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Phytotaxa 541 (1): 073–078
https://www.mapress.com/pt/
Copyright © 2022 Magnolia Press Article PHYTOTAXA
ISSN 1179-3155 (print edition)
ISSN 1179-3163 (online edition)
Accepted by Sin Yeng Wong: 4 Mar. 2022; published: 22 Mar. 2022
https://doi.org/10.11646/phytotaxa.541.1.7
73
Lithocarpus eiadthongii (Fagaceae), a new stone oak species from southern part of
Thailand
AROON SINBUMROONG1,5, SUKID RUEANGRUEA2, ATCHARA TEERAWATANANON3,4 & SARAWOOD
SUNGKAEW4,5,*
1 Protected Area Regional Office 4 (Surat Thani), Department of National Parks, Wildlife and Plant Conservation, 84000, Thailand.
�
aroon5561@gmail.com; https://orcid.org/0000-0001-8504-4106
2 Forest Herbarium (BKF), Department of National Parks, Wildlife and Plant Conservation, 61 Phahonyothin Rd., Chatuchak, Bangkok
10900, Thailand.
�
sukidku@hotmail.com; https://orcid.org/0000-0003-1512-5976
3 Natural History Museum, National Science Museum, Technopolis, Pathum Thani 12120, Thailand.
�
teerawaa@tcd.ie; https://orcid.org/0000-0002-7232-2709
4 Center for Advanced Studies in Tropical Natural Resources, Kasetsart University, Bangkok 10900, Thailand.
5 Department of Forest Biology, Faculty of Forestry, Kasetsart University, Bangkok 10900, Thailand.
�
fforsws@ku.ac.th; https://orcid.org/0000-0003-0389-7223
*Corresponding author:
�
fforsws@ku.ac.th
Abstract
A new species of the genus Lithocarpus, L. eiadthongii, from southern part of Thailand is described and illustrated. Its
colour photographs are also provided and its conservation status is assessed. The new species is superficially similar to L.
melataiensis, L. pusillus and L. vuquangensis in terms of leaf and fruit size. Notwithstanding, it differs from the three species
in several aspects e.g. leaf apex, leaf blade covering, cupule stalk, cupule size, nut size and nut enclosure.
Keywords: Asia, conservation, diversity, oak, tree
Introduction
Lithocarpus Blume (1826: 526) is the second largest genus, coming after Quercus Linnaeus (1753: 994), of the oak
family Fagaceae Dumortier (1829: 11). So far, of 514 scientific plant names of species rank for Lithocarpus, 336 are
accepted species names (The Plant List, 2013). According to previous works (e.g. Barnett, 1940; Soepadmo, 1972;
Phengklai, 2008; and Strijk et al., 2014a,b), Thailand possesses a relatively low number of Lithocarpus species. A
comprehensive work on Thai Fagaceae (Phengklai, 2008), reports 56 species of this genus occurring in Thailand. In
later days, only two new records (L. corneus (Lour.) Rehder (1917: 3569) and L. gigantophyllus (Hickel & A.Camus)
A.Camus (1931: 40)) and a new species (L. orbicapus Strijk (Strijk et al., 2014b: 34)) of this genus were reported from
the country (Strijk et al., 2014a,b; Strijk & Son, 2019). During field excursions in southern part of the country for the
Flora of Thailand project, an unknown Lithocarpus species was collected and studied.
Materials and methods
Identification using conventional herbarium techniques was made according to Barnett (1940), Soepadmo (1972),
Phengklai (2008) and Strijk et al. (2014b). The holotype of the new species, L. eiadthongii, was designated and all
isotypes were examined. The vegetative and reproductive characters were measured using a stereomicroscope and
graticule (Olympus SZ30). Dimensions given in the description are based mainly on the types, and are accompanied
by observations made of living plants in the field. Morphological traits and natural distributions of its most similar
species, L. melataiensis Julia & Soepadmo (1998: 137), L. pusillus Soepadmo (1970: 270) and L. vuquangensis Ngoc
& V.H.Nguyen (Ngoc et al., 2018: 21), from their protologues and type specimens from following herbaria were
SINBUMROONG ET AL.
