Jack (1822) established the genus Adinandra with a single species A. dumosa from Sumatra and the Malay Islands. There are about 85 species mainly distributed in Bangladesh, Cambodia, China, India, Indonesia, Southern Japan, Laos, Malaysia, Myanmar, New Guinea, Philippines, Sri Lanka, Thailand, China and the African tropical forest (Min and Bruce 2007). The genus is characterized by sepals 5, persistent; petals 5, imbricate; stamens from 1560 in 1-5 whorls; connate or distinct filaments, adnate to the base of sepals; filiform anther trichomes, connecting with an apiculum; ovary (2-)3-5-loculed; ovules 20-100 per locule; style l, simple or apically 3-5-lobed; and fruit many- seeded, with a persistent style (Humbert 1941, Min and Bruce 2007).
Eleven species of the genus Adinandra occur in Vietnam, including A. annamensis Gagnep., A. dongnaiensis Gagnep., A. caudata Gagnep., A. glischroloma Hand-Mazz., A. hainanensis Hay., A. integerrima T. And. ex Dyer, A. microcarpa Gagnep., A. millettii Benth. & Hook. f. ex Hance, A. megaphylla Hu.; A. poilanei Gagnep., and A. rubropunctata Merr. & Chun. (Ho 1999, Nguyen Tien Ban et al. 2003), of which A. megaphylla Hu is listed in the Vietnam Red Book (2007).
During botanical expeditions (performed in 2006-2009) in Hon Giao, Bidoup Nui Ba National Park, Lam Dong Province, very distinctive specimens of Adinandra species bearing leaves and fruits were collected at the altitude of 1600 m a.s.l., but they were not referable to any known species and probably represent an undescribed species. In October, 2009, more specimens including leaves, fruits and flowers of the same trees were collected. After examining the specimens and comparing with the extant species in Vietnam, we come to the conclusion that the specimens collected from Hon Giao are similar to Adinandra poilanei Gagnep. (Gagnepain 1938) in certain characters and, but are distinguished from it and represent an undescribed species. The main differences between the new species and A. poilanei are summarized in Table 1.
Fig. 1. Adinandra hongiaoensis H. T. Son & L. V Dung.
A. Leafy branch. B. Leaf blade. C. Flower buds. D. Flower. E. Calyx and ovary. F. Petal (abaxial view). G. Petal (adaxial view). H. Stamens. I. Fruits. K. five locules with many seeds inside. L. Seeds.
Table 1. Morphological comparison between Adinandra hongiaoensis and A. poilanei Gagnep.
Adinandra hongiaoensis H. T Son & L. V. Dung, sp. nov.
Similissima Adinandrae poilanei Gagnep., sed quod per modum laminis magnis (35-45 x 8-12 cm), foliis basi vulgo cordatis, pedicellis brevioribus, foliis subtus pubescentibus differt.
Type: VIETNAM. Lam Dong Province, Bidoup Nui Ba National Park, Hon Giao peak, elevation 1600 m a.s.l., 16 October 2009, Hoang Son HS09 (VAFS [Vietnamese Academy of Forest Science, Vietnam]-holotype; DLU [Da Lat University, Vietnam]-isotype).
Evergreen, trees up to 10 m tall, young branches with dense gray hairs. Petiole is very short, almost sessile, white at the base; leaves alternate; leaf blade oblong or oblong-elliptic, 30-45 cm long and 8-12 cm wide, adaxial surface green, glabrous, abaxial surface light green, grayish-yellow hairy, midvein abaxially prominent extended in the form of wings, lateral veins inconspicuous, leaf base obtuse or cordate, apex acuminate, margins serrate. Flowers axillary, solitary or paired; peduncle 0.5-0.7 cm long, dense white hairs; bracts 2, ovate, 0.8-1.0 x 0.7-0.8 cm, abaxial surface with dense hairs, sepals ovate, 1.0-1.2 x 1.3-1.7 cm, abaxial surface grayish brown sericeous, apex slightly acute to sub-rounded; outer sepals thick, margins reddish hairs; inner sepals membranous, margins entire. Petals white, oblong to oblong- elliptic, 2.2-2.5 x 1.6-1.7 cm, apex obtuse, adaxial surface pubescent. Stamens numerous, in 2 whorls, 20-24 per whorl, 1.5-1.7 cm long; filaments 0.3-0.4 cm long, with dense hairs, adnate to base of sepals; anthers linear, 0.2-0.3 cm long. Ovary conical shaped, locules 5, 18-45 ovules per locule; styles 5 lobed, shallow, 0.40.6 cm long. Fruit purplish black, globose, 2-2.2 cm in diam., pubescent, many seeds per locule. Seeds brown-black, semicircular, kidney-shaped, 0.1-0.3 mm long, back creased (not smooth).
Distribution and habitat: The new species Adinandra hongiaoensis is endemic to Bidoup Nui Ba National Park, in the southern highlands of Vietnam, between 1600-2000 m a.s.l. associated with Fokienia hodginsii Henry & Tomas (Cupressaceae), Podocarpus imbricatus Blume, Podocarpus neriifolius D. Don (Podocarpaceae), Quercus macrocalyx Hick. & A. Camus, Quercus langbianensis Hick. & A. Camus (Fagaceae) and Camellia sp. (Theaceae).
Etymology: The specific epithet 'hongiaoensis’ derived from the type locality 'Bidoup Nui Ba National Park’.
The authors would like to thank the Management Board of Bidoup Nui Ba National Park for their kind help in locating field surveys. We would like to thank Dr. Nguyen Hoang Nghia (Vietnam Academy of Forest Sciences) and Dr. Tran Van Tien (Dalat University) for critical reading earlier version of the manuscript. The authors are also grateful to Mrs. Luong Thi Minh Hoa for making illustration.
Calarence E. K. 1947. Adinandra. J. Arn. Arb. 28: 1-98. Gagnepain F. 1938. Adinandra. In: Lecomte P. H. (ed.), Supplément a La Flore Générale de L’Indo-chine 1: 290. Gallice, Paris.
Humbert H. 1941. Notulae Systematicae. Tome X,Fasicules 1 et 2: 112-116. Paris.
Ho P. H. 1999. Cay Co Vietnam (An Illustrated Flora of Vietnam). 1: 415-417. Youth Publishing House, Ho Chi Minh (in Vietnamese).
Jack W. 1822. Adinandra. Malayan Miscellanies 2(7): 49. Ministry of Science and Technology. Vietnam Red Data Book. Part II - Plants: 342. Ministry of Natural Sciences and Technology, Ha Noi.
Min T. L. and Bruce B. B. 2007. Theaceae. In: Wu Z. Y, Raven P. H. and Hong D. Y (eds.), Flora of China 12: 435-443. Science Press, Beijing and Missouri Botanical Garden Press, St. Louis.
Nguyen T. B. (ed.) 2003. A List of All Plant Species in Vietnam. 2: 341-343. Agriculture Publish House, Ha Noi.
Key words: Adinandra, Adinandra hongiaoensis, new species, Theaceae, Vietnam.
Hoang Thanh Son
Silviculture Research Institute, Vietnamese Academy of Forest Sciences, Ha Noi, 10999 VIETNAM
Luong Van Dung
bBiology Department, Dalat University, Dalat, 61999, VIETNAM