/walking trails may have a negative impact on the species .

Figures

FIGURE 4. Begonia ×dinglensis. A. habit. B. inflorescence. C. staminate flower. D. pistillate flower. E. developing capsule. F. leaf, abaxial view. G. rhizome. Scale bars for A is 10 cm, B and G are 1 cm, C–E are 0.5 cm, F is 3 cm. [All photos from Ching-I Peng 23859 (HAST).]

FIGURE 6. Somatic chromosomes at metaphase. A. B. ×dinglensis (2n = 29: Ching-I Peng 23859). B. Begonia camiguinensis (2n = 28: Ching-I Peng 23853). C. B. nigritarum (2n = 30: Ching-I Peng 23858).