Five new species of Syzygium (Myrtaceae) from Indochina and Thailand Author Tagane, Shuichiro Center for Asian Conservation Ecology, Kyushu University, 744 Motooka, Fukuoka, 819 - 0395, Japan. & The Kagoshima University Museum, Kagoshima University, 1 - 21 - 30, Korimoto, Kagoshima, 890 - 0065, Japan. Author Dang, Van-Son The VNM Herbarium, Institute of Tropical Biology, Vietnam Academy of Science and Technology, 85 Tran Quoc Toan Street, District 3, Hochi Minh City, Vietnam. Author Souladeth, Phetlasy Faculty of Forest Science, National University of Laos, Dongdok campus, P. O. Box 7322, Vientiane, Lao PDR. Author Nagamasu, Hidetoshi The Kyoto University Museum, Kyoto University, Yoshida Honmachi, Sakyo-ku, Kyoto, 606 - 8501, Japan. Author Toyama, Hironori Center for Asian Conservation Ecology, Kyushu University, 744 Motooka, Fukuoka, 819 - 0395, Japan. & Iriomote Station, Tropical Biosphere Research Center, University of the Ryukyus, 870 Uehara, Taketomi-cho, Yaeyama-gun, Okinawa, 907 - 1541 Japan. Author Naiki, Akiyo Iriomote Station, Tropical Biosphere Research Center, University of the Ryukyus, 870 Uehara, Taketomi-cho, Yaeyama-gun, Okinawa, 907 - 1541 Japan. Author Fuse, Kengo Center for Asian Conservation Ecology, Kyushu University, 744 Motooka, Fukuoka, 819 - 0395, Japan. Author Tran, Hop University of Science Ho Chi Minh City, 227 Nguyen Van Cu Street, District 5, Ho Chi Minh City, Vietnam. Author Yang, Ceng-Jui Institute of Ecology and Evolutionary Biology, National Taiwan University, Taipei, Taiwan. Author Prajaksood, Amornrat Department of Biology, Khon Kaen University, Khon Kaen 40002, Thailand. Author Yahara, Tetsukazu Center for Asian Conservation Ecology, Kyushu University, 744 Motooka, Fukuoka, 819 - 0395, Japan. text Phytotaxa 2018 2018-11-14 375 4 247 260 http://dx.doi.org/10.11646/phytotaxa.375.4.1 journal article 10.11646/phytotaxa.375.4.1 1179-3163 13728284 Syzygium phamhoangii Tagane, V.S.Dang & Yahara , sp. nov. ( Figure 3 ). TYPE:— VIETNAM . Khanh Hoa Province , Mt. Hon Ba, 12°06′46.88″N , 108°58′14.43″E , elev. 919 m , 20 Feb. 2014 , Toyama H., Dang V.S., Tagane S., Fuse K., Yahara T., Nagamasu H., Tran H., Nguyen V.N. , Nguyen Q.C., Do N.T. & Ho N.P.H. V909 [fl.] ( holotype KYO!, isotypes FOF!, KAG!, VNM !, the herbarium of Hon Ba Nature Reserve). Syzygium phamhoangii is similar to Syzygium balsameum ( Wight 1841: 16 ) Walpers (1843: 179) in the shape of leaves and axillary inflorescences but distinguished by its obtuse to slightly cordate leaf base (vs. cuneate to long attenuate), shorter petioles ((1–) 2–4 mm long vs. 4–15 mm long), larger hypanthium ( 3.5–4 mm long vs. 2.5–3.5 mm long) and more ovules per locule in ovary (12–16 ovules vs. 3–8 ovules). Shrub, 1.5 m tall. Young twigs slightly compressed, yellowish to reddish brown, old twigs terete, yellowish brown, glabrous, internode (1.5–) 2.5–7.4 cm long. Leaves opposite, blade elliptic-oblong, (5–)9.3–17 × (2.2–) 3.4–6.5 cm , 2.1–3.5 times longer than wide, thinly coriaceous, grayish green to dull brownish yellow adaxially, light yellowish brown abaxially, glabrous on both surfaces, apex acuminate, acumen to 1.5 cm long, base obtuse, rounded, slightly cordate, margin entire, slightly recurved when dry, midrib sunken adaxially, prominent abaxially, secondary veins 10–12 pairs, (0.5–) 1–2.1 cm apart, slightly prominent abaxially, intersecondary veins usually distinct, tertiary veins indistinct on both surfaces, intramarginal vein 1, outer one ca. 0.8 mm from margin, inner one ca. 5 mm apart from margin; petiole (1–) 2–4 mm long, glabrous. Inflorescences axillary on leafy twig, paniculate, 4–5.8 cm long, 18–48 flowered, peduncle up to 1.3–1.9 cm long, rachis and lateral branches slightly compressed, bracteoles triangular, ca. 1.1 mm long, apex acute, glabrous, caducous. Flower bud ca. 2 mm in diam., whitish ( in vivo ). Hypanthium funnel shaped, 3.5–4 mm long, reddish brown when dry, glabrous, sessile. Sepals 4, broadly triangular, ca. 0.5 × 1.5 mm , petals 4, orbicular, ca. 2 mm in diam., membranous, 3 gland dots per petal. Stamens 44–50, 1.7–3 mm long, anthers ca. 0.6 mm long, filaments white ( in vivo ), 1.2–2.4 mm long. Style ca. 2 mm long. Ovary 2-locular, ovules 12–16 per locule. Fruit and seeds not seen. Distribution:— Vietnam (so far only known from the type locality, Mt. Hon Ba). Habitat and Ecology:— Hill evergreen forest, at ca. 920 m elevation. Phenology:— Flowering specimens were collected in February. Etymology:— The specific epithet is chosen in honor of the excellent Vietnamese botanist Prof. Dr. Phạm Hoàng Hộ, who significantly contributed to the study of the flora of Vietnam . Vernacular name:— Trâm phạm hoàng hộ. Preliminary conservation assessment:— Critically Endangered (CR). Syzygium phamhoangii is known only from a single population in Mt. Hon Ba, at ca. 900 m above the sea level. The population with fewer than 15 mature individuals is very close to the road and can be easily affected by human disturbance. Therefore, this species is qualified as CR under criterion D ( IUCN 2012 ).