1. Introduction

Southeast Asia includes four overlapping biodiversity hotspots: Indo-Burma, Philippines, Sundaland and Wallacea (Myers et al., 2000, Sodhi et al., 2004). Each of these hotspots has a unique geological history that has contributed to its rich and often unique biota (Mittermeier et al., 1999). Southeast Asia covers about 4.5 million km², which is approximately 3% of earth's total land area. However, approximately 20%-25% of earth's higher plant species occur in this area (Myers et al., 2000, Jin et al., 2018). Massive anthropogenic habitat modifications, forest fires, and the overexploitation of wildlife in Southeast Asia are clear-and-present dangers to its biodiversity (Sodhi et al., 2004). Myanmar (Burma) vegetation spans tropical evergreen, mixed deciduous, savanna and alpine types, supporting a wealth of plant diversity that constitutes a significant component of the Indo-Burma biodiversity hotspot (Tanaka, 2005, Kang et al., 2017).

Botanical exploration in the former Burma began in the late 19th century when it was still under the British colonial rule. The earliest works were those of Kurz, 1877a, Kurz, 1877b and Hooker, 1872, Hooker, 1879, Hooker, 1882, Hooker, 1885, Hooker, 1890, Hooker, 1894, Hooker, 1897, and then, British botanists such as F. Kingdon-Ward, J.H. Lace, R.E. Cooper and others made botanical surveys in the country over half a century ago (Tanaka, 2005). These studies were used to compile a checklist of over 11, 800 plant species in Myanmar (Kress et al., 2003). However, these studies greatly underestimated biodiversity of Myanmar. More recently, many new species (Murata et al., 2010, Ormerod and Wood, 2010, Tanaka et al., 2010a, Tanaka et al., 2010b, Tanaka et al., 2010c, Tanaka et al., 2011, Tanaka et al., 2015b, Tanaka et al., 2016, Yukawa et al., 2010, Kress et al., 2010, Tanaka and Hayami, 2011, Schaefer et al., 2012, Gowda et al., 2012, Tong and Xia, 2014, Peng et al., 2014, Pradheep et al., 2014, Tan et al., 2015, Tan et al., 2017, Tan et al., 2018, Tanaka and Peng, 2016, Sangnark et al., 2016, Cho et al., 2016a, Phutthai and Hughes, 2017, Liu et al., 2017, Liu et al., 2018, Aung et al., 2017, Ruchisansakun et al., 2017, Zhou et al., 2017, Zhou et al., 2018, Yang et al., 2017a, Yang et al., 2017b, Yang et al., 2017c, Yang et al., 2018a, Yang et al., 2018b, Aung and Jin, 2018, Ding et al., 2018) and newly recorded species (Tanaka et al., 2006a, Tanaka et al., 2007, Tanaka et al., 2018, Ito et al., 2009, Ito et al., 2014, Nemoto et al., 2010, Kurzweil et al., 2010, Rodda and Simonsson, 2011, Kurzweil and Lwin, 2012a, Kurzweil and Lwin, 2012b, Kurzweil and Lwin, 2015, Ormerod, 2012, Nemoto and Murata, 2013, Wang and Xia, 2013, Paszko, 2014, Watthana et al., 2015, Aung et al., 2015a, Aung et al., 2015b, Mood et al., 2016, Ibaragi et al., 2017, Kang et al., 2017, Kang et al., 2018) have been recorded in Myanmar.

To understand and conserve biodiversity in Myanmar, the Southeast Asia Biodiversity Research Institute (SEABRI), Forest Research Institute (FRI), and the Forest Department (FD) of Myanmar conducted several joint biodiversity surveys from November of 2014 to December of 2018 in northern and western Myanmar. Here, we report noteworthy taxa new to the flora of Myanmar.

2. Materials and methods

Several biodiversity surveys were conducted during different seasons from November 2014 to December 2018. The location details of the survey areas are shown in Fig. 1. Specimens were identified and were first checked in Kress et al. (2003) and other recently published local botanical literatures for their distribution in Myanmar (e.g., Tanaka et al., 2006b, Lee et al., 2014, Lee et al., 2016, Fujikawa et al., 2015, Tanaka et al., 2015a, Turner, 2015, DeFilipps and Krupnick, 2018). Species not recorded in these references were further checked in different volumes of floristic records (e.g., Clarke, 1882, Forman, 1991, Phengklai, 1993, Li and Hedge, 1994, Hwang and Grimes, 1996, Chen and Pipoly, 1996, Larsen and Hu, 1996, Zhang and Tzvelev, 1998, Fu et al., 1999, Chen et al., 2000, Chen et al., 2009, Pan et al., 2001, Qiu and Philbrick, 2003, Huang and Murata, 2003, Tang et al., 2007, Parnell, 2008, Luo et al., 2008, Peng and Howard, 2008, Lu et al., 2011, Pedersen et al., 2011, Esser, 2017) and most recent checklists of adjacent countries (e.g., Newman et al., 2007, Schuiteman et al., 2008, Cho et al., 2016b, Kumar et al., 2018). Voucher specimens were deposited at the herbarium of Xishuangbanna Tropical Botanical Garden (HITBC) and the herbarium of the Forest Research Institute (RAF). The flowering plants of this paper are arranged following the Angiosperm Phylogeny Group classification for the orders and families (APG IV, 2016), along with their voucher information. Taxonomic comments, notes on their distribution and type information are provided when necessary.

3. Results

Based on herbarium specimens from our collections made in the last five years, some noteworthy taxa are new to the flora of Myanmar. Polyosmaceae (Polyosma wallichii Benn.) is a newly recorded family for Myanmar; Amentotaxus Pilger (Taxaceae), Hydrobryopsis Engler (Podostemaceae), Cyrtosia Blume and Biermannia King & Pantling (Orchidaceae), Eleutharrhena Forman and Haematocarpus Miers (Menispermaceae), Craigia W.W. Smith & W.E. Evans (Malvaceae), Amblyanthopsis Mez (Primulaceae), Huodendron Rehder and Rehderodendron Hu (Styracaceae), Platea Blume (Metteniusaceae), Achyrospermum Blume (Lamiaceae), Christisonia Gardner (Orobanchaceae) are new record genus for Myanmr; Tupistra natmataungensis, Biermannia burmanica, Impatiens megacalyx, Amblyanthopsis burmanica, Platea kachinensis are new to science. The data presented here may also be important in understanding the floristic elements of north Myanmar and the relationship with those of neighboring regions.

3.1. Amentotaxus Pilger (Taxaceae)

About 6 species in this genus, mainly distributed in China and Vietnam.

Amentotaxus assamica D.K. Ferguson in Kew Bull. 40(1): 115. 1985. — Amentotaxus yunnanensis H.L. Li var. assamica (D.K. Ferguson) Silba in Phytologia 68(1): 25. 1990; — Amentotaxus argotaenia (Hance) Pilg. var. assamica (D.K. Ferguson) Eckenw. in Conifers World 647. 2009. Type: India, Arunachal Pradesh Camp Chibaon Camp Chibaon, Delei valley, 1928-06-04, Kingdon Ward, F., 8026 (holotype: K000287687!) (Fig. 2A-C).

Specimens examined: MYANMAR, Kachin state, Putao district, on the way from Kawlei to Shinsanku, 27°39′55.98″N, 97°53′29.00″E, Alt. 987 m. 2017-05-08, Myanmar Exped. M1502 (HITBC, RAF).

Distribution: India, Myanmar.

