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| Chroesthes faizaltahiriana Siti-Munirah in Siti-Munirah, 2021. |
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
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.
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| 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). |
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| 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). |
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| 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). |
Chroesthes faizaltahiriana Siti-Munirah, sp. nov.
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).
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| 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). |
Distribution: endemic to Peninsular Malaysia, Kelantan. Currently known only from the type collection from Berangkat FR.
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).
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.
Siti-Munirah Mat Yunoh. 2021. Chroesthes (Acanthaceae) in Peninsular Malaysia, including A New Species from Kelantan and A New Record from Terengganu. PhytoKeys. 174: 127-146. DOI: 10.3897/phytokeys.174.62023
