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Chroesthes (Acanthaceae) in Peninsular Malaysia, including a new species from Kelantan and a new record from Terengganu
expand article infoSiti-Munirah Mat Yunoh
‡ Forest Research Institute Malaysia, Kepong, Malaysia
Open Access

Abstract

Chroesthes is a small genus that includes three species from Peninsular Malaysia: Chroesthes faizaltahiriana Siti-Munirah sp. nov., C. lanceolata (T. Anderson) B.Hansen and C. longifolia (Wight) B.Hansen. Chroesthes faizaltahiriana, recently discovered in the State of Kelantan, is described and illustrated. This species is similar to the common species C. longifolia, but is distinguished mainly by its inflorescence type, calyx shape and its flowers being bright orange instead of dark purple internally. Chroesthes lanceolata is a new record for Peninsular Malaysia and has only been collected once. Following the IUCN Red List Categories and Criteria, these three species are assessed (national scale assessment) as Critically Endangered (C. faizaltahiriana and C. lanceolata) and Least Concern (C. longifolia).

Keywords

Conservation status, revision, taxonomy

Introduction

The small genus Chroesthes Benoist (1927), Acanthaceae, currently consists of three species distributed in South China, Indo-China and Malaysia (Hansen 1983; Govaerts 1999; POWO 2019). In the current classification of the family Ranunculaceae, it is placed within the putative members of tribe Barlerieae (Scotland and Vollesen 2000; McDade et al. 2008; Champluvier and Darbyshire 2012). This genus can be distinguished from other genera of Acanthaceae by the structure of the calyx and corolla, the presence of bicalcarate anthers, i.e. anther thecae spurred at the base or awned anther thecae and are diagnostic within Barlerieae, for which quincuncial aestivation is diagnostic and seeds are shortly pubescent (Hansen 1983; Hu et al. 2011; Darbyshire et al. 2019). The three species of Chroesthes are distributed as follows: Chroesthes lanceolata (T. Anderson) B.Hansen occurs in Myanmar, N Thailand, N Laos, N Vietnam SW China (Yunnan) and Peninsular Malaysia (Hansen 1983; Ummul-Nazrah et al. 2011); Chroesthes bracteata (J.B. Imlay) B.Hansen occurs in SE Thailand (Hansen 1983); and Chroesthes longifolia (Wight) B.Hansen is endemic in Peninsular Malaysia (Hansen 1983).

The Forest Research Institute Malaysia (FRIM) launched the Peninsular Malaysia Flora Project (FPM) in 2005, which aims to provide a more complete and up-to-date account of the national flora (Middleton et al. 2019). To achieve this goal, the FRIM flora team continues to conduct vegetation surveys throughout Peninsular Malaysia, especially in unexplored and ecologically-significant areas. Through this fieldwork, the number of species encountered within the Flora region has increased. A few new species are discovered every year and published in journals. For example, many new fairy lantern species (Thismia) have been described in recent years, including Thismia kelantanensis Siti-Munirah, T. domei Siti-Munirah and T. terengganuensis Siti-Munirah (Siti-Munirah 2018; Siti-Munirah and Dome 2019). Moreover, new gesneriad species have also been described, including Codonoboea norakhirrudiniana Kiew, C. rheophytica Kiew, C. sallehuddiniana Lim (Kiew and Lim 2019) and, most recently, Codonoboea kenaboiensis Syahida-Emiza, Sam & Siti-Munirah and C. ruthiae Syahida-Emiza, Sam & Siti-Munirah have been described (Syahida-Emiza et al. 2020).

During a recent botanical survey at Berangkat Forest Reserve (FR), Kelantan, an upright shrub with an unusual bright orange corolla colour was encountered growing in a patch of forest, under shade beside an old logging road. Its morphological characteristics, including its stamen type, indicated that it belongs to the genus Chroesthes, but is unmatched amongst the three species currently recognised. This new species is described here as Chroesthes faizaltahiriana Siti-Munirah, which brings the total species for Chroesthes in the world to four. It is also an additional endemic species in Peninsular Malaysia. With this recent discovery, an account of the genus Chroesthes in Peninsular Malaysia is provided, including the key to Chroesthes of the world; however, only the Malaysian species are considered in the remainder of the treatment.