Note: Amentotaxus has been placed in its own tribe (Amentotaxeae W. C. Cheng & C. D. Chu) or family, Amentotaxaceae. Amentotaxus assamica D.K. Ferguson was described from SE Xizang, in temperate rainforests on steep, north-facing slopes. It is apparently similar to A. argotaenia (Hance) Pilger, but differs in having leaves without sclereids, the adaxial surface smooth or with only longitudinal striations (due to shrinkage) when dry. Further collections are needed to establish whether it is truly distinct from A. argotaenia (Fu et al., 1999).

3.2. Hydrobryopsis Engler (Podostemaceae)

Only one species occurs in South India.

Hydrobryopsis sessilis (Willis) Engl. in Nat. Pflanzenfam., ed. 2 [Engler & Prantl] 18a: 60. 1930. — Hydrobryum sessile Willis Ann. Roy. Bot. Gard. (Peradeniya) 1: 239. 1902. Type: India, Madras, 1900-11-25, Barber, C.A., 2520 (syntype: K000786798!) (Fig. 2D-F).

Specimens examined: MYANMAR, Kachin state, Putao district, Gathtu, 27°28′07.51″N, 97°56′38.58″E, Alt. 540 m. 2016-12-13, Y.H. Tan, S.S. Zhou & Q. Liu M0916 (HITBC).

Distribution: S India, Myanmar.

Note: It grows in swift-running streams and cascades, clinging to rocks.

3.3. Tupistra Ker Gawler (Asparagaceae)

The genus Tupistra Ker Gawler is a relatively small genus, comprising about 16 species, and distributed mainly in South and Southeast Asia, including Bhutan, China, India, Indonesia, Malaysia, Myanmar, Nepal, Sikkim, Thailand, Vietnam (Chen et al., 2000, Tanaka, 2003). Tupistra is characterized by spiked inflorescence, anthers positioned lower than stigma, filaments nearly wholly adnate to perianth tube, style long, stigma peltate to mushroom-shaped (Chen et al., 2000). So far, just one species of Tupistra has been recorded in Myanmar, Tupistra stoliczana Kurz (Kress et al., 2003).

The Natma Taung (Mt. Victoria) National Park is located in the western part of Myanmar. Mount Victoria is the highest mountain in this range and regarded as an ecological refugium, offering a temperate climate that is absent from neighboring regions (Tanaka et al., 2010c). During our field expeditions in this area in 2018, specimens of Tupistra were found in Natma Taung (Mt. Victoria) National Park. But based on a detailed examination of the morphological characters of our material and possible closely similar species, we now conclude that the specimens of Tupistra collected in Myanmar belong to a species new to science, which we hereby describe and illustrate.

3.3.1. Taxonomic treatments

Tupistra natmataungensis Y.H. Tan & H.B. Ding, sp. nov. (Fig. 3).

Type: MYANMAR, Chin State: Natma Taung National Park, near Ko Long waterfall, 21°11′21.20″N, 94°00′32.58″E, Alt. 1315 m, 2018-11-28, flowering, Y.H. Tan, B. Yang, H.B. Ding, X.D. Zeng & G.S. Aung M5029 (holotype: HITBC!; isotypes: RAF!).

Diagnosis: Tupistra natmataungensis is similar to T. fungilliformis F.T. Wang & S. Yun Liang in linear leaves and subcampanulate perigone, but differs in having shorter peduncle (1.0-1.6 cm long vs. 1.5-3.0 cm long), is completely purple-red adaxially, yellow-orange with purple-red spots abaxially (vs. completely purple); has longer style (9-11 mm long vs. 4-5 mm long), peltate stigma (vs. mushroom-shapedm stigma).

Description: Plant herbaceous, perennial, rhizomatous, evergreen. Rhizome creeping, subterete, nodes dense, 13-15 mm thick, with some cataphylls and 2-6 leaves. Roots grey or dull brownish yellow, 2-4 mm in diam., with dense hairs persistent up to root base. Leaf at tip of rhizome embraced by some grey cataphylls, papyraceous, splitting into irregular fibrous-papyraceous remains with age. Foliage leaves not easily divided into petiole and lamina, gradually narrowing towards base, petiole stiffly erect, adaxially sulcate, 5.5-12 cm long. Lamina dark to light bright green, linear, distally narrowly acuminate, base cuneate, gradually narrowing into a petiole, 70-100 × 2.4-3.8 cm, margin entire, midvein prominent abaxially, with 2-3 secondary vein at each side of midvein. Spikes short, almost horizontal, 5.1-6.0 cm long, 3-flowered; peduncle 1.0-1.6 cm long, 3-7 mm in diam., greenish yellow. Flower c. 2.7 × 3.2 cm, bracts 2-3 per flower, ovate-cucullate, concave, scarious, brownish yellow, 9-12 × 5-9 mm. Perigone subcampanulate, tube 10-13 mm long, perigone tube mouth 14-18 mm in diam., outside yellow-orange with sparsely purple-red spots, inside purple-red; perigone lobes 6, subequal, fleshy, completely purple-red adaxially, yellow-orange with purple-red spots abaxially, triangular-ovate, slightly acuminate, 10-15 mm long, 10-15 mm broad at base. Stamens 6, in the same number as perigone lobes, filaments nearly wholly adnate to perigone tube, with very short free part (2-3 mm long), yellow-orange, anthers positioned lower than stigma; anthers dorsifixed, brownish yellow. Pistil 15-16 mm high. Style purple-red, cylindrical, 9-11 mm long, c. 3 mm in diam., Stigma enlarged, peltate, 5-6 mm in diam., yellow-orange, 3 lobes at margin, lobe apex emarginated or concave. Ovary inconspicuous, superior, 3-locular.

Phenology: Flowering in January.

Etymology: The specific epithet refers to the geographical origin of the species.

Distribution and habitat: This new species is known only from Natma Taung National Park, Chin State, where it grows in evergreen broad-leaf forests along the stream bank.

Similar species: Morphologically, T. natmataungensis is similar to T. fungilliformis F.T. Wang & S. Yun Liang sharing linear leaves and subcampanulate perigone, but differs from it by having shorter peduncle (1.0-1.6 cm long vs. 1.5-3 cm long), perianth purple-red adaxially, yellow-orange with purple-red spots abaxially (vs. completely purple perianth), longer perianth tube (10-13 mm long vs. 3-7 mm long), longer perianth lobes (10-15 mm long vs. 5-8 mm long), longer style (9-11 mm long vs. 4-5 mm long), peltate stigma (vs. mushroom-shapedm stigma). Tupistra natmataungensis also shares similarity with Tupistra khasiana D.K. Roy, A.A. Mao & Aver (Roy et al., 2017), both of them with creeping rhizomatous stem and short spike, but the later with broadly oblanceolate leaves (vs. linear leaves), 5-7-flowered (vs. c. 3-flowered), perianth lobes light green externally (vs. yellow-orange with purple-red spots), stigma dark purple (vs. yellow-orange), which allows it to be easily distinguished from the new species.

3.4. Cyrtosia Blume (Orchidaceae)

This is a small genus with only 5 species, mainly distributed in tropical Asia to East Asia.

Cyrtosia javanica Blume in Bijdr. Fl. Ned. Ind. 8: 396, t. 6. 1825; Seidenf. in Opera Bot. 114: 73. 1992; Averganov Iden. Guide Vietnam. Orch. 77. 1994; Flora Reipublicae Popularis Sinicae 18: 5. 1999; Chen and Cribb in Fl. China 25: 168. 2009; — Galeola javanica (Blume) Benth. & Hook.f., Gen. Pl. [Bentham & Hooker f.] 3(2): 590. 1883. Type: Indonesia, Waitz, F.A.C., none (syntype: L0061302!) (Fig. 4A-C).