74 • Phytotaxa 541 (1) © 2022 Magnolia Press
also examined: A, K and L, here appropriate, cited (https://plants.jstor.org/), and taken into account to complete the
comparisons. The designated type specimens were deposited in BKF, KUFF and THNHM. Herbarium acronyms follow
Index Herbariorum (Thiers, 2020, continuously updated) except for the herbaria of the Kasetsart University, Faculty
of Forestry, Bangkok, Thailand (KUFF) and the Natural History Museum, National Science Museum, Technopolis,
Pathum Thani, Thailand (THNHM); the abbreviations have been coined for use in this study.
Taxonomic treatment
Lithocarpus eiadthongii Sinbumr., Rueangr. & Sungkaew, sp. nov. (Figs. 1 & 2)
Diagnosis:—Lithocarpus eiadthongii is superficially similar to L. melataiensis, L. pusillus and L. vuquangensis. In
terms of leaf characters, it may look like L. vuquangensis, but it is, however, much different from the latter in terms
of fruit characters (having cupule size of 4−7 mm high by 8−13 mm across; cupule surface with (5)6−9 lamellae; nut
size of 0.8−1.5 cm across; nut basal scar of 4−8 mm across in L. eiadthongii vs cupule size of ca 14 mm high by ca
18 mm across; cupule surface with 4−5 lamellae; nut size of 2.1−2.4 cm across; nut basal scar of ca 11 mm across
in L. vuquangensis). Whilst, in terms of fruit characters, it may look similar to L. melataiensis and L. pusillus, but L.
eiadthongii differs from the latter two in having a stalked cupule of 3−6 mm long (vs sessile cupule in L. melataiensis
vs sessile to stalked cupule of 2−3 mm long in L. pusillus. Moreover, in terms of leaf characters, L. eiadthongii is much
different from the latter two in having a leaf acumen of 3−10 cm long and leaf undersurface with sparsely white to
creamy-white waxy to glabrous (vs leaf acumen of 15−22 mm long and leaf undersurface with densely yellowish brown
tomentose, sometimes with simple hairs in L. melataiensis vs leaf acumen of 10−30 mm long and leaf undersurface
with densely greyish brown tomentose by adpressed, minute, stellate hairs in L. pusillus) (Table 1).
Type:—THAILAND. Ranong province: Mueang Ranong district, Ngao subdistrict, Namtok Ngao National Park,
hillside, UTM 47P E459665 N1090233, elev. 214 m, 4 July 2020, Sinbumroong 04072020 (holotype: BKF!; isotypes:
BKF!, Kasetsart University, Faculty of Forestry, Bangkok, Thailand!, Natural History Museum, Thailand!).
Description:—Medium to large sized evergreen tree, 15−35 m tall, 20−85 cm in diam. at breast height; buttresses
usually present, up to 2 m tall. Outer bark greyish brown or greenish grey, smooth and lenticellate, usually with
superficial horizontal lines, becoming finely winding- and shallow-fissured to finely scaly. Inner bark easily detached
from the sapwood, reddish brown to dark brown, surface of inner bark facing sapwood equipped with numerous
longitudinal ridges resulting numerous longitudinal and slightly depressed purplish lines with 0.5−1.5 cm long on
white to slightly creamy sapwood. Branchlets yellowish green in vivo and reddish brown to dark brown in sicco,
grooved, sparsely covered with white wax and lenticels, becoming glabrous. Terminal buds tiny, ovoid, ca. 1 by 1 mm;
scaly, scales ovate, spirally imbricate. Stipules not seen. Leaves simple, spirally arranged along twig, not crowded near
the end of each flush; blades narrowly elliptic, lanceolate-elliptic, oblong-ovate to lanceolate-ovate, (linear-elliptic
in sapling stage,) thin coriaceous, rigid, 6−12.5 by 1.5−3.5 cm; adaxially green, glabrous, dull to glossy, abaxially
pale greyish to creamy green, sparsely covered with white to creamy-white wax to glabrous; base acute or cuneate to
slightly attenuate, apex acute to bluntly acuminate, acumen 3−10 mm long; margin entire, sometimes slightly undulate;
midrib thin, slightly raised on both surfaces; secondary veins (9−)11−13(14) pairs, thin, obscure to slightly distinct both
sides, subparallel, at an angle of 50°−60°, slightly arcuating and faintly anastomosing near the margin; veinlets fine
reticulated, irregular or areolate, obscure on both sides; petiole 6−10 mm long, 1.3−2 mm in diam., usually straight to
slightly curved, adaxially furrowed, abaxially rounded, sparsely covered with white to creamy-white wax to glabrous.