Materials and methods

Specimens of Chroesthes species from Peninsular Malaysia, held in the herbaria at Kepong Herbarium (KEP) and Singapore Botanic Gardens Herbarium (SING), were examined. All cited specimens were observed by the author. The study of the new species was based on material collected by the author on 26 February 2020 from the only populations found during a botanical trip to Berangkat FR, Gua Musang, Kelantan. The specimens were pressed as herbarium specimens and an inflorescence was also preserved as a spirit collection. Morphological characters were studied using a stereomicroscope and high-resolution macro photography. Measurements were taken from living plants and herbarium material. The specimen details were compared with original drawings and descriptions given in the protologues for each species of the genus Chroesthes and also with information gathered from the relevant literature (Wight 1850; Clarke 1908; Ridley 1923; Hansen 1983, Hu et al. 2011). The conservation status assessments were made with reference to the Categories and Criteria of IUCN (2019).

Taxonomy

Chroesthes Benoist

Bull. Mus. Natl. Hist. Nat. 33: 107. 1927, in Fl. Gen. I.C. 4: 684. 1935; Hansen, Nordic J. Bot. 3: 209. 1983; Hu, J.C., Deng, Y.F., Daniel, T. & Wood, J.R.I. Acanthaceae. In: Wu, Z.Y., Revan, P. & Hong, D.Y. (Eds.) Flora of China 19: 472. 2011.

Description

Shrubs; cystoliths present. Leaves opposite, petiolate; leaf blade margin entire; subisophyllous or anisophyllous. Inflorescences terminal thyrses (the thyrses are branched (then paniculiform) or unbranched (then racemoid); bracts and bracteoles greenish. Calyx unequally five-lobed: posterior lobe largest, two lateral lobes smaller than two anterior lobes. Corolla tube basally cylindrical, expanded distally into a throat; limb two-lipped, upper lip two-lobed, lower lip three-lobed; lobes quincuncial in bud; four stamens, connate to the corolla, not connate to one another, posterior pair shorter than anterior pair, inserted at the base of the corolla throat; anthers bi-thecous; thecae parallel, inserted at different heights, dorsally pubescent, base of each theca spurred; ovary with two ovules per locule; style basally sparsely pubescent; stigma capitate. Capsule stipe absent or barely present; retinacula present. Seeds compressed, brownish, shortly pubescent.

Distribution

China, Laos, Malaysia, Myanmar, Thailand, Vietnam. Three species in Malaysia.

Ecology

Lowland dipterocarp forest to upper hill dipterocarp forest.

Key to species of Chroesthes

1 Bracts approximately half the length of the calyx C. lanceolata
Bracts approximately as long as the calyx 2
2 All calyx lobes narrow, linear C. bracteata (only in Thailand)
Posterior and anterior calyx lobes elliptic to elliptic-lanceolate, the lateral lobes linear 3
3 Inflorescence terminal branched; corolla entirely dark purple to purplish-red or sometimes white externally C. longifolia
Inflorescence terminal unbranched; corolla yellow to dark orange C. faizaltahiriana

Chroesthes faizaltahiriana Siti-Munirah, sp. nov.

Figs 1, 2, 3

Diagnosis

Chroesthes faizaltahiriana most closely resembles C. longifolia; however, it differs in its inflorescence type, the presence of a terminal raceme not branching (vs. terminal raceme branching) and posterior lobe size ratio 1:4 (vs. 1:2) and corolla length 4.5–5.5 cm (vs. 2–3 cm) and in the corolla tube and lobes being entirely bright yellow to dark orange (vs. entirely dark purple, purplish-red or occasionally white externally) and other significant characters (see Table 1).

Table 1.

Morphological comparison between Chroesthes faizaltahiriana and C. longifolia.