Specimens examined: MYANMAR, Kachin state, Putao district, on the way from Gathu to Tongwang, 27°30′53.65″N, 97°58′56.90″E, Alt. 679 m. 2018-06-04, Myanmar Exped. M4012 (HITBC, RAF).

Distribution: Thailand, Myanmar, China (Taiwan), India, Indonesia, Malaysia, Philippines, Sri Lanka.

Note: This species is characterized by entire, obovate, orange, fleshy, strongly concave labellum, its inner surface covered callus, concavity towards base of the labellum, and inflorescence terminal and lateral.

3.5. Biermannia King & Pantling (Orchidaceae)

The subtribe Aeridinae (Sarcanthinae), a monopodial group with approximately 1350 species in approximately 90 genera that are mainly distributed throughout the warm-temperate and tropical areas of Asia, Australia, and the eastern Pacific islands, forms a large proportion of tribe Vandeae in Orchidaceae (Chase et al., 2003, Chase et al., 2015). Biermannia is a small genera of subtribe Aeridinae. Biermannia has 11 species distributed from Northeastern India to Java and Sumatra through Thailand, Indochina, Malaysia, Singapore and Indonesia (Seidenfaden, 1988, Seidenfaden, 1992, Seidenfaden and Wood, 1992, Rao, 2006). Two species have been described new to science from Vietnam recently (Averyanov et al., 2018a, Averyanov et al., 2018b). All species of this genus are miniature, canopy epiphytes with small, unattractive fugacious flowers, and so are easily overlooked in botanical surveys (Averyanov et al., 2018b). One potential new species of Biermannia was recently discovered in Northern Myanmar, representing a newly recorded genus to the Orchid Flora of Myanmar.

3.5.1. Taxonomic treatments

Biermannia burmanica Y.H. Tan & Bin Yang, sp. nov (Fig. 5).

Type: MYANMAR. Kachin State, Putao district, on the way from Kawlei to Shinsanku, near Kawlei village, 97°53′34.14″E, 27°37′04.67″N, Alt. 650 m, 2017-05-09, Y.H. Tan, B. Yang, H.B. Ding, M.B. Maw & T.S. Tin M1593 (holotype: HITBC!).

Diagnosis: The new species is morphologically similar to B. bimaculata (King & Pantl.) King & Pantl. and Biermannia jainiana S.N. Hegde & A.N. Rao with hardly opening white flowers and spurless lip, but clearly differs from its congener in having 25-35 pale brownish calluses inside the lip.

Description: Monopodial, epiphytic herbs, generally glabrous. Stem 0.8-1.5 cm, densely covered by distichous leaf sheaths, slightly flattened, with many pale green wiry roots clustered near stem base. Leaves 4-6, sessile, joined, oblong-elliptic, slightly falcate, 3.5-14.5 × 2.0-4.2 cm, apex with two acute oblique unequal lobes. Inflorescence stout, glabrous; peduncle glabrous, terete, 1.8-3.0 cm long, with 1-3 distant sterile triangular acute bracts, bracts 1.0-2.0 mm long and wide; rachis flattened, with 4-8 distichous triangular floral bracts; floral bracts separated by 3.5-7.0 mm, triangular, acute, 2.5-3.0 mm long and wide; 3-6 flowers blooming simultaneously; Flowers subsessile, fugacious, not widely opening, sepals and petals pale white. Pedicel and ovary light yellow green, grooved, 0.8-1.2 cm long, 1.0-1.2 mm in diameter. Sepals subequal, oblong-elliptic, acute or obtuse at apex, 14-16 × 3-4 mm, pale white or with slightly light yellowish-green tint near base, lateral sepals attached to column foot. Petals oblong to oblong-elliptic, acute or obtuse at apex, 13-15 × 3-4 mm, nearly the same size as petals, white. Lip spurless, entire, hardly lobed, oblong-elliptic, 13-14 × 5-6 mm, attenuate at apex with dropwise tip, white, with 4-6 pale brownish blotches above the middle, usually along the margin, involute below the middle, inside with 25-35 pale brownish calluses, callus 0.8-1 mm in diameter; Column white, 3.5-4.0 × c. 2.0 mm; stigma almost circular, concave; column foot very short, c. 2 mm. Operculum hemispheric, 1.6-1.7 mm in diameter, with an insignificant beak. Pollinia 2.

Phenology: Flowering from May to June.

Etymology: The species epithet refers to its type locality country, where it was discovered, Myanmar.

Distribution and habitat: B. burmanica is hither to known from the type locality of Putao, Kachin state in northern Myanmar; it is epiphytic on Terminalia myriocarpa, at an elevation of c. 600-800 m.

Similar species: Biermannia burmanica has white and hardly opening flowers with lip not saccate at base, which is similar to B. bimaculata (King & Pantl.) King & Pantl (King and Pantling, 1898, Pridgeon et al., 2014, Averyanov et al., 2018b), the new species, however, differs from its with 25-35 pale brownish calluses on inside surface of the lip (vs. lip with 2 calli at base and 2 calli at base of mid lobe). Additionally, B. burmanica has oblong-elliptic leaves, 2.0-4.2 cm wide, flowers 1.6-2.0 cm in diameter, sepals oblong-elliptic, 14-16 × 3-4 mm, petals oblong to oblong-elliptic, 13-15 × 3-4 mm; whereas leaves of B. bimaculata are linear-oblong and no wider than 1 cm, flowers are smaller size 0.8-1.0 cm in diameter, sepals ovate-lanceolate, no longer than 10 mm, petals ovate, 7-8 mm long. Biermannia burmanica also shares similarity with B. jainiana S.N. Hegde & A.N. Rao (Chowlu and Jalal, 2018), both of them with lip entire and hardy lobed, but the later can be distinguished from the new species by the presence of a solitary stipitate callus near base, brown hairs inside of the lip, and sepals and petals less than 10 mm long. Geographically, B. burmanica is endemic to Myanmar while B. bimaculata and B. jainiana are distributed in Northeast India, Bhutan, while records of B. bimaculata for Vietnam remain highly doubtful (Averyanov et al., 2018b). We conclude that B. burmanica is sharply distinct from B. bimaculata and B. jainiana.

