ISSN 1346-7565
Acta Phytotax. Geobot. 67 (2): 127–130 (2016)
doi: 10.18942/apg.201602
A New Record of Gaertnera junghuhniana Miq. (Rubiaceae) from
Southern Vietnam
Shuichiro Tagane 1,*, Akiyo Naiki 2, Van Son Dang 3 and Tetsukazu Yahara1
1
Center for Asian Conservation Ecology, Kyushu University, 744 Motooka, Fukuoka, Fukuoka 819-0395, Japan.
2
* [email protected] (author for correspondence); Iriomote Station, Tropical Biosphere Research
3
Center,University of the Ryukyus, 870 Uehara, Taketomi-cho, Yaeyama-gun, Okinawa 907-1541, Japan; The VNM
Herbarium, Institute of Tropical Biology, Vietnam Academy of Science and Technology, 85 Tran Quoc Toan Street,
District, Ho Chi Minh City, Viet Nam
Gaertnera junghuhniana was newly recorded from Hon Ba Nature Reserve, Khanh Hoa Province, southern Vietnam.
Key words: Gaertnera, Gaertnera junghuhniana, Hon Ba Nature Reserve, Rubiaceae, Vietnam
The genus Gaertnera Lam. (Rubiaceae) comprises ca. 70 species of small trees and shrubs native to continental Africa, Madagascar, Sri Lanka, India, continental Southeast Asia, Sumatra,
Borneo and Sulawesi (Malcomber & Taylor
2009). In Vietnam, only Gaertnera sralensis
(Pierre ex Pit.) Kerr has been reported (Pitard
1922–1924, Malcomber & Taylor 2009). It is distributed from the south to the center of the country, and is also in Cambodia, Thailand and Peninsular Malaysia. Ho (2000) treated G. sralensis as
a synonym of G. vaginans subsp. junghuhniana
(Miq.) Beusekom, but Malcomber & Taylor
(2009) considered the Vietnamese plants to be G.
sralensis. The description in Ho (2000) and characteristics of all the specimens collected in Vietnam and deposited in the herbarium P (digitalized
images examined) are identical to G. sralensis.
During our field surveys on Mt. Hon Ba,
Khanh Hoa Province, southern Vietnam, in 2013
and 2014, we found another species of Gaertnera,
which corresponds to Gaertnera junghuhniana
Miq. in the treatment of Malcomber & Taylor
(2009). The plants we collected lack flowers, but
are clearly distinguishable from G. sralensis by
their taller shoots (4 m vs. usually 1 m in G.
sralensis), larger leaves (7.5–23.3 × 1.8–5.2 cm
vs. 4–13 × 1–4.5 cm), more secondary veins (7–9
pairs vs. 4–7 pairs) and larger infructescences
(laxly cymose, ca. 10 cm long, 9.5–11 cm wide
with peduncles 3.5–4 cm long vs. congested cymose, 1–2 cm long, 1–2 cm long wide, sessile or
peduncle to 0.3 cm long) (Fig. 1), according to Ho
(2000) and Malcomber & Taylor (2009). Measurements of the Vietnamese plants are within
the limits of previous descriptions of G. junghuhniana (Malcomber & Taylor 2009): the leaves are
oblanceolate to narrowly elliptic, 7.5–23.3 × 1.8–
5.2 cm with 7–9 pairs of secondary veins.
Here we report the presence of Gaertnera
junghuhniana in Vietnam and provide a description and photographs based on our new collections. We also provide DNA barcodes of the rbcL
and matK regions (CBOL Plant Working Group
2009). The methods of DNA barcoding followed
the protocols of Kress et al. (2009) and Dunning
& Savolainen (2010).
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Acta Phytotax. Geobot.
Gaertnera junghuhniana Miq., Fl. Ned. Ind. 2:
383 (1857); Malcomber & C. M. Taylor, Ann.
Missouri Bot. Gard. 96(4): 626, figures 6A–F
(2009).
