Research Article |
Corresponding author: Ngoc Nguyen Van ( mr.ngocnv@gmail.com ) Academic editor: Hanno Schaefer
© 2018 Ngoc Nguyen Van, Hung Nguyen Viet, Binh Hoang Thi, Shuichiro Tagane, Hironori Toyama, Hoang Thanh Son, Ha Tran Viet, Tetsukazu Yahara.
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:
Nguyen Van N, Nguyen Viet H, Hoang Thi B, Tagane S, Toyama H, Son HT, Tran Viet Ha, Yahara T (2018) Lithocarpus vuquangensis (Fagaceae), a new species from Vu Quang National Park, Vietnam. PhytoKeys 95: 15-25. https://doi.org/10.3897/phytokeys.95.21832
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Lithocarpus vuquangensis Ngoc & Hung is described from Vu Quang National Park, North Central Vietnam. The morphological comparison and phylogenetic analysis based on rbcL, matK and ITS provided evidence that the new species was not assignable to any of the previously known taxa in Vietnam and its surrounding countries. The description, photographs, preliminary conservation status and DNA barcode sequences are also provided for the new species.
Fagaceae , Lithocarpus , new species, phylogeny, taxonomy, Vietnam, Vu Quang National Park
It has been known that species richness of the genus Lithocarpus Blume (Fagaceae Dumorier) is high in Vietnam where 120 species and two varieties have been reported including the recently published species, L. dahuoaiensis Ngoc & L. V. Dung (
Vu Quang National Park covers an area of ca. 56,000 ha from lowlands (alt. 10–300 m) to the highlands (the highest peak of Rao Co, alt. 2,286 m). Two new species of mammals (Sao La - Pseudoryx nghetinhensis, Artiodactyla and the world’s largest muntjac - Muntiacus vuquangensis, Cetartiodactyla) were discovered from this national park in the 1990s (
From 2015 to 2016, floristic expeditions were carried out in Vu Quang National Park and trees of the genus Lithocarpus were discovered that did not match any described species. Here, the authors describe and name it as Lithocarpus vuquangensis Ngoc & Hung, sp. nov. accompanied with its photographs and the morphological comparison with related species. In addition to the morphological examination, DNA sequences and phylogenetic analysis are extremely helpful for identifying and delimiting species (
The morphological traits of the new species were compared with its putative relatives based on systematic literature (
Total DNA was extracted from 17 silica-gel dried leaf pieces collected in the field. DNA extraction was performed using the CTAB method (
A total of 16 accessions representing 15 species of Lithocarpus, collected throughout Vietnam, were analysed (Table
List of taxa used in this study with vouchers and GenBank accession number.
Species | Vouchers | GenBank accession number | ||
---|---|---|---|---|
rbcL | matK | ITS | ||
Lithocarpus aggregatus | Tagane et al. V6288 (DLU, FU) | LC318967 | LC318550 | MF770309 |
Lithocarpus bidoupensis | Tagane et al. V4320 (DLU, FU, VNM) | LC318961 | LC318547 | KY940070 |
Lithocarpus coalitus | Tagane et al. V4191 (DLU, FU, VNM) | LC318959 | LC318545 | MF770305 |
Lithocarpus dahuoaiensis | Ngoc et al. V3194 (DLU, FU, HN, K, KYO, P, VNM) | LC318953 | LC318551 | KY436002 |
Ngoc et al. V5404 (DLU, FU) | LC318964 | LC318548 | MF770307 | |
Lithocarpus gigantophyllus | Ngoc et al. V3185 (DLU, FU) | LC318951 | LC318538 | MF770299 |
Lithocarpus hancei | Ngoc et al. V5111 (DLU, FU) | LC318963 | LC318970 | MF952868 |
Lithocarpus hongiaoensis | Ngoc et al. V3235 (DLU, FU) | LC318956 | LC318542 | KY851759 |
Lithocarpus lemeeanus | Tagane et al. V4273 (DLU, FU) | LC318960 | LC318546 | MF770306 |
Lithocarpus licentii | Ngoc et al. V3205 (DLU, FU) | LC318954 | LC318540 | MF770301 |
Lithocarpus longipedicellatus | Nguyen et al. V3813 (DLU, FU) | LC318958 | LC318544 | MF770304 |
Lithocarpus ombrophilus | Yahara et al. V3000 (DLU, FU) | LC318949 | LC318420 | MF770297 |
Lithocarpus pseudomagneinii | Ngoc et al. V3223 (DLU, FU) | LC318955 | LC318541 | MF770302 |
