Systematic Botany (2007), 32(4): pp. 718–721 # Copyright 2007 by the American Society of Plant Taxonomists
A New, Dioecious, Dimorphic Species of Licuala (Palmae) from Hainan, China ANDREW HENDERSON,1,4 GUO LIXIU,2 and ANDERS S. BARFOD3 1
New York Botanical Garden, Bronx, New York 10458, U.S.A.; 2 South China Botanical Institute, Guangzhou 510650, China; 3 Department of Biological Sciences, University of Aarhus, Ny Munkegade bygn. 1540, DK-8000 Aarhus C, Denmark 4 Author for correspondence (
[email protected]) Communicating Editor: Alan W. Meerow ABSTRACT. A description and illustration of a new species of Licuala, L. hainanensis, from Hainan, China is given. This species, endemic to Hainan, was previously confused with the widespread L. spinosa. The distribution of the new species is mapped, and it is compared and contrasted to morphologically similar species from Vietnam. Evidence is presented that L. hainanensis is both dioecious and sexually dimorphic, based on its flower and rachilla morphology. Other potential cases of sexual dimorphism in Licuala are discussed. KEYWORDS:
Dioecy, Hainan, Licuala hainanensis, new species, sexual dimorphism.
Licuala contains about 136 species, widely distributed from Bhutan and northeastern India throughout southern and southeast Asia and into the Pacific as far west as Vanuatu (Govaerts & Dransfield 2005). Two species have been recorded from the Chinese island of Hainan (Pei et al. 1991) – Licuala spinosa Wurmb, the most widespread species in the genus, and L. fordiana Becc. Licuala spinosa is elsewhere known from the Andaman Islands, Borneo, Cambodia, the Philippines, Sumatra, Thailand, Vietnam, and West Malaysia. Licuala fordiana is known from Hainan and from one other site in southern Guangdong. The specimens cited below have been identified in the herbarium either as Licuala spinosa or as Licuala robinsoniana Becc., a species known only from the central part of Vietnam. However, new collections made recently in Hainan, and examination of specimens in herbaria, including the types of L. spinosa, L. robinsoniana, L. hexasepala Gagnep., and L. fatua Becc., have shown that these specimens belong to an undescribed species. This species appears more closely related to others from Vietnam, such as L. hexasepala and L. fatua. Licuala hainanensis Henderson, Guo & Barfod, sp. nov.—TYPE: CHINA. Hainan: Diaoluoshan, 18u45’N, 109u52’E, 270 m, 21 Mar 2006, Guo Lixiu, Zhou Lianxuan, & A. Henderson 135 (holotype: IBSC!; isotype: NY!). Figs. 1, 2. Species nova Licuala hexasepala et L. fatua affinis floribus parvis in sicco fuscatis, petalis profunde fissis recuvartis sub anthesi usque ad fructus maturitatem persistens, et annulo staminalium
brevi. Ab Licuala hexasepala, L. fatua et specierum affinium differt antheris filis longioribus, calyce glabro lobos no altos habens. Caespitose, dioecious palm, stems up to 4 m tall. Individual stems 2–3 cm diameter, without persistent leaf bases. Leaves 12–15 in the crown; leaf sheaths ca. 40 cm long, brown, disintegrating into fibers, extended above the petiole into a short ocrea; petioles 50–160 cm long, 0.8 cm wide near the base, 0.5 cm wide near the apex, the basal part with regularly spaced, recurved, brown spines to 0.5 cm long; blades to 1.2 m wide, green on both surfaces, split into 12–17 segments; transverse veinlets obscure; middle segment only slightly wider than the others, 36–41 cm long, 7–8 cm wide at the apex; indentations leading to adaxial fold 0.7–1.3 cm deep, those leading to adaxial fold 0.2– 0.3 cm deep, indentations deeper on lateral segments. Inflorescences up to 1 m long, erect amongst the leaves; prophyll ca. 26 cm long; peduncle ca. 50 cm long; peduncular bracts not seen; rachis ca. 50 cm long, with 3–5 partial inflorescences branched to two orders, each subtended by sheathing bracts 9–18 cm long; rachillae 9–16 on each partial inflorescence, 8–17 cm long, moderately covered with short, brown tomentum; flowers solitary on pistillate plants, solitary or borne in distant groups of 2–4 flowers on staminate plants; flower buds bullet–shaped, 3–3.5 mm long; calyx tubular, ca. 2 mm long, glabrous, lobes 3, to 0.5 mm long, apically acute; receptacle and calyx fused for about 0.4 mm, corolla yellow, glabrous, recurving at anthesis; staminate flowers with 6 stamens, fused to corolla for 0.8–1 mm in a staminal ring, the filaments subulate, 0.6–0.8 mm long;
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FIG. 1.