Key to the species of Biermannia, adapted from Rao (2006)

1. Lip entire, hardly lobed … 2

— Lip distinctly or obscurely 3 lobed … 5

2. Inflorescence about 3.5 mm long; flowers yellow; sepals and petals less than 4 mm long … B. flava (Malaysia)

— Inflorescence more than 3 cm long; flowers white; sepals and petals more than 5 mm … 3

3. Lip with more than 20 pale brownish calli on inside surface … B. burmanica (Myanmar)

— Lip with no more than 4 calli on inside surface … 4

4. Lip with 4 transverse calli on upper half of disc … B. quinquecallosa (India)

— Lip with a solitary stipitate callus near base … B. jainiana (India)

5. Lip not saccate at base … 6

— Lip saccate at base … 8

6. Lip without any calli inside … B. arunachalensis (India)

— Lip with 2 or 4 calli … 7

7. Flowers white, not widely opening, lip with 2 calli at base and 2 calli at base of midlobe … B. bimaculata (India)

— Flowers pale yellow, widely opening, lip with no 2 calli at base and 2 calli at base of midlobe … B. canhii (Vietnam)

8. Lip base protruded into a globular or hemispheric spur … 9

— Lip base not protruded … 10

9. Lip elliptic-ovate, less than 9 mm long, spur c. 2 mm long … B. calcarata (Vietnam)

— Lip long narrowly conoidal, 11-12 mm long, spur-like protrusion less than 1 mm long … B. longicheila (Vietnam)

10. Midlobe of lip a thin walled pouch … B. sigaldii (Vietnam)

— Midlobe of lip not pouch-like … 11

11. Sepals and petals spotted; midlobe of lip with toothed edges … B. laciniata (Malasia, Singapore)

— Sepals and petals unspotted; midlobe with entire edges … 12

12. Midlobe of lip with 2 calli at base … B. bigibba (Sumatra)

— Midlobe without any calli at base … 13

13. Inflorescence and flowers about 7 mm long … B. sarcanthoides (Malaysia)

— Inflorescence up to 5 cm long; flowers more than 10 mm long …. B. ciliata (Thailand, Malasia)

3.6. Eleutharrhena Forman (Menispermaceae)

This is a monotypic genus that was previously recorded only in SW China and NE India, but now has also been recorded in Myanmar.

Eleutharrhena macrocarpa (Diels) Forman in Kew Bull. 30(1): 99. 1975; Fl. Yunnan 3: 226. 1983; Flora Reipublicae Popularis Sinicae 30(1): 9. 1996; Luo et al. in Fl. China 7: 4. 2008. — Pycnarrhena macrocarpa Diels in Engler, Pflanzenr. 46(IV. 94): 52. 1910. Type: China, Yunnan, Szemao, S. E., Henry, A., 12810 (isotype: K000644534!) (Fig. 4D-F).

Specimens examined: MYANMAR, Kachin state, Putao district, on the way from Namti to Nahsihbo, 27°24′32.73″N, 97°39′57.77″E, Alt. 872 m. 2017-05-16, Myanmar Exped. M1827 (HITBC); Kachin state, Putao district, on the way from Putao to Upper Shankhaung, 27°26′28.57″N, 97°15′43.35″E, Alt. 584 m. 2017-05-19, Myanmar Exped. M1900 (HITBC); Kachin state, Putao district, near around Camp 1, 27°24′07.50″N, 97°36′38.52″E, Alt. 920 m. 2017-12-11, Myanmar Exped. M3399 (HITBC, RAF); Kachin state, Putao district, Camp 1 to Namti (Camp 2), 27°24′48.07″N, 97°39′29.28″E, Alt. 795 m. 2017-12-12, Myanmar Exped. M3441 (HITBC, RAF).

Distribution: China (Yunnan), India (Assam), Myanmar.

3.7. Haematocarpus Miers (Menispermaceae)

This genus has 5 recorded species names, these names are all unresolved. And the genus was previously known to occur in Bangladesh, India, Malaysia, Thailand, Indonesia, Bhutan, Brunei, Vietnam and Philippines.

Haematocarpus validus (Miers) Bakh.f. ex Forman in Kew Bull. 26(3): 420. 1972; 43: 374. 1988; in Fl. Males. I. 10: 184. 1986. — Baterium validum Miers, Ann. Mag. Nat. Hist. Ⅲ, 13: 124. 1864. Type: Bangladesh, Khalia, [I.D.H.V.T.T.] s.n. (holotype: K000644532!) (Fig. 6A-C).

Specimens examined: MYANMAR, Kachin state, Putao district, Zeyadam, tropical montane forest, 27°34′23.34″N, 97°04′03.20″E, Alt. 1380 m. 2017-05-18, Myanmar Exped. M2342 (HITBC).

Distribution: India, Myanmar, Bangladesh, Malaysia, Thailand, Indonesia, Bhutan, Brunei.

3.8. Craigia W.W. Smith & W.E. Evans (Malvaceae)

Two species occur in China and adjacent Vietnam.

Craigia yunnanensis W.W. Smith & W.E. Evans, Trans. & Proc. Bot. Soc. Edinburgh 28: 69. 1921; Chang and Miau in Acta Sci. Nat. Univ. Sunyatsen 3: 21. 1978; Flora Reipublicae Popularis Sinicae 49(1): 112. 1989; Tang et al. in Fl. China 12: 248. 2007. — Burretiodendron combretoides W.Y. Chun & F.C. How, Acta Phytotax. Sin. 5(1): 8. 1956; — Burretiodendron yunnanense Kosterm., Reinwardtia vi. 8. 1961. Type: China, Yunnan, Shweli valley, 1912-06, Forrest, G., 8253 (isosyntype: K000687715!) (Fig. 6D-F).

Specimens examined: MYANMAR, Kachin state, Putao district, on the way from Shinsanku to Kawlei, 27°40′49.09″N, 97°53′59.05″E, Alt. 1167 m. 2016-12-14, Myanmar Exped. M0960 (HITBC).

Distribution: China (Guangxi, S Guizhou, W and SE Yunnan, SE Xizang), N Vietnam, Myanmar.

3.9. Impatiens Linn. (Balsaminaceae)

Impatiens Linn., is one of largest angiosperm genera, containing over 1000 species (Fischer, 2004), and is a well-known example of a taxonomically difficult group (Yu et al., 2015). It is distributed largely in the tropical and subtropical mountains of the E hemisphere (Chen et al., 2007), with the greatest diversity seen in tropical Africa, Madagascar, Southern India, Southeast Asia and Eastern Himalayas (Yuan et al., 2004). Within each area, most species of Impatiens have very restricted narrow distributions (Tanaka et al., 2015b).

The diversity of this genus coupled with insufficient field work has meant that many new species are still being discovered (e.g., Gogoi and Borah, 2013, Gogoi and Borah, 2015a, Gogoi and Borah, 2015b, Gogoi and Borah, 2017, Tanaka et al., 2015b, Hareesh et al., 2016, Hareesh et al., 2017, Hareesh and Sabu, 2017a, Hareesh and Sabu, 2017b, Ruchisansakun et al., 2017, Gogoi et al., 2017, Yang et al., 2017c). Considering the richness of Impatiens species of adjacent countries (i.e., China: c. 270 species (240 endemic) (Yu, 2012); India: c. 203 species (137 endemic) (Gogoi and Borah, 2015a); Thailand: c. 100 species (60 endemic) (Ruchisansakun et al., 2014); Laos: c. 40 species (Souvannakhoummane and Suksathan, 2015)), that there are only 48 species (19 endemic) of Impatiens recorded in Myanmar thus far is surprisingly low (Kress et al., 2003, Tanaka et al., 2015b, Ruchisansakun et al., 2017). Therefore, we have reason to believe that there are still many new species of Impatiens waiting to be discovered in Myanmar.

3.9.1. Taxonomic treatments

Impatiens megacalyx Y.H. Tan & H.B. Ding, sp. nov (Fig. 7).

Type: MYANMAR. Kachin State: Putao district, Maza. Understory herbs in tropical seasonal rain forests, 27°29′24.16″N, 97°44′35.05″E, Alt. 632 m, 2017-05-12, Y.H. Tan, B. Yang, H.B. Ding, M.B. Maw & T.S. Tin M1693 (holotype: HITBC!).

Diagnosis: Impatiens megacalyx is morphologically similar to Impatiens laevigata var. laevigata and I. laevigata var. grandifolia but can be distinguished by having drooping racemes, bigger elliptic outer lateral sepals, lanceolate inner lateral sepals, suborbicular upper petal and longer filaments.

