Corresponding author: Wannachai Chatan (
Academic editor: Peter Bruyns
Promprom W, Chatan W (2020) A new species of
Specimens were collected from Phu Pha Yol National Park, Sakon Nakhon Province, Thailand in 2017. Morphological observations of the new species were carried out on living plants from the field, as well as on herbarium specimens in BK and BKF. Measurements were made with a Vernier caliper or with an ocular micrometer in a dissecting microscope. We consulted the relevant taxonomic literature (e.g.
Thailand, Sakon Nakhon Province: Phu Pha Yol National Park, 300–400 m alt.,
Flowering in July–September and fruiting in Aug–December.
The new species is endemic to Thailand and is known only from the type locality, Phu Pha Yol National Park, Sakon Nakhon Province, north-eastern Thailand (Figure
Distribution of
This new species grows in both slightly open and in shaded areas in mixed deciduous forest at an elevation of 300–400 m.
Thao Rag Noi.
The specific epithet of
One population of
The genus
Distinguishing features between
Characters |
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1. Leaf shape | elliptic or narrowly elliptic or slightly oblanceolate | ovate to ovate-elliptic, rarely obovate |
2. Corolla colour outside | tube yellow at base, light yellow or white towards apices of lobes | white or orange-yellow tube and lobes |
3. Corolline corona | Absent | present |
4. Staminal corona lobes | stalked, anchor shaped with apex obtuse | stalked, anchor shaped with apex retuse |
1 | Leaves broadly ovate or orbicular or orbicular-peltate; if elliptic, then mixed with others that are peltate or orbicular |
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– | Leaves narrowly ovate, elliptic, narrowly elliptic, obovate, lanceolate, oblanceolate, or spathulate; not mixed with peltate or orbicular leaves |
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2 | Leaves broadly ovate or orbicular or elliptic, abaxial sides slightly flattened |
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– | Leaves peltate or orbicular, abaxial sides distinctly concave; |
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3 | Branches pubescent |
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– | Branches glabrous |
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4 | Staminal corona lobes ± absent |
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– | Staminal corona lobes consisting of spreading horn-like projections |
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5 | Leaves abruptly laterally expanded at the middle or in upper half |
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– | Leaves not expanded in upper half |
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6 | Leaves linear or narrowly elliptic or spathulate; proportion of length /width is 3.8–16 |
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– | Leaves ovate, elliptic, lanceolate, obovate, slightly oblanceolate or broadly obovate; proportion of length/width ratio smaller than 3.8 |
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7 | Leaves broadly obovate, rarely elliptic; staminal corona lobes broadly saddle-shaped |
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– | Leaves ovate, elliptic, slightly elliptic, lanceolate, slightly oblanceolate; staminal corona lobes anchor shaped or sagittate or reduced to minute swellings |
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8 | Branches pubescent, tomentose or hirsute |
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– | Branches glabrous |
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9 | Corolla pink, red, dark red or purple, 6–7 mm long, with two rings of hairs inside around mouth of tube |
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– | Corolla white or creamy white, less than 5.5 mm long, mouth of corolla tube glabrous or with a single ring of hairs |
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10 | Corolla ribbed inside; apices of corona lobes sagittate |
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– | Corolla smooth inside; apices of corona lobes cuneiform |
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11 | Staminal corona lobes reduced to minute swellings |
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– | Staminal corona lobes stalked and anchor-shaped or sagittate |
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12 | Branches and leaves succulent |
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– | Branches and leaves not succulent |
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13 | Apices of staminal corona lobes obtuse |
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– | Apices of staminal corona lobes retuse |
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14 | Corolla tube and lobes glabrous inside |
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– | Corolla with hairs at mouth of tube or on adaxial side of lobes |
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15 | Corolla with two distinct rings of hairs only in mouth of tube |
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– | Corolla with a single ring of hairs around mouth of tube |
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16 | Corolla lobes adaxially pubescent |
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– | Corolla lobes adaxially glabrous |
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17 | Corolla lobes triangular, with a ring of hairs around base only |
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– | Corolla lobes lanceolate, with hairs from base to the middle |
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18 | Leaves 1.5–3.0 × 0.7–1.3 cm; corona lobes anchor-shaped with rounded apices |
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– | Leaves 2.5–6.5 × 0.9–2.5 cm; corona lobes sagittate with obtuse or truncate apices |
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19 | Corolla greenish-white with purple lines alternating with lobes, mouth of corolla tube hairy throughout |
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– | Corolla white or creamy white, with a ring of hairs in mouth of tube |
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The authors thank the herbaria BK, BKF and K for providing information on the type specimens for this study. We thank the officers in Phu Pha Yon National Park for help while collecting plant specimens on field trips. Thanks for linguistic advice from Dr. Adrian Roderick Plant, Mahasarakham University. Thanks for valuable comments and suggestions from the editor and reviewers. This research project was financially supported by Mahasarakham University (Fast Track 2020).