Research Article |
Corresponding author: Xuan Bach Nguyen-Le ( nlxbach@gmail.com ) Academic editor: Duilio Iamonico
© 2024 Hong Truong Luu, Nga Nguyen-Phi, Quoc Dat Nguyen, Hieu Cuong Nguyen, Hong Thien Van, Xuan Bach Nguyen-Le.
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:
Luu HT, Nguyen-Phi N, Nguyen QD, Nguyen HC, Van HT, Nguyen-Le XB (2024) A new species of Typhonium (Araceae) from Vietnam. PhytoKeys 238: 119-126. https://doi.org/10.3897/phytokeys.238.112973
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Typhonium obtusum is described as a new species endemic to Vietnam. It is unique in the genus in having an oblong-elliptic spathe limb with an obtuse apex and yellowish-greenish filiform staminodes with a down-curved acumen. The ecology, distribution and assessment of the conservation status of the new taxon, as well as a key to all known Typhonium species in Vietnam, are provided.
Araceae, endemic, new species, Typhonium obtusum, Vietnam
The genus Typhonium (
As part of ongoing study of Typhonium in Vietnam, we have collected several putatively new taxa, one of which was found in Phu Yen Province, central Vietnam. At the first glance, the plant looks like T. rhizomatosum A.Galloway and P.Schmidt (
The studied material was collected from Phu Yen Province, Central Vietnam. Specimens were sampled and processed using methods guided by the Royal Botanic Gardens, Kew (
Vietnam. Phu Yen Province, Tay Hoa District, Hoa Thinh Ward; 12°54'30.1"N, 109°14'15.1"E, 30 m elevation; 5 August 2015; Nguyen Le Xuan Bach & Nguyen Hieu Cuong PY495-505 (holotype SGN!; isotypes SGN!, PHH!).
Typhonium obtusum is morphologically similar to T. rhizomatosum and T. cordifolium in having ovate leaf blades with cordate base, oblong and elongate spathe limb as long as the spadix and an elongated fusiform spadix appendix. However, the novel taxon can be distinguished from T. rhizomatosum by its subcylindrical (vs. globose to subglobose) tubers without (vs. with) rhizomatous offsets, stipitate and fusiform (vs. sessile and conical) spadix appendix) and oblong-elliptic (vs. narrowly triangular ovate) spathe limb and from T. cordifolium by its subcylindrical (vs. subglobose) tubers, leaves without (vs. with) adventitious buds, oblong-elliptic (vs. narrowly triangular ovate) spathe limb and stipitate and fusiform (vs. sessile and cylindrical) spadix appendix.
Herbs, seasonally dormant, 10–17 cm tall; tuber underground, subcylindrical, fleshy, 2–2.5 cm long, 1–1.5 cm in diameter, with many filiform roots. Leaves 2–3 together. Petiole smooth, slender, 5–9 cm long, 1.8–2.2 mm in diameter, white to brown at base, green towards the apex. Leaf blade entire or trilobate, strongly cordate, glabrous, adaxially green, abaxially lighter green, concave, 3.2–4.7 cm long, 3–4 cm wide; entire leaf blade ovate, rounded at apex, venation pinnate with abaxially prominent midrib, lateral veins 5–8, brochiododromous, collective veins at 2–5 mm from margin; anterior lobes ovate, broadly elliptic to obovate, 2.5–3.7 cm long, 2.3–3.0 cm wide, obtuse to rounded at apex with a minute mucro, mid-rib abaxially prominent, lateral veins 4–6, brochiododromous, collective veins at 1–2 mm from margin; lateral lobes elliptic to ovate, 2.2–3.1 cm long, 0.6–1.6 cm wide, obtuse at apex, oblique at base. Inflorescences solitary; peduncle white, 2.5–6 cm long, ca. 4 mm in diameter; spathe 5–6 cm long, tube and limb separated by a constriction, outside green-brown, inside purple-brown; spathe tube ovoid, 1.1–1.3 cm long, 7–8 mm in diameter; spathe limb oblong-elliptic, 4–4.5 cm long, 1.1–1.3 cm wide, obtuse at apex, hardly open at base at anthesis; spadix equal or slightly shorter than spathe, sessile; female part conical, 1.6–2 mm long, 3.9–4.3 mm in diameter at the base, 2–3 mm in diameter at the top, with 3–4 rows of crowded pistils; ovary obovate, ca. 1 mm long, 0.6–0.8 mm in diameter, yellowish-greenish, with purple spots, unilocular, uniovulate placentation, transparently white; ovule light yellow, on a basal placenta and hold obliquely on a funicle; stigma sessile, disciform, 0.3–0.5 mm in diam., 0.1–0.2 mm high, light yellow, penicillate; interstice 1–1.3 cm long, lower part ca. 4 mm densely covered with staminodes, upper part naked, smooth, white to yellowish; staminodes filiform, subulate, 1–3 mm long, 0.4 mm in diameter, apically curved downward, yellowish-greenish; male part cylindrical, ca. 4.5 mm long, ca. 2.5 mm in diameter; stamens free, sparsely to (mostly) densely arranged; thecae globular, ca. 0.3 mm in diameter, dark purple, opening by apical slit; pollens translucent white; appendix stipitate, elongated fusiform, pale yellowish, 2.5–3.9 cm long, 2–3 mm in diameter, stipe ca. 3.5 mm long, pale yellow. Fruits ovoid to capsule-shaped, 3–4 mm long, 1.5–1.8 mm in diameter, white at base, green towards the apex with many dark purple spots.