Character C. faizaltahiriana C. longifolia
Habit
Height (m) 0.7–1 1–2.5
Stem Unbranched Branching
Inflorescence
Type Terminal raceme not branching (single) Terminal raceme always branching (always two)
Length (cm) 8–13 up to 25
Flowers
Bract (mm) 20–30 × 2–5 15–20 × 4.5–6
Shape Narrowly lanceolate Lanceolate
Bracteoles (mm) 10–15 × 1–2 10 × 3
Calyx length (cm) 2–3 1.6–1.8
Posterior lobe (mm) 30 × 7 18 × 8–9
Anterior lobe (mm) 22 × 2–2.5 16 × 5–6
Lateral lobe (mm) 20 × 1 10–12 × 0.5
Calyx colour Completely always greenish Green or green to purplish (especially purplish at apex)
Total corolla length (cm) 4.5–5.5 2–3
Corolla colour Entirely yellow to dark orange: pale yellow externally, bright orangish-yellow with darker spots internally Entirely dark purple to purplish-red or sometimes white externally
Filament length (cm)
Longer pair 1.5 1
Shorter pair 1.2 0.8
Figure 1. 

Chroesthes faizaltahiriana Siti-Munirah A habit of the whole plant B inflorescence (front view) C inflorescence (side view) D flower with bracteoles and calyx E perianth lobes (flower from front view) showing the anthers F calyx and bracteoles G bract H bracteoles I calyx (a) anterior, (l) lateral, (p) posterior lobes (photo of a dry specimen) J corolla (inner view) K corolla (outer view) L stamens. (All photos by Siti-Munirah MY).

Type

Malaysia. Peninsular Malaysia: Kelantan, Gua Musang Distr., Berangkat FR, ca. 822 m alt., 26 Feb 2020, Siti-Munirah, FRI 91215 (holotype KEP!, barcode KEP 280001).

Description

Shrubs 0.7–1 m high. Stems terete, erect, not branched, surface glabrous, diameter ca. 2 mm, swollen at nodes. Leaves opposite; petiole 0.2–1 cm long; straight or twisted (makes the leaf arrangement look decussate); leaf blades elliptic, lanceolate to oblanceolate, 4.5–19 × 1.5–5.5 cm, both surfaces glabrous, lateral veins ca. 8–10 on each side of mid-vein, base attenuate to cuneate, margin entire, apex acute to acuminate. Inflorescence a terminal raceme (unbranched), up to 13 cm long; flowers secund (one bract at each node being sterile, the other bracts subtending each flower), ca. 10-flowered; glandular-pubescent on most parts; peduncles ca. 1 cm; bracts narrowly lanceolate, 20–30 × 2–5 mm, apex acute, glandular-pubescent, conspicuously 1-nerved; bracteoles narrowly lanceolate, 10–15 × 1–2 mm; pedicel short, ca. 1–2 mm long. Calyx 2–3 cm long, posterior lobe lanceolate, 30 × 7 mm, 3–5-nerved, apex acuminate; two anterior lobes, elliptic-lanceolate, 22 × 2–2.5 mm, 1-nerved, apex acuminate; two lateral lobes, linear-lanceolate, 20 × 1 mm, 1-nerved; all glandular-pubescent on both sides; all greenish. Corolla bilabiate, orange-yellow, ca. 4.5–5.5 cm long; outer surface pale yellow, glandular-pubescent; inner surface bright orange-yellow to orange with dark orange spots (or stripes), glabrous; tube with cylindrical basal portion ca. 2 cm long, expanded throat ca. 1.5 cm long; upper lip shortly two-lobed (8–9 mm long), lower lip deeply three-lobed (8–10 mm long). Stamens 4, didynamous, included in the throat, inserted at the base of the inflated part of the corolla, longer pair with filaments ca. 1.5 cm long, shorter pair with filaments ca. 1.2 cm long, all filaments with sparse glandular trichomes on the surface; anther thecae ca. 1–2 mm long, basal spur pointed, surface cover with simple trichomes. Pistil whitish-green; ovary ovoid, 1.5–2 mm long, apex pubescent; style ca. 3.2 cm long, pilose below, glabrous above; stigma subcapitate, minutely bilobed. Fruit not known.

