Hoya meliflua (Blanco) Merrill (1918a: 318)

Rodda, Michele, 2016, Taxonomy and typification of Hoya meliflua (Apocynaceae, Asclepiadoideae), Phytotaxa 247 (4), pp. 287-291 : 288-290

Hoya meliflua (Blanco) Merrill (1918a: 318)

≡ Stapelia meliflua Blanco (1837: 202)

TYPE:— PHILIPPINES, Luzon, Bataan, Mt Marivales, Lamao River, 11–14 June 1903 E.D. Merrill 2565 (neotype US, here selected [ US 00026727])

= Hoya luzonica Schlechter. in Schlechter & Warburg (1904: 130)

TYPE:— PHILIPPINES, Luzon, Zambales Prov., O. Warburg 13765 (lectotype B, here selected [ B 100277206], BM photo).

= Hoya treubiana Schlechter (1908: 16) syn. nov. TYPE:— INDONESIA, ex hort. Bot. Bogoriensis, 1906, Treub s.n. (lectotype B, here selected [B100277174]).

= Hoya meliflua ssp. fraterna Green (1995b: 9) syn. nov. ≡ Hoya meliflua ssp. fraterna Green (1995a: 2) nom inval. ≡ Hoya fraterna non Blume ( Hooker 1852) TYPE:—Curtis’s Botanical Magazine 78 [ser. 3, vol. 8]: t. 4684 (1852); Cultivated at Royal Botanic Gardens Kew, June 1864 (epitype K, here selected [K000554909])

= Hoya davaoensis Kloppenburg (2013: 9) [before 15 Nov. 2013] syn. nov.

TYPE:— PHILIPPINES, Davao Prov. Mindanao, Mati, March–April 1927, M. Ramos & G. Edano 49272 (holotype UC, isotypes B [ B 100271891], P [ P 05391580])

Distinguishing features: — Climber 10 m or more long, terrestrial or epiphytic. Stems (3–)5–8(–10) mm in diam., internodes 10–20(–30) cm long, petioles 1–2.5 cm × 3–5 mm. Lamina oblong or elliptic, fleshy, coriaceous when dry, (5)10–25(30) × 3–8 cm, apex acute or round(apiculate), base rounded (cuneate), margins recurved, venation pinnate, secondary veins barely visible on live material, tertiary venation reticulate. Inflorescences convex to globular 4–6 cm in diam. with 5–20(–30) flowers; peduncles (1–)3–7(–12) cm × 3–6 mm, pedicels 1.5–2.5cm × c. 1 mm; corolla reflexed, 17–20 mm diam. when flattened, orange, light pink to purple, pubescent inside and covered in coloured (pink to maroon) nectar, glabrous outside; corona staminal, white with a purple centre, fleshy, 6–8 mm in diam.; corona lobes ovoid or rhomboid when observed from above, upper surface concave, with a hump in proximity with the outer lobe, inner process acuminate, outer process round to sub-acute.

Notes: —The synonymy of H. luzonica with H. meliflua ( Merrill 1918a) is here confirmed and a syntype of H. luzonica [B100277206] is selected as neotype of H. meliflua .

Green (1993) stated that H. meliflua ssp. fraterna ( Green 1995a, 1995b) could be separated from H. treubiana because “the leaves are a bit different and the coronal lobes are not beaked, according to Schlechter’s Berlin sheet and sketch”. Green is likely referring to the drawing attached to the sheet that is here selected as the lectotype of H. treubiana [B100277174] ( Fig. 2a ). However, the drawing was made based on rehydrated dry flowers and upon further examination of the flowers, Schlechter’s drawing appears to be quite inaccurate as the corona lobes are ovate and almost flat with a concave surface, while on the drawing they narrow towards the outer lobe and appear to be raised ( Fig. 2a ). Therefore H. meliflua ssp. fraterna and H. treubiana are conspecific. Green (2015) used leaf size to separate between H. meliflua ssp. meliflua and H. meliflua ssp. fraterna mentioning that H. meliflua ssp. fraterna has “consistently larger leaves (7.5 cm × 25 cm) vs. (2.5 cm × 13 cm) than the Type of Hoya meliflua ”. Leaf size does not appear to be consistently different on specimens and is potentially influenced by environmental conditions. Both the type of H. meliflua ssp. fraterna and the neotype designated by Green (2015) are from cultivation and this may be the reason for generally larger leaves as compared with wild collected specimens.

A comparison between flowers from the type of H. treubiana and the epitype of H. meliflua does not highlight any significant differences ( Fig. 2 ) apart from a small variance in size and in the shape of the corona lobes, which are slightly more round in the type of H. meliflua vs. oblong-ovate in the type of H. treubiana . The upper surface of the corona lobe in both specimens, however, is flat or slightly convex with a small raised hump toward the outer process of the lobe.

A taxon recently described from the Philippines, Hoya davaoensis Kloppenburg (2013: 9) was compared by Kloppenburg with Hoya pubicalyx Merrill (1918b: 331) . Kloppenburg however was aware of the similarity of H. davaoensis and H. meliflua as he mentioned, “This is not Hoya meliflua Merrill. ” without further remarks. Hoya davaoensis falls once again within the morphological variation of H. meliflua as here circumscribed. The closest morphological match to H. meliflua in the Philippines is Hoya diversifolia Blume (1826: 1064) , a widespread species occurring continuously from China to Java. The two species can be easily separated because H. diversifolia has a much smaller, flat, rotate corolla <15 mm in diam. vs. a reflexed corolla> 17 mm in diam. in H. meliflua (measured flattened). The differences between H. diversifolia and H. meliflua are minor and it is possible that upon completion of a revision of Hoya of the Philippines, where the two taxa cooccur, their taxonomic status may need to be re-assessed.

In conclusion, the lack of typification of H. meliflua has led to a proliferation of synonyms. Now that the names of H. luzonica , H. meliflua ssp. fraterna and H. treubiana are typified, they can be considered conspecific with H. meliflua .

Additional specimens examined:— PHILIPPINES: Davao, Mindanao, Mati , March–April 1927 M. Ramos & G. Edano 49272 ( B, K, P) ; Luzon, Rizal, Montalban , May 1905, A. Loher 6498 ( K) ; Luzon, Rizal, Montalban , s.d., A. Loher 4060 ( K). UNLOCALISED. Cultivated in USA, Hawaii, Haaawa, Green Plant Research Nursery , 2012, T. Green s.n. ( BISH [ BISH1072388 ]) .

Figures

FIGURE. 2. Comparison between the flowers of H. meliflua from a. The drawing attached to the lectotype of H. treubiana [B100277174], b & c. Flowers from the lectotype of H. treubiana [B100277174], d. A flower from the syntype of H. luzonica and neotype of H. meliflua [US00026727] e. A flower from the epitype of H. meliflua ssp. fraterna [K000554909]. Reproduced with the consent of the Berlin herbarium (a, b & c), the Smithsonian Institution (d) and the Royal Botanic Gardens, Kew (e). Photographs by M. Rodda (a–c, e) and I. Lin (d).