Feddes Repertorium 122 (2011), 1 – 7 Short Communication Hoya mappigera (Apocynaceae, Asclepiadoideae), a new campanulate flowered species from Peninsular Malaysia and southern Thailand MICHELE RODDA*, 1 & NADHANIELLE SIMONSSON JUHONEWE2 1 2 Herbarium, Singapore Botanic Gardens, 1 Cluny Road, Singapore 259569 P.O. Box 1–524, Ukarumpa, Eastern Highlands Province 444, Papua New Guinea Keywords: Campanulate corolla, corona, Hoya campanulata, Hoya wallichii, Hoya wongii * Corresponding author: Senior Researche, Herbarium, Singapore Botanic Gardens, 1 Cluny Road, Singapore 259569, E-mail: rodda.michele@gmail.com., Tel.: 00658281842 Accepted for publication: January 18th, 2012. DOI 10.1002/fedr.201100019 Abstract A new species, Hoya mappigera is described and illustrated. Despite its oldest herbarium record being more one century old it has been confused up to now with either the co-occurring Hoya campanulata or the Singapore endemic Hoya wallichii because of the common presence of showy, broadly campanulate corollas. A close examination of the corona morphology revealed that the closest morphological match is neither of these species but instead the recently described Brunei endemic Hoya wongii. The two species can be easily separated because the latter has bi-toothed inner corona lobes whereas the new species presents sulcate inner corona lobes ending in an acuminate tip. Introduction Hoya R.BR species bearing campanulate corollas have been puzzling taxonomists ever since the first species displaying this character was described, Hoya campanulata BLUME. The campanulate corolla has been an overlooked character, and although in the past it brought to the segregation of taxa in different genera such as Physostelma WIGHT and Cystidianthus HASSKARL, it concealed other characters helpful to separate campanulate Hoya species, such as the shape of the corona. Only the recent study of the coronas of type specimens allowed to separate Hoya campanulata BLUME from Hoya wallichii (WIGHT) C.M.BURTON, the first presenting star shaped coronas, 3 – 4 mm high, 7 – 14 mm diameter with boat shaped narrow lobes, the latter presenting erect kidney shaped lobes, ca. 5 mm high, ca. 2 mm wide, basally broadened into a swollen process with revolute margins, apically forming a single acuminate appendage ca. 1.2 mm long (RODDA & SIMONSSON submitted). This study also revealed two new species, one endemic of Borneo, Hoya danumensis RODDA & NYHUUS (2009), the other endemic to Brunei, Hoya wongii RODDA et al. (2011). The examination of specimens from Peninsular Malaysia permitted the separation of a further undescribed taxon bearing similarities in coronal morphology with H. wongii. We herein name the new species as Hoya mappigera RODDA & SIMONSSON. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 0014-8962 2 The new species has been collected in five localities in Peninsular Malaysia and one locality in southern Thailand. Thailand is usually recognized high in Hoya species and about 40 taxa have been reported as occurring there (THAITHONG 2001). Peninsular Malaysia instead presents 26 species and two varieties (RINTZ 1978; KIEW 1989, 1995; VELDKAMP & HANSEN 1996). The new species, described and illustrated below, is the first campanulate flowered species for Thailand and brings to 27 the number of Hoya species for Peninsular Malaysia. Hoya mappigera RODDA & SIMONSSON, sp. nova T y p e: Malaysia, State of Dingdings, Lumut Dindings, 1894, RIDLEY s.n. (holotype SING, barcode SING0120871). Ad Hoyam wongii Rodda, SIMONSSON & L. WANNTORP similis ob corollam campanulatam et coronam lobis inferius inflatis sed differt coronae lobis superne erectis, cum acuminatis apicis. Epiphytic or terrestrial glabrous climber. Leafy stems cylindrical ca. 5 mm in diameter, dark brown with conspicuous lenticels, adventitious roots absent. Internodes 8– 15 cm long. Leaves opposite, petiolate; petiole channelled along upper side, 7– 11 mm long, 1 –2 mm in diameter; lamina dark green, lighter underneath, chartaceous when dry, stiff-coriaceous when fresh, ovate-lanceolate, 7– 12 cm by 3 – 4 cm, apex apiculate-caudate, base attenuate, colleters not observed, margin entire, main vein depressed on adaxial surface, evident on abaxial surface, secondary veins 6 –9 each side, branching at 60 –80° from main nerve. Inflorescences bearing a single open flower at a time, lasting 1 – 2 days; peduncle extra-axillary, perennial, bearing scars of previous flowerings 3 – 6 cm long, ca. 1.5 mm in diameter; pedicels green flushed pink on one side 1.5 – 3 cm long, 1 mm in diameter, glabrous. Calyx green ca. 5 mm in diameter, sepals elliptic to broadly ovate 1.5 –2 mm × 1 – 1.5 mm, apex obtuse to round, with 