Figure 2. 

Chroesthes faizaltahiriana Siti-Munirah with scale A inflorescence B one floral unit with calyx and bracteole C corolla lobes (All photos by Siti-Munirah MY).

Figure 3. 

Chroesthes faizaltahiriana Siti-Munirah A habit B a flower with bracteoles and calyx front side view C perianth lobes (flower from front view) D bract E bracteole F calyx G corolla (inner view) showing the stamens and pistil H pistil I cross-section of the ovary J stigma K1 anthers front view K2 anthers side view. All from FRI 91215, drawn by Mohamad Aidil Noordin).

Distribution

Endemic to Peninsular Malaysia, Kelantan. Currently known only from the type collection from Berangkat FR, 5°07'55.5"N, 101°55'28.5"E (Map 1).

Map 1. 

Distribution of Chroesthes faizaltahiriana (▲) and C. lanceolata (■) in Peninsular Malaysia.

Ecology

Chroesthes faizaltahiriana is found in upper hill dipterocarp forests under shade at 822 m elevation. It was found flowering in February in patches of unlogged forest beside a logging road (Fig. 4).

Figure 4. 

Habitat of Chroesthes faizaltahiriana Siti-Munirah A plant in its original habitat B new logging road beside the population C plant found on the bank of an old logging road (white arrow). (All photos by Siti-Munirah MY).

Etymology

Chroesthes faizaltahiriana is dedicated to Mohd Faizal Mat Tahir (known as Faizal Tahir), the husband of Siti-Munirah for his strong support in many ways towards the author’s botanical work.

Conservation status

Critically Endangered B2 ab(ii,iii). Following the IUCN Red List Categories and Criteria (IUCN 2019), this species is assessed as critically endangered because it is only known from one locality and AOO is less than 10 km2. Furthermore, about eight individuals were observed (all at the flowering stage). The collection locality is within the forest reserve, in an area of disturbed forest near a logging road at an elevation of 822 m. The status of the population is uncertain because the active selective logging activity within the forest reserve is ongoing. It is certainly not within a Totally Protected Area. During the 3-day visit to Berangkat FR, no other populations of C. faizaltahiriana were found. A further survey is needed to obtain more information that could estimate and determine the population size of this species.

Notes

Based on the general morphology of this plant, C. faizaltahiriana is close to C. longifolia, which was previously the only known species of Chroesthes in Peninsular Malaysia. However, a detailed comparison has shown that its inflorescence type is entirely different (Fig. 5, Table 1). Additionally, its phytogeography is also different when compared to C. faizaltahiriana, which is endemic to Gunung Berangkat (Kelantan) in upper hill dipterocarp forest (822 m a.s.l.), while C. longifolia is a widely distributed species inhabiting lowland dipterocarp forest. Based on herbarium specimen collections of C. longifolia at Kepong Herbarium (KEP) and the Singapore Herbarium (SING), it has been recorded in Kedah, Perak, Kelantan, Terengganu, Pahang, Selangor, Negeri Sembilan, Melaka and Johor. C. faizaltahiriana is a distinctive species amongst Chroesthes due to its flower colour. It is the only Chroesthes species with bright orange flowers internally. The flowers of C. longifolia are entirely dark purple to deep purplish-red (occasionally white externally), while the flowers of C. lanceolata are white, spotted pink to purple and those of C. bracteata are reported as pale pink, spotted with red.

Figure 5. 

Inflorescence of Chroesthes longifolia from four localities A, A1 Pasoh FR (Negeri Sembilan) B, B1 Tembat FR (Terengganu) C, C1 Nerus FR (Terengganu) D, D1 Gn. Aais FR (Pahang). (Photos: A, A1 Yao TL B, B1 Siti-Munirah MY C, C1 Imin K D, D1 Sam YY).