Lithocarpus stenopus | Ngoc et al. V3187 (DLU, FU) | LC318952 | LC318539 | MF770300 |
Lithocarpus vinhensis | Nguyen et al. V3787 (DLU, FU) | LC318957 | LC318543 | MF770303 |
Lithocarpus vuquangensis | Yahara et al. V5743 (DLU, FU) | LC319671 | LC319670 | KY786083 |
Trigonobalanus verticillata | Yahara et al. V5764 (DLU, FU) | LC318965 | LC318549 | MF770308 |
Bayesian Inference (BI) of phylogeny was performed on the concatenated data set of three genes (rbcL, matK and ITS) using MrBayes v. 3.2 (
The morphological comparison showed that Lithocarpus vuquangensis is most similar to L. nantoensis (Hayata) Hayata distributed in Taiwan, in having entire leaf margin, mostly solitary, rarely 2 or 3 clustered cupules, cupules not completely enclosing nut and glabrous nut. The Vietnamese species sharing the above diagnostic feature of L. vuquangensis are L. hongiaoensis, in ined. (
Morphological comparison of Lithocarpus vuquangensis with three related species: The measurements of L. nantoensis is derived from
Characters | L. vuquangensis | L. nantoensis | L. hongiaoensis | L. vinhensis |
---|---|---|---|---|
Leaf margin | Entire | Entire | Entire | Entire |
Leaf surface | Glabrous adaxially, adaxially white farinose | Abaxially glaucous to light green and with adherent, waxy scalelike trichomes | Glabrous upper, adherent waxy scale abaxially | Glabrous adaxially, covered with very short white villi abaxially |
Leaf blade size | 7.5–11 × 2.3–3.6 cm | 12–16 × 2.5–3.5 cm | 9.6–14.5 × 2.5–3.8 cm | 7.5 cm × 3 cm |
Petiole length | 1–1.5 cm long | 0.7–1.3 cm long | 2.1–3 cm long | 1 cm long |
Number of secondary veins | 7–10 pairs | 10–15 pairs | 8–11 pairs | 11–12 pairs |
Infructescences length | 4–7 cm long | 16 cm long | 12.5–16.5 cm long | 10 cm long |
Fruiting stalk length | 4–6 mm long, 4–7 mm in diam. | Almost sessile | Sessile to 2 mm long | 5–6 mm long |
Cupule | Solitary, 0.6–0.9 cm high by 1.8–2.2 cm in diam. | Solitary, 1.2–1.5 cm in diam. | Solitary, 1–1.2 cm high by 1.8–2.1 cm in diam. | Solitary, 1.2–1.3 cm high by 0.8–1 cm in diam. |
Scale arrangement | Arranged into concentric rings | Arranged into concentric rings | Imbricate | Arranged into concentric rings |
Nut size | 1.7–2.0 cm high by 2.1–2.4 cm in diam. | 1.4–1.7 cm high by 1.5–1.6 cm in diam. | 0.6–0.8 cm high by 1.2–1.5 cm in diam. | 0.9–1 cm high by 1 cm in diam. |
Nut enclosure by cupule | Only basal to 1/4 of the nut | Only basal part of the nut | Enclosing ca. 1/3–1/2 of the nut | Enclosing ca. 1/3–1/2 of the nut |
Basal scar of the nut | Concave, ca. 1.1 cm in diam. | Concave, 0.5–0.8 cm in diam. | Slightly concave, 1.2–1.4 cm in diam. | Nearly flat |
In the molecular phylogenetic tree (Fig.
Both Lithocarpus vuquangensis and L. vinhensis were collected in Vu Quang National Park, but these two species occur at different altitudes: L. vuquangensis was found between 1,500 m and 1,700 m altitude, while L. vinhensis was found at a lower elevation, below 1,100 m.
Phylogenetically, L. vuquangensis is sister to L. hongiaoensis in ined. collected from Lam Dong Province located in southern Vietnam. These two species are morphologically distinguished in their length of infructescences and fruiting stalk, the arrangement of cupule bracts, nut size and other characteristics as summarised in Table
Lithocarpus vuquangensis is also morphologically similar to L. vinhensis in having an entire leaf margin, solitary cupules not completely enclosing nut, scales arranged into concentric rings and glabrous nut, but these two species are not closely located in the phylogeny. This morphological similarity may have evolved in the similar habitat of the montane evergreen forest in Vu Quang National Park. Whereas L. vuquangensis and L. vinhensis were collected at 1,518 m and 1,062 m, respectively, altitudinal distributions of the two species may overlap in the montane evergreen forest.
