Research Article |
Corresponding author: Yun-Hong Tan ( tyh@xtbg.org.cn ) Academic editor: Xiao-Hua Jin
© 2018 Bin Yang, Shi-Shun Zhou, Hong-Bo Ding, Ren Li, Kyaw Win Maung, Yun-Hong Tan.
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:
Yang B, Zhou S-S, Ding H-B, Li R, Maung KW, Tan Y-H (2018) Two new species of Trivalvaria (Annonaceae) from northern Myanmar. In: Jin X-H, Shui Y-M, Tan Y-H, Kang M (Eds) Plant diversity in Southeast Asia. PhytoKeys 94: 3-12. https://doi.org/10.3897/phytokeys.94.21553
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Trivalvaria rubra and Trivalvaria casseabriae, two new species of Annonaceae from Putao, Kachin State, Myanmar, are here described and illustrated. They are morphologically similar to T. costata and T. macrophylla. The major differences between them are outlined and discussed. A diagnostic key to the species of Trivalvaria is provided.
Kachin state, Trivalvaria costata , Annonaceae , field expedition, Myanmar
Trivalvaria (Miq.) Miq. (Miquel, 1865) is a small genus with six species now recognised, which are mainly distributed in Indochina and Southeast Asia (
Since 2014, repeated China-Myanmar joint field expeditions have been carried out to survey plant diversity in Northern Myanmar, specimens of Trivalvaria being found in Putao, Kachin state. Based on a detailed examination of the morphological and anatomical characters of the material and possible closely similar species (
Measurements and morphological character assessments of the two possible new species Trivalvaria rubra and Trivalvaria casseabriae were examined based on dried specimens and fresh materials in field observations. They were compared with the morphologically similar species T. costata, T. macrophylla and T. nervosa, with affinities inferred using descriptions, type specimens and other herbarium specimens (
Trivalvaria rubra is similar to Trivalvaria costata in flower size and petal shape and size and also shares similarities with T. macrophylla in leaf shape, but can be distinguished by its pink flowers, androdioecious, petals spreading, outer petal lanceolate to narrowly oblong, 14–20 × 4–6 mm, inner petal 17–25 × 4–7 mm, oblong-ovate to ovate-triangular.
MYANMAR. Kachin State, Putao District, on the way from Nanmti to Nahsihbo, 27°24'29"N, 97°39'59"E, 890 m a.s.l, 16 May 2017, Myanmar Exped. 1801 (holotype, HITBC!; isotype, RAF!).
Shrubs up to 1.2 m high. Young twigs densely to very sparsely pubescent, older twigs glabrous to pubescent. Leaves subcoriaceous, glabrous above, sparsely pubescent beneath, obovate to narrowly elliptic or oblong-lanceolate, 13.5–27.5 × 4.2–10.5 cm, base cuneate to obtuse, apex attenuate to acuminate or acute, sometimes retuse, midrib sunken above, prominent beneath, sparsely pubescent, lateral veins 9–11 pairs, faintly distinct above, prominent beneath, smaller veins faintly prominent beneath. Petiole 5–10 mm long, 2–3 mm thick, pubescent to glabrous. Flowers pink, androdioecious 2.6–2.8 cm in diam., extra-axillary or ramiflorous, solitary or sometimes in pairs, Bracts 2–4 (Fig.
Trivalvaria rubra Y.H.Tan, S.S.Zhou & B.Yang, sp. nov. A Habitat B Branch with flowers (adaxial view) C Branch with flowers (abaxial view) D Male flower (abaxial view) E Flower bud (side view) F Female flower (abaxial view) G Flower (G1 Bracts; G2 Sepals; G3 Outer petals; G4 Inner petals; G5 Androphore) H Fruit. Photographed by Y.H. Tan, H.B. Ding and B. Yang.
Flowering in May to June and fruiting occurs from June to December.
The species epithet refers to its pink flower.
Trivalvaria rubra is hitherto known from the type locality of Putao, Kachin state in Northern Myanmar, it is a small shrub that grows in the understory in tropical dipterocarpa forests, the dominant tree species are Shorea assamica, Dysoxylum mollissimum, Aglaia elaeagnoidea, Garcinia spp., Goniothalamus peduncularis, Antidesma spp., shrub species are Hymenandra wallichii, Ardisia sp., Zingiber sp., at an elevation of ca. 600–900 m a.s.l.
Trivalvaria rubra was collected on the way from Namti to Nahsihbo, Putao, Northern Myanmar, this area being difficult to travel due to its rugged terrain. At least three populations and ca. 60 individuals per population have been discovered. Currently, the locality is not legally protected and, although young individuals were recorded in field, the fragmented habitat and continuous logging severely threaten its survival. At present, it is suggested that it be considered as ‘Vulnerable’ (VU) on the basis of current IUCN Red List Categories and Criteria (
(paratypes). MYANMAR. Kachin State, Putao District, near Nahsihbo village, 27°24'36"N, 97°36'26"E, 970 m a.s.l, 11 Dec. 2017, Myanmar Exped. 3373 (HITBC!); Putao District, near Namti village, 27°24'43"N, 97°39'56"E, 820 m a.s.l, 15 Dec. 2017, Myanmar Exped. 3698 (HITBC!).