Chroesthes lanceolata (T. Anderson) B. Hansen

Fig. 6

Chroesthes lanceolata (T. Anderson) B. Hansen, Nordic J. Bot. 3: 209. 1983; Hu, J.C., Deng, Y.F., Daniel, T. & Wood, J.R.I. Acanthaceae. In: Wu, Z.Y., Revan, P. & Hong, D.Y. (Eds.) Flora of China 19: 472. 2011. Basionym: Asystasia lanceolata T. And., J. Linn. Soc., Bot. 9: 524. 1867. Type: Myanmar, Pegu, Thaungyin, Brandis s.n. (holotype CAL).

Description

Shrubs 0.5–3 m tall, anisophyllous. Stems terete, slender, rarely branched, glabrous. Leaves petiole 1–2.5 cm; leaf blade elliptic to oblanceolate to lanceolate, 10–16 × 3–7 cm, both surfaces glabrous, secondary veins 6–9 on each side of mid-vein, base cuneate, margin entire or sub-sinuate, apex acuminate. Inflorescence thyrses 3–7 cm; cymes sessile, 1–3-flowered; peduncles ca.2 cm; bracts elliptic to broadly lanceolate, 3–9 × 1–3 mm, apex acute, glandular-pubescent; bracteoles narrowly elliptic to broadly lanceolate, 4–9 × 0.7–1.2 mm; pedicel 1–5 mm long. Calyx 1–1.6 cm, outside glandular-pubescent; posterior lobe lanceolate, ovate or subelliptic; anterior lobes connate to two-thirds of their length. lateral lobes linear-lanceolate. Corolla white with pink or purple spots, ca. 2.5 cm, outside pubescent; tube basal portion ca. 9 mm, throat ca. 1.5 cm; upper lip two-lobed; lower lip three-lobed. Stamens 4, included in throat; filaments 1–1.2 cm, glabrous; anther thecae 2.1–2.3 mm, pubescent at the apex and along sides, basal spur pointed; ovary apex pubescent; style ca. 2.5 cm. Capsule subellipsoid to obovoid, 1.2–1.6 cm, glabrous or only at apex pubescent, four-seeded. Seeds subcircular in outline.

Distribution

Myanmar, N Thailand, N Laos, N Vietnam, SW China (Yunnan), Malaysia. In Peninsular Malaysia, recorded from one specimen collected from the trail to Gunung Padang, Ulu Brang, Terengganu in 2010 (FRI 66129) (Map 1).

Ecology

In Peninsular Malaysia, found in a lowland dipterocarp forest at 473 m a.s.l., under a canopy near a small river. (Trail to Gunung Padang).

Conservation status

Critically Endangered B2 ab(ii). Following the IUCN Red List Categories and Criteria (IUCN 2019), this species is assessed as critically endangered at a national level in Peninsular Malaysia because it is currently known from only one specimen in one locality. It is certainly a very rare species. The forest area is lowland dipterocarp forest which was previously logged in the past and it is not a Totally Protected Area. Globally, its conservation status possibly lists it as least concern (LC), by its wide range distribution.

Specimen examined

Terengganu: Hulu Terengganu, Ulu Brang, Ummul-Nazrah et al. FRI 66129 (KEP).

Figure 6. 

Chroesthes lanceolata (T. Anderson) B. Hansen collected from Gunung Padang, Terengganu. (FRI 66129).

Chroesthes longifolia (Wight) B. Hansen

Figs 7, 8

Chroesthes longifolia (Wight) B. Hansen Nordic J. Bot. 3: 210. 1983. Basionym: Lepidagathis longifolia Wight, Icones Plantarum Indiae Orientalis 4 (4): 8–9, Pl: t.1564. 1850; Ridley, The Flora of the Malay Peninsula 2: 587. 1923. Type: Malaysia, Malacca, Griffith s.n. (lectotype K).

