Research Article |
Corresponding author: Fang Wen ( wenfang760608@139.com ) Corresponding author: Truong Van Do ( dovantruong_bttn@yahoo.com ) Academic editor: Kang Ming
© 2018 Xin Hong, Zhen-Long Li, Stephen Maciejewski, Fang Wen, Truong Van Do.
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:
Hong X, Li Z-L, Maciejewski S, Wen F, Do TV (2018) Didymocarpus puhoatensis (Gesneriaceae), a new species from Vietnam. In: Jin X-H, Shui Y-M, Tan Y-H, Kang M (Eds) Plant diversity in Southeast Asia. PhytoKeys 94: 87-93. https://doi.org/10.3897/phytokeys.94.21650
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Didymocarpus puhoatensis, a new species from Vietnam is described and illustrated with photographs. The new species is morphologically similar to D. brevicalyx and D. epithemoides, but can be easily distinguished by a combination of characters. So far, five species have been recorded in the genus Didymocarpus from Vietnam.
Didymocarpus , Gesneriaceae , plant taxonomy, Vietnam
The delimitation of the genus Didymocarpus Wallich (1819: 378) has varied considerably over time (
During a floristic expedition to northern Vietnam in 2015, the authors observed a population of an interesting Gesneriaceae in Pu Hoat Nature Reserve, Nghe An province, Vietnam. It was confirmed that it is member of the genus Didymocarpus based on its disc-like stigma (
After thorough comparisons of diagnostic morphological and anatomical features of similar taxa from China, Vietnam, Thailand and adjacent regions (
Measurements and morphological character assessments of the putative new species were performed and described using specimens’ work by the current authors, living material observed in the field and also those cultivated at the Gesneriad Conservation Centre of China. All available specimens of Southeast Asian Didymocarpus kept in the following herbaria were examined: E, GH, HN, IBK, K, KUN, MO, PE, PH, US and VNMN. The images of type specimens were also obtained from Tropicos (http://www.tropicos.org), JSTOR Global Plants (http://plants.jstor.org) and the International Plant Names Index (http://www.ipni.org). All morphological characters were studied under dissecting microscopes and are described using the terminology presented by Wang et al. (1990,
Although it is morphologically similar to D. brevicalyx, it differs by stem densely pubescent, orbicular purple bracts, apices of calyx lobes obtuse, filaments glabrous, staminodes 2; and also similar to D. epithemoides, but differs from the latter in having purple calyx, funnel-form corolla, 4–5 cm long, glabrous, dark purple-blackish, ovary glandular puberulent.
VIETNAM. Nghệ An Province: Quế Phong, Thông Thụ, Pu Hoat Nature Reserve (Khu Bảo tồn thiên nhiên Pù Hoạt), 19°52'30.5"N, 104°56'15.1"E, alt. 390 m, 18 July 2014, flowering, Truong Van Do et al. VNM-CN439 (holotype: IBK; isotype: VNM).
Deciduous, perennial, lithophytic herb, 10–30 cm tall. Stems erect, single, sparsely puberulent to glabrescent, the upper, leaf-bearing part and young stems densely covered with whitish multicellular eglandular hairs. Dry season plants unknown. Rainy season leaves opposite, anisophyllous; petioles terete, 0.5–2.5 cm long, densely covered with multicellular eglandular hairs as on the stems; blades asymmetrically ovate, 6–10 cm long, 5–8 cm wide, apex bluntly acute, base slightly oblique, obtuse-cuneate, margin finely serrate or finely doubly serrate, papery, upper surface densely covered with whitish multicellular eglandular hairs, green, lower surface sparsely covered with hairs as on upper surface, pale green, venation pinnate, secondary veins 4–8 on each side of midrib, mostly opposite sometime alternate, obscure above, prominent beneath, covered with whitish multicellular eglandular hairs. Inflorescences terminal or from the upper leaf axils, cymose, ca. 12 cm long, 4–10 (–30) flowered; peduncles slender, 6–10 cm long, light green, sparsely covered with multicellular glandular hairs; pedicels 1–1.5 cm long, pale green, with indumentum as on the peduncle. Bracts paired, orbicular, ca. 5 mm long and wide, green to pale purple, glabrous. Calyx consisting of a tube and shallowly 5-lobed margin, symmetrical, campanulate, 6 mm long, glabrous, somewhat tawny to pinkish purple, tube ca. 5 mm long, 3 mm in diameter; lobes triangular, ca. 1 mm long, ca. 2 mm wide, apices obtuse. Corolla funnelform, 4–5 cm long, glabrous outside, blackish purple, becoming light purple at base; tube ca. 3.5 cm long, base narrow, ca. 2 mm wide, dilated and slightly ventricose towards the throat; widest at throat, diameter ca. 9 mm; corolla bi-lipped, lobes suborbicular; lower lip 3-lobed, ca. 8 mm long, 6 mm wide, more or less equal; upper lip 2-lobed, ca. 4 mm long and wide. Fertile stamens adnate to corolla ca. 1.5 cm from base; anther locules, ca. 2.5 mm long, ca. 1.5 mm wide, densely covered with brownish multicellular eglandular hairs; filaments slender, ca. 1 cm long, white, glabrous; staminodes 3, reduced to thin filaments, lateral ones 3 mm long, the other one 1 mm long, glabrous, adnate to corolla ca. 1 cm from base. Disc cylindrical, ca. 2 mm long, margin irregular. Pistil ca. 2–3 cm long; ovary narrowly linear, ca. 2 cm long, sparsely glandular puberulent, base reddish, with purple tinge towards stigma and apex green; stigma 1, peltate, concave, papillose, cream. Capsules unknown.
