Phlogacanthus geoffrayi Benoist (Acanthaceae): A New Record to the Flora of Viet Nam

VNU Journal of Science: Natural Sciences and Technology, Vol. 36, No. 2 (2020) 49-53 49 Original Article Phlogacanthus geoffrayi Benoist (Acanthaceae): A New Record to the Flora of Vietnam Do Van Hai1,2*, Duong Thi Hoan1, Ritesh Kumar Choudhary3 1Institute of Ecology and Biological Resources, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay, Hanoi, Vietnam 2Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay, Hanoi, Vietnam 3Agharkar Research Institute, G.G. Agarkar Road, Pune-411 004, India Received 14 October 2019 Revised 07 February 2020; Accepted 09 February 2020 Abstract: Phlogacanthus geoffrayi is reported here as a newly recorded species from Vietnam. This species is morphologically allied to Phlogacanthus turgidus but differs in having a significantly bigger calyx and staminodes. The specimens were collected from Song Cau district of Phu Yen province. Description, line-drawing, photographs, and notes on ecology and distribution are provided. Keywords: New record, Acanthaceae, Phlogacanthus geoffrayi, Phu Yen, Vietnam. 1. Introduction The genus Phlogacanthus Nees belongs to the tribe Andrographideae of the family Acanthaceae [1,2]. It consists of about 40 species distributed in the tropical regions of Asia [2]. In Vietnam, the genus is represented by 11 species [3]. During a floristic exploration trip to Song Cau district of the Phu Yen province of Vietnam, an interesting species of Phlogacanthus was encountered. After thorough scrutiny of the available literature and type materials it was identified as Phlogacanthus geoffrayi Benoist [4-7]. This species was so far recorded only from ________  Corresponding author. Email address: dovanhaiiebr@gmail.com https://doi.org/10.25073/2588-1140/vnunst.4962 Cambodia but never from Vietnam [2,6,8-10]. Hence, it is reported here as a new addition for the flora of Vietnam. A detailed description, colour photos (Figure 1), and illustration (Figure 2) are provided here. With this addition, eleven species are recognized in Phlogacanthus for the flora of Vietnam. 2. Materials and Methods 2.1. Materials Specimens of Phlogacanthus housed in the herbaria E, HN, HNU, IBSC, K, P, VNM were D.V. Hai et al. / VNU Journal of Science: Natural Sciences and Technology, Vol. 36, No. 2 (2020) 49-53 50 examined, and relevant literature were also consulted [8-10]. Morphological comparison of our specimen with allied species was carried out for confirming the identity of the plant. Vouchers were prepared following the standard protocol [11]. Specimens of Phlogacanthus geoffrayi were deposited in the herbarium of the Institute of Ecology and Biological Resources, VAST (HN). 2.2. Methods The morphological comparison method was used to study the plants. It is one of the most suitable methods in plant taxonomic studies. 3. Results and Discussion 3.1. Key to the species of Phlogacanthus in Vietnam 1A. Corolla tube cylindric and slightly curved. 2A. Bracteoles leaf-like, ovate to ovate- lanceolate, > 12 mm long. 3A. Corolla red, 3-3.5 cm long .......................................... 1. P. cornutus 3B. Corolla white with purple dotted stripes on throat, 1.5-1.8 cm long ................................................................. ................................................................. ..................................... 2. P. annamensis 2B. Bracteoles not leaf-like, linear or subulate, < 10 mm long. 4A. Corolla light yellow or white, 2-2.5 cm long; filaments hirsute at base.. ................................................................. ................................................................. ....................................... 