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Research Article
Quercus mangdenensis, a new species of Quercus (Fagaceae) from Kon Tum Province, Vietnam
expand article infoNguyen Van Ngoc‡, Hoang Thi Binh‡
‡ Dalat University, Dalat, Vietnam

Corresponding author: Hoang Thi Binh ( binhht@dlu.edu.vn )

Academic editor: Norbert Holstein
© 2022 Nguyen Van Ngoc, Hoang Thi Binh.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation: Ngoc NV, Binh HT (2022) Quercus mangdenensis, a new species of Quercus (Fagaceae) from Kon Tum Province, Vietnam. PhytoKeys 215: 73-79. https://doi.org/10.3897/phytokeys.215.93684
Open Access

Abstract

Quercus mangdenensis Binh & Ngoc, sp. nov. (Fagaceae) is newly described from Mang Den Town in the central highland of Vietnam. The new species is characterized by lanceolate to oblong-lanceolate leaves with entire margin, 1–5-fruited infructescence, larger fruit size 6–10.5 cm long, broadly bowl-shaped cupules enclosing 1/5 of the nut, bracts of cupule entire and arranged in 5–7 rings, and cylindrical-ellipsoid and basally flat nuts 4.5–7.5 cm long. Quercus mangdenensis is morphologically similar to Q. bidoupensis Binh & Ngoc and Q. kontumensis A.Camus in having similar leaf shape, cuneate leaf base, and bracts arrangement in cupules. However, it differs from Q. bidoupensis and Q. kontumensis by cupules broadly bowl-shaped, much larger fruits, cylindrical-ellipsoid nut shape, and cupule enclosing 1/5 of the nuts. A description, photographs, and preliminary species conservation status of the new species are also provided.

Keywords

Fagales, flora, Kon Plong, Mang Den, taxonomy

Introduction

Quercus L. is the biggest genus of the family Fagaceae, comprising more than 500 species widely distributed in Europe, North America, the Mediterranean, temperate deciduous forests in East Asia, and tropical montane forests in Southeast Asia (Nixon 1993; Huang et al. 1999; Phengklai 2008; Hubert et al. 2014; Valencia-A et al. 2016). In Vietnam, a total of 52 Quercus species have been reported (Ho 2003; Ban 2005; Li et al. 2016; Binh et al. 2018a, b, c; Binh et al. 2021; Ngoc et al. 2022), of which, recent efforts in taxonomic works of the genus Quercus have resulted in the description of seven new species from Vietnam (Binh et al. 2018a, b, c; Binh et al. 2021; Ngoc et al. 2022), indicating that the species diversity of Quercus of the country is significant. Therefore, taxonomic studies of the Vietnamese Quercus are still required.

Mang Den town belongs to Kon Plong District, Kon Tum Province of Vietnam with a total area of 148.07 km2 (Kon Tum Province 2022) (Fig. 1). In this area, the annual temperature range is 18.7–24.9 °C and the average annual rainfall is around 1780–2200 mm with the rainy season from August to February (Tri et al. 2022). In the region, 273 woody plants have been recorded (265 angiosperms and 8 gymnosperm species). As for Fagaceae, 20 species have been recorded from Kon Plong District (Thanh et al. 2001).

Figure 1. 

Type locality of Quercus mangdenensis Binh & Ngoc A map of Vietnam B map of Kon Tum province C map of Kon Plong District, the red star indicated the type locality: Mang Den Town, Dak Long Commune.

From April to July 2022, we conducted botanical surveys in Mang Den and collected several individuals of the genus Quercus that could not be placed with any previously described species. After careful morphological examination and taxonomic review, here we describe those individuals as Quercus mangdenensis Binh & Ngoc along with morphological comparisons with the most similar species, photographs, and a preliminary conservation assessment of the new species.

Materials and methods

Plant materials

In this study, six specimens of the new species (Binh et al. QC204, 205 206, 207, 208, 209) were collected from Mang Den, Kon Plong District, Kon Tum Province (Fig. 1). In addition, we used type specimens and specimens that were collected from the type locality of the following species: Q. bidoupensis (Tagane et al. V4328 [DLU!], Binh et al. QC27, 29, 30, 45, 57 [DLU!]) and Q. kontumensis (Poilane 18381 [P00754004] and [P00754005]), which are morphologically most similar to the new species in having a lanceolate to oblong-lanceolate leaf shape, cuneate leaf base, and bracts of cupule fusing in 5–7 rings.