The morphological comparison provided evidence to distinguish L. vuquangensis from a Taiwanese species, L. nantoensis, although the relationship between them remains to be clarified by further molecular phylogenetic studies.
Similar to Lithocarpus nantoensis, L. hongiaoensis and L. vinhensis, but distinguished from L. nantoensis mainly by its fewer secondary veins, shorter infructescences, longer fruiting stalk, larger nut size and larger scar size of the nut, from L. hongiaoensis by its much shorter petioles and infructescences, longer fruiting stalk, scales united into concentric rings and much larger nut size and from L. vinhensis by having fewer secondary veins, shorter infructescences and much larger nut size (Table
VIETNAM. Ha Tinh Province, Vu Quang National Park, in lower montane forest, along trail to the summit of Mt. Rào Cô, alt. 1518 m, 18°12'12.2"N, 105°23'15.3"E, 22 June 2016, Yahara T., Nguyen Van Ngoc, Toyama H., Tagane S., Okabe N., Nguyen Viet Hung V5743 (holotype: KYO!; isotypes: DLU!, FU!, HN!, K!, P!, VNM!).
Trees, to 20 m tall; young branches mostly glabrous, yellowish in vivo, reddish-brown in sicco. Leaves alternate, spirally arranged, blade narrowly elliptic to lanceolate, 7.5–11 × 2.3–3.6 cm, crunchy, glabrous adaxially, white farinose abaxially, apex long acuminate, acumen up to 1.2 cm long, base cuneate to attenuate, margin entire and wavy; midrib flat or slightly prominent near base adaxially, prominent abaxially, greenish-yellow in vivo, reddish-brown in sicco, secondary veins 7–10 pairs, at an angle of 40–50 degrees from the midrib, prominent abaxially, tertiary veins scalariform, faintly visible to invisible on both sides; petiole 1–1.5 cm long, glabrous, terete. Male inflorescence a spike, 7–8.5 cm long. Male flower solitary; calyx 6-lobed, lobes ovate, 0.5–0.6 mm × 0.4–0.5 mm, pubescent on both surfaces; stamens 12, 0.7–0.9 mm long, anthers 0.1–0.15 mm long. Infructescences erect, woody spike, up to 7 cm long, axis ca. 2 mm thick at base, greyish-brown, lenticellate. Cupule solitary, broadly obconical to saucer-shaped, 1.4 cm long, 1.8 cm in diam., enclosing only basal to 1/4 of the nuts; scales triangular, arranged into 4–5 concentric rings, apex shortly acuminate, densely covered with tawny minute hairs; fruiting stalk ca. 4–6 mm long, 4–7 mm in diam. Nut obovoid or globose, 1.7–2.0 cm long, 2.1–2.4 cm in diam., glabrous, dehiscent; basal scar concave, ca. 1.1 cm in diam.
Lithocarpus vuquangensis Ngoc & Hung: A Branch with male inflorescences B Lower leaf surface C Holotype (KYO) D Spike with cupule E Young acorn F–H Side view, top view and scar of the mature nut, respectively I A part of infructescence K, L Inside and outside of the cupule. C, D, F–L From Yahara et al. V5743. Scale bars: 2 cm (D), 1 cm (F–H, K, L).
Mature fruits were collected in June.
Vietnam (so far known only from Vu Quang National Park, Ha Tinh Province) (Figure
The specific epithet is derived from its type locality, Vu Quang National Park.
Critically Endangered (CR). In the field observation, less than 10 individuals were found along the trail to the summit of Mt. Rào Cô, in lower montane forest. The habitat is inside the protected areas of Vu Quang National Park, but based on criterion D of the IUCN Red List criteria (
The authors thank the Director of Vu Quang National Park for providing us with opportunities to undertake field surveys in the protected area. We thank the curators and staff of the following herbaria BKF, DLU, FOF, HN, KYO, P, RUPP, TI and VNM for making their materials accessible. The present study was supported by the Environment Research and Technology Development Fund (S9 & 4–1601) of the Ministry of the Environment, Japan and MEXT/JSPS KAKENHI (Grant Number JP15H02640 and JP16H02553).