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กระดิ่งดอยตุง Didymocarpus alboroseus Nangngam & de Bult; ข้าวก่ำภูวัว D. phuwuaensis Nangngam, D.J.Middleton & Suddee; ม่วงสามหมอก D. hongsonensis Nangngam, Punchay & Suksathan, in Nangngam, Middleton, Suksathan et Suddee. 2026. |
Abstract
Ten new species of the genus Didymocarpus are described from Thailand: Didymocarpus alboroseus, D. flaviflorus, D. hongsonensis, D. kiewbangii, D. kwanjaiae, D. mekongensis, D. niveus, D. phuwuaensis, D. suchartii and D. vilaiwaniae. Full descriptions, distributions, ecology and colour plates are provided for all taxa. These additional new species increase the total number of Didymocarpus in Thailand to thirty-five species, and therefore, a key to the species of Didymocarpus in Thailand is also provided in this paper.
Keywords: Flora of Thailand, taxonomy, Didymocarpinae, Trichosporeae
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| Didymocarpus alboroseus Nangngam & de Bult: A. habit showing leaves and dichasial cyme inflorescence; B. corolla shape; C. flower in bud and immature capsule. Photographs: All by Thanakorn Wongsa. |
Didymocarpus alboroseus Nangngam & de Bult, sp. nov.
Vernacular.— Krading doi tung (กระดิ่งดอยตุง)(Proposed here).
Etymology.— The specific epithet refers to the corolla colour with the white tube and lobes reddish brown to orange brownish inside.
Didymocarpus flaviflorus Nangngam, Suksathan & Rujich., sp. nov.
This species is similar to Didymocarpus citrinus Ridl. in the corolla colour but they differ in corolla size (c. 3.5 cm long in Didymocarpus flaviflorus, 2–2.7 cm long in D. citrinus), calyx shape (tubular in Didymocarpus flaviflorus, lobes free in D. citrinus), and in leaf shape and margin (elliptic-oblong and denticulate in D. flaviflorus, ovate to ovate-lanceolate and serrate in D. citrinus).
Vernacular.— Krading lueang wiangchai (กระดิ่งเหลืองเวียงชัย) (Proposed here).
Etymology.— The specific epithet refers to the bright yellow corolla.
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| Didymocarpus hongsonensis Nangngam, Punchay & Suksathan: A. habit and habitat; B. corolla front view and young fruits; C. corolla shape side view; D. opened flower showing stamens, staminodes and pistil; E. stamens showing anthers coherent. Photographs: All by Kittiyut Punchay. |
Didymocarpus hongsonensis Nangngam, Punchay & Suksathan, sp. nov.
Vernacular.— Muang sam mok (ม่วงสามหมอก)(Proposed here).
Etymology.— The specific epithet refers to Mae Hong Son Province, the type locality.
Didymocarpus kiewbangii Nangngam & Suddee, sp. nov.
This species is similar to Didymocarpus insulsus Craib in general appearance and in having 5 free calyx lobes but differs in the leaf arrangement and a longer corolla (leaves opposite and corolla c. 3 cm long in D. kiewbangii, ternate and c. 2.5 cm long in D. insulsus).
Vernacular.— Muang si kieobang (ม่วงศรีเขียวบาง)(Proposed here).
Etymology.— The specific epithet is given in honour of Mr Wittawat Kiewbang, a former BKF staff member who has accompanied botanists to various parts of the country and contributed valuable photographs and specimens.
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| Didymocarpus kwanjaiae Nangngam & Suddee: A. Habit and habitat; B. flower showing calyx and corolla shape; C. opened corolla showing stamens, staminodes and pistil; D. flower bud. Photographs: All by Kwanjai Khammmongkol. |
Didymocarpus kwanjaiae Nangngam & Suddee, sp. nov.
This species is similar to Didymocarpus middletonii Souvann., Soulad. & Tagane from Laos in the red corolla colour but differs in the calyx tube campanulate and glabrous (tube campanulate and glabrous in D. kwanjaiae, tube urceolate and with multicellular eglandular hairs in D. middletonii).
Vernacular.— Krading Daeng Phaseeda (กระดิ่งแดงผาสีดา)(Proposed here).
Etymology.— The specific epithet is given in honour of Dr Kwanjai Khammongkol, the former chief assistant of Phu Langka National Park and the collector of the known specimens.
Didymocarpus mekongensis Nangngam & Suddee, sp. nov.