Morphological observations

To confirm that the species was undescribed, the relevant literature including Camus (1934), Soepadmo (1972), Huang et al. (1999), Ho (2003), Ban (2005), and Phengklai (2008), Binh et al. 2018a, b, c; Binh et al. 2021; Ngoc et al. 2022 were consulted. Then, we examined specimens in the herbaria at DLU, K, P, and VNM as well as digital images on the websites of JSTOR Global Plants (https://plants.jstor.org/) and the Chinese Virtual Herbarium (http://www.cvh.ac.cn/).

Taxonomic treatment

Quercus mangdenensis H.T.Binh & Ngoc, sp. nov.

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Fig. 2

Diagnosis

Quercus mangdenensis is morphologically most similar to Q. bidoupensis and Q. kontumensis with a lanceolate to oblong-lanceolate leaf shape, cuneate leaf base, and bracts of cupule fusing in 5–7 rings. However, Q. mangdenensis is distinguished from Q. bidoupensis by its entire leaf margin (vs. undulate, distinctly serrate in the upper 1/2), longer petioles 2.5–4 cm long (vs. 1.3–2 cm long), broadly bowl-shaped cupules (vs. obconical-shaped), larger cupule (2.6–3.5 cm high × 4–5 cm in diam. vs. 1.3–1.5 cm high × 1.3–1.7 cm in diam.), enclosure of cupule (1/5 vs. 1/3 of the nut), cylindrical-ellipsoid nut (vs. ovoid), larger nut (4.5–7.5 cm high × 3–4 cm in diam. vs. 2.2 cm high × 1.4 cm in diam.), and flat basal scar of the nut (vs. convex). It differs from Q. kontumensis in having larger cupule enclosing 1/5 of the nut (2.6–3.5 cm high × 4–5 cm in diam. vs. 1–1.2 cm long × 1.5–2 cm in diam., enclosing 1/2 of the nut), larger cylindrical-ellipsoid nut 4.5–7.5 cm high × 3–4 cm in diam. (vs. cylindrical-ovoid, 2 cm high × 1.5 cm in diam.), and scales of cupule fusing into 5–7 entire ridges (vs. undulate) (Table 1).

Table 1.
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Morphological comparison amongst Quercus mangdenensis Binh & Ngoc, sp. nov., Quercus bidoupensis Binh & Ngoc and Quercus kontumensis A. Camus.

Characters Q. mangdenensis Q. bidoupensis (1,2) Q. kontumensis (3,4)
Buds shape gobose to oblate oblong to ellipsoid ovoid to ellipsoid
Leaf shape lanceolate to oblong-lanceolate oblong-lanceolate lanceolate to oblong-lanceolate
Leaf margin entire margins undulate, distinctly serrate in the upper 1/2 entire or distinctly serrate in the upper 1/5
Length of petioles (1.3–)2.5–4 cm long 1.3–2 cm long 2.5–4.2 cm long
Number of secondary veins (5–)7–9 pairs 10–13 pairs 5–8 pairs
Cupule shape and size broadly bowl-shaped, 2.6–3.5 cm high, 4–5 cm in diam. obconical-shaped, 1.3–1.5 cm high, 1.3–1.7 cm in diam. cup-shaped, 1–1.2 cm long, 1.5–2 cm in diam.
Number of rings on cupule 5–6 rings 5–6 rings 6–7 rings
Cupule bract margin entire entire undulate
Cupule coverage enclosing 1/5 of the nut enclosing 1/3 of the nut enclosing 1/2 of the nut
Nut shape and size cylindrical-ellipsoid, 4.5–7.5 cm high, 3–4 cm in diam. ovoid, 2.2 cm high, 1.4 cm in diam. cylindrical-ovoid, 2 cm high, 1.5 cm in diam.
Base of the nut Flat Convex Flat

(1) From the protologue (Binh et al. 2018b); (2) From Binh et al. QC27 (DLU); (3) From Camus (1934); (4) From the material E. Poilane 18381 (P [P00754005, P00754005]).
Figure 2. 

Quercus mangdenensis Binh & Ngoc: A twigs with young fruit B terminal buds C infructescences D fallen mature fruit E, F adaxial and abaxial surface of the leaves G nuts H outside of cupule I densely reddish hairs inside of cupules J basal scar of the nut K, L inside and outside of bud scale. Materials from H.T. Binh and N.V. Ngoc QC204.

Type

Vietnam. Kontum Province, Kon Plong District, Mang Den Town, alt. 1179 m, 14°36'39.1"N, 108°15'00.5"E, 23 July 2022, H.T. Binh & N.V. Ngoc QC204 (holotype DLU!; isotypes HN!, VNM!)

