Begonia fulgurata C.-I Peng, C.W. Lin & Phutthai, 2017

Begonia fulgurata C.-I Peng, C.W. Lin & Phutthai View in CoL , sp. nov. — Fig. 1 View Fig , 2 View Fig ; Map 1 View Map 1

Type. THAILAND, Chiang Mai Province, Doi Lohn (Lahn), west side, Mae Lai Village, south slope above Mae Lai Stream , Huay Gayo Subdistrict , Mae Awn District . Sterile specimen collected on 23 Oct. 2005, Peng 20548, with

1 Herbarium ( HAST), Biodiversity Research Center , Academia Sinica, Nan- gang, Taipei 115, Taiwan .

2 Herbarium of Taiwan Forestry Research Institute ( TAIF), No. 53, Nanhai Road, Taipei 100, Taiwan.

3 Faculty of Environment and Resource Studies,Mahidol University (Salaya campus), Nakhon Pathom 73170, Thailand; corresponding author e-mail: thamarat.phu@mahidol.ac.th.

Chien-I Huang,Tsung-Han Tsai, J. F . Maxwell and Pranee Palee. Type specimens pressed from plants brought back for cultivation in the experimental greenhouse of Academia Sinica, 26 Aug. 2008 (holo HAST; iso BKF) .

Etymology. The specific epithet fulgurata is derived from the fine, silvery-white venation on the leaf upper surface, which resembles lightning.

Plant perennial, monoecious, epipetric or terrestrial. Tuber globose or subglobose with fibrous roots. Stem erect or ascending, to 40 cm long, 3–7 mm across, fleshy, unbranched, densely white-velutinous and sparsely glandular hairy, internodes 3.2–11 cm long. Tuber subglobose, to c. 10 mm across. Bulbils sometimes present at lower stem, white, globose, c. 2 mm across. Stipules ovate-triangular, 4–10 mm long, 3–6 mm wide, hyaline, pale green, strongly keeled, abaxially densely velutinous, margin entire, apex mucronate or apiculate. Leaves 3–6, oblique, held pendent, distant; petiole terete, 1.3–9.5 cm long (longer in lowermost leaves, progressively shortened above), 3–5 mm across, pale green to pinkish, densely white-velutinous; slightly grooved adaxially; lamina ovate-lanceolate to widely ovate, basifixed, asymmetric, base cordate, margin undulate or denticulate, hirsute, apex acuminate, attenuate to caudate, 7–13(–18) cm long (basal lobes included), 3–7(–10) cm wide, basal lobes unequal, 0.7–3.5(–7) cm long; leaf chartaceous, succulent, adaxially dark green, embellished with maroon to dark brown irregular patches, veins silvery to snow white, veins passing through maroon patches becoming rosy pink to silvery magenta; abaxially pale green, magenta be- tween veins; venation palmate-pinnate, midrib distinguishable, 5–9(–13) cm long, with c. 3 major lateral veins on either side of midrib, other primary veins branching dichotomously or nearly so, tertiary veins reticulate; all venation prominently raised on the underside. Bracts pale green, hyaline, persistent, those at basal nodes of inflorescence ovate, c. 1 cm long, 6 mm wide, outside densely erect velutinous and glandular hairy, apex obtuse, margin with glandular hairs or velutinous; bracts on upper part of inflorescence similar but progressively smaller. Inflorescence a terminal, bisexual, cymosely branching panicle 4–7 cm long, pale green, densely glandular hairy, peduncle to 4.5 cm long; protandrous. Staminate flower: pedicel 8–14 mm long, glandular hairy; tepals 2, white to pinkish, suborbicular, outside glandular hairy, margin entire, 5–8 mm across, sometimes with an additional, narrowly elliptic tepal c. 5 mm long, 2.5 mm wide; androecium zygomorphic, stamens c. 25, yel- low, obovate, filaments shortly fused at base; anthers c. 1 mm long, subequal to filaments. Pistillate flower: pedicel c. 1 cm long, glandular hairy; ovary pale green or pinkish, shortly beaked at apex, body trigonous-ellipsoid, 3.5–5 mm long, c. 3 mm across, 3-winged; wings subequal, triangular, obtuse or nearly rounded at summit; c. 7 mm long, 2.5–4 mm wide; ovary 3-locu- lar but the septa not completely fused midway up, placentas bilamellate; tepals 5, white to pinkish, tepals ovate to lanceolate, 3–7 mm long, 1.5–4 mm wide, outer two glandular hairy on outside; styles 3, yellowish green, each bifid, c. 3 mm long, shortly fused at base; stigmas in a spiral band and papillose all around. Capsule: pedicel c. 1 cm long, capsule body globose, c. 6–8 mm across long, 5 mm wide, glandular hairy, placentae bilamellate; wings 3, subequal, c. 1 cm long, 2–5.5 mm wide.

Distribution & Ecology — Begonia fulgurata is endemic to Chiang Mai, northern Thailand ( Map 1 View Map 1 ), at 1000–1200 m altitude, where it is known only from the type locality.

Additional specimens examined. THAILAND, Chiang Mai Province, Doi Lohn (Lahn), west side, above Mae Lai Village,along Mae Lai Stream , Huay Gayo Subdistrict , Mae Awn District . On shady soil slope. Sterile plant with bulbil on petiole, N18°52'57" E99°21'59", c. 1150 m elevation, 25 Oct. 2005, Peng 20623 ( HAST), with Chien-I Huang, Tsung-Han Tsai, J GoogleMaps . F GoogleMaps . Maxwell and Pranee Palee, loc. cit., fertile specimens pressed from plants brought back for cultivation in the experimental greenhouse of Academia Sinica , 11 Sept. 2007, Peng 20623a ( HAST) GoogleMaps .

Conservation assessment — Begonia fulgurata is a smallendemic species known only from the type locality in northern Thailand. It is very attractive, and has been collected and entered into cultivation in and outside of Thailand. Locations of populations of the species are classified as recreation areas ( IUCN protected area category VI – [ Category Ib : Wilderness Area ]) that receive many tourist visitors during the high season. The handsome new species may be collected or tramped upon by hiking tourists. We consider a category of vulnerable ( VUD2 ) to be appropriate, as the populations are prone to the effects of human activities or stochastic events within a very short period of time ( IUCN 2012) .

Note — Begonia fulgurata is somewhat similar to the widespread (in SE Asia) B. integrifolia Dalzell (1851: 230) of sect. Parvibegonia in having a tuberous base, erect stem with hairy leaves and the periodically dormant habit. However, the new species is easily distinguishable by its lamina maculated with maroon patches and silvery-white veins (vs uniformly green or with white spots) and densely hirsute (sparsely puberulous); inflorescence densely glandular hairy (vs glabrous); staminate flowers with 2 or rarely 3 (vs 4) tepals, and staminate and pistillate tepals with glandular hairy (vs glabrous). The new species also bears some resemblance to B. grandis Dryand. (1791: 163) of sect. Diploclinium in its deciduous habit, erect stem and ovate to broadly ovate leaves, mainly 3-locular ovary. However, B. fulgurata markedly differs from B. grandis in the leaf upper side with fine silvery (vs green) veins; inflorescence densely glandular hairy (vs glabrous), staminate tepals 2 or rarely 3 (vs 4) and pistillate tepals 5 (vs 3), ovary glandular hairy (vs glabrous). A detailed comparison of B. fulgurata with B. integrifolia and B. grandis is presented in Table 1.