Description: Shrubby herb, 50-70 cm tall, glabrous. Stem erect, terete, robust, succulent, and simple or two bifurcations branched from middle, long naked in lower part. Leaves alternate, often scattered at upper of stem; petiole 1.5-3.5 cm, with 0-2 sessile glands at base; leaf blade light green abaxially, dark green adaxially, elliptic or oblong, 14-27 × 4-7 cm, membranous, glabrous, lateral veins 7-10 pairs, base cuneate, margin serrulate, teeth glandular-mucronulate, apex long acuminate. Inflorescences in leaf axils, 14-17 cm long, drooping, racemes lax, 3- or 4-flowered; peduncles very long, 8-10 cm, pedicels 1-4 cm, slender, glabrous, bracteates at base, bracts persistent, entire, ovate or elliptic, 7-9 × 3-5 mm, membranous, acute at apex. Flowers yellowish white and reddish purple-tinged, 2-3 cm long. Lateral sepal 4, very large, wrap the lower sepal and lateral united petals, so that the spur is almost invisible; outer 2: elliptic, 2.2-2.6 × 1.1-1.4 cm, conspicuously veined, reddish purple at the base, margin entire, apex mucronulate; inner 2: narrowly lanceolate, 1.9-2.4 × 0.6-0.7 cm, apex acuminate. Lower sepal saccate, narrowed into an incurved, 0.8-1.0 cm deep, and hooked spur c. 1.2 cm long, mouth oblique, c. 2.0 cm wide, tip acute. Petals yellow to yellowish white, dorsal petal suborbicular, 2.2-2.5 cm in diam., apex emarginated, mucronulate, abaxial midvein narrowly carinate; lateral united petals not clawed, c. 3.3 cm long, bilobed; upper petal of each pair dolabriform, 2.2-2.4 cm long, 1.1-1.2 cm wide, with red spotted at the base, apex retuse or obtuse; lower petal of each pair dolabriform, 1.5-1.9 cm long, 0.9-1.1 cm wide, auricle small. Filaments linear, c. 1.2 cm, anthers obtuse. Capsule linear (young), 1.9-2.3 cm.

Phenology: Flowering from May to July.

Etymology: The specific epithet "megacalyx" of this new species refers to having very large sepals.

Distribution and habitat: At present, I. megacalyx is only known from the type locality, Putao, Kachin State, Myanmar. It occurs in primary forest, at 500-700 m elevation.

Similar species: After detailed studies, we found that I. megacalyx is close to I. laevigata var. laevigata and I. laevigata var. grandifolia superficially (Gogoi et al., 2013), e.g., elliptic or oblanceolate leaves, yellowish white and reddish purple-tinged flowers, 4 lateral sepals and linear capsule. But after comparing with the specimens and literature, we found that I. megacalyx can be clearly differentiated from the latter two, even from vegetative characters: I. laevigata var. laevigata and I. laevigata var. grandifolia are shrubs up to 100 cm, having much branched, sub-umbellate, 1-4 flowered, whereas the new species is a shrubby herb, 50-70 cm, with simple or two bifurcation branching from the middle, drooping racemes lax, 3- or 4-flowered, longer spur (1.6-2.2 cm long), shorter filaments (6-7 mm long). Impatiens megacalyx furthermore differs in having entire bracts (acute, 7-9 × 3-5 mm), elliptic outer lateral sepals (margin entire, 2.2-2.6 × 1.1-1.4 cm), lanceolate inner lateral sepals (1.9-2.4 × 0.6-0.7 cm), shorter spur (c. 1.2 cm long), suborbicular upper petal (2.2-2.5 cm in diam.), longer filaments (c. 1.2 cm long). Impatiens laevigata var. laevigata has toothed bracts (acute, 4-5 × 3-4 mm), orbicular outer lateral sepals (minutely 2-4-toothed, 1.1-1.2 cm diam.), falcate inner lateral sepals (1.4-1.6 × 0.3-0.4 cm), reniform upper petal (1.5-1.6 × 2.2-2.3 cm). Impatiens laevigata var. grandifolia has aristate bracts (entire, oblong, arista usually more than half as long as lamina, 14-15 × 5-6 mm), sub-ovate outer lateral sepals (1.2-1.4 cm diam.).

3.10. Amblyanthopsis Mez (Primulaceae)

Amblyanthopsis Mez is a small genus in Primulaceae of approximately three species, namely A. bhotanica (C.B. Clarke) Mez from NE India, Bhutan and Bangladesh, A. membranacea (Wall. ex A. DC.) Mez from India and Bangladesh (Mez, 1902), A. philippinensis Mez from Philippines (Mez, 1906). The genus is defined by having crenate leaves, style shorter than or slightly longer than the ovary and anthers coherent but not connate (Mez, 1902, Ståhl and Anderberg, 2004). During field work, specimens of Amblyanthopsis were found in Putao, Kachin state, which is a newly recorded genus for Myanmar. Based on detailed examination of the morphological characters of our material and possible closely similar species (Mez, 1902, Mez, 1906), we conclude that the specimens of Amblyanthopsis collected in Myanmar belong to a species new to science, which we hereby describe and illustrate.

3.10.1. Taxonomic treatments

Amblyanthopsis burmanica Y.H. Tan & H.B. Ding, sp. nov (Fig. 8, Fig. 9).

Type: MYANMAR. Kachin State: Putao district, NaungMung Township, Maza, understory shrubs in tropical seasonal rain forests, 27°30′54.83″N, 97°46′13.65″E, Alt. 560 m, 2017-05-12, flowering, Y.H. Tan, B. Yang, H.B. Ding, M.B. Maw & T.S. Tin M1682 (holotype: HITBC!; isotypes: RAF!).

Diagnosis: Amblyanthopsis burmanica is similar to A. bhotanica (C.B. Clarke) Mez, but can be distinguished by its emarginated corolla.

Description: Shrub, 40-60 cm tall, stalk terete, thick, herbaceous, ferruginous-furfuraceous on stalk, petioles and abaxial leaf surface. Terminal bud c. 1.0 cm long, acicular, brownish. Leaf blade usually lanceolate, or rarely elliptic, alternate, chartaceous, 10-17 × 2.0-3.8 cm, base cuneate, sometime one side 5 mm above the other, apex long acuminate, acumen 1.5-2.0 cm, margin crenulate to undulate-crenate, recurved, with sub-marginal glands below crenatures, glands oblong or ellipsoid, 1-2 mm long, dark brown; midrib and lateral nerves slightly raised above, much raised beneath, lateral nerves opposite to alternate, 14-20 on either side, usually forked or branched near margin, ending in sub-marginal glands; profusely dotted with dark brown glands on both surfaces, glabrous, glands conspicuous when dry, round, or elliptic; petioles strong, channeled, 1.0-2.0 cm long, glabrous. Inflorescence axillary, 3.0-7.0 cm long, condensed, paniculate, branches sub-umbellate; bracts oblong, brownish, 2.0-3.0 × 1.0-1.5 mm, apex acute and with crenulate, with dark brown glands on both surfaces, glands conspicuous when dry, sometimes caducous. Flowers small, flowers buds nearly globose, obtuse, c. 2.0 mm; pedicels c. 5.0 mm long, scattered dark brown gland-dotted, bracteoles 0 or caducous. Calyx-tube obconic, connate up to middle, lobes 5, ovate, c. 1.5 mm long, apex acute, margin sub-entire, scattered dark brown gland-dotted, very conspicuous when dry. Corolla whitish, broadly ovate, connate up to middle, apex usually emarginated, lobes 5, c. 1.2 × 1.2 mm, extrorse in flower, margin hyaline, entire, both surfaces glabrous, scattered gland-dotted, glands brownish, having a hyaline bump like corona at the base of corolla. Stamens 5, included, filaments free, c. 1 mm, as long as or slightly longer than the anthers, attached at base of corolla, scattered gland-dotted; anthers coherent but not connate, broadly ovate, 0.7 × 0.5 mm, dorsifixed, opening through longitudinal slits. Ovary ovoid, glabrous; style columnar, stigma capitate. Fruit c. 5 mm in diameter globose.