This species is similar to Didymocarpus biserratus Barnett in having a united and glabrous calyx tube and a funnelform and glabrous corolla but differs in having a symmetrical tubular white-cream and greenish-whitish calyx tube and a white corolla (asymmetrical green-maroon to purple campanulate calyx tube and dark violet corolla in D. biserratus). It is also similar to D. niveus in the white corolla but differs in the symmetrical calyx (asymmetrical in D. niveus) and corolla size (c. 2.5 cm long in D. mekongensis, c. 3.5 cm long in D. niveus).
Vernacular. — Krading Khao Lam Kong (กระดิ่งขาวลําโขง)(Proposed here).
Etymology.— The specific epithet refers to the Mekong Basin, the type locality.
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| Didymocarpus niveus Nangngam, Vidthay., Wongsa & Suddee: A. corolla front view; B. inflorescence, cyme 3–5-flowered; C. ovary and stigma. D. stamens showing anthers coherent and 2 longer staminodes. Photographs: A–B by Pranee Nangngam; C by Thanakorn Wongsa. |
Didymocarpus niveus Nangngam, Vidthay., Wongsa & Suddee, sp. nov.
This species is similar to Didymocarpus mekongensis Nangngam & Suddee in its white funnelform corolla but differs in having a longer calyx tube and corolla (calyx tube 8–10 mm long and corolla c. 3.5 cm long in D. niveus vs calyx tube c. 5 mm long and corolla c. 2.5 cm long in D. mekongensis).
Vernacular.— Krading Khao Khun Phawo (กระดิ่งขาวขุนพะวอ)(Proposed here).
Etymology.— The specific epithet refers to the snow-white colour of the corolla.
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| Didymocarpus phuwuaensis Nangngam, D.J.Middleton & Suddee: A. habit; B. capsules; C. inflorescence and front view of corolla; D. side view of corolla. Photographs: All by Wittawat Kiewbang. |
Didymocarpus phuwuaensis Nangngam, D.J.Middleton & Suddee, sp. nov.
This species is similar to Didymocarpus formosus Nangngam & D.J.Middleton in the large paired bracts and funnelform corolla but differs in having bracts not embracing the calyx in bud, a ubular calyx tube, and a dark purple corolla (bracts embracing calyx in bud, campanulate calyx tube, and dark red maroon corolla in D. formosus).
Vernacular.— Khao kam phu wua (ข้าวกําภูวัว)(Proposed here).
Etymology.— The specific epithet refers to Phu Wua Wildlife Sanctuary, the type locality.
Didymocarpus suchartii Nangngam, Makerd & Suddee, sp.nov.
This species is similar to Didymocarpus megaphyllus Barnett in the corolla covered with multi-cellular glandular hairs but differs in having calyx lobes free, ovary with multicellular glandular hairs, corolla dark purple (calyx formed into a campanulate tube at base, ovary glabrous, corolla crimson-red in D. megaphyllus). Also similar to D. hongsonensisin having a dark purple funnelform corolla but differs in having calyx lobes free (formed into a tube at base in D. hongsonensis).
Vernacular.— Muang chan hom huan (ม่วงจันทร์หอมหวล)(Proposed here).
Etymology.— The specific epithet is given in honour of Mr Suchart Chanhomhual, who has contributed a lot to protecting plant diversity in Umphang District, and for his photographs and the type collection.
Didymocarpus vilaiwaniae Nangngam, Moungmaith. & Chamch., sp. nov.
This species is similar to Didymocarpus glandulosus (W.W.Smith) W.T.Wang var. minor (W.T.Wang) W.T.Wang from South China in general appearance and in having free calyx lobes and a salverform corolla but differs in leaf characters (leaves congested at the top of stem and silvery on upper surface in D. vilaiwaniae, scattered along stem and not silvery on upper surface in D. glandulosus var. minor).
Vernacular.— Muang Si Anusarn (ม่วงศรีอนุสาร)(Proposed here).
Etymology.— The specific epithet is given in honour of Associate Prof. Dr Vilaiwan Anusarnsunthorn, the founder of CMUB herbarium.
Pranee Nangngam, David J. Middleton, Piyakaset Suksathan and Somran Suddee. 2026. Ten New Species of Didymocarpus (Gesneriaceae: Didymocarpoideae) from Thailand. Thai Forest Bulletin (Botany). 54(2); 128-149. DOI: doi.org/10.20531/tfb.2026.54.2.13 [2026-08-19]