Trivalvaria casseabriae is similar to Trivalvaria argentea in leaf shape, but can be distinguished by its larger flower size and outer petals equal to inner petals, petals 6–10 × 3–5 mm (vs. 2 × 3 mm), 2–2.5 times as long as wide and elliptic to ovate-elliptic.
MYANMAR. Kachin State, Putao District, Wasadam to Upper Shankhaung, 27°26'42"N, 97°14'27"E, 850m a.s.l, 21 May 2017, Myanmar Exped. 2379 (holotype, HITBC!; isotype, RAF!).
Shrubs up to 1.5 m high. Young twigs pubescent, older twigs glabrous to sparsely pubescent. Leaves subcoriaceous, glabrous above, sparsely pubescent beneath, lanceolate to oblong, 12.5–24.5 × 2.5–5.5 cm, base cuneate to obtuse, apex acuminate to caudate, midrib immersed above, prominent beneath, sparsely pubescent, lateral veins 5–7 pairs, immersed and faintly distinct above, prominent beneath, smaller veins faintly prominent beneath. Petiole 3–8 mm long, 1–3 mm in diameter, pubescent. Flowers white, androdioecious, 14–20 mm in diam., solitary or in pairs between leaf axils (extra-axillary), rarely ramiflorous. Bracts 1–2, triangular to ovate-triangular, 2–3 × 1–2 mm, pubescent to densely pubescent outside. Pedicel 2–3 mm long, pubescent. Sepals 3 per flower, free or sometimes shortly connate, ovate to broadly ovate, 2–3.5 × 2–3 mm, pubescent outside, puberulous inside and apex acute to obtuse, base rounded. Petals 6 per flower in two whorls, imbricate, spreading, subequal, outer petals (Fig.
Flowering at May to July.
The specific epithet is derived from the abbreviation of Southeast Asia Biodiversity Research Institute, Chinese Academy of Sciences (CAS-SEABRI); noun in apposition. The name is dedicated to its three-part mission, viz., (a) Serve China’s “the Silk Road Economic Belt and the 21st Century Maritime Silk Road” initiative; (b) Integrate efforts by CAS and international institutes to organise professional research groups and train researchers in Southeast Asian countries; and (c) Provide support to all domestic and international partners.
Trivalvaria casseabriae is only known from the type locality of Putao, Kachin state in Northern Myanmar, where it grows in the understory of tropical montane broadleaf forests, the dominant tree species being Altingia excels, Dysoxylum spp., Garcinia spp., Elaeocarpus spp., at an elevation of ca. 700–900 m.
Although Trivalvaria casseabriae was collected on the way from Wasadam to Upper Shanhkaung, Putao District, Northern Myanmar, only one population and less than 50 individuals, has been discovered. Potential populations and more individuals may be found in future field surveys. Currently, the locality is not legally protected and, although young individuals were recorded in field, the fragmented habitat and continuous logging severely threaten its survival. At present, it is suggested that it be considered as ‘Vulnerable’ (VU) on the basis of current IUCN Red List Categories and Criteria (IUCN, 2012).
(paratypes). MYANMAR. Kachin State, Putao District, on the way from Wasadam to Upper Shankhaung, 27°26'39"N, 97°14'23"E, 800 m a.s.l, 21 May 2017, Myanmar Exped. 2389 (HITBC!), Putao District, Upper Shanhkaung, 27°26'30"N, 97°14'26"E, 680 m a.s.l, 28 April 2016, Myanmar Exped. 201614 (HITBC!).