1 – 2 basal colleters between each sepal ca. 0.35 × 0.3 mm glabrous with thinly dentate margins. Buds 5-angular, light green, © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Feddes Repert., Weinheim 122 (2011) purplish only towards the pedicel. Corolla campanulate, outside cream white, flushed pink in proximity to the calyx lobes, inside cream white with dull purplish centre and greenish white around the edge and between the lobes, 4 – 5 cm in diameter overall glabrous with pubescence limited to the area beneath the corona; corolla nearly entirely fused to a bowl-shaped tube, 3.5 –4.5 mm in diameter, corolla lobes triangular, ca. 5 mm long, acute, corolla with intermediate lobules of nearly the size and shape of the corolla lobes, but with a longitudinal fold. Corona staminal 6 –8 mm high, 6– 7 mm in diameter, lobes subdivided into two distinct processes, a basal one, white, round, free from the filament tube, with revolute lateral margins, the second connate with the filament tube, purple, sulcate and bent towards the centre of the corona, ending in an acuminate appendage, nearly touching in the centre, about 3 mm higher than tip of outer process and 0.7 mm higher than anther appendages; anther skirt revolute, free from the filament tube. Guide rail forming a vertical ridge, laterally compressed, prominent at the base of the anther skirt and extending 0.4 –0.7 mm laterally. Stigma head prominent, convex. Pollinarium (all measures ca.) 1000 × 650 μm with two oblong pollinia, 630 by 320 μm, apex and base rounded to obtuse, retinaculum 300 × 120 μm, caudicles broad, 180 × 80 μm. Ovary bi-carpellate, bottle shaped, 2 mm long, each carpel ca. 1 mm in basal diameter. Fruits and seeds not seen. E ty m o lo g y: The specific epithet “mappigera” (mappa = napkin, -ger = to carry) refers to the morphology of the corolla, white and broad, resembling a napkin hanging from the pedicel. Further, on herbarium specimens the broad corolla folds around the corona like a napkin, hiding the diagnostic characters for this taxon. Habitat & distribution: Hoya mappigera was collected in five localities in Peninsular Malaysia and one locality in southern Thailand (Fig. 3). So far recorded in lowland forests only but appears to be adapted to a range of habitats from swamp forest to the mixed dipterocarp forest and kerangas-type vegetation usually typical of thin sandy soils found in Klang Gates ridge (KIEW 1982). Describing a new Hoya species with showy campanulate flowers based on six specimens is rather unusual since most www.feddes-journal.com 3 M. Rodda & N. S. Juhonewe: Hoya mappigera sp. nov. Fig. 1 Hoya mappigera sp. nova A, B — corona, side; C — corona, above; D — calyx; E — pollinarium; F — corolla. (s. coll. AP1116, SING). Scale bar: A, B, C, D = 1 mm, E = 500 μm, F = 5 mm © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.feddes-journal.com 4 Feddes Repert., Weinheim 122 (2011) Fig. 2 Hoya mappigera sp. nova RIDLEY s.n. (holotype SING, barcode SING1020871) © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.feddes-journal.com M. Rodda & N. S. Juhonewe: Hoya mappigera sp. nov. new taxa are described on single gatherings (e.g. RODDA & SIMONSSON 2011, RODDA et al. 2011) whereas examples of species described on the basis of multiple collections are limited to endemic but locally abundant species such as Hoya poilanei RODDA, SIMONSSON & T.B.TRAN (RODDA et al. accepted) or widely distributed species such as H. danumensis (RODDA & NYHUUS 2009) or Hoya ignorata T. B. TRAN, RODDA, SIMONSSON & JOONGKU LEE (TRAN et al. 2011). Hoya mappigera appears to belong to the second case: it is a highly adaptable species that despite being limited to lowland conditions it occurs in different forest types and therefore its potential distribution area is most lowland forests in Peninsular Malaysia and southern Thailand. IUCN Red List category: Population size of H. mappigera cannot be estimated and despite being known from six specimens, its present distribution area cannot be evaluated since only three specimens are less than 50 years old. Of the current known localities, three have been most likely converted to plantations (RIDLEY s.n, SING; CURTIS s.n., SING; KIEW RK1193, KEP), one, Klang Gates ridge (SINCLAIR 10730, E) has been suffering from the impact of human activities since the 1970s 5 (KIEW 1982) and despite being rich in endemic species, is still threatened by human impact and development (WONG et al. 2010). Recent investigation in the area failed to recollect the taxon (RODDA, pers. obs.). The conservation status of the Thai population and the northernmost Malaysian collections (CORNER S. F. 30338, SING; s. coll. AP1116, SING) are not