Description

Shrub 1–2.5 m high. Stem branches terete, glabrous. Leaves with petiole 0.5–2 cm long; lamina lanceolate, 16–24 × 3.4–8 cm, glabrous, lateral nerves up to 14 pairs, base attenuate, margin entire, apex acuminate. Inflorescence terminal raceme branching, up to 25 cm long; flowers secund, peduncles up to ca. 2.5 cm; one bract at each node being sterile, the other bract subtending one flower; bracts lanceolate, 15–20 × 4.5–6 mm, base obtuse, apex acuminate, glandular-pubescent, nerves conspicuous; bracteoles lanceolate, 10 × 3 mm, as bracts; pedicel very short. Calyx 1.6–1.8 cm long, posterior and anterior lobes elliptic-lanceolate, acuminate, conspicuously nerved, one posterior lobe, elliptic-lanceolate, 18 × 8–9 mm, 3–5 nerved/conspicuously nerved, apex acuminate; two anterior lobes, elliptic-lanceolate, 16 × 5–6 mm, 1-nerved/conspicuously nerved, apex acute; two lateral lobes, linear-lanceolate, 10–12 × 0.5 mm, one-nerved; all glandular-pubescent on both sides; lateral segments linear, one-nerved, glandular-pubescent on both sides; calyx greenish to purplish on the upper part or at the apex. Corolla bilabiate, dark purple-maroon (or claret), 2–3 cm long; outer surface dark purple, dark maroon, claret, sometimes turning white, glandular-pubescent outside; inner surface, dark purple, dark maroon, claret, sometimes whitish on nerves and base, glabrous; narrow part of tube 0.6 cm long, inflated part 1 cm; upper lip shortly emarginate, ca. 3–4 mm long, lower lip deeply trifid, ca. 5 mm long. Stamens 4, inserted at the base of the inflated part of the corolla; longer pair filament 1 cm, shorter pair filament 0.8 cm, filaments 0.8–1 cm long, glabrous, sometimes with glandular trichomes; anthers thecae ca. 1 mm long, glandular-pubescent along the back, bicalcarate at the base. Pistil whitish-green, stigma capitate; ovary glabrous; style ca. 1.4 cm long, pubescent. Capsule ca. 1.5 cm long, glabrous.

Figure 7. 

Chroesthes longifolia (Wight) B. Hansen. The drawing from the original protologue. Source: Icon. Pl. Ind. Orient. 4 (1850) t. 1564.

Distribution

Malaysia. Endemic to Peninsular Malaysia: Kedah, Perak, Kelantan, Terengganu, Pahang, Selangor, Negeri Sembilan, Melaka and Johor (Map 2).

Map 2. 

Distribution of Chroesthes longifolia (●) in Peninsular Malaysia.

Ecology

In primary lowland forest up to upper hill dipterocarp forest at 60 to 700 m a.s.l. Sometimes also found in logged and disturbed forests.

Conservation status

Least concern (LC). This is a widespread species throughout Peninsular Malaysia. However, many old collections are from places that have already changed its habitat. Development of these areas has led to population declines. However, its occurrence still has a wide range of distribution and many are still in totally protected areas.

