ISSN 1346-7565 Acta Phytotax. Geobot. 68 (2): 101–104 (2017) doi: 10.18942/apg.201622

A New Species of Heteroblemma (Melastomataceae) from West Kalimantan, Borneo, Indonesia

1, 2,* 3,4 5 Hiroshi Okada , Hirokazu Tsukaya and Akiko Soejima

1 Institute of Natural Environmental Sciences, University of Hyogo, Sanda, Hyogo 669-1546, Japan; 2Osaka City University, Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan. *[email protected] (author for correspon- dence); 3Department of Biological Sciences, Faculty of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; 4Okazaki Institute for Integrative Biosience, National Institutes of Natural Sciences, Aichi 444-8585, Japan; 5Department of Biological Science, Faculty of Advanced Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan

Heteroblemma sibauense H. Okada, Tsukaya & A. Soejima, Melastomataceae, a new species from Sg. (River) Sibau Area, Putussibau, West Kalimantan, Indonesia, is described and illustrated. It is unique in having cauliflorous flowers borne singly in each inflorescence.

Key words: biodiversity, Borneo, Heteroblemma, Melastomataceae, new species, wet tropics

Melastomataceae are a relatively large family an interesting vine belonging to Heteroblemma. with 165 genera and more than 5,000 species Based on detailed observations in the field and (Christenhusz & Byng 2016). The family is main- laboratory, we concluded that it is an undescribed ly distributed in the tropics and subtropics, rarely species with the noteworthy characters given in in temperate regions, and is composed of shrubs, the following description. small trees, herbs, and very rarely vines (Hey- wood 1978). Medinilla, one genus of Melastoma- taceae, exhibits a heterogeneous phyllotaxis; op- Heteroblemma sibauense H. Okada, Tsukaya & posite, verticillate, and alternate. Among the sec- A. Soejima, sp. nov. —Figs. 1, 2 tions of Medinilla, however, only members of sect. Heteroblemma Blume have pseudo-alter- Similar to Heteroblemma decurrens (Cogn.) Cámara-Le- nate leaves [actually strongly anisophyllous ret, Ridd.-Num. et Veldk. in the glabrous lower surface of mature leaf blades and winged petioles, but differing in leaves that appear to be alternate (Clausing & having a single flower on a bostryx-like inflorescence vs. Renner 2001)]. Heteroblemma is represented by many flowers in dense fascicles on old wood, pedicels nine species on Borneo (Regalado 1990). Recent- pale green vs. pale red, teeth of sepals minute, rarely pi- ly Cámara-Leret et al. (2013) established a new lose vs. teeth absent, glabrous, petals pale pink with pink genus of vines, Heteroblemma, based on this sec- tip vs. yellow or pink, style pink vs. creamy or white. tion, that includes 14 species (Peninsular Malay- Typus. INDONESIA, West Kalimantan, Kabupaten Kapuas Hulu, Putussibau, Betung Kerihun National Park, sia, 1 sp.; Sumatra s.l., 3 spp.; Borneo, 11 spp.; Sungai (River) Peo, a branch upstream of Sg. Sibau, Sulawesi, 1 sp.; New Guinea, 1 sp.; and Vietnam, 1°14´35´´N, 113°9´18´´E, 6 May, 2016. H. Okada, A. Soeji- 3spp.). ma and H. Tsukaya STO-105 (holo-BO, iso-TI, HYO) During botanical research in natural forests in the backbone mountain area of Borneo, we found Liana, climbing by adventitious roots; wood 102 Acta Phytotax. Geobot. Vol. 68

Fig. 1. Heteroblemma sibauense in life (type specimen, H. Okada, A. Soejima and H. Tsukaya STO-105 ST, is from this indi- vidual). A: Flowers borne singly on creeping bostryx-like inflorescences at various points on the climbing stem. B: Flow- er. Note characteristic color of pedicel and style. Base of pedicel joined to inflorescence by a node. C: Lower surface of leaves. Note winged petiole. D: Anther with recurved lateral appendage. Scale in A: 10 mm, B: 5 mm, C: 50 mm, D: 2 mm. June 2017 Okada & al.— A New Heteroblemma from West Kalimantan, Borneo 103