Inflorescences usually androgynous (terminal) and branched, occasionally female (subterminal) and unbranched,
erect, 4−10 cm long, peduncle 1−2 mm in diam. (androgynous inflorescence) or 1.5−3 mm (female inflorescence),
densely covered by creamy stellate and single hairs; bracts and bracteoles deltoid to ovate-acute, ca 0.1−0.4 mm. Male
flowers solitary on the upper part of androgynous inflorescence; perianth 5−6-lobed, coriaceous, broadly ovate-acute
to broadly ovate-rounded, 0.3−0.5 by 0.5−1.2 mm; stamens 10−12; filaments 0.8−1.1 mm long, anthers 0.2−0.3 mm
long; pistillode globose, 0.5−0.8 mm in diam. Female flowers solitary on the lower part of androgynous inflorescence
or in clusters of 2−7 on female inflorescence; perianth 5−6-lobed, coriaceous, broadly ovate-acute to broadly ovate-
rounded, 0.3−0.6 by 0.3−0.7 mm; staminodes 10−12, rudimentary; styles 3(4), conical, 0.2−0.4 mm long, erect to
slightly recurved. Infructescence woody, as long as inflorescence. Ripe cupule solitary (that from female inflorescence
not seen); 3−6 mm stalked, lamellate, usually set in 2−3 regular lines; deeply cup or obconical, 4−7 mm high, 8−13 mm
across; densely and creamy tomentose with stellate and simple hairs, lamellate; wall woody, thin; rim thin, enclosing
1/6−1/5 part of the nut; lamellae distinct, rim entire or faintly denticulate, set in (5)6−9 regular lines. Nut obovoid
A NEW SPECIES OF LITHOCARPUS EIADTHONGII Phytotaxa 541 (1) © 2022 Magnolia Press • 75
or ovoid, 1.5−2.2 cm long by 0.8−1.5 cm across, greater part glabrous, only densely covered with appressed creamy
stellate and single hairs upward, chocolate-brown, base slightly rotundate to rotundate-truncate, top sharply acute; scar
concave, 4−8 mm in diam., 0.7−1.4 mm deep; wall bony, thin, 0.5−1 mm thick.
FIGURE 1. Lithocarpus eiadthongii. A. Fruiting leafy twig; B. Androgynous inflorescence on leafy twig; C. Female flower; D. Male
flower. Drawn from Sinbumroong 04072020 by A. Teerawatananon.
Etymology:—The specific epithet eiadthongii is named in honour of a well-known Thai dendrologist, Associate
Professor Wichan Eiadthong who specialized in many families of Thai flora including Fagaceae (Eiadthong, 1993).
Vernacular:—Ko look eiad (Thai), meaning an oak tree with small fruit.
Ecology and distribution:—Currently, it is only known from peninsular Thailand; in Namtok Ngao National
Park and Klong Naka Wildlife Sanctuary of Ranong province and Si Phang-nga National Park of Phangnga province.
They grow in the co-dominant and intermediate layers of the evergreen forest canopy, particularly along the hillsides,
between 60 m and 260 m elevation.
SINBUMROONG ET AL.
76 • Phytotaxa 541 (1) © 2022 Magnolia Press
TABLE 1. Morphological comparisons and their natural distributions of Lithocarpus eiadthongii, L. melataiensis, L. pusillus and L. vuquangensis.
Morphological traits and
species distribution L. eiadthongii L. melataiensis
(from Julia & Soepadmo, 1998)
L. pusillus
(from Soepadmo, 1970; Anderson 4560
(holotype: L!; isotypes: A!, K!))