Phenology: Flowering from May to June.

Etymology: The specific epithet refers to the geographical origin of the species.

Distribution and habitat: This new species is known only from Putao district, Kachin State, where it grows in the understory in tropical rain forests and montane tropical forests.

Similar species: This new species is similar to A. bhotanica (C.B. Clarke) Mez (1902), particularly in the lanceolate leaves and calyx and corolla connate to middle, but it differs in its emarginate corolla, narrower leaves (wide 2.0-3.8 cm vs. 5.8-6.3 cm). A diagnostic key of the genus is provided.

A diagnostic key to the species of Amblyanthopsis Mez is given below.

1. Inflorescence terminal, leaves elliptic … A. philippinensis

— Inflorescence axillary, leaves lanceolate to oblong-lanceolate, rarely elliptic … 2

2. Free parts of filaments shorter than the anthers … A. bhotanica

— Free parts of filaments as long as or longer than the anthers … 3

3. Filaments much longer than the anthers … A. membranacea

— Filaments as long as or slightly longer than the anthers … A. burmanica

3.11. Huodendron Rehder (Styracaceae)

About 4 species, mainly distributed in East Asia.

Huodendron tibeticum (J. Anthony) Rehder, J. Arnold Arbor. 16: 342. 1935; Hu and Chun Icon. Pl. Sin. 5: 41. Pl. 241. 1937; Flora Reipublicae Popularis Sinicae 60(2): 126. 1987; Hwang and Grimes in Fl. China 15: 264. 1996. — Styrax tibeticus J. Anthony, Notes Roy. Bot. Gard. Edinburgh 15(74): 245. 1927. Type: China, Forrest, G., 21648 (isotype: P00648234!) (Fig. 10A-C).

Specimens examined: MYANMAR, Kachin state, Putao district, Shinsanku, 27°40′08.88″N, 97°53′35.65″E, Alt. 1065 m. 2018-06-10, Myanmar Exped. M4347 (HITBC, RAF); Kachin state, Putao district, on the way from Kawlei to Shinsanku, 27°40′08.91″N, 97°53′35.76″E, Alt. 1060 m. 2017-05-08, Myanmar Exped. M1469 (HITBC, RAF); Kachin state, Putao district, Shinsanku, 27°40′08.75″N, 97°53′35.70″E, Alt. 1072 m. 2016-12-13, Myanmar Exped. M0891 (HITBC); Kachin state, Putao district, Hkinlum, 26°53′11.02″N, 98°12′24.27″E, Alt. 1000 m. 1953-04-30, F. Kingdon-Ward 20750 (BM000997556, BM000997557, BM000997558).

Distribution: China, Vietnam, Myanmar.

3.12. Rehderodendron Hu (Styracaceae)

There are about 5 species of this genus, mainly in China and Vietnam.

Rehderodendron gongshanense Y.C. Tang, Acta Bot. Yunnan. 10(3): 350. 1988; Hwang and Grimes in Fl. China 15: 269. 1996. Type: China, Yunnan, 1982-08-11, Tibet Exped. 9227 (holotype: PE00027882) (Fig. 10D, E).

Specimens examined: MYANMAR, Kachin state, Putao district, on the way from Gathu to Langsa, 27°31′36.52″N, 97°56′34.91″E, Alt. 573 m. 2018-05-31, Myanmar Exped. M3827 (HITBC, RAF); Kachin state, Putao district, near Langsa, 27°31′37.98″N, 97°56′35.84″E, Alt. 571 m. 2018-06-02, Myanmar Exped. M3938 (HITBC, RAF); Kachin state, Putao district, NaungMaung township, Khasanku Village, 27°33′16.30″N, 97°46′48.40″E, Alt. 615 m. 2018-06-12, Myanmar Exped. M4405, M4432 (HITBC, RAF); Kachin state, Putao district, NaungMaung township, 27°30′16.76″N, 97°47′21.66″E, Alt. 670 m. 2016-12-21, Myanmar Exped. M1122 (HITBC); Kachin state, Putao district, on the way from NaungMung to Maza, 27°31′37.33″N, 97°45′46.49″E, Alt. 590 m. 2017-05-13, Myanmar Exped. M1694 (HITBC); Kachin state, Putao district, NaungMung Township, buffer zone of Hkakaborazi National Park, Pi Kot hill between NaungMung village and Gumlin village, 27°28′50.5″N, 97°50′37.7″E, Alt. 529 m. 2017-06-15, Kate et al. 2902 (NY02653967, NY02654008); Kachin state, Putao district, Hponganrazi Wildlife Sanctuary, Between Ye Khe Sap camp and Upper Thit Pin Cyi camp, 27°31′35.0″N, 96°58′6.8″E, Alt. 2454 m. 2016-10-24, Kate et al. 2060 (NY02653551).

Distribution: China (Gongshan), Myanmar.

3.13. Platea Blume (Metteniusaceae)

Platea Blume is a small genus in Metteniusaceae of approximately six species (Stull et al., 2015), namely P. bullata Sleumer from Sarawak in Malaysia (Sleumer, 1971), P. latifolia Blume from China, Bangladesh, India, Indonesia, Laos, Malaysia, Philippines, Singapore, Thailand, Vietnam (Peng and Howard, 2008), P. sclerophylla Sleumer from Kinabalu in Malaysia (Sleumer, 1971), P. excelsa Blume from Malaysia and Indonesia (Sleumer, 1971), P. parvifolia Merr. & Chun is endemic to Hainan in China; Platea malayana Utteridge is endemic to Malaysia (Utteridge, 2010). Platea is characterized by large dioecious trees, leaves with a dense covering of stellate hairs and appressed scales underneath at least in the young state, axillary compound racemes (on male plants) or racemes (female plants), pentamerous unisexual flowers with small free sepals and petals, free filaments fixed to the base of the petal, female flowers lacking petals with thick-cylindrical ovaries with a large sessile discoid stigma and elongate-ovoid drupes ripening purplish-black.

During field work, specimens of Platea were found in Putao, Kachin state, which is a newly recorded genus for Myanmar. Based on a detailed examination of the morphological characters of our material and possible closely similar species (Sleumer, 1971, Peng and Howard, 2008, Utteridge, 2010), we conclude that the specimens of Platea collected in Myanmar belong to a species new to science, which we hereby describe and illustrate.

3.13.1. Taxonomic treatments

Platea kachinensis Y.H. Tan & H.B. Ding, sp. nov. (Fig. 11)

Type: MYANMAR, Kachin state, Putao district, Shinsanku, 27°40′30.87″N, 97°53′35.98″E, Alt. 1122 m. 2018-06-10, fruiting, Y.H. Tan, B. Yang & H.B. Ding M4346 (holotype: HITBC!; isotypes: RAF!).