Description

Tree, evergreen, 20–25 m tall, 60–80 cm girth. Bark whitish gray. Buds perulate, globose to oblate, 2.5–4 mm high, 2.5–3.5 mm in diam., bud scales imbricate, in 2–3 rows, ovate-triangular, 2.0–3.0 × 1.5–2.0 mm, apex obtuse, margin ciliate, covered with appressed white hairy outside, glabrous inside. Young twigs dark pale green, hairy, old twigs grayish-brown, glabrous, sometimes sulcate, lenticellate. Leave alternate; blades thickly coriaceous, lanceolate to oblong-lanceolate, (5.5–)11–16.5(–19.5) × (2.6–)3.5–5.5 cm, acute at apex, broadly cuneate at base, margin entire, glossy green adaxially, bright green abaxially, conspicuously pale creamy brown to yellowish brown in sicco, glabrous on both surfaces, midrib slightly raised on the upper surface, prominently raised on the lower surface, lateral veins (5–)7–9 pairs, prominent on the lower surface, at an angle of 45–55 degree from the midrib, straight and then curved near margin, tertiary veins scalariform-reticulate, faintly visible on both surfaces; petioles (1.3–)2.5–4 cm long, yellowish brown when dry, glabrous. Male and female inflorescences not seen. Infructescences axillary or pseudo-terminal (sometimes in upper leaf-scars), erect, rachis 1–1.5 cm long, 1–1.3 cm in diam., woody, glabrous, dark yellow in vivo, yellowish brown in sicco, lenticellate. Mature fruits 6–10.5 cm high (including cupule), solitary, sessile on woody rachis; nuts cylindrical-ellipsoid, 4.5–7.5 cm high, 3–4 cm in diam., rounded at the top, white tomentose around stylopodia, stylopodia 1.5–2.5 mm long, basal scar 2–2.5 cm in diam., flat; cupules broadly bowl-shaped, 2.6–3.5 cm high, 4–5 cm in diam., enclosing 1/5 of the nut when mature, outside tomentose with reddish hairs to glabrous, inside with appressed densely reddish hairs, wall 0.5–1.3 cm thick, woody, bracts fusing and arranged in 5–7 ridges (rings), the rings’ margin completely entire (without scale-like structure).

Distribution

Vietnam. Kon Tum Province, Kon Plong District, Mang Den Town (Fig. 1).

Habitat

Quercus mangdenensis were found in the scattered evergreen forest, from 1050 to 1200 m elevation.

Etymology

The specific epithet is derived from its type locality, Mang Den Town, Kon Plong District, Kon Tum Province, Vietnam.

Vernacular name

Sồi Măng Đen (suggested here).

Phenology

Fruiting specimens and fallen mature fruits were collected in July.

Additional specimens examined

Vietnam. Kontum Province, Kon Plong District, Mang Den, alt. 1168 m, 14°36'37.4"N, 108°15'11.6"E, 23 July 2022, H.T. Binh & N.V. Ngoc QC205 [fr.] (DLU!, HN!, VNM!); ibid., 1180 m elev., 14°36'32.5"N, 108°15'18.2"E, 23 July 2022, H.T. Binh & N.V. Ngoc QC207 [fr.] (DLU!, HN!, VNM); ibid., 1130 m elev., 14°36'36.5"N, 108°15'31.3"E, 23 July 2022, H.T. Binh & N.V. Ngoc QC208 [fr.] (DLU!, HN!, VNM); ibid., 1065 m elev., 14°36'36.5"N, 108°15'31.3"E, 23 July 2022, H.T. Binh & N.V. Ngoc QC209 [fr.] (DLU!, HN!, VNM!).

Preliminary conservation status

Our botanical inventories were conducted at Mang Den and the surrounding areas from April to July 2022 and we found five subpopulations of 5–7 mature individuals of Quercus mangdenensis in the scattered evergreen forests. In addition, the forest in this area is severely fragmented and continuing to decline caused by human activities, such as farming, logging, and harvesting of non-timber forest products, etc., while almost all of the individuals of Q. mangdenensis are distributed along the boundary between the evergreen forest and local people’s farms. According to criterion D of the IUCN Red List criteria (IUCN 2019), the species classifies as Critically Endangered (CR). The area of occupancy (AOO) and the extent of occurrence (EOO) were calculated are 0.415 km2 and 8.0 km2, respectively. Based on criterion B of the IUCN Red List criteria (IUCN 2019), the new species is qualified as Critically Endangered [CR B1ab(i,ii,iii,iv,v) B2ab(i,ii,iii,iv,v)].

Acknowledgements

The authors would like to thank Mr. Nguyen Van Duc and Mrs. My from Kon Tum city who kindly supported us during our fieldwork in Mang Den Town. We wish to thank the curators and staff of the following herbaria DLU, K, P, and VNM for making their materials accessible. This research is funded by the Vietnam National Foundation for Science and Technology Development (NAFOSTED) under grant number 106.03-2019.19.

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