HENDERSON ET AL.: NEW LICUALA FROM CHINA
Licuala hainanensis, habit in Diaoluoshan, Hainan.
anthers ca. 0.5–0.6 mm long, oblong, the gynoecium small with aborted ovules and poorly developed styles and stigmas; pistillate flowers with with a 6–lobed staminal ring, lacking vestigial anthers, the gynoecium 1.3–1.5 mm long, turbinate, glabrous, tricarpellate, carpels distinct basally, connate through stylar regions, with well developed, short, tubular style and punctiform stigmas, the locules 0.3–0.4 mm long, basal in each carpel. Fruits globose, 0.7–0.9 cm diameter, basally with split remnants of the calyx, orange or red at maturity. Distribution and Habitat. China (Hainan); lowland moist forest, to 600 m elevation (Fig. 3). Local Names and Uses. ci zhou lu, chun shue, dong fang zhou lu. The leaves are used for making provisional rain coats in the forest. Additional Specimens Examined. CHINA. Hainan: Qiongzhong County, 12 Oct 1956, Chen Shao Qing 10573 (IBSC); Mt. Jiangfenglin, Tian Chi, 12 May 1979, Chen 18881 (HITBC); Wanning County, Xinglong, 19 May 1979, Chen 18888 (HITBC); Ledong County, Mt. Jianfenling, 30 May 1959, Chen Zhe Lian 30277 (IBSC); same locality, 2–31 Jan 1935, Lau 5236 (A, IBSC); same locality, 14 May 1962, Zeng 13105 (HITBC); Wuzhishan City, 1700 ft., 14 Aug 1932, Chun & Tso 43425 (IBSC, NY); same locality, 8 Nov 1959, Sino–German
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FIG. 2. Licuala hainanensis, details of inflorescences and flowers. A. Partial pistillate inflorescence (Lau 5236). B. Rachilla of staminate inflorescence (Guo et al. 135). C. Staminate flower bud, section of calyx, and corolla (Guo et al. 135). D. Opened staminate flower showing 6 stamens (Guo et al. 135). E. Staminate flower gynoecium with poorly developed ovule, style, and stigma (Guo et al. 135). F. Pistillate flower bud, section of calyx, and corolla (Lau 5236). G. Opened pistillate flower showing 6 staminodes (Lau 5236). H. Left, pistillate flower gynoecium; right, longisection with well-developed ovule, style, and stigma (Lau 5236).
FIG. 3.
Distribution of Licuala hainanensis in Hainan.
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Team 1898 (IBSC); Baoting County, Dengliang 463 (IBK); Lingshui County, 16 Oct 1956, Dengliang 2608 (IBSC); Tai Pin, foot of Loi Mother mountain, Jun–Jul 1935, Gressitt 1127 (E); Sanya City, 1800 ft., Mar–Jul 1933, How 70315 (A, IBSC, NY); same locality, 15 Aug 1933, Liang 62646 (NY); Sanya City, Yeung Lam Shan, near Yeung Lam village, Yai–hsien District, 4–24 May 1935, Lau 6261 (A, IBSC); Baisha County, 23 Mar 1936, Lau 25832 (A, IBSC); Ledong County, 1 Jun 1936, Lau 26987 (A, IBSC); Danzhou, Nada, 3 Nov 1922, McClure 21539 (A, E); Hung Mo Tung, SW of Fan Ta, 25 Aug 1929, McClure & Fung 18035 (NY).
