Jasminanthes hosei Rodda, 2019

Rodda, Michele, 2019, A revision of Jasminanthes (Apocynaceae) with four new species from Borneo, Phytotaxa 405 (3), pp. 127-146 : 133-135

Jasminanthes hosei Rodda spec. nov. ( Figs 1 , 4 )

Similar to J. suaveolens because both species have narrow lanceolate corolla lobes but distinguished because of the wider corolla tube (5–6 mm basal diam. in J. hosei and 2–2.5 mm diam. in J. suaveolens ).

Type:— Malaysia. Sarawak: Baram mouth, December 1894, C. Hose 410 (holotype BM [BM001135065]; isotypes BM [BM001135064], E, K, L [L.2716807]) .

Stems 3–5 mm in diameter; internodes 10–20 cm long, pubescent to glabrescent. Leaves petiolate; petiole (1–) 2–4 cm long, 1–1.5 mm in diameter, pubescent with antrorse trichomes, lamina ovate, (7–)10–15 × (3.5–) 5–8 cm; base cordate; apex apiculate or cuspidate; adaxial surface glabrous except sparsely pubescent midrib, basal colleters in a cluster of c. 10 at each lamina base, conical; abaxial surface sparsely pubescent at base, pubescent along midrib, secondary and tertiary veins; venation pinnate, lateral veins 5–7 each side. Inflorescences extra-axillary, simple, racemiform, up to 8-flowered; peduncle (0.5–) 2–8 cm long, 2–3 mm in diameter, pubescent with antrorse trichomes, bracts at base of pedicels triangular, 3–4 × 1–2 mm, inside glabrous, outside pubescent. Pedicel 10–30 mm long, 1–1.5 mm in diameter, pubescent with antrorse trichomes. Flower bud just before anthesis fusiform, 22–25 mm long, c. 5 mm in diameter, corolla lobes contorted. Calyx lobes triangular-lanceolate, 8–15 × 3–6 mm, apex acuminate, adaxial surface glabrous, abaxial surface very sparsely pubescent with antrorse trichomes; colleters occurring singly or in pairs between the lobes, ovate, 0.2–0.3 × 0.1–0.15 mm. Corolla salverform, coriaceous, tube 10–12 mm long, basally bulbous. 5–6 mm diam., throat 3.5–5 mm wide, adaxially with 5 patches c. 4 mm long of retrorse trichomes, c. 1 mm long, throat pubescent, abaxially glabrous, lobes lanceolate, 12–15 × 2.5–4 mm, glabrous, base symmetrical. Corona staminal absent. Gynostegium conical, 5.5–6.5 mm tall, 3–3.5 mm wide. Guide rails c. 2 mm long. Pollinia erect, oblong, 900– 1000 × 300–350 μm; caudicle not observed; corpusculum ovate, c. 750 × 450 μm. Anther appendages erect, covering the style head, c. 2 × 1.5 mm. Style head umbonate, c. 1.0 mm diam. Ovary bi-carpellate, carpels conical, 1.5–2 mm long, c. 0.5 mm wide at the base, apex pubescent. Fruit and seed not observed.

Etymology:— named after Charles Hose (1863–1929), British colonial administrator stationed in Baram District, Sarawak and collector of the type specimen.

Distribution and ecology:— Sarawak, at the mouth of the Baram River and Labuan. It was collected in lowland forest.

Conservation status:— The species is only known from two collections from north Borneo and it is therefore assessed as Vulnerable (VU, D2, IUCN 2012).

Notes:— Dry specimes of Jasminanthes hosei are characteristic because of the stiff and coriaceous flowers with narrow lanceolate folding corolla lobes. The corolla of all other species when dry is generally thinner and chartaceous. Among the other Bornean species all apart from J. borneensis can have cordate lamina base. Jasminanthes maingayi and J. kinabaluensis can be separated from J. hosei because they have much larger flowers, while J. sarawakensis can be separated from J. hosei because it has smaller flowers. Jasminanthes suaveolens can be separated because of its narrower corolla tube (5–6 mm basal diam. in J. hosei vs. 2–2.5 mm diam. in J. suaveolens ).

Figures

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

FIGURE 4. Jasminanthes hosei. 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; G, Pollinarium. Based on Hose 410, drawn by Waiwai Hove.