Description. Trees, 4 m tall; branches terete
or slightly flattened, glabrous, ca. 2 mm in diam.,
internodes 2.8–6.6 cm long, blackish brown when
dry. Stipules tubular, thinly chartaceous, sparsely
hairy near base and apex, hairs of ca. 0.05–0.1
mm long, caducous or deciduous through fragmentation, tube 0.9–1.6 cm long, ca. 3.5 mm in
diam., with 4 low ribs, arising below petiole, encircling the bottom and side of petiole, extending
nearly or completely to lobes, the part encircling
the petiole fringed by minute hairs 0.05–0.1 mm
long, apex with 1 incision, lobes 4, 1.5–4 mm
long. Petiole 0.9–2.2 cm long. Leaf blade oblanceolate to narrowly elliptic, 7.5–23.3 × 1.8–5.2
cm, base cuneate, apex acuminate, chartaceous,
glabrous on both surfaces except midrib puberulent; midrib prominent on both surfaces, secondary veins 7–9 pairs, distinct on both surfaces, tertiary veins reticulate, prominent on both surfaces; domatia present, membranous, hairy. Infructescences terminal, cymose, ca. 10 cm long, 9.5–
11 cm in diam., branched to 4 to 6 orders; peduncle 3.5–4 cm long, peduncle and rachis glabrous,
drying blackish brown; bracts deltate, 2.5–4 mm
long, sparsely fringed by minute hairs; bracteoles
deltate, 0.8–2.2 mm long, sparsely fringed by
minute hairs; pedicels sessile to 2 mm long in immature fruit. Flowers 5-merous. Calyx cup
shaped, ca. 1.5 mm in diam., outside glabrous,
lower half inside densely pubescent, lobes triangular, to 0.5 mm long. Corolla not seen. Drupes
globose, ca. 7 mm in diam., green when young,
glabrous, with many raphids. Pyrenes 2 per
drupe, (hemi)spherical, ca. 5 mm in diam., with
many raphids. The description is based on a collection with immature fruits. –Fig. 1(A–G).
Specimens examined: Vietnam. Khanh Hoa Province: Mt. Hon Ba: alt. 919 m, 12°06'46.88"N,
108°58'14.43"E, 16 July 2014, Tagane et al. V1703 [fr.]
(Hbnr!, P, VNM!); ibid., 20 Feb. 2014, Toyama et al. V844
(Hbnr!, KYO, VNM!); alt. 890 m, 12°06'51.31"N,
108°58'23.34"E, 21 July 2013, Tagane et al. V641 [fr.]
Vol. 67
(FU!, Hbnr!, VNM!). Hbnr = the herbarium of Hon Ba
Nature Reserve.
Distribution. Brunei, Indonesia (Kalimantan,
Sumatra, Sulawesi), Malaysia (Peninsula, Borneo), Thailand (Peninsula), Vietnam (new record).
Habitat and Ecology in Vietnam. in thick
broad-leaved evergreen forest, only in a narrow
area on Mt. Hon Ba; alt. ca. 900 m.
GeneBank accession No. Tagane et al. V1703:
LC035391 (rbcL); LC035392 (matK).
Notes. Gaertnera junghuhniana is a species
most commonly collected and widely distributed
in the Malesian region and in peninsular Thailand (Malcomber & Taylor 2009). Mt. Hon Ba,
southern Vietnam, is remotely isolated from the
main range of distribution and is an example of a
Malesian element in the flora of southern Vietnam (Averyanov et al. 2003). Some other species
found on Mt. Hon Ba showing similar distribution patterns include Aglaia macrocarpa (Miq.)
Pannell (Meliaceae, Pannell 1992), Hancea penangensis (Müll.Arg.) S. E. C. Sierra, Kulju &
Welzen (synonym: Mallotus penangensis Müll.
Arg., Euphorbiaceae, van Welzen et al. 2007; Sierra et al. 2009) and Heteroblemma alternifolium
(Blume) Cámara-Leret (Melastomataceae, Cámara-Leret et al. 2014). Further botanical surveys
in southern Vietnam may find additional examples of such disjunction.
We wish to thank the directors and staff of Hon Ba Nature
Reserve for permitting our field surveys. We sincerely
thank the curators and staff of the herbaria BKF, SING,
VNM for assistance during our visits to their institutions.
We also would like to thank Keiko Mase for her help in
DNA barcoding. This study was supported by the Environment Research and Technology Development Fund
(S9) of the Ministry of the Environment, Japan.
June 2016
Tagane & aL –Gaertnera junghuhniana, new to Vietnam
129
Fig. 1. Gaertnera junghuhniana Miq. from Mt. Hon Ba, Vietnam (A-G) and G. sralensis (Pierre ex Pit.) Kerr from Mt. Bokor,
Cambodia (H). A, Leafy twigs; B, abaxial leaf surfaces; C, fruiting branch; D, stipules; E, base of petiole showing ridges
encircling sides and base of petiole; F, calyx and young fruits; G, immature drupe; H, fruiting branch. Photographed on
20 Feb. 2014 (A & D), 16 July 2014 (B & C) and 7 Dec. 2013 (H). E–G: Tagane et al. V1703 (FU). Scale bars: E = 1 mm;
F = 5 mm; G = 2 mm.
130
Acta Phytotax. Geobot.
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Received April 7, 2015; accepted January 16, 2016