Fig. 2. Diagnostic characters of sepals and stem of Heteroblemma sibauense (type specimen, H. Okada A. Soejima and H. Tsukaya STO-105 ST, is from this individual). A: pale pink minute teeth on sepal (t: black arrows), B: short, thin hairs on sepal (h: white arrows), C: cross section of stem. Note stellately lobed stele. Scale in B: 5 mm for A and B, scale in C: 2 mm. stellately lobed (Fig. 2C). Innovation not seen. nesian Borneo. Petioles winged, 8–13 cm by 2–4 mm, glabrous. Habitat. Lower layer of well protected prima- Leaves narrowly ovate — ovate, 26–31 × 11–14 cm, 2–2.5 times as long as wide, 2–3 times as long as petiole, base obtuse (Fig. 1C) , margin laxly serrulate, apex acuminate, thin (herba- ceous), lower surface glabrous, upper surface deep green, primary nerves 3–5, rarely brown pi- lose at base, secondary nerves on lower surface conspicuous, 21–5 pairs, tertiary nerves on lower surface conspicuous. Flowers 1 per creeping bos- tryx-like inflorescence (Fig. 1B), cauliflorous (Fig. 1A), pedicel 12–20 mm long, pale green, glabrous, on internodes ca. 2–3 mm long (Fig. 1B; ca. 4 mm in fresh material). Mature flower buds 8–11 × 3–4 mm. Hypanthium campanu- late, 3–4 mm long, pale red, glabrous. Sepals 0.5–1 mm long, teeth minute (Fig. 2A), rarely pi- lose (Fig. 2B). Petals 14–18 × 10–12 mm (in fresh material), pale pink with pink tip. Stamens 8, fil- aments ca. 10 mm long (in fresh material), an- thers 6–7 mm long (in fresh material), creamy, lateral appendage recurved (Fig. 1B, D), ca. 2–3 mm long (in fresh material), dorsal spur ca. 2 mm long (in fresh material). Style 9–12 mm long, pink, stigma white. Fruits not seen. Fig. 3. Part of herbarium specimen of H. formanii (Church, Distribution. Only known from the Sibau A.C., Mahyar, U.W., Ruskandi, A. and Nurdin 91; BO). Red arrows indicate old erect inflorescences with persis- River area, Putussibau, West Kalimantan, Indo- tent internodes. Scale: 1 mm. 104 Acta Phytotax. Geobot. Vol. 68 ry tropical rain forest near small streams. U.W., Ruskandi, A. and Nurdin 91 (BO; Fig. 3). Further studies of the morphology and anatomy Specimen examined of Heteroblemma formanii (Re- of the inflorescences of Heteroblemma are re- galado) Cámara-Leret et al. West Kalimantan, Sintang, quired. Bukit Baka National Park, Panjung Butung, 250 m north of camp down Sungai Ella; along bank and near environs. We express our sincere thanks to the Secretariat of Per- 0°38´S 112°17´E 315 m alt. Church, A. C. et al. 91. (BO) missions for Foreign Research, the Ministry of Research and Technology, Republic of Indonesia (RISTEK), who kindly gave us permission for field research in West Kali- Notes: We observed various stages of floral mantan, and the Indonesian Institute of Science (LIPI) development, ranging from flower buds to open and the Betung Kerihun National Park Office, Depart- flowers to only the hypanthium without petals ment of National Parks, for kindly allowing this study at and stamens, in Heteroblemma sibauense in its Betung Kerihun National Park, West Kalimantan. We thank Dr. Dedy Daernadi of the Research Center for Biol- natural habitat. All of the inflorescences had only ogy, LIPI for kindly arranging the field research and sup- one flower. We therefore concluded that the flow- port in the field. We are also grateful to the director and ers are borne singly in each inflorescence. Ac- curators of Herbarium Bogoriense (BO), LIPI, for their cording to Cámara-Leret et al. (2013), nearly all kind permission to examine herbarium specimens. This cauliflorous species of Heteroblemma show mul- study was supported financially by the Japan Society for the Promotion of Science, no. 15H05236 to Soejima. tiple flowers in a fascicle. For example, flowers of Heteroblemma serpens (Stapf) Cámara-Leret et al. are described as borne in dense fascicles (Cá- mara-Leret et al. 2013). Clausing & Renner (2001) References present drawings of H. serpens [cf. Fig. 5B (p. 56)] with several flowers in dense fascicles. Only Cámara-Leret, R., J. W. A. Ridder-Numan.& J. F. Veld- H. kemulense (Regalado) Cámara-Leret et al. kamp. 2013. Revision of Heteroblemma gen. nov. (Dissochaeteae – Melastomataceae) from Malesia and shows single flowers in the leaf axils (Cámara- Vietnam. Blumea 58: 229–240. Leret et al. 2013). Heteroblemma sibauense rep- Christenhusz, M. J. M. & J. W. Byng. 2016. The number resents the second example of a single flower in of known plants species in the world and its annual in- each inflorescence in Heteroblemma. crease. Phytotaxa 261: 201–217. We observed a creeping bostryx-like inflores- Clausing, G. & S.S. Renner. 2001. Evolution of growth form in epiphytic Dissochaeteae (Melastomataceae) cence Heteroblemma sibauense. Such an inflo- Organisms Diversity Evol. 1: 45–60. rescence was not mentioned by Regalado (1990) Heywood V. H. 1978. Flowering Plants of the World. 335 or Cámara-Leret et al. (2013). We also observed pp. Oxford University Press, London. similar but erect inflorescences in a herbarium Regalado, J. C. 1990. Revision of Medinilla (Melastoma- specimen of H. formanii (Church, A.C., Mahyar, taceae) of Borneo. Blumea 35: 5–70.

Received October 13, 2016; accepted November 17, 2016