Specimens examined

Peninsular Malaysia. Johor: Batu Pahat: 6 November 1892, Lake HW s.n. (SING); Ibid., November 1900, Ridley HN 11127 (SING); Johor Bahru: Sedenak, August 1908, Ridley HN 13496 (SING); Kluang: 16 November 1922, Holttum RE SFN9268 (SING); Kluang FR, 28 August 1950, Sinclair J SFN38950 (SING); Kota Tinggi: Gn. Panti, 23 June 1963, Burkill HM HMB 3178 (SING); Mawai, 9 September 1934, Corner EJH s.n. (SING); Mawai Rd., 24 January 1961, Sinclair J 10563 (SING); Sg. Linggiu, 26 July 1991, Tay EP 91-0052 (SING); Sg. Linggiu, 26 July 1991, Tay EP 91-52 (KEP); Muar: Bkt. Keyara, 1902, Fox W 11283 (SING); Gn. Ledang, June 1892, Ridley HN s.n. (SING); Ibid., Muar, April 1901, Curtis C s.n. (SING); Segamat: Sg. Juasseh, 28 June 1970, Samsuri A SA304 (SING); Kedah: Langkawi, Gn. Machinchang FR, 17 March 1969, Chan YC FRI11209 (SING); Kelantan: Gua Musang, 14 July 1935, Henderson MR SFN29657 (KEP,SING); Gua Musang: Relai FR, 1 September 1992, Hamid H2 (KEP); Kuala Krai: Gn. Stong, 5 March 1924, Mhd Nur SFN12180 (SING); Stong FR, 31 March 2009, Rosdi M FRI66253 (KEP SING); Stong Tengah FR, 6 February 2007, Chew MY FRI53481 (KEP); Kuala Lumpur, February 1890, Curtis C 2362 (SING); Melaka: Jasin: Air Panas, 5 September 1886, Watchman under Derry 667 (SING); Air Panas, November 1893, Goodenough JS 1690 (SING); Chabau, 22 September 1885, Alvins MV 2256 (SING); Merlimau, June 1889, Derry R 221 (SING); Negeri Sembilan: Jelebu: Pasoh FR, 3 June 1987, LaFrankie JV LJV2276 (KEP); Ibid., 4 July 1982 Kiew R RK1186 (KEP); Ibid., 30 August 2010, Yao TL FRI65469 (KEP); Kuala Pilah: Angsi FR, Gn. Angsi, 10 December 1930, Syed A FMS23764 (KEP, SING); Senaling, 24 June 1930, Corner EJH s.n. (SING); Senaling Inas,18 November 1929, Symington CF FMS 21356 (KEP, SING); Senaling Inas FR, 28 November 1922, Holttum RE 9788 (SING); Rembau: Perhentian Tinggi, December 1898, Ridley HN s.n. (SING); Pahang: Bentong: Clough FR, Cpt. 37, 16 July 1958, Kochummen KM KEP78709 (KEP); Bentung, Karak FR, 14 July 1924, Best, GA, SFN13899 (SING); Jerantut: Gn. Aais FR, 5 July 2004, Sam YY FRI49062 (KEP); Ibid., 6 July 2004, Chua LSL FRI46691 (KEP); Kota Gelanggi, August 1891, Ridley HN 2174 (SING); P. Tawar, July 1891, Ridley HN s.n. (SING); Taman Negara Gn. Tahan, 31 July 1996, Kiew R RK3978 (KEP); Taman Negara, Sg. Riul, 12 July 1970, Everett B FRI14436 (KEP); Taman Negara Ulu Sat Tg. Petir, 12 July 1970, Whitmore TC FRI15267 (KEP); Taman Negara Kuala Keniam, 7 September 2020, Siti Munirah MY FRI94881 (KEP); Lipis: Chegar Perah,14 October 1927, Henderson MR SFN19364 (SING); Maran: Jengka FR, 10 April 2001, Sam YY FRI 46518 (KEP); Temerloh: Gn. Benom, 14 June 1968, Teo LE 2714 (SING); Temerluh: Fort Iskandar, 2 March 1950, Woods MC KL1720 (SING); Ibid., 2 March 1959, Woods MC KL1720 (KEP); Gn. Senyum, 30 July 1928, Henderson MR s.n. (SING); Kemasul FR, 16 September 2006, Hamid FMS10598 (KEP); Krau WR, 10 November 1999, Damahuri S FRI45314 (KEP); Krau WR 12 July 2007, Mohd Hairul MA FRI58921 (KEP); Perak: Hulu Perak: Belum FR, 30 December 1993, Davison GWH UPM 6077 (KEP); Selangor: Gombak: Bkt. Lagong FR, 5 May 1976, Chan YC FRI23956 (KEP, SING); Ibid., 11 November 1959, Kochummen KM KEP94047 (KEP, SING); Kanching FR, 17 September 1925, Strugnell EJ FMS10508 (KEP); Kepong, 27 May 1970, Teo LE 2862 (SING); Ulu Gombak, 4 July 1918, Sanger-Davies AE FMS2376 (KEP, SING); Hulu Langat: Bkt. Batu Balai, 1 August 1959, Gadoh U KL1630 (KEP); Bkt. Enggang, 3 April 1930, Symington CF FMS 24134 (SING); Bkt. Tangkol, 1 October 1959, Gadoh U KL1810 (KEP); Bkt. Tangkol, 25 July 1959 Gadoh U KL1621 (KEP); Ulu Langat, 7 June 1979, Rajoo SA237 (KEP); Hulu Selangor: Gading Forest Reserve, 19 July 1969, Chan YC FRI11235 (KEP); Klang, Klang Water Catchment Forest, 12 March 1922, Burkill IH SFN6849 (SING); Petaling: Air Hitam Forest Reserve, 12 September 1985, Kiew R RK2065 (KEP); Petaling Rd., 21 June 1889, Ridley HN s.n. (SING); Sungai Buloh Forest Reserve, 7 October 1926, Strugnell EJ 12495 (KEP); Sungai Buloh Forest Reserve, 13 August 1923, Hamid FMS 8888 (KEP); Labu River, Ridley HN s.n. (SING); Sungai Buloh, 12 December 1923, Mhd Nur SFN11886 (SING); Sungai Buloh, 23 November 1956, Burkill HM HMB (SING); Terengganu: Dungun: Bukit Bauk, 25 January 1994, Kiew R RK3793 (KEP); Hulu Terengganu: Sg. Petuang, 26 March 1974, Ng FSP FRI22026 (KEP); Tasik Kenyir, 3 August 2007, Kamarul Hisham M FRI52138 (KEP, SING); Tasik Kenyir, 3 August 2007 Julius A FRI56144 (KEP); Tembat Forest Rerserve, 6 April 2009, Rosdi M FRI66281 (KEP); Tembat Forest Reserve, 3 April 2009, Siti Munirah MY FRI67889 (KEP); Setiu: Ulu Setiu Forest Reserve, 7 March 2002, Saw LG FRI44390 (KEP); Nerus Forest Reserve, Gunung Sarut, 24 June 2019, Imin K FRI 94046 (KEP).

