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| Alysicarpus littoralis Satthaphorn & Leerat., in Satthaphorn et Leeratiwong. 2024. |
Abstract
Alysicarpus littoralis Satthaphorn & Leerat. (Fabaceae, Desmodieae), a species confined to Samui Island, Surat Thani province, southern Thailand, is described and illustrated as a species new to science. Initially identified as A. vaginalis (L.) DC., the re-examination of morphological characters revealed distinctions of A. littoralis such as the length of inflorescence internode, length of calyx lobes, the colour of corolla and the type of pods at maturity. The newly proposed species is sometimes similar to A. monilifer (L.) DC. And A. ovalifolius (Schumach.) J. Léonard as it exhibits moniliform pods and lax inflorescence, respectively. The conservation status of the new species is assessed as Critically Endangered (CR, B2(bii+ciii)) following IUCN conservation guidelines since populations are surrounded by human disturbances. A morphological description, line drawing and updated key to species of Alysicarpus in Thailand are presented.
Keywords: coastal area, Desmodieae, Papilionoideae, Samui Island, Surat Thani
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| Line drawings of Alysicarpus littoralis: A. habit with inflorescences and infructescences; B. flowers; C. calyx; D. standard; E. wing petal; F. keel petal; G. diadelphous stamens; H. pistil; I. moniliform pod; J. article with reticulation (side view of an article); K. septum between articles (top view of an article); L. seed. Drawn by J. Satthaphorn from the dried specimen, Leeratiwong 21-1634. |
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| Alysicarpus littoralis: A. habit; B. inflorescence with two-tone-coloured corolla; C. close-up flowers; D. moniliform pods. Photos by C. Leeratiwong. |
Alysicarpus littoralis Satthaphorn & Leerat., sp. nov.
Type: Thailand, Surat Thani, Ko Samui, Bo Phut, Ban Bo Phut, 20 m alt., 3 Jan. 2021, Leeratiwong 21-1634 (holotype PSU!; isotypes BKF!, KKU!). Figs. 1–2.
Diagnosis.— Alysicarpus littoralis superficially resembles A. vaginalis in its herbaceous habit, unifoliolate leaves, pseudoracemose inflorescence, valvate calyx and erect loment pods (Fig. 3). However, A. littoralis is distinguishable by longer petiolules (1–1.5 mm long vs ca. 0.3 mm long in A. vaginalis), longer inflorescence internodes (8–12 mm long and lax-flowered vs 2–5 mm long and compact-flowered), longer calyx lobes (3–5 mm long vs 2.3–3 mm long), two-tone-coloured corolla (orangish-yellow standard but pink wings vs monotone-coloured-pink to purple in all petals) and moniliform pods with barrel shaped articles at maturity (vs terete pods with cylindrical articles).
Etymology.— The specific epithet refers to its habitat which can be found in coastal areas.
Vernacular.— Thua lisong na samui (ถั่วลิสงนาสมุย).
Jiratthi Satthaphorn and Charan Leeratiwong. 2024. Alysicarpus littoralis, A New Species of Alysicarpus (Fabaceae) from Thailand. THAI JOURNAL OF BOTANY. 16 (1): 41–52.
