Hoya nuttiana Rodda and Simonsson, 2013

Rodda, Michele & Juhonewe, Nadhanielle Simonsson, 2013, Hoya nuttiana (Apocynaceae, Asclepiadoideae), a new species from Sarawak, Malaysian Borneo, Phytotaxa 140 (1), pp. 56-60 : 56-57

Hoya nuttiana Rodda and Simonsson , spec. nov. ( Figs. 1 & 2 ).

The flowers of H. nuttiana can be compared to those of Hoya devogelii Rodda & Simonsson (2011a: 35) because both bear a pubescent campanulate corolla, a stalked gynostegium and a broad anther skirt. However, in H. devogelii the flowers are smaller (ca. 1 cm vs. ca. 2 cm in diam.), more numerous (4–7 vs. up to 100 flowers), and the stalked gynostegium is taller (column 2.5–3 mm vs. 1.2–1.5 mm).

Type:— MALAYSIA. Sarawak: near Kuching , 24 October 1894, Haviland & Hose 8530 (holotype K!, barcode K000014447 ) .

Vigorous lithophytic climber (fide Yii Puan Ching et al. S 53778 , KEP), with white exudate in all vegetative parts; all vegetative parts glabrous. Leafy stems cylindrical, up to 5 mm in diam., dark brown or grey, with membranaceous peeling bark; internodes 5–20 cm long. Petioles cylindrical, slightly channelled above in proximity to the lamina base, 8–12 × ca. 2 mm in diam., lamina elliptic-lanceolate, coriaceous, (6.5)10–15 × 3–6.5 cm, apex shortly acuminate or cuspidate, base acute, penninerved, main vein depressed on adaxial surface, evident on abaxial surface, secondary veins 5–7 pairs, evident when dry, held at 70–85°, anastomosing near leaf margins, tertiary venation reticulate. Inflorescences pseudo-umbelliform or globular, ca. 10 cm in diam., up to 100-flowered; peduncles extra-axillary, terete, 8–12 cm × 2–3 mm in diam., glabrous; pedicels 3.5–4.5 cm × 0.6–1 mm in diam., pubescent. Calyx lobes triangular, 0.7–1 × 1–1.2 mm, apex acute or round, glabrous adaxially, pubescent abaxially, ciliate; colleters 1(2), in each sepal sinus, ovoid. Corolla campanulate, ca. 1 cm in diam., greenish-yellow (fide Yii Puan Ching et al. S 53778 , KEP), pubescent throughout inside, more so on the lobes and upper 1/3 of the tube (long villous in Haviland & Hose 8530, K), outside glabrous, tube 4–5 mm long, 6–7 mm in diam., lobes broadly triangular, revolute, 2–3 × 4–5 mm, apex acute. Gynostegium stalked, corona column conical, 2.5–3 mm × ca. 2 mm (base) or ca. 1 mm (apex) pubescent; Corona staminal, ca. 2.5 mm high, 5–6 mm in diam., fleshy; corona lobes apically oblong, 2.5–3 mm × 0.7–0.9 mm, inner process depressed, round, terminating in an erect, acute tip as high as the anthers, outer process erect, narrowly round, basally forming a broad ‘anther skirt’ with revolute lateral margins. Style-head convex, just shorter than the anther appendages. Pollinia oblong, with round apex and base and evident pellucid margin, 255–280 × 110–120 µm; caudicles attached at the centre of the retinaculum, winged, retinaculum 120–130 × 50–60 µm; ovary bi-carpellate, conical, ca. 2 mm long, each carpel ca. 0.7 mm wide at the base. Fruits and seeds unknown.

Etymology: ― Hoya nuttiana is named after Pia Nutt who first recognized the taxon as a new species ( Nutt, 2001).

Distribution area & Ecology: ―The species occurs in three localities in Sarawak, Malaysian Borneo. The type specimen was collected in an unspecified locality near Kuching in 1894. Two further specimens were collected in 1987 on sandstone boulders at the base of a waterfall in the Hose Mountains (Yii Puan Ching et al. S53778 ) and in 2007 in Pulong Tau National Park (Siti Eryani et al. S97648 ).

IUCN Red List category:— The taxon is only known from three collections, one of which poorly localised (Haviland & Hose 8530), the others within a National Park (Siti Eryani et al. S97648 ) and a proposed National Park (Yii Puan Ching et al. S53778 ), and therefore likely protected from local extinction. However, the extent of occurrence and the population size are unknown, For these reasons H. nuttiana is assessed as Data Deficient (DD) according to IUCN Red List criteria (IUCN 2012).

Additional specimens examined: — MALAYSIA. Sarawak: 7 th Division, Hose Mountains, Ulu Sg. Merarai Batang Balleh, sandstone boulders at the base of waterfall, 550 m a.s.l., 29 March 1987, Yii Puan Ching et al. S 53778 ( SAR!, KEP!); ibid, Marudi, Pulong Tau National Park (western part) trail from long Lobang to camp A , 10 May 2007, Siti Eryani et al. S 97648 ( SAR!, KEP, K, L) .

Figures

FIGURE 1. Drawings prepared from Siti Eryani et al. S97648 (SAR): a. Corolla from above; b. corolla from side; c, corona and column; d. corona from below; e. calyx and ovaries; f. pollinarium. Scale 1 mm (a–e); 100 µm (f). Drawn by M. Rodda.

FIGURE 2. Photograph of the holotype of Hoya nuttiana, Haviland & Hose 8530 (K). Reproduced with the consent of the Royal Botanic Gardens, Kew.