Newly Naturalized and Rediscovered Decalobanthus (Convolvulaceae) Species from Taiwan 臺灣金鐘藤屬(旋花科)的新歸化種與再發現種

 Newly Naturalized and Rediscovered Decalobanthus (Convolvulaceae) Species from Taiwan 

臺灣金鐘藤屬(旋花科)的新歸化種與再發現種 

Po-Hao Chen1, An-Ching Chung2, Shih-Siang Wong3, Zhi-Xiang Chang4, 

Shih-Wen Chung5 and Wei-Jie Huang5

陳柏豪1 、鍾安晴2*、翁士翔3、張智翔4、鐘詩文5、黃偉傑5 

1 Graduate Institute of Bioresources, National Pingtung University of Science and Technology, Pingtung, Taiwan, R.O.C. (國立 屏東科技大學農學院生物資源博士班，屏東，臺灣，中華民國) 

2 Liouguei Research Center, Taiwan Forestry Research Institute, Kaohsiung, Taiwan, R.O.C. (行政院農業委員會林業試驗所六 龜研究中心，高雄，臺灣，中華民國) 

3 Tree Walker Arboris Company Limited, Changhua, Taiwan, R.O.C. (樹沃客樹藝有限公司，彰化，臺灣，中華民國)

4 Fushan Research Center, Taiwan Forestry Research Institute, Yilan, Taiwan, R.O.C. (行政院農業委員會林業試驗所福山研究 

中心，宜蘭，臺灣，中華民國)

5 Botanical Garden Division, Taiwan Forestry Research Institute, Taipei, Taiwan, R.O.C. (行政院農業委員會林業試驗所植物 

園組，臺北，臺灣，中華民國)

*Corresponding author(通訊作者): An-Ching Chung, e-mail: cac335@tfri.gov.tw 

Abstract: Merremia s.l. has been proved polyphyly, and is now delimitated into 4 genera: Camonea Raf., Merremia Dennst. ex Endl., Decalobanthus Ooststr. and Distimake Raf. This article reports the two species of the genus Decalobanthus in Taiwan, the red flower one D. similis (Elmer) A. R. Simões & Staples, and the yellow flower one D. boisianus (Gagnep.) A. R. Simões & Staples var. boisianus. D. similis, the sole native species of the genus Decalo- banthus in Taiwan, had not been recorded in local flora since its first report in 1971, and was rediscovered in 2021. Also, a population of D. boisianus var. boisianus was newly found at the seashore in northern Taiwan in recent years, and is extremely aggressive in the field and would probably become a seriously invasive plant in Taiwan. Thus, it is important to continually monitor the expansion of D. boisianus var. boisianus population in Taiwan and to prevent it endangering the native plant communities. 

摘要:過去廣義的菜欒藤屬被證實為多系群，現今則劃分為4個屬:耳 節藤屬(Camonea Raf.)、菜欒藤屬 (Merremia Dennst. ex Endl.)、金鐘藤屬 (Decalobanthus Ooststr.)、萼龍藤屬(Distimake Raf.)。本文報導臺灣金鐘藤 

屬兩個物種─紅花的紅花金鐘藤(D. similis (Elmer) A. R. Simões & Staples) 及黃花的金鐘藤(D. boisianus (Gagnep.) A. R. Simões & Staples var. boi- sianus)。其中紅花金鐘藤在1971年發表後再無其他採集紀錄，直到2021 年再次發現其族群。另外於臺灣北部沿海地區發現金鐘藤的族群，於野 地是非常強勢的外來種，極有可能成為嚴重的入侵種，未來需持續監測 其擴散情形，以免對原生植物造成危害。 

Keywords: Convolvulaceae, Decalobanthus, invasive species, Merremia, Taiwan 

關鍵詞:旋花科、金鐘藤屬、入侵種、菜欒藤屬、臺灣 

Introduction 

The family Convolvulaceae comprising 1,660 species of 53 genera could be separated into 12 tribes (Staples and Brummitt, 2007; Christenhusz and Byng, 2016), of which the tribe Merremieae was divided into 9 genera in the current research (Simões and Staples, 2017). In the past, the genus Merremia in Merremieae consisted of over 1,000 species worldwide (Staples, 2010), in which 11 species were recorded in Taiwan, including 6 native and 5 naturalized species: M. tuberosa (L.) Rendle (Staples and Yang, 1998); M. dissecta (Jacq.) Hallier f. (Tsai et al., 2010); M. cissoides (Lam.) Hallier f. (Ko and Liu, 2011); M. umbellata (L.) Hallier f. (Chao et al., 2017) and M. quinquefolia (L.) Hallier f. (Chung et al., 2017). Recently, molecular phylogenetic evidence has shown that the genus Merremia was polyphyly and could be delimitated into 4 genera: Camonea Raf., Merremia Dennst. ex Endl., Decalobanthus Ooststr. and Distimake Raf. (Simões and Staples, 2017). Therefore, the species of the Merremia s.l. in Taiwan now include Camonea [C. umbellata (L.) A. R. Simões & Staples, C. vitifolia (Burm. f.) A. R. Simões & Staples]; Decalobanthus [D. similis (Elmer) A. R. Simões & Staples]; Disti- make [D. cissoides (Lam.) A. R. Simões & Staples, D. dissectus (Jacq.) A. R. Simões & Staples, D. quinatus (R.Br.) A. R. Simões & Staples, D. quinquefolius (L.) A. R. Simões & Staples, D. tuberosus (L.) A. R. Simões & Staples]; Merremia s.s. [ M. gemella (Burm.f.) Hallier f., M. hed- eracea (Burm.f.) Hallier f., M. hirta (L.) Merr.]. 

Among the 17 species of the genus Decalobanthus which mainly distributed in Asia and the Pacific region (Simões and Staples, 2017; Simões et al., 2020), only one species, D. simi- lis, has been recorded in Taiwan with no further collection after Chang (1971) first reported it in Bulletin of Taiwan Provincial Pingtung Institute of Agriculture. It was not until Dec 11, 2021 that Mr. Ming-Yu Kuo (郭明裕) rediscovered the population in Fenshuiling, Manzhou Township, Pingtung County, Taiwan. Of this taxon found in 2021, the characteristics e.g. leaves large, inflorescence corymbose cymes, sepals elliptic, glabrous, corolla red, corresponded to which