Hoya unirana Rodda & Simonsson, 2022

Hoya unirana Rodda & Simonsson View in CoL , sp. nov. — Fig. 15 View Fig

Similar to Hoya chloroleuca in the large, densely placed chartaceous leaves with acute bases, but differing in corolla size and shape (rotate, flat, 20–22 mm diam with reflexed lobe margin in H. unirana vs rotate, slightly concave, c. 1.2 cm diam, with flat lobe margin in H. chloroleuca ). — Type: G. Versteeg 1235 (holo L [ L0834580 ]; iso BO [ BO0110494 ]), Indonesia, Papua Province, Zandvoort-Sabang , 15 June 1907 .

Etymology. Named after its type locality, Sungai Unir (formerly Lorentz river). The two duplicates of the type collection were labelled in 1991 as ‘ Hoya greenii P.Forster & Liddle ms.’, a nomen nudum, and likely intended to name the species after Ted Green of Kaaawa, USA.Another species from the Philippines, H. greenii Kloppenb. was named after him in 1995.

Climber, likely epiphytic, latex colour unknown, all vegetative parts glabrous. Stems cylindrical, slender, 2–4 mm diam, internodes 3–12 cm long. Roots not observed. Leaves: petiole terete, channelled above, 10–25 by 1.5–2 mm; lamina elliptic to ovate, chartaceous, 8–15 by 4–6 cm, apex acuminate-cuspidate, base acute; venation pinnate, midrib depressed on adaxial surface, secondary veins 4–8 each side. Basal colleters one, broadly triangular, 0.5–0.8 mm long. Inflorescence one per node, tropism unknown, likely positive, pseudo-umbelliform, consisting of 6 or more flowers; peduncle extra-axillary, terete, 2–8 cm by 1.5–2.5 mm, older peduncles forming a rachis from previous flowerings, glabrous; pedicels filiform, 28–33 by c. 0.8 mm, glabrous. Calyx c. 4 mm diam; lobes deltate, 1.3–1.6 by c. 1 mm, apex acute, glabrous. Basal colleters scattered along the inner base of the calyx lobes, globose, c. 0.2 mm long. Corolla rotate, 20–22 mm diam when flattened, creamy greenish-yellow; tube c. 5 mm long, outside glabrous, inside pubescent, with shorter hairs towards the centre; lobes elliptic-ovate, 8–10 by 6–8 mm, apex acute, margin reflexed, outside glabrous, inside densely pubescent. Corona staminal, 1.5–2 mm high, 8.5–10 mm diam, creamy yellow with pink centre; lobes lanceolate, 5–5.5 by 1.9–2.1 mm, inner process oblong, covering the style head and joining in the middle, c. 1.5 mm long, outer processes spreading, apex truncate, with basal revolute margins. Pollinia lunate, 600–700 by c. 300 µm, with pellucid margin; corpusculum oblong, c. 330 by 140 µm; caudicles linear, c. 150 µm long. Ovary conical, c. 1.5 mm long, glabrous. Fruit and seed not observed.

Distribution — Only known from one location in Indonesia, Papua Province, Sungai Unir (formerly Lorentz river).

Habitat & Ecology — Based on the label data it was collected in a forest habitat with bamboos.

Conservation status — Data Deficient ( DD; IUCN 2012 ). Hoya unirana is known only from the type specimen collected 115 years ago .

Note — Hoya unirana is most similar to the two lowland species H. chloroleuca and H. tarikuensis (described above), in having thin leaves that can grow to> 10 cm long, with acute bases, and having inflorescences with at least 6 flowers, but can be distinguished in the corolla size (c. 2 cm in H. unirana ), compared to 0.8–1.2 cm in H. chloroleuca and H. tarikuensis . Hoya subglabra Schltr. also has similar leaves and rotate flowers of c. 2 cm diam, but it grows only at 400–1500 m altitude.