Wednesday, August 10, 2016

[Botany • 2016] Hoya isabelchanae • A New, Showy Species of Hoya R.Br. (Apocynaceae, Asclepiadoideae) with Pomegranate Red Flowers from Sulawesi, Indonesia

Hoya isabelchanae 
 Rodda & Simonsson 

DOI:  10.3897/phytokeys.68.8803

A new species of Hoya R.Br. from Sulawesi (Indonesia), Hoya isabelchanae Rodda & Simonsson, is described and illustrated. It is one of the largest flowered species in Hoya section Acanthostemma (Blume) Kloppenb. Its flowers are of comparable size to those of Hoya benchaii Gavrus et al., Hoya kloppenburgii T.Green, Hoya rundumensis (T.Green) Rodda & Simonsson and Hoya sigillatis T.Green ssp. sigillatis, all from Borneo. Among Sulawesi species it is compared with the vegetatively similar Hoya brevialata Kleijn & van Donkelaar and Hoya pallilimba Kleijn & van Donkelaar.

Keywords: Borneo, Cultivation, Gunung Boliohutu, Malesia, Marsdenieae

Hoya isabelchanae Rodda & Simonsson, sp. nov.

Diagnosis: Among Sulawesi Hoya species similar to H. brevialata and H. pallilimba in habit (prostrate and pendant epiphyte), lamina shape (convex round to elliptic) and inflorescence type (positively geotropic, convex) but separated because both H. brevialata and H. pallilimba have smaller flowers (c. 5 vs. 8–10 mm in diameter in H. isabelchanae) with a finely pubescent corolla (vs. setose corolla in H. isabelchanae).

Type: Indonesia, Sulawesi, Gorontalo, Gunung Boliohutu, 400 m, 23 Apr 2002, S.M. Scott 02-116, grown on at the Royal Botanic Garden Edinburgh (Acc no. 20021229), Sep 2012, C.E. Berthold 0013 (holotype: E; isotype: SING)

Etymology: Hoya isabelchanae is named after Isabel Claire Chan Yuen Ching, late daughter of Elisabeth Chan, Singaporean patron of botanical research and a gardener with an interest in Hoya.

Distribution and ecology: Hoya isabelchanae is only known from the base of Gunung Boliohutu, Sulawesi, where it was collected as a sterile cutting in 2002 and brought into cultivation at the Royal Botanic Garden Edinburgh where it regularly blooms in a heated greenhouse from May to October. The species was collected in primary forest and it was growing in shaded but exposed area on a decaying tree 12 m tall. A further collection is widely available in cultivation under Gerard Paul Shirley number GPS10161 and 7-35 [accessed on 24 June 2016]. This accession is apparently also from Sulawesi but no further collection information is available.

 Michele Rodda and Nadhanielle Simonsson Juhonewe. 2016. Hoya isabelchanae Rodda & Simonsson, A New, Showy Species of Hoya R.Br. (Apocynaceae, Asclepiadoideae) with Pomegranate Red Flowers from Sulawesi, Indonesia. PhytoKeys. 68: 45-50. DOI:  10.3897/phytokeys.68.8803