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| Dalbergia calcarea Lanors., Mattapha & Lamxay, in Mattapha, Lanorsavanh, Lamxay; Souvannakhoummane et Chanthavongsa, 2024. |
Abstract
Dalbergia calcarea, a new species currently only known from the limestone mountains of Khammouan Province, central Laos, is described and illustrated. The key characters such as habit, colour and limb of standard, and number of ovules of the new species are discussed and compared with its closest relatives. A detailed description along with etymology, conservation status, illustrations and colour photographs are provided for a new species. This discovery increases the number of Laotian species in the genus Dalbergia to seventeen taxa.
Keywords: Faboideae, Indo-China, Laos, new taxon, taxonomy
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| Dalbergia calcarea Lanors., Mattapha & Lamxay: A. Leaves and inflorescences; B. Leaf; C. Leaflet; D. Flower; E. Standard, outer surface (left) & inner surface (right); F. Wing petals; G. Keel petals; H. Stamens & calyx; I. Ovary; J. Fruits bearing one seed; K. Fruit bearing 4 seeds. A–I: S. Lanorsavanh & V. Lamxay SL1641; J & K: S. Lanorsavanh & K. Souvannakhoummane SL1721. Drawn by Keooudone Souvannakhoummane. |
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| Dalbergia calcarea Lanors., Mattapha & Lamxay: A. Leaves and inflorescences; B. Close up of flowers; C. Flowers (front view, left; side view, right); D. Wing petals; E. Keel petals; F. Stamens enclosing the ovary, inside the calyx; G. Fruits. Photos by Soulivanh Lanorsavanh. |
Dalbergia calcarea Lanors., Mattapha & Lamxay, sp. nov.
This species is characterised by being a tree, leaves with 9–33 leaflets with equal-sided lateral bases, the limb of the standard petal 7–8 mm long, monadelphous stamens (5+5), a pubescent ovary with 3–6 ovules and glabrous fruits. It resembles Dalbergia pinnata (Lour.) Prain in having a similar shape and size of the leaflets, however, it is distinct by the equal-sided bases of the lateral leaflets (vs strongly unequal-sided in D. pinnata), leaflets pubescent on both sides (pubescent only on lower surface in D. pinnata), longer inflorescences (4–6.5 cm long vs 2–3 cm long in D. pinnata), larger bracts (2–)4–6 × 2–2.5 mm vs ca 0.5 × 0.2 mm in D. pinnata),the limb of the standard petal broadly obovate, 7–8 mm long (vs orbicular, 1–2 mm long in D. pinnata) and ten stamens (vs 9 stamens in D. pinnata).
Type: Lao PDR, Khammouan Province, Khounkham Distr., Phou Pha Man Hill, mixed deciduous forests on limestone mountains, ca 325 m, ...
Etymology.— The specific epithet refers to the habitat of the species where it grows on the range of karst.
Vernacular.— ຄໍາພີ້ເຫຼືອງ (Kham pee lueang).
Sawai Mattapha, Soulivanh Lanorsavanh, Vichith Lamxay; Keooudone Souvannakhoummane and Khamfa Chanthavongsa. 2024. Dalbergia calcarea, A New Species of Dalbergia (Fabaceae: Dalbergieae) from Lao PDR. Thai Forest Bulletin (Botany). 52(2), 62–67. DOI: doi.org/10.20531/tfb.2024.52.2.08