Diagnosis: Platea kachinensis is similar to P. latifolia Blume and P. excelsa Blume in coriaceous and elliptic to oblong or ovate leaves, but can be distinguished from them by ellipsoid and smaller drupe (2-3 cm long vs. ovoid-oblongiod, 3-4 cm long in P. latifolia and ovoid-oblongiod, 3.5-4.5 cm long in P. excelsa).

Description: Tree, 7-15 m. Bark dark grey to brown, smooth. Indumentum of branchlets, young leaves, inflorescences and drupe giving a scaly appearance to the naked eye, under the lens appearing to consist of rusty stellate scales, sometimes tips of branchlets densely covered with rufous-brownish tomentose so that the scales are invisible. Branches terete 2-4 mm in diameter, with persistently scaly, drying dark grey to brown. Leaves oblong to elliptic-lanceolate, coriaceous, 9-18 × 3.0-5.3 cm; apex acuminate, base broadly cuneate, sometimes unequal; margins entire or sometimes with sparsely serrated leaves near the tips of branchlets; midrib adaxially sulcate and glabrous, abaxially prominent and sparsely scaly, secondary veins 8-15 pairs, subparallel, disappearing near margin, conspicuously raised abaxially; foveolate reticulation fine adaxially; adaxially densely scaly when young, at maturity very sparsely scaly or glabrous and shining above, dark yellow-green or light bright green in fresh state, dark greyish brown when drying; abaxially densely scaly persistent so the reticulation invisible, grayish silvery in fresh state, light yellowish brown when drying; petiole 1.3-2.2 cm, densely scaly. Staminate flowers: Inflorescences axillary or solitary, simple spikes or by them composed (then almost pyramidal), 1.5-12 cm, consisting of spikes with spaced glomeruli or short panicles, covered with a rusty short hairs and scales. Flowers c. 5 mm, sub-globular in bud, 1.5-2.5 mm, each subtended by a small persistent bract, bract ovate, c. 1 mm, reddish brown, covered with rusty short hairs and scales. Calyx lobes 5, ovate, c. 1 mm, reddish brown, covered with rusty short hairs and scales. Petal lobes 5, light bright green, 1.5-2.0 mm, sparsely scaly abaxially, glabrous adaxially. Anthers cells elliptic, brownish yellow, c. 1.5 mm. Pistillate flowers: Inflorescences axillary or solitary, raceme-like, few-flowered (reduced to a single flower in fruit), 1-1.5 cm, reddish brown, covered with rusty short hairs and scales. Pedicels stoutish, 5-8 mm, slightly elongated in fruit, with persistent bract 2-4 mm, reddish brown, covered with rusty short hairs and scales. Flowers sub-globular in bud, 1.5-2.5 mm, each on a distinct pedicel and subtended by a sub-persistent bract immediately below the calyx lobes, bract 4-9 mm, reddish brown, covered with rusty short hairs and scales. Drupe ellipsoid, densely minutely rusty stellate scales, 2.0-3.0 × 1.2-2.0 cm, on short pedicel, 7-10 mm, base included by the dorsally rusty scaly sepals (ovate, 2.0-3.0 × 2.5-3.0 mm), exocarp thin-fleshy, pale dull yellow to purplish blackish when ripe.

Phenology: Flowering from April to May, fruiting from June to December.

Etymology: The specific epithet refers to the geographical origin of the species.

Distribution and habitat: This new species is known from Putao, Kachin State, where it grows in montane tropical forests.

Selected specimens examined (all paratypes): MYANMAR, Kachin state, Putao district, near Shinsanku, 27°40′30.43″N, 97°53′35.97″E, Alt. 1121 m. 2017-05-09, Myanmar Exped. M1543 (HITBC!); Kachin state, Putao district, on the way from Maza to the mountain top, 27°27′54.22″N, 97°42′20.90″E, Alt. 1405 m. 2017-05-13, Myanmar Exped. M1736 (HITBC!); Kachin state, Putao district, on the way from Kawlei to Shinsanku, 27°39′57.83″N, 97°53′36.85″E, Alt. 1011 m. 2017-05-08, Myanmar Exped. M1520 (HITBC!).

Similar species: Morphologically, P. kachinensis is similar to P. latifolia Blume both having coriaceous leaves and compound racemose, but differs from it by having oblong to elliptic-lanceolate leaves, 9-18 × 3.0-5.3 cm (elliptic or ovate, 10-19 × 4-9 cm in P. latifolia), shorter petiole, 1.3-2.2 cm (2-3.5 cm in P. latifolia), smaller drupe, 2-3 × 1.2-2 cm (ovoid-oblongiod, 3-4 × 1.5-2 cm in P. latifolia). P. kachinensis is also similar to P. excelsa Blume in having coriaceous and elliptic to oblong leaves. However, the pale greenish yellowish or pale pink petals and ovoid-oblongiod, 3.5-4.5 cm long drupe in P. excels differ from P. kachinensis (light bright green petals and ellipsoid, 2-3 cm long drupe). P. kachinensis is also similar to P. fuliginea Elmer (1915) in having oblong leaves and similar leaf size, but indumentum on the undersurface of leaves giving a woolly appearance to the nake eye (stellately tomentose) in P. fuliginea differ from P. kachinensis (scaly apprarance).

3.14. Achyrospermum Blume (Lamiaceae)

About 30 species of this genus, mainly distributed in Asia and Africa.

Achyrospermum wallichianum (Benth.) Benth. ex Hook.f., Fl. Brit. India. 4(12): 673. 1885; Flora Reipublicae Popularis Sinicae 66: 38. 1977; Li and Hedge in Fl. China 17: 187. 1994. — Teucrium wallichianum Benth., Pl. Asiat. Rar. 2: 19. 1830. Type: Bangladesh, Sylhet, Wall. Cat. 2758 (Fig. 10F, G).

Specimens examined: MYANMAR, Kachin state, Putao district, near around Namti (Camp 2), 27°25′13.44″N, 97°39′57.67″E, Alt. 1009 m. 2017-12-14, Myanmar Exped. M3677 (HITBC, RAF).

Distribution: China (Xizang), India, Myanmar.

3.15. Christisonia Gardner (Orobanchaceae)

About 20 species occurring from India through to China.

Christisonia siamensis Craib in Bull. Misc. Inform. Kew 1914: 129. 1914; Craib in Barnett, Fl. Siam Enum 3: 196. 1962; P.H. Ho, Cayco Vietnam 3: 2. 1992; Tan in Guihaia 33(4): 521. 2013. — Aeginetia siamensis (Craib) Livera in Ann. Roy. Bot. Gard. (Peradeniya) 10: 155. 1927. Type: Thailand, Lampang, Sop Nao, c.f. Ngao River, 1912-02-22, Kerr, A.F.G., 2406 (type: BM000997981!) (Fig. 12A-D).

Specimens examined: MYANMAR, Kachin state, Putao district, Gathu to Tongwang Cave, 27°30′38.37″N, 97°58′38.91″E, Alt. 624 m. 2018-06-04, Myanmar Exped. M4022 (HITBC, RAF); Sagaing Region, Hkamti District, Homalin Township, Just outside Htamanthi Wildlife Sanctuary, Nam Sa Bi village Management Area, 25°18′59.3″N, 95°21′37.3″E, Alt. 196 m. 2016-09-26, Kate et al. 1625 (NY02654991); Sagaing Region, Hkamti Township, Basin of Chindwin River, Htamanthi Wildlife Sanctuary, Nam Eizu area, 25°17′29.1″N, 95°15′39.6″E, Alt. 190 m. 2014-10-21, Kate et al. 6 (NY02648307).