3. P. publiflorus 4B. Corolla purplish red, 4.5-5 cm long; filaments glabrous... .... . 4. P. curviflorus 1B. Corolla tube abruptly inflated near middle and usually bent ca. 90°. 5A. Corolla outside pubescent with gland- tipped trichomes. 6A. Corolla white or light purple; leaf blade oblong to oblong-lanceolate; calyx 12-15 mm ............................... 5. P. paniculatus 6B. Corolla pale yellow with thin to dense purplish dots; leaf blade ovate to oblong; calyx 7-10 mm .. .......................6. P. datii 5B. Corolla outside glabrous or non-glandular pubescent. 7A. Bracteoles leaf-like, ovate to ovate- lanceolate, > 10 mm long. 8A. Calyx > 10 mm, staminodes 4-5 mm long. ............................... 7. P. geoffrayi 8B. Calyx < 7 mm, staminodes ca. 1 mm long. ............................... 8. P. turgidus 7B. Bracteoles not leaf-like, linear, < 6 mm long. 9A. Bracts leaf like, much longer than calyx; corolla glabrous outside ......................... ................................... 9. P. pyramidalis 9B. Bracts small and not leaf like, subequal to calyx; corolla pubescent outside. 10A. Leaf blade secondary veins ca. 6 on each side of midvein .......................... ............................. 10. P. abbreviatus 10B. Leaf blade secondary veins 9-17 on each side of midvein .......................... .................................. 11. P. colaniae 3.2. Taxonomic treatment Phlogacanthus geoffrayi Benoist – Hỏa rô geoffray (Figure 1 & 2). Benoist, 1928. Bull. Soc. Bot. France, 74: 910; Benoist, 1935. Fl. Gen. Indoch. 4: 706. Shrubs 80 cm tall, erect. Stems quadrangular or slightly 4-angled, glabrescent. Petiole 2-4 mm; leaf blade lanceolate, 5-10 × 18-28 cm, glabrous on both side, base attenuate and decurrent onto petiole, margin entire or sinuate, apex acuminate to obtuse, secondary veins ca. 5- 6 on each side of midvein. Inflorescences terminal racemes, 10-15 cm tall; bracts lanceolate, 12-15 × 4-5 mm, light purple, petiole very short, puberulent on both side; bracteoles very small, 1 mm long, or absent. Calyx ca. 10 mm, outside pubescent, lobes linear, ca. 8-9 × 1 mm, equal, apex acute. Corolla light purple, 2 cm long, ventricose, incurved, outside pubescent; tube basally ca. 2 mm wide and short then wide at middle; usually bent ca. 90º and D.V. Hai et al. / VNU Journal of Science: Natural Sciences and Technology, Vol. 36, No. 2 (2020) 49-53 51 abruptly inflated near middle; limb 2-lipped; lower lip 3-lobed, lobes ovate and equal, middle lobes with the yellow patch; upper lip 2-lobed, lobes ovate with acute at apex; lobes ascending cochlear in bud. Stamens 2; filaments 10-12 mm, glabrescent and basally pilose; anther thecae oblong, 3-4 mm, connective barbate; staminodes filiform, 4-5 mm. Ovary 3-4 mm, oblong, glabrescent, with 4 ovules per locule; style ca. 15 mm, sparsely pubescent or glabrescent; stigma 2-cleft. Capsule clavate, 2.5-3 cm, pubescent, 8- seeded. Seeds ovate, compressed. Loc. class.: Cambodge: Kampot, chaîne de l' Eléphant. Type: C. Geoffray 348 (holo.-P, photo!). Flowering: March to May. Ecology and habitat: Grows in the edge of the forest, along roadside. Distribution: Cambodia, Vietnam (Phu Yen province, Song Cau district, Xuan Loc commune). Specimens examined: VIETNAM, Phu Yen province, Song Cau district, Xuan Loc commune, N 13°39'41.3", E 109°10'52.0", D.V. Hai s.n. (HN). Figure 1. Phlogacanthus geoffrayi Benoist: a. Flowering and fruiting twig; b. Bracts; c. Calyx; d. Flower (front view); e. Bract, calyx and flower; f. Flower (opened); g-h. Stamens; i. Ovary and style (Photos by D.V. Hai). D.V. Hai et al. / VNU Journal of Science: Natural Sciences and Technology, Vol. 36, No. 2 (2020) 49-53 52 Figure 2. Phlogacanthus geoffrayi Benoist: a. Flowering twig; b. Bract; c. Calyx; d. Corolla (open) without lower middle lobe; e. Lower middle lobe; f. Ovary and style (Illustration drawn by Mrs Le Kim Chi, from D.V. Hai sine num., HN). 