It flowers and fruits from June to September.
The specific epithet is derived from the type locality, Pu Hoat Nature Reserve, Nghệ An Province, Vietnam.
This new taxon is an endemic species from Pu Hoat Nature Reserve of Vietnam. The species grows on limestone rocks in tropical monsoon forest with sufficient seasonal run-off water, at an elevation of 390 m a.s.l. It distributes much lower in altitude and the habitat is much hotter and more humid than other species with stems of the genus.
As population information of Didymocarpus puhoatensis is still unclear, it is not appropriate to make an assessment of the extinction risk faced by this new taxon. Thus, the category of Data Deficient (DD) should be appropriate, according to
1 | Ovary smooth | 2 |
– | Ovary hair | 4 |
2 | Corolla outer hair; leaf blade ovate or elliptic, ca. 4–10 × 2–6 cm | D. pulcher |
– | Corolla outer smooth; leaf blade near round or broadly elliptic, ca. 1–4 × 1–4 cm | D. kerrii |
4 | Base of leaf often axisymmetric; bract lanceolata, ca. 2–3 mm long; sepal tube ca. 3 mm long, sepal lobed ca. 1–1.5 mm long | D. poilanei |
– | Base of leaf often oblique; bract elliptic ovate or orbicular, ca. 3–8 mm long; sepal tube ca. 8–9 mm long, sepal lobed ca. 2–3 mm long | 5 |
5 | Peduncle 4–10 cm, glabrous; bracts connate at base; calyx 1–1.2 cm; corolla 3–4 cm, purple to pinkish purple | D. purpureobracteatus |
– | peduncles 6–10 cm, glandular hairs; bracts separate; calyx 6 mm; corolla 4–5 cm, blackish purple | D. puhoatensis |
It is morphologically similar to D. brevicalyx and D. epithemoides in having the calyx consisting of a tube, similar shape and colour of corolla, both morphological affinities being distributed in Thailand. However, D. puhoatensis can be clearly differentiated from both by several characters. The major differences between the species are outlined in Table
Diagnostic characters for Didymocarpus puhoatensis sp. nov. and its relatives.
Character | Didymocarpus puhoatensis | D. brevicalyx | D. epithemoides |
---|---|---|---|
Indumentum of Stem | densely pubescent | densely glandular pubescent | densely pubescent |
Bracts | orbicularc. 5 mm long and wide | triangular c. 2 mm long and 1.5 mm wide | orbicular, 5 mm long and wide |
Calyx | lobes apices obtuse, purple | lobes apices acute, reddish | lobes apices rounded, violet |
Corolla | funnelform, 4–5 cm long, glabrous, dark purple-blackish | funnelform, 4.5 cm long, glabrous, dark purple-blackish | salverform, 3–3.5 cm long, glandular pubescent outside, dark violet |
filaments | glabrous | gland-tipped hairs on the upper part | glabrous |
Indumentum of ovary | sparsely glandular puberulent | densely glandular pubescent | glabrous |
This study was financially supported by the Anhui University Doctor Startup Fund, Key University Science Research Project of Anhui Province (No. KJ2017A022), Fund of Guangxi Key Laboratory of Plant Conservation and Restoration Ecology in Karst Terrain (16-B-01-01), Plant germplasm resources projects of the germplasm bank of Wild species of Kunming Institute of Botany, Chinese Academy of Sciences (WGB-1411), the Guangxi Natural Science Foundation (2015GXNSFBB139004 & 2016GXNSFBA380071) and the Key Research and Development Project of Guangxi (Guike AB16380053).