Distribution: Thailand, China, Myanmar, India.

Note: Very sparsely represented in herbaria; probably very under-collected and therefore of wider distribution than herein indicated (Parnell, 2008). C. siamensis was considered a species endemic to Thailand, but new records have expanded its ranges to China and India (Benniamin et al., 2012, Tan, 2013).

3.16. Polyosma Blume (Polyosmaceae)

About 60-80 species, mainly distributed from India and China through Malesia to New Caledonia, with the main diversity in Malesia (Lundberg, 2016, Esser and Saw, 2015).

Polyosma wallichii Benn. in Pl. Jav. Rar. 196. 1840. Esser H.-J. & Saw L.G. Phytotaxa 221(1): 90. 2015. —Polyosma elongata Geddes, in Craib W.G., Bulletin of Miscellaneous Information Kew: 66. 1928. Type: Lectotype (designated by Esser and Saw, 2015: 90 (Esser and Saw, 2015)), Banglanesh. Chittagong Division: Silhet, in montibus Pandooah, s. dat. (fl), N. Wallich 8471 (BM!, isolectotypes G!, K!, K-W) (Fig. 12E-K).

Description: Small evergreen trees 5-15 m tall. Young branchlets puberulous. Leaves opposite, usually clustered at apex of branchlets; petiole 1.5-2.7 cm, puberulous; leaf blade elliptic-oblanceolate or oblong-elliptic, 12.0-19.0 × 3-6.5 cm, thinly leathery, base cuneate to obtuse, margin entire to sparsely dentate, apex attenuate to acuminate. abaxially surface slightly puberulous to glabrous, conspicuously puberulous along midvein and lateral veins, adaxially glabrous or sometimes slightly puberulous, midvein and 13-20 pairs lateral veins sunken above and raised below. Inflorescences in upright unbranched spike-like clusters 9-24 cm with many flowers. Bracts linear to linear-lanceolate, c. 5 mm, caducous. Rachis green to pale yellow green, puberulous. Flowers buds cylindrical, pale yellow green to white, c. 1.5 cm. Pedicel 3-4 mm, puberulous, with 3 bracteoles at base, the central one is larger, lanceolate or liner-triangle. Calyx tube puberulous, 2-2.5 mm; lobes ovate-triangular, minute, 1-1.5 mm 4 petals white, linear or narrowly strap-shaped, c. 1.5 cm, free at base, apex acute, becoming strongly recurved when mature, puberulous both sides. Stamens 4, shorter than petals, c. 1.2 cm, filaments pilose, anthers 4.5-5 mm. Ovary puberulous. Style is shorter than petals, 1.2-1.3 cm, slender at base, hairy-chested in the middle. Berry cylindrical to ovoid, 1.4-1.6 × 0.8-0.9 cm, pale yellow green to white, and then pale blue to deep blackish blue when mature, black when dry. Seeds ovoid, c. 1.4 × 0.8 cm.

Distribution: Thailand, India, Bangladesh (Esser, 2017, Esser and Saw, 2015), Myanmar.

Ecology: Grows in humid seasonal tropical rainforest, 500-800 m in altitude.

Phenology: Flowering in November to December and fruiting occurs from March to May.

Specimens examined: MYANMAR, Kachin state, Putao district, Shinsanku, 27°40′43.50″N, 97°53′36.25″E, Alt. 1165 m. 2016-12-13, Myanmar Exped. M0901 (HITBC); Kachin state, Putao district, on the way from Putao to Babaw Village, 27°17′51.84″N, 97°45′31.81″E, Alt. 800 m. 2017-05-06, Myanmar Exped. M1426 (HITBC); Kachin state, Putao district, on the way from Kawlei to Shinsanku, 27°40′43.42″N, 97°53′36.20″E, Alt. 1163 m. 2017-05-08, Myanmar Exped. M1471 (HITBC); Kachin state, Putao district, Shinsanku, 27°40′43.89″N, 97°53′36.21″E, Alt. 1165 m. 2017-05-09, Myanmar Exped. M1565 (HITBC); Kachin state, Putao district, Upper Shankhaung, 27°25′45.58″N, 97°15′59.79″E, Alt. 540 m. 2017-05-19, Myanmar Exped. M1902 (HITBC); Kachin state, Putao district, Meukyawwa 27°20′54.51″N, 97°22′52.06″E, Alt. 450 m. 2017-05-24, Myanmar Exped. M1995 (HITBC); Kachin state, Putao district, Near around Putao (2 km from Putao), 27°20′47.98″N, 97°22′51.87″E, Alt. 439 m. 2017-11-22, Myanmar Exped. M2573 (HITBC, RAF); Kachin state, Putao district, From Madwal (Camp 1) to Camp 2, 27°20′47.86″N, 97°22′51.75″E, Alt. 437 m. 2017-11-22, Myanmar Exped. M2778 (HITBC, RAF); Kachin state, Putao district, Gathu Village, 27°28′16.22″N, 97°57′10.52″E, Alt. 600 m. 2018-06-01, Myanmar Exped. M3878 (HITBC, RAF); Kachin state, Putao district, Ratbaw, 27°24′01.86″N, 97°55′51.96″E, Alt. 550 m. 2018-06-06, Myanmar Exped. M4099 (HITBC, RAF); Kachin state, Putao district, Shinsanku, 27°40′43.78″N, 97°53′36.18″E, Alt. 1166 m. 2018-06-10, Myanmar Exped. M4326 (HITBC, RAF); Kachin state, Putao district, Naungmung Township, buffer zone of Hkakaborazi National Park, Gathu village, 27°27′59.9″N, 97°56′59.7″E, Alt. 586 m. 2015-10-14, Kate et al. 1394 (NY02649214); Kachin state, Putao district, Naungmung Township, Hkakaborazi National Park, between Aliaung village and Ran Nam rest house, 27°42′21.7″N, 98°4′53.8″E, Alt. 1105 m. 2015-11-01, Kate et al. 1195 (NY02649063).

Note: Polyosma is a morphologically isolated genus that has been repeatedly moved between families. According to recent molecular studies, it could be classified either in a separate family, Polyosmaceae, or in Escalloniaceae, to which it is certainly closely related (Esser, 2017). P. wallichii is a relatively widespread species in north Myanmar. During our field expeditions, we collected it several times in different localities in lowland evergreen forests with flowers or fruits in different seasons. It is similar to Polyosma mutabilis Blume (Gardner et al., 2015) in leaf characters and unbranched spike-like inflorescence. All the flowers of P. wallichii are white, without pale-yellow and fruits are not flattened at base. This species represents a new familial record in the flora of Myanmar.

None declared.

The authors are grateful to the Forest Research Institute of Myanmar for permission to conduct this study in Myanmar, and for their supports and collaboration. We are also grateful to Xiao-Dong Zeng, Qiang Liu, Rui-Chang Quan, Ren Li, Mynt Zaw, Mynt Kyaw and Kyaw Saw for their kind helps in the field work. We thank Xiao Song for her help preparing the map of research areas and Zeng-Meng Yang for the illustration. This work was financially supported by a project of the Southeast Asia Biodiversity Research Institute, Chinese Academy of Sciences, China (Y4ZK111B01) and Lancang-Mekong Cooperation (LMC) Special Fund, China(Biodiversity Monitoring and Network Construction along Lancang-Mekong River Basin project) and the CAS 135 program (No. 2017XTBG-F03).