L. vuquangensis
(from Ngoc et al., 2018)
Leaf blade
Narrowly elliptic, lanceolate-elliptic, oblong-
ovate to lanceolate-ovate; 6−12.5 cm long by
1.5−3.5 cm wide
Narrowly elliptic; 9−13.5 cm long by 2−3 cm
wide
Narrowly elliptic or lanceolate-elliptic to
lanceolate-ovate; (4−)6−10(−12.5) cm long by
(1.7−)2.5−4(−5) cm wide
Narrowly elliptic to lanceolate; 7.5–11 cm
long by 2.3–3.6 cm wide
Leaf apex Acute to acuminate, acumen 3−10 mm long Caudate or long acuminate, acumen 15−22 mm
long Acuminate-caudate, acumen 10−30 mm long Long acuminate, acumen up to 12 mm long
Leaf blade covering Upper surface glabrous, lower surface sparsely
white to creamy-white waxy to glabrous
Upper surface sparsely appressed brownish
tomentose, lower surface densely yellowish
brown tomentose, sometimes with simple hairs
Upper surface glabrous, lower surface (except
midrib and nerves) densely greyish brown
tomentose by adpressed, minute, stellate hairs
Upper surface glabrous, lower surface white
farinose
Cupule
Stalked, 3−6 mm long; usually solitary; deeply
cup or obconical; 4−7 mm high by 8−13 mm
across
Sessile; solitary; deeply saucer-shaped; 4−7 mm
high by 12−17 mm across
Sessile to stalked, 2−3 mm long; solitary; cup
to saucer-shaped; ca 3 mm high by 8−12 mm
across
Stalked, ca 4−6 mm long; solitary; broadly
obconical to saucer-shaped; ca 14 mm high
by ca 18 mm across
Cupule surface
Densely and creamy tomentose with stellate
and simple hairs; lamellae (5)6−9, rim entire or
faintly denticulate
Densely tomentose with stellate and simple
hairs; lamellae 6−8, rim minutely denticulate
Densely greyish stellate hairy, hairs minute,
adpressed; lamellae 4−5, rim entire or
denticulate
Densely covered with tawny minute hairs;
lamellae 4−5, rim shortly acuminate
Nut shape
Obovoid or ovoid, 1.5−2.2 cm long by 0.8−1.5
cm across, base slightly rotundate to rotundate-
truncate
Conical, 1.7−2.0 cm long by 1.1−1.5 cm.
across, base not applicable
Ovoid-conical, 0.8−1.5 cm long by 0.8−1.6 cm
across, base rotundate
Obovoid or globose, 1.7−2.0 cm long by
2.1−2.4 cm across, base rotundate
Nut enclosure Cupule enclosing 1/6−1/5 part of the nut Cupule enclosing less than half of the nut Cupule enclosing basal part of the nut Cupule enclosing only basal to 1/4 part of
the nut
Nut basal scar Concave, 4−8 mm across, 0.7−1.4 mm deep Concave, 7−10 mm across Concave, 3−7 mm across Concave, ca 11 mm across
Species distribution Peninsular Thailand Endemic to Borneo (Sarawak) Borneo (Sarawak, Kalimantan, Sabah) Vietnam (so far known only from Vu Quang
National Park, Ha Tinh Province)
A NEW SPECIES OF LITHOCARPUS EIADTHONGII Phytotaxa 541 (1) © 2022 Magnolia Press • 77
FIGURE 2. Lithocarpus eiadthongii. A. Habit of fruiting leafy twig (from the holotype Sinbumroong 04072020); B. Trunk, showing outer
bark and buttresses; C. Flowering leafy twig, showing androgynous inflorescences; D. Dry and mature cupules and nuts, showing inside
and outside of cupules, basal scar of the nuts and a longitudinal section of a nut. Photos by A. Sinbumroong.
Conservation status:—Lithocarpus eiadthongii is, so far, known from only three populations, all of them occur
in three neighboring protected areas. According to the IUCN Red List categories and criteria (IUCN Standards and
Petitions Committee, 2019), this plant could be assigned to a category of Vulnerable (VU) D2 based on its limited area
of occupancy and the low number or known populations. However, insufficient data exists regarding its distribution,
so we provisionally propose the species conservation status as Data Deficient (DD).
Additional specimens examined:—Thailand. Ranong province, Suk Samran district, Naka subdistrict, Klong
Naka Wildlife Sanctuary, hillside, UTM 47P E445772 N1045984, elev. 63 m, 12 May 2021, Sinbumroong 12052021-
3 (BKF!, KUFF!, THNHM!); Phangnga province, Khura Buri district, Bang Wan subdistrict, Si Phang-nga National
Park, evergreen forest, 47P E438646 N992049, elev. 253 m, 3 June 2021, Sinbumroong 03062021 (BKF!, KUFF!,
THNHM!).
Acknowledgements
We thank the staff of IDTs (Identify Trees-Identification Dream Team) and Dr Somran Suddee of BKF for their help
in sourcing data and specimens. We are especially thankful to Mr Kasemsanti Pluemchit, Mr Apichat Rungrueng and
Mr Girawit Srichaikhan who helped collect plant specimens.
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