4. Conclusion Understanding species diversity and distribution record are important for biodiversity assessment. An update to the available data facilitates effective analysis and interpretation of biodiversity and distribution data. Our research for the first time reports occurrence of Phlogacanthus geoffrayi in Vietnam, a species hitherto known only from Cambodia. We believe this report will help to understand the Vietnam flora in a better way. At the same time, it will help to prioritize the conservation strategy for the country's valuable flora. D.V. Hai et al. / VNU Journal of Science: Natural Sciences and Technology, Vol. 36, No. 2 (2020) 49-53 53 Table 1. Morphological comparison of Phlogacanthus geoffrayi with its allied species Morphological characters P. geoffrayi P. turgidus [5,6] Habit shrubs, up to 80 cm tall shrubs 0.5-3 m tall Stems quadrangular or slightly 4-angled, glabrescent subterete and round on maturity, puberulent Leaf blade lanceolate, 5-10 × 18-28 cm, glabrous blade lanceolate or oblong, 3-6 × 10-18 cm, glabrous Inflorescence racemes, 10-15 cm long thyrses, 5-20 cm long Bract lanceolate, 12-15 × 4-5 mm lanceolate, 12-14 × 5-6 mm Bracteole 1 mm long or absent oblong, ca. 10 × 3 mm, apex acute Calyx ca. 10 mm 4-7 mm Corolla light purple, ca. 2 cm long; lower lip 3- lobed, lobes ovate and equal, middle lobes with yellow patch corolla white or pink, 2.5-3.5 cm long, lower lip 3-lobed, middle lobes with purple dots. Fruits 2.5-3 cm long 3-4 cm long Acknowledgments Authors are grateful to Mrs Le Kim Chi for preparing the illustrations. Thanks are due to the curators of HN, HNU, VNM and P herbaria for the kind permission to access the herbarium material. This research was funded by Vietnam National Foundation for Science and Technology Development (NAFOSTED) (grant no 106.03-2017.301). RKC thanks Director, Agharkar Research Institute, Pune for encouragements. References [1] E.C.G. Nees, Acanthaceae Indiae Orientalis, in: N. Wallich (Ed.), Plantae Asiaticae Rariores, Vol. 3, Treuttel, Würtz, Richter, London, 1832, pp. 70-112. [2] C. Xia, Y.F. Deng, Phlogacanthus yangtsekiangensis, a new combination in Chinese Acanthaceae, Phytotaxa 104 (1) (2013) 58-60. 11646/phytotaxa.104.1.9. [3] D.V. Hai, N.T. Mai, N.T.T. Huong, R.K. Choudhary, Y.F. Deng, An updated taxonomy of the genus Phlogacanthus (Acanthaceae) in Vietnam, Phytotaxa 372 (2) (2018) 167-175. [4] R. Benoist, Acanthacées nouvelles asiatiques, Bulletin de la Société Botanique de France 74 (1928) 907-912. 1927.10837070. [5] R. Benoist, Acanthacées, in: M.H. Lecomte (Ed.), Flore Générale de l’Indochine, Vol. 4, Mason et Cie, Paris, 1935, pp. 610-772. [6] P.H. Ho, Acanthaceae, in: P.H. Ho (Ed.), An Illustrated Flora of Vietnam, Vol. 3, Tre Publishing House, Ho Chi Minh, 2000, pp. 30-82 (in Vietnamese). [7] T.K. Lien, Acanthaceae, in: N.T. Ban (Ed.), Checklist of plant species of Vietnam, Vol. 3, Agricultural Publishing House, Hanoi, 2005, pp. 251-281 (in Vietnamese). [8] C.C. Hu, X.P. Fu, Phlogacanthus, in: L.K. Fu, T. Hong (Eds.), Higher plants of China, Vol. 10. Qingdao Publishing House, Qingdao, 2005, pp. 386-388. [9] C.C. Hu, Phlogacanthus and Cystacanthus, In: C.C. Hu (Ed.), Flora Reipublicae Popularis Sinicae, Vol. 70, Science Press, Beijing, 2002, pp. 207-214. [10] C.C. Hu, Y.F. Deng, T.F. Daniel, Phlogacanthus and Cystacanthus, in: Z.Y. Wu, P. Raven, D.Y. Hong (Eds.), Flora of China, Vol. 19, Science Press, Beijing & Missouri Botanical Garden Press, St. Louis, 2011, pp. 474-477. [11] S.K. Jain, R.R. Rao, A Handbook of Field and Herbarium Methods, Today and Tomorrow’s Printers and Publishers, New Delhi, 1977.