Tuesday, November 6, 2018

[Botany • 2018] Begonia yenyeniae (Begoniaceae) • A New Species from Endau Rompin National Park, Johor, Malaysia.

Begonia yenyeniae  J.P.C.Tan

in Tan, Tam & Kiew, 2018.

Begonia yenyeniae is a new species of horticultural value known only from the Endau Rompin National Park, Peninsular Malaysia. It is similar to Begonia rajah with which it had previously been confused in the number of tepals and leaf characters. The new species is compared with three similar species, B. foxworthyi, B. rajah and B. reginula and photographs of all four species and descriptions of B. yenyeniae and B. rajah are provided. Molecular analysis using the ndhF-rpl132 chloroplast marker confirms the four species as distinct. Amongst native species, the three variegated species, B. yenyeniae, B. rajah and B. reginula, are some of the most popular Malaysian begonias in cultivation. Based on its restricted distribution, Begonia yenyeniae, under the IUCN Red List Categories and Criteria, is assessed as Critically Endangered.

Keywords: new species, Begonia yenyeniae, Begonia rajah, Begonia reginula, ornamental, conservation

Figure 2. Begonia yenyeniae  J.P.C.Tan, sp. nov. A Side and front view female flower B Back and front view of male flower C Stamen mass D Anthers E Habitat: moss-covered rocky slope by waterfall F Young fruit with stigma still attached G Transverse section of fruit H Seeds I Mature leaf J Upper leaf surface (moderately bullate) K Veins completely prominent on lower leaf surface L Petiole M Young blade N Stipules O–Q Upper, lower and side view of leaf margin R A pair of bracts and bracteole at peduncle and rachis; hairs scarcely on ventral surface of outer tepals.
(Photographs by E Y.Y. Sam, D P.T. Ong)

Begonia yenyeniae J.P.C.Tan, sp. nov.
Section Jackia M.Hughes

Diagnosis: Similar to Begonia rajah Ridl. (1894:213) in its handsome leaves, striking brownish-pink to brownish-red with greenish-yellow veins in young leaves becoming bronzy variegation at maturity; in its creeping growth habit, number of tepals in male (4 tepals) and female flowers (3), palmate leaf venation and many-flowered cymes, but several notable characters distinguish the new species, including its orbicular-reniform leaf blades (vs. subrotund with an abruptly acute apex in B. rajah), smaller stipules, 9–12 × 3–4 mm, three times longer than wide (vs. 15–20 × 10–12 mm, less than twice as long as wide), smaller ovate or obovate bracts 2–3 × 1.5–2 mm (vs. bracts bowl-shaped, wide ovate, 5–8 × 7.5–8 mm), margin shallowly crenate (vs. margin angular), bullate leaf surface (vs. conspicuously pronounced bullate). Furthermore, the leaf colour of cultivated B. rajah is more vivid and, in contrast, its tepals, stipules and bracts are also a deeper shade of pink, compared to those of B. yenyeniae.

It is also similar to B. reginula Kiew (2005: 218) in its habit, leaf colour, less pronounced bullate blade, palmate venation, bracts, ovary with 3 equal wings of similar shape, but B. yenyeniae is different in its relatively smaller and narrower tepals 5–7 × 6 mm (vs. 6–10 × 9–11 mm in B. reginula), 3 in male or 4 tepals in female flowers (vs. 2 tepals in both male and female flowers) and rounded base (vs. subcordate), stipules with prominently keeled (vs. keel absent), and apex rounded (vs. apex attenuate).

Although molecular data indicate a close relationship to B. foxworthyi ((1925: 311), the latter species is morphologically distinct in its conspicuously oblique leaf with an acute to acuminate apex (vs. orbicular-reniform with a rounded apex), its entire margin (vs. crenate) and plain green, non-bullate leaf surface (vs. purplish-green to brownish-purple and bullate) and its male flowers with 2 tepals (vs. 4 tepals). In addition, it usually grows on limestone substrates (vs. confined to granite substrates.

Distribution: Endemic in Peninsular Malaysia, Johor, Mersing District, Endau-Rompin National Park, Sungai Selai. It is apparently a rare species as it is known only from the type locality in Endau Rompin National Park.

Etymology: Named after Dr Sam Yen-Yen, Malaysian botanist, specialist in Zingiberaceae who first discovered the species and recognised its potential as an ornamental plant.
Ecology: In primary lowland mixed dipterocarp forest, growing on moss-covered rocks, rarely epiphytic, near a waterfall in deep shade.

Joanne Pei-Chih Tan, Sheh May Tam and Ruth Kiew. 2018. Begonia yenyeniae (Begoniaceae), A New Species from Endau Rompin National Park, Johor, Malaysia. PhytoKeys. 110: 23-37. DOI: 10.3897/phytokeys.110.25846


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