Hoya migueldavidii Cabactulan, Rodda & Pimentel, 2017

Cabactulan, Derek D., Rodda, Michele & Pimentel, Reynold, 2017, Hoya of the Philippines part I. Hoya migueldavidii (Apocynaceae, Asclepiadoideae), a new species from Northern Mindanao, Philippines, PhytoKeys 80, pp. 105-112 : 105

Hoya migueldavidii Cabactulan, Rodda & Pimentel sp. nov. Fig. 1 , 2

Diagnosis.

Among Philippine Hoya species similar to Hoya loheri in inflorescence type (positively geotropic, convex) but separated because Hoya loheri has a flattened, turban-shaped corolla (vs. almost round in Hoya migueldavidii ) and leaves and stems are entirely glabrous (vs. pubescent in Hoya migueldavidii )

Type.

Philippines, Mindanao, Bukidnon, Mount Kitanglad , 11 Aug 2016, R. Pimentel s.n. (CMUH, holotype, sheet number CMUH 827; SING, isotype) .

Description.

Epiphytic scandent vine rooting along the stems, roots adventitious on internodes and just below the nodes; stems slender, terete, 3.0-5.0 mm diameter, green or maroon, densely strigose, internodes 2.5-9 cm long. Leaf blades fleshy, stiff, slightly concave, variable in shape, from lanceolate, elliptic-lanceolate to ovate-elliptic, 2-7.5 × 1.80-2.50 cm base rounded, apex obtuse, dark green or maroon, reddish pigmentation often occurs on the underside of the leaves, margins thickened, venation pinnate, secondary veins not visible on dry specimens, adaxially and abaxially papillate-strigose, basal colleters 1-3 at each lamina base, ovoid, 0.15-0.20 mm long × c. 0.15 mm in diameter, dark brown; petiole thickened, terete, 1-2.3 × 0.28-0.30 mm diameter, flattened approaching the lamina base, usually curved, dark green or maroon, densely strigose. Inflorescences extra-axillary, umbelliform, slightly concave, up to 25 flowered. Peduncles terete, positively geotropic, 2-8 cm long, strigose, rachis up to 3 cm long. Pedicels, terete, 2.50-3.80 cm × 0.70-0.72 mm in diameter, sparsely strigose, the outer pedicels strongly curved. Calyx lobe triangular, oblong, 0.80-1.3 mm long × 0.80-1.00 mm wide, red, outer surface strigose, inner surface glabrous. Corolla revolute, 5-5.3 mm diameter, 8.5-9 mm diameter when flattened, red to pink; corolla lobes reflexed, triangular ovate, 2.6 × 4.6 mm long, apex acute-acuminate, inside silky-pubescent, tip glabrous, outside glabrous. Gynostegium stipitate; column cylindrical, 0.04 × 0.03 mm diameter; corona staminal, 2.3-3.0 mm high, 4-5 mm in diameter; lobes ovoid-spathulate, 3.0-3.3 × 0.30-0.35 mm wide, inner processes erect above the anthers, almost linear, red, outer process long bilobed, with basal revolute margins. Pollinia erect, oblong, 300-320 µm long and 115-130 µm wide with a sterile edge along the outer margin; translator arms c. 60 µm long, each with a rounded projections c. 60 µm diam.; corpusculum oblong 90-110 × 35-50 µm. Ovary conical with an acute tip, c. 1.5 × 0.6 mm at the base, ventricose, glabrous. Fruit and seed not seen.

Etymology.

Hoya migueldavidii is named after Dr. Miguel David de Leon, viteoretina surgeon and plant and wildlife conservationist.

Distribution and ecology.

This new species was only once collected in Mindanao Island, Philippines but the full distribution is still unknown. It is an epiphytic climber, growing at about 1000 m in disturbed primary broad leaf forest in full sun to part shade.

Conservation status.

The forested area where Hoya migueldavidii was collected is threatened by habitat destruction due to extensive farming, charcoal production, land conversion and illegal logging. However, the species is only known from a single collection and therefore the conservation status is proposed as Data Deficient (DD, IUCN 2016) until more information is known about its area of occurrence.

Notes.

The long peduncles, shape of the inflorescences and the slender pedicels of Hoya migueldavidii are similar to those of Hoya loheri (Fig. 3 ). The two species can be separated because of the indumentum of the vegetative parts that are pubescent throughout in H. migueldavidii vs. glabrous in H. loheri ; the shape of the corolla that is revolute and almost spherical in H. migueldavidii and instead revolute yet flattened in H. loheri ; the gynostegium is sessile in H. migueldavidii whereas it is stipitate in H. loheri . Additionally the leaves of H. migueldavidii are similar to those of Hoya isabelchaniae Rodda & Simonsson from Sulawesi (Indonesia) both in shape, convex ovate-elliptic (to round in H. isabelchaniae ) and in indumentum (pubescent). However, H. migueldavidii has smaller flowers of c. 7 mm vs. 8-10 mm in diameter in H. isabelchaniae ) and different pubescence of the corolla (finely pubescent vs. setose in H. isabelchaniae ).

Specimens of Hoya loheri examined.

Hoya loheri . Philippines, unknown locality, cultivated in Thailand, Chonburi, Nong Nooch Tropical Garden vouchered on 22 September 2014, M. Rodda MR748 (SING). Luzon, Rizal Province, Paningtingan. 15 March 1915 A. Loher s.n. (UC [UC229373])

Figures

Figure 1. Hoya migueldavidii photographed from R. Pimentel s. n. (CMUH) prior to pressing A A single flower, front view B, C Corolla, side view D Corolla, with removed corona E Revolute margins of the corolla lobes F Corona, from underneath G, H Pedicel, calyx and ovary I Pollinarium (Photographs by M. D de Leon)

Figure 2. Hoya migueldavidii photographed from R. Pimentel s. n. (CMUH) prior to pressing A Inflorescence B Branch C, D leaf (C adaxial surface D abaxial surface). (Photographs by M. D de Leon).

Figure 3. Hoya loheri photographed from Rodda M MR 748 (SING) prior to pressing A Leafy branch and inflorescence B Inflorescence. (Photographs by M. Rodda)