DISCUSSION Licuala hainanensis has been most often confused with L. spinosa. It is smaller than L. spinosa in leaf size, and also differs in its smaller, erect inflorescences, which are not longer than the leaves. Licuala hainanensis has brown tomentose rachillae and glabrous flowers, in contrast to the densely hairy rachillae and flowers of L. spinosa. Licuala spinosa does not occur on Hainan and its nearest known localities are a considerable distance away in the southern parts of Vietnam, Cambodia, and Thailand.The other species from Hainan, Licuala fordiana, is quite distinct with its narrow, about 8 mm long, flowers. The flowers of Licuala hainanensis show affinities to those of a group of species from Vietnam, characterized by small flowers that dry dark brown, deeply split petals that are recurved at anthesis and remain recurved as the fruits develop, very short or absent staminal rings, and threelobed calyces in which the lobes split as the fruits expand, resulting in a six-lobed fruiting calyx. The group comprises species such as Licuala hexasepala and L. fatua. Licuala hainanensis differs from these species by having anthers that are longer than the filaments and a more shallowly lobed, glabrous calyx, and by having sepals in which the lobes do not split. Evidence such as reduced styles and size differences of the anthers suggests that several of these Vietnamese species may be at least functionally dioecious. Saw et al. (2003) considered that dioecy was very rare in Licuala, but was known in one species, L. gracilis Blume from Java. This was said to have plants which produced pistillate flowers and others which produced hermaphrodite flowers. Such gynodioecy was suspected by Saw et al. (2003) to occur in other species, such as Licuala hexasepala and an unidentified species from Guangxi, China (which we consider to be L. dasyantha Burret). Twelve of the 18 specimens of Licuala hainanensis examined here (those at or on loan to NY) were studied for evidence of dioecy. Four of these specimens had inflorescences with clusters of 2–4 flowers (Fig. 2B), and all had flowers and none had
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fruits. All flowers had six well-developed stamens and a reduced gynoecium with poorly developed styles and stigmas (Fig. 2C–E). The mean length and width of the basalmost rachilla of these specimens was 15.0 cm and 1.1 mm. The remaining eight specimens had inflorescences with solitary flower scars (Fig. 2A), and seven had fruits. The eighth had flowers (Fig. 2F–H). These flowers had the stamens reduced to staminodes and a gynoecium with apparently fertile ovules and well-developed styles and stigmas. The mean length and width of the basalmost rachillae of these eight specimens was 11.7 cm and 1.8 mm. We conclude from this that Licuala hainanensis is both sexually dimorphic and dioecious (rather than gynodioecious, as in L. gracilis). Staminate plants have longer and narrower rachillae with clustered flowers with six stamens and a reduced gynoecium without styles and stigmas, while pistillate plants bear shorter and wider rachillae with solitary flowers with staminodes and a well-developed gynoecium with styles and stigmas. In Licuala hainanensis, sexual dimorphism is restricted, as far as we know, to the length of the rachillae, clustering of flowers, staminate flowers with a reduced gynoecium (pistillode), and pistillate flowers with staminodes. However, leaves may also differ between staminate and pistillate plants in this and/or other species. For example, Magalon (1930, pages 42–44), in his discussion of an apparently undescribed Vietnamese species of Licuala, noticed two distinct leaf forms on different plants, and plants of one leaf form had flowers with a different type of sepal from the other. He wrote (page 44, our translation): ‘‘Calyx tubular, 2.5 mm long and 2 mm diameter, that of flowers from plants with leaves with three segments with the sepals divided at their apices, that of plants with leaves with four segments with the sepals undivided. Although the plants with three-segmented leaves differ from those with four segmented leaves by the splitting of the sepals, I think there is only one species.’’ Examination of the specimens seen by Magalon (M. Magalon 6 at P) confirms that the species is probably dioecious and has two different leaf forms. This phenomenon needs further study in the field. ACKNOWLEDGEMENTS. Herbarium and field work in China was supported by a grant from the International Palm Society. The paper was written during Andrew Henderson’s 2006 visit to AAU, which was generously funded by the University of Aarhus Research Foundation. We thank Mr. Zhou Lianxuan for his assistance in the field, the curators of A, AAU, E, HITBC, IBK, IBSC, NY, and P for making specimens available for study, and Bobbi Angel for the line illustration.
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LITERATURE CITED GOVAERTS, R. and J. DRANSFIELD. 2005. World Checklist of Palms. Kew: Royal Botanic Gardens. MAGALON, M. 1930. Contribution a l’e´tude des palmiers de l’Indochine Franc¸aise. Paris: Les Presses Modernes.
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PEI, S. J., S. Y. CHEN, and S. Q. TONG. 1991. Palmae. Flora Reipublicae Popularis Sinicae 13(1). Beijing: Science Press. SAW, L., J. DRANSFIELD, and D. KEITH-LUCAS. 2003. Morphological diversity of the genus Licuala (Palmae). Telopea 10: 187–206.
