Jasminanthes sarawakensis Rodda, 2019

Rodda, Michele, 2019, A revision of Jasminanthes (Apocynaceae) with four new species from Borneo, Phytotaxa 405 (3), pp. 127-146 : 141-143

Jasminanthes sarawakensis Rodda spec. nov. ( Figs 1 , 7 ).

Similar to J. borneensis in lamina base (usually round), distinguished on the length of the corolla tube (5–6 mm in J. sarawakensis vs. 9–11 mm in J. borneensis ).

Type:—Borneo, Malaysia, Sarawak river, Bidi, 5 April 1909, C.J. Brook 1056 (holotype BM [BM001135066]).

Stems twining, 2–3 mm in diameter; internodes 8–20 cm long, sparsely pubescent to glabrescent. Leaves petiolate; petiole 1.2–2.5 cm long, c. 1 mm in diameter, pubescent with antrorse trichomes, lamina oblong, (4–)7–15 × (2–) 3.5–6 cm, base round to very shallowly cordate; apex apiculate-cuspidate; adaxial surface glabrous except pubescent midrib, basal colleters in a cluster of 6–10 at each lamina base, oblong; abaxial surface glabrous except sparsely pubescent midrib and secondary veins; venation pinnate, lateral veins 5–8 each side. Inflorescences extra-axillary, simple, racemiform, up to 5-flowered; peduncle 1–3 cm long, 1–1.5 mm in diameter, glabrous or very sparsely pubescent, bracts at base of pedicels triangular, 1–2 × 0.5–1 mm, inside glabrous, outside sparsely pubescent, ciliate. Pedicel 10–13 mm long, c. 1 mm in diameter, pubescent with antrorse trichomes. Flower bud just before anthesis fusiform, 12–15 mm long, c. 4 mm in diameter, corolla lobes contorted. Calyx lobes triangular-lanceolate, 6–7 × 2–2.5 mm, apex apiculate, adaxial and abaxial surfaces glabrous or sparsely pubescent with antrorse trichomes, ciliate; colleters not observed. Corolla salverform, tube 5–6 mm long, basally slightly swollen. 3–3.5 mm diam., 3–3.5 mm at throat, adaxially with 5 patches c. 5 mm long of dense trichomes, c. 1 mm long, reaching the throat, the lowest third retrorse, the upper 2/3 antrorse, abaxially pubescent, lobes lanceolate, 10–12 × 2.5–3.5 mm, adaxially glabrous, abaxially pubescent, more in the middle of the lobe, base symmetrical. Corona staminal absent; Gynostegium conical 3.5–3.7 mm high, c. 2 mm wide, glabrous. Guide rails 1.2–1.4 mm long. Pollinia erect, oblong, 600–650 × 250–300 μm; caudicle c. 100 μm long; corpusculum oblong, 550–600 × 250–300 μm. Anther appendages erect, covering the style head, c. 2 × 1 mm. Style head umbonate c. 1 mm diam. Ovary bi-carpellate, carpels oblong, c. 1.5 mm long, c. 0.5 mm wide at the base, apex sparsely pubescent. Fruit and seed not observed.

Etymology:— named after the Malaysian state of Sarawak, where all specimens of J. sarawakensis have been collected.

Distribution and ecology:— only known from Sarawak, Malaysia, it has been collected in lowland forest along rivers.

Conservation status:— The species is only known from four collections, two of which unlocalised the other two collected along the Sarawak River. The proposed conservation assessment is Vulnerable (VU, D2, IUCN 2012).

Notes:— Jasminanthes sarawakensis is one of three Bornean species with non-cordate lamina base, the others being J. borneensis and J. suaveolens . Jasminanthes sarawakensis can be separated from both species by the length of the corolla tube (5–6 mm in J. sarawakensis vs.> 9 mm in the other species). Further distinguishing characters are indicated in Tab. 1.

Figures

FIGURE 1. Distribution map of Jasminanthes species in Borneo, based on the examined specimens listed. Generated using SimpleMappr (www.simplemappr.net).

FIGURE 7. Jasminanthes sarawakensis. A, Flowering branch; B, Calyx and ovary; C, Bud; D, Open corolla; E, A single corolla lobe and section of corolla tube showing the arrangement of the hairs; F, Gynostegium lobe; G, Pollinarium. Based on Brooks, CJ 1056, drawn by Loh Xiang Yun.