Notes

Ridley (1923) mentioned Chroesthes macrantha as present in Peninsular Malaysia based on Wray 3385 from Perak and that it is similar to C. longifolia. Hansen (1983) suggested that C. macrantha was probably a form of C. longifolia, but he had not observed Wray 3385, so was not able to clarify its status. Efforts to search for this specimen have also been unsuccessful. To date, the status of this taxon is uncertain. Besides, this name also appears not to have been validly published.

Figure 8. 

Chroesthes longifolia (Wight) B. Hansen, collected from Taman Negara, Pahang (Kuala Keniam) A habit B–D inflorescence B front view C side view D back view E bract F–I flower with bracteoles and calyx F from the top view G lower view H–I side view J corolla (inner view) showing the stamens and pistil K corolla lips (flower from front view) showing anthers (All photos by Siti-Munirah MY).

Acknowledgements

This research was conducted as part of the Flora of Peninsular Malaysia Project (FPM) at the Forest Research Institute Malaysia, Kepong, funded by the Ministry of Energy and Natural Resources of Malaysia under the 11th Malaysian Plans (SPPII No. P23085100018003). I should like to thank the State Forestry Department of Kelantan, Malaysia for permission to make botanical collections at Berangkat FR, to the Department of Wildlife and National Parks (PERHILITAN) and Universiti Teknologi Mara (UiTM) for organising the scientific expedition to Taman Negara (Kuala Keniam) and to Serena Lee for providing images of the SING collections of Peninsular Malaysian Chroesthes. I should also like to thank Imin Kamin, Yao Tze Leong and Sam Yen Yen for allowing me to use their Chroesthes longifolia photos. I also thank my colleagues Ahmad Firdaus, Imin Kamin and Wan Mohamad Shafiq Wan Putra for their assistance in the field, to Nor Adilah Abdul Rahman for help in the herbarium and to Mohamad Aidil Nordin for drawing Fig. 3. I am grateful to Deng Yunfei for confirming the generic status of this new species. I am indebted to Ruth Kiew, George Staples and all reviewers for their constructive comments for improving this manuscript, to Wendy SY Yong for assisting in assessing the conservation status and to Mohd Faizal Mat Tahir for his encouragement and help during the preparation of this manuscript.

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