1 | Flowers minute, less than 10 mm in diam.; inner petals ca. 2–4 mm long | 2 |
– | Flowers conspicuous, more than 10 mm in diam.; inner petals more than 5 mm long | 3 |
2 | Leaf blade obovate to oblong; petals glabrous inside; monocarps ellipsoid-oblong, 14–20 × 7–10 mm | T. argentea |
– | Leaf blade lanceolate; petals puberulous inside; monocarps subglobose, 9–10 mm in diam. | T. kanjilalii |
3 | Petals pubescent or puberulous inside | 4 |
– | Petals glabrous inside | 5 |
4 | Tree to 15 m, elliptic-oblong to oblong-lanceolate, 2.8–3.5 times as long as wide | T. nervosa |
– | Shrub up to 1.5 m, leaf blade lanceolate to oblong, 4.5–5 times as long as wide | T. casseabriae |
5 | Petals densely hairy outside, inner petals of mature flowers connivent, less than 1.5 times as long as wide | T. macrophylla |
– | Petals pubescent or hairy outside, inner petals of mature flowers spreading, 2–4 times as long as wide | 5 |
6 | Flowers pink | T. rubra |
– | Flowers white | 6 |
7 | Monocarps subglobose; inner petals oblanceolate, tip triangular to ligulate, ca. 2 times as long as wide; leaf blade less than 2.5 times as long as wide | T. carnosa |
– | Monocarps elliptic-oblong; inner petals oblanceolate, elliptic to narrowly oblong, 3–4 times as long as wide; leaf blade 3 times as long as wide | T. costata |
Also as a genus, Trivalvaria was revised and mentioned by several experts (Heusden 1997,
Morphological comparison of key characters and distribution in Trivalvaria rubra, T. casseabriae and the similary taxa. Morphological characters of T. costata, T. macrophylla, T. nervosa, T. argentea following Heusden (1997) and
Character | Trivalvaria rubra | T. casseabriae | T. costata | T. macrophylla | T. nervosa | T. argentea | T. kanjilalii | T. carnosa |
---|---|---|---|---|---|---|---|---|
Habitat | shrub up to 1.2 m | shrub up to 1.5 m | shrub to 3 m | tree or shrub up to 12 m | tree to 15 m | shrub | shrub 2–3 m | shrub to1m |
Leaf blade | obovate to narrowly elliptic or oblong-lanceolate, 13.5–27.5 × 4.2–10.5 cm | lanceolate to oblong, 12.5–24.5 × 2.5–5.5 cm | narrowly elliptic to obovate or oblong-lanceolate, 12–20 × 4–7 cm | elliptic-oblong to oblanceolate 9(–16)–(22–)30 × 3–10 cm | elliptic-oblong to oblong-lanceolate, 17–37 × 5–13 cm | obovate to oblong, 9–20 × 2.5–7 cm | lanceolate 12–15 × 3–4 cm | ovate-oblong, 15–17 × 6.5–7 cm |
Flowers | pink, polygamous (male and bisexual), 26–28 mm in diam. | white, male and bisexual, 14–20 mm in diam. | white, male and bisexual, ca.12–24 mm in diam. | white to pale brownish creamy, bisexual, ca. 12 mm in diam. | white, polygamous (male and bisexual), ca. 14–26 mm in diam. | minute, ca. 6–8 mm in diam. | bisexual, ca. 5–6 mm in diam. | white, bisexual, 14–20 mm in diam. |
Sepals | triangular to triangular-ovate, 6–9 × 3–6 mm | ovate to broadly ovate, 2–3.5 × 2–3 mm | triangular to broadly ovate, 2–3.5 × 1.5–4 mm | broadly ovate or triangular, 3–4 × (4–)5–6 mm | broadly ovate, 1.5–3 × 2–3.5 mm | broadly triangular-ovate, 1.5 × 2 mm | broadly ovate, 3–4 × 4 mm | broadly ovate, 2–3 × 2 mm |
Petals | glabrous inside | puberulous inside | glabrous or downy inside | glabrous inside | pubescent inside | glabrous inside | puberulous inside | glabrous inside |
Outer petals | lanceolate, or oblong-ovate to ovate-triangular, 14–20 × 4–7 mm | elliptic to ovate-elliptic, 6–10 × 4–5 mm | oblong-lanceolate, elliptic-oblong, 4–8(–12) × (1–)2–4 mm | broadly ovate or or triangular, 4–8 × 4–7 mm | obovate to elliptic- oblong, (6–)8–15 × 3.5–10 mm | ca. 2 mm long | ovate, 2.5–3 × 2.5 mm | broadly ovate, 5–6 × 4–5 mm |
Inner petals | spreading, lanceolate or narrowly oblong, 17–25 × 4–6 mm | spreading, elliptic to ovate-elliptic, 6–10 × 3–5 mm | spreading, oblanceolate, elliptic to narrowly oblong, 4–12 × 1–4 mm | connivent, broadly ovate to broadly elliptic, or broadly triangular-ovate, 5–13 × 4–10 mm | spreading, obovate to elliptic-oblong, (5–)7–17 × 3–9 mm | ca. 2 mm long | tip incurved, more or less rhomboid, 3–4 × 2.5–3 mm | oblanceolate, tip triangular, 10–12 × 5–6 mm |
Monocarps stipe | 2–5 mm | unknown | 1–6 mm | 2–6 mm | 9–(25–)30 mm | 3–6 mm | 5–6 mm | 5–6 mm |
Monocarps | ellipsoid or oblong, 15–18 × 7–10 mm | unknown | elliptic-oblong, 12–24 × 6–10 mm | ovoid to ellipsoid or oblong, 14–20 × 7–10 mm | oblong, 20–25 × 13–15 mm | ellipsoid-oblong, 14–20 × 7–10 mm | subglobose, 9–10 mm in diam. | subglobose, 10–12 × 8–10 mm |
Distribution | Myanmar | Myanmar | Southeast Asia, China (Hainan) | S. Thailand, Malaya, Sumatra, Java, Borneo | S. Thailand and Malaysia | NE India, Bangladesh | E India | Java |
We are grateful to many personnel in Myanmar for their exhaustive help in the field work. We thank Professor Richard M. K. Saunders and Professor Xiaohua Jin for their constructive comments on the manuscript. This work was financially supported by a project of the Southeast Asia Biodiversity Research Institute, Chinese Academy of Sciences (Grant No.Y4ZK111B01).