The species is named for the obtuse apex of its spathe limb.
Bán hạ mo tù (Vietnamese); Obtuse-spathed typhonium (English, here proposed).
The new species was found growing in clumps on basalt soils in open places of rural farms. It appears in September to December and becomes dormant in January to August. Flowering and fruiting were seen in August.
Typhonium obtusum has been recorded only from the type locality.
Data Deficient (DD) (
The key morphological similarities and differences of T. obtusum versus T. rhizomatosum and T. cordifolium are presented in the diagnosis. In addition, the two latter are different from the new species by their unique characters in the genus: T. cordifolium with adventitious buds appearing at the mature leaf blade apex or sometimes at the top of the sheath, while T. rhizomatosum often forms large colonies thanks to its rhizomatous offsettings (
The new species may be morphologically close to T. hayatae Sribonnma & J.Murata (
T. obtusum | T. hayatae | T. inopinatum | T. medusae | T. varians | T. rhizomatosum | T. cordifolium | |
---|---|---|---|---|---|---|---|
Tuber | subcylindrical, without rhizomatous offsets | globose, without rhizomatous offsets | subcylindrical, globose, without rhizomatous offsets | depressed, without rhizomatous offsets | depressed, without rhizomatous offsets | globose to subglobose, with rhizomatous offsets | subglobose, without rhizomatous offsets |
Leaf blade | ovate, smooth | – | ovate to triangular or hastate, smooth | broadly triangular, 10 cm long, 14 cm wide, hairy | broadly triangular, more or less distinctly trilobate to subpentalobate, smooth | ovate to elliptical-ovate, smooth | narrowly ovate elliptic to narrowly elliptic, acuminate, with a bulbil when mature |
Spadix appendix | 2.5–3.9 cm long, 0.2–0.3 cm in diameter, pale yellowish, fusiform, stipe ca. 0.35 cm long, base gradually narrowing | 6–14 cm long, 0.5–1.5 cm in diameter, conical, stipe short, base truncate | 4–6 cm long, 0.4–0.5 cm in diameter, yellow, yellowish-brown, elongate conical, subsessile, base truncate | 1 cm long, 0.3 cm in diameter, reddish-brown, elongate conical, stipe 0.15 cm long, base truncate | 4.5–9 cm long, to 1 cm in diameter, dark grey, elongate conical, stipe 0.5 cm long, base truncate | 8 cm long, 0.35 cm in diameter, beige, conical, sessile, base truncate | 3.6–7.7 cm long, 0.1–0.2 cm in diameter, brick orange, cylindrical, sessile, base gradually narrowing |
Spathe tube | ovoid, 1.1–1.3 cm long, 0.7–0.8 cm in diameter, green with brown dots | oblong-ovoid 2.5–4.5 cm long, 1–2 cm wide, dark brownish-purple | ovoid, 0.8‒1.5 cm long, ca. 1 cm in diameter, green | ovoid, 1.8–2 cm long, 1.2–1.5 cm in diameter, white with pinkish or purplish-brown flushing | ovoid, ca. 2.5 cm long, ca. 1.5 cm in diameter, glossy green | subglobose, 1 cm long, 0.8 cm in diameter, outside bright pale green, inside as outside, but with pale pink flush | ovoid, 1.2 cm long, 1 cm in diameter, light brown-green outside, brown or reddish-brown inside |
Spathe limb | oblong-elliptic, 4–4.5 cm long, 1.1–1.3 cm wide, green with brown mottling | widely ovate in lower part, narrowly triangular in upper part, 12–26 cm long, 7.5–12 (–15) cm wide, dark brownish-purple | narrowly ovate to lanceolate, 5.5–7 cm long, 1.2–2 cm wide, basally brownish, apically green | orbicular, 2.7–3 cm long, 3 cm wide, whitish-greenish with a dense pinkish-brownish or brownish mottling | triangular ovate, 7–14 cm long, 4–7.5 cm wide, dark green flushed with dirty brown | narrowly triangular ovate, 7–9.5 cm long, 0.9–1.5 cm wide, bright pale green with brown longitudinal veins | narrowly triangular ovate, 5–9 cm long, to 3 cm wide, light brown-green |
Staminode | slender filiform, decurved, yellowish-greenish | unknown | filiform, horizontally spread and slightly curved, yellow | subulate, upper ones straight, lower ones variously curved, mostly downwards, pale yellow or cream | subulate, upper ones straight, lower ones strongly curved downward, pale yellow | cylindrical, mostly perpendicular to axis, creamy white | cylindrical, spreading, dark yellow |
Ovary | obovoid, yellowish-greenish | unknown | ellipsoid, yellowish-greenish | elongate, tapering to the base, basal half white, upper part spotted reddish-pink | more or less ellipsoid, pale green | elongate obovate, creamy white | elongate, white |
