Rhaphidophora lacduongensis V.D.Nguyen & B.H.Quang, 2015

Rhaphidophora lacduongensis V.D.Nguyen & B.H.Quang , sp. nov. — Fig. 1 View Fig , 2

Rhaphidophora lacduongensis resembles R. megaphylla by having a large ( 18–30 cm wide) entire leaf blade and straight peduncle. Rhaphidophora lacduongensis differs from R. megaphylla by its much smaller spadix (size c. 9 by c. 1.7 cm), a pistil with the surface of stylar region concave (not pointed),and the leaf blade base rounded,not cordate.— Type: Vietnam, Lam Dong, Lac Duong, Da Chais, nearby the road from Nha Trang to Da Lat, N12°7'45.86 " E108°42'29.18 ", altitude c. 1700 m, 15 Aug.2013, Nguyen Van Du & Bui Van Huong 721 ( holotype HN; isotype HN, L).

Etymology. The specific epithet refers to Lac Duong district of Lam Dong province, Vietnam, the type locality.

Climbing secondary hemiepiphyte on medium height trees, juvenile plants creeping on rocks, mature stems cylindrical, reaching to 10 m, branching shoots long, many at upper part. Juvenile stem cylindrical, smooth, internodes 2.5– 4 cm long, 6 –10 mm diam, green, occasionally light grey, rarely with delicate and drying decayed sheath at the nodes; adult stem cylindrical, 1.5 cm diam, internodes 7–20 mm long, with leaf petiole scars obvious, falcate, to 1.2 cm long, sheath scars prominent and encircling

1 Institute of Ecology and Biological Resources, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Hanoi, Vietnam; corresponding author e-mail: vandu178@gmail.com.

stem, brownish. Leaf blades entire, abundant in young plants, in adult plants leaves mainly concentrated at shoot tips; petiole slender, 20– 30 cm long, canaliculate, margin with sheath up reaching to pulvina, petiolar sheath soon drying black, degrade into delicate bands, deciduous; petiole base strongly pulvinate, 1–1.5 cm wide, apex pulvinate, pulvinus 1–2.5 cm long, smooth; leaf blade oblong-ovate to ovate, 18–32 by 5 –18 cm, base round, oblique, apex finely acuminate; primary lateral veins in 9 –12 pairs, diverging at 40 – 45° to midrib, prominent; interprimary veins obvious, 1– 2 cm distant from each other; smaller veins dull, 3 mm distant; secondary venation reticular. Inflorescence solitary on free flowering shoot; peduncle stout, stiff, straight, 9–10 cm long, 1.2 cm diam, dark green; spathe not seen; spadix cylindrical, 8.5 – 9 cm long, 1.5 – 1.7 cm diam, apex round to blunt, light yellow. Stamens 4; filament flat, sub- equal to ovary in length, 1 mm wide, anther elliptic, raised above pistil at staminate anthesis period, c. 1 mm; ovary 4 by c. 3 mm, stylar region slightly wider than ovary, hexagonal in plane view, surface deeply concave; stigma punctiform, slightly prominent from stylar region surface; ovules c. 15, attached along axil placenta, 1–1.5 mm long, stipe slender, shorter than ovule.

Vernacular name — Trâm đài lạc dƯƠng (in Vietnamese).

Distribution & Habitat — Known only from Lam Dong and Khanh Hoa Province, Vietnam. Rhaphidophora lacduongensis climbs on medium height trees of Lauraceae in evergreen montane forest at 1500 –1700 m altitude.

Phenology — Flowering (possibly) from March to May; fruit- ing from May to August.

Conservation status — The species occurs on two sites that are less than 40 km distant, giving an extent of occurrence of less than 100 km 2. Both sites are very restricted areas (each less than 10 km 2). In Lac Duong ( Lam Dong prov.), the plant grows nearby the road from Khanh Hoa to Da Lat, and would be threatened by any road construction programme. In Hon Ba Nature Reserve ( Khanh Hoa prov.), the plant is very rare (fewer than 50 mature individuals observed). It is vulnerable to anthropogenic threats such as forest fire, forest clearance, etc. According to IUCN (2012) criteria, R. lacduongensis is provisionally categorized as VU B1,2 D2 (Vulnerable) .

Other specimens examined. VIETNAM, Khanh Hoa, Cam Lam, Hon Ba Nature Reserve , N12°07'04.00 " E108°56'46.00 ", altitude c. 1520 m, 10 Aug. 2013, Nguyen Van Du & Bui Van Huong 550 ( HN) GoogleMaps .

204 Blumea – Volume 59 / 3, 2015