known. Further, the species is most likely to be more widely distributed than we now know from herbarium records since it can be easily overlooked in the field because it produces short-lasting single flowers. Based on these observations the proposed conservation status is Near Threatened (NT, IUCN, 2010) awaiting a re-evaluation based on direct field observations. Additional specimens examined (paratypes): Malay Peninsula, Flora of Kemaman, Bukit Kayang, 500 ft. 8 Mar 1935, CORNER, S. F. 30338 (SING0121241, SING); Ibid, Dindings, Bruas Rd. to Sungai Rotan, Feb. 1900. CURTIS s.n. (SING0120875, SING); Ibid, 9th mile Klang-Banting Road, 7 Jul 1982, KIEW RK1193 (KEP160392, KEP); Ibid, Klang Gates ridge (west) Selangor, Quarz ridge, 19 November 1962, SINCLAIR 10730 (E00312531, E); Thailand, southern Thailand, Betong, Yala province, cultivated in Thailand, Bangkok, Fig. 3 Distribution of Hoya mappigera in peninsular Malaysia and Thailand based on the examined specimens (indicated by a full circle). Peninsular Malaysia is indicated in light grey colour. Map constructed using SimpleMappr (www.simplemappr.net) © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.feddes-journal.com 6 Feddes Repert., Weinheim 122 (2011) Table 1 Morphological comparison between Hoya mappigera and other campanulate Hoya species H. mappigera H. wongii H. campanulata H. wallichii H. danumensis Corona diameter 6 – 7 mm ca. 6 mm 7 – 14 mm 6 – 7 mm 10 – 14 Corona lobe subdivided in subdivided in boat shaped basal and apical basal and apical process process erect, kidney shaped oblong ovoid Corona colour basal process white, apical process purple pale yellow white purple white Corona outer lobe shape round round acute round round Corona inner lobe shape sulcate with an acuminate tip ending in two acute bi toothed membranaceous appendages acuminate acute Number of flowers for inflorescence 1 1 1 ca. 20 Aug. 2011, s. coll. AP1116 (SING0165301, SING). ca. 20 stiff apical process (Fig. 1A, B, C). A comparison between H. mappigera, H. wongii and other species bearing a campanulate corolla is presented in Table 1. Discussion Acknowledgements The process of species discovery may be delayed by decades if not even centuries since the collection of specimens (BEBBER et al. 2010). In the case of H. mappigera, the misapplication of the names H. campanulata and H. wallichii to most Hoya specimens bearing a campanulate corolla has been the cause of the delay in its classification. The first specimen of this taxon was in fact collected 118 years ago, in 1894 (RIDLEY s.n., SING). The closest morphological match of H. mappigera is surprisingly neither the cooccurring H. campanulata nor H. wallichii, endemic of the island of Singapore (RODDA & SIMONSSON submitted) but instead the Brunei endemic H. wongii. The two species present a similar broad corolla and their corona lobes are similarly subdivided in a basal round process and an erect apical process. They can be easily separated because the apical coronal process in H. wongii is subdivided in two bidentate membranaceous appendages while in H. mappigera it is entire, sulcate and bears a single acuminate © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim This study is part of an ongoing research project on the systematics of Hoya. Financial support has been received from the National Parks Board Singapore and the Synthesys programme, grants no GB-TAF5657, NL-TAF-676 and DETAF-675 for Rodda and from Helge Ax:son Johnsons Stiftelse for Simonsson Juhonewe. We would like to thank the curators of the following herbaria: A, B, BM, BRUN, E, FI, HBG, K, L, P, SAN, SING, SNP and TO for help with material and for providing high quality images of herbarium specimens, JF Veldkamp for his advice on Latin etymology, Graham Hardy for providing field notes of J. Sinclair conserved in RBGE library, Rapeepattadha Chamwong and Sutthisak Sangkhakorn for supplying information on the Thai collection (s. coll. AP1116, SING), and two anonymous reviewers for their valuable comments on the manuscript. References BEBBER, B. P.; CARINE, M. A.; Wood, J. R. I.; WORTLEY, A. H.; PRANCE, G. T.; DAVIDSE, G.; PAIGE, J.; PENNINGTON, T. D.; ROBSON, N. K. B. www.feddes-journal.com M. Rodda & N. S. Juhonewe: Hoya mappigera sp. nov. & SCOTLAND R. W. 2010: Herbaria are a major frontier in species discovery. – PNAS 107(51): 22169 – 22171. IUCN Standards and Petitions Subcommittee. (2010) Guidelines for Using the IUCN Red List Categories and Criteria. Version 8.1. Prepared by the Standards and Petitions Subcommittee in March 2010. Downloadable from http:// intranet.iucn.org/webfiles/doc/SSC/RedList/Red ListGuidelines.pdf. 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