Stigma | light yellow | unknown | yellow | reddish-pink | dirty whitish-greyish | creamy white | white |
Distribution | C. Vietnam | S. Vietnam | N. and Central India to Thailand | C. Thailand | N. Thailand | Thailand | Thailand, Myanmar, S. Vietnam |
1 | Sterile interstice of spadix entirely covered with staminodes | T. flagelliforme |
– | Only base of sterile interstice of spadix covered with staminodes | 2 |
2 | Leaves perfectly trifoliolate | 3 |
– | Not as above | 4 |
3 | Plant with 3 leaves; appendix stipitate; female section of spadix with 5–6 rows of pistils | T. thatsonense |
– | Plant with 1 leaf; appendix sessile; female section of spadix with 2–3 rows of pistils | T. hangiae |
4 | Inflorescence appearing before the leaves | 5 |
– | Inflorescence appearing together with the leaves | 6 |
5 | Spathe 6–9 cm long; staminodes ca. 6 mm long | T. penicillatum |
– | Spathe 14–30 cm long; staminodes ≤ 3 mm long | T. hayatae |
6 | Spathe limb elongate, narrowly lanceolate-triangular | 7 |
– | Spathe limb wide, oblong-elliptic, ovate to lanceolate | 15 |
7 | Staminodes red with a light yellow acumen | 8 |
– | Staminodes unicolourful | 9 |
8 | Spathe tube globose, to 1.5 cm long; staminodes 5 mm long, clavate | T. bachmaense |
– | Spathe tube oblong or cylindrical, 2 cm long; staminodes 12 mm long, acute | T. kbangense |
9 | Spathe limb white | T. praelongum |
– | Not as above | 10 |
10 | Spathe limb corrugated | T. corrugatum |
– | Not as above | 11 |
11 | Leaf 3-lobed | 12 |
– | Not as above | 13 |
12 | Stigma funnel-shaped and lobed | T. stigmatilobatum |
– | Stigma disciform and unlobed | T. huense |
13 | Leaves with 7 leaflets, leaflets linear to or linear-lanceolate | T. lineare |
– | Not as above | 14 |
14 | Spathe limb much shorter than spadix appendix | T. vermiforme |
– | Spathe limb as long as spadix appendix | T. dongnaiense |
15 | Spadix longer than spathe | 16 |
– | Spadix as long as or shorter than spathe | 18 |
16 | Staminodes folded 180° apically | T. phuocbinhense |
– | Staminodes straight up to parallel to axis | 17 |
17 | Male zone cylindrical, staminodes cylindrical to conical | T. khonkaenensis |
– | Male zone subglobose, staminodes clavate | T. acetosella |
18 | Leaves developing bulbils at the top and/or the base, upper surface ften grey variegated | T. cordifolium |
– | Not as above | 19 |
19 | Spathe limb very strongly circinnately recoiled over the entire length | T. circinnatum |
– | Not as above | 20 |
20 | Tuber producing rhizomatous offsets about 5 cm apart | T. rhizomatosum |
– | Not as above | 21 |
21 | Staminodes ≤ 3 mm long | 22 |
– | Staminodes > 5 mm long | 23 |
22 | Spathe tube above the ground; spathe limb oblong-elliptic, with obtuse apex | T. obtusum |
– | Spathe tube underground; spathe limb triangular ovate, with acute apex | T. vietnamense |
23 | Staminodes red with a light yellow acumen, upward straight or slightly curved | T. blumei |
– | Staminodes whitish, curly | T. trilobatum |
The authors have declared that no competing interests exist.
No ethical statement was reported.
This research is funded by Vietnam National Foundation for Science and Technology Development (NAFOSTED) under grant number 106.03-2020.37.
Conceptualization, Hong Truong Luu, Xuan Bach Nguyen-Le; Formal analysis, Hong Truong Luu, Nga Nguyen-Phi, Xuan Bach Nguyen-Le, Hong Thien Van; Funding acquisition, Hong Truong Luu; Investigation, Xuan Bach Nguyen-Le, Hieu Cuong Nguyen; Methodology, Hong Truong Luu, Nga Nguyen-Phi, Quoc Dat Nguyen, Quoc Dat Nguyen; Supervision, Hong Truong Luu; Visualization, Hong Truong Luu, Nga Nguyen-Phi, Xuan Bach Nguyen-Le; Writing – original draft, all authors; Writing – review & editing, Hong Truong Luu, Nga Nguyen-Phi, Xuan Bach Nguyen-Le. All authors have read and agreed to the published version of the manuscript.
Hong Truong Luu https://orcid.org/0000-0002-7036-7081
Nga Nguyen-Phi https://orcid.org/0000-0001-7429-3641
Quoc Dat Nguyen https://orcid.org/0000-0002-3687-1567
Hieu Cuong Nguyen https://orcid.org/0000-0001-8707-2944
Hong Thien Van https://orcid.org/0000-0003-0151-5068
Xuan Bach Nguyen-Le https://orcid.org/0000-0001-8391-338X
All of the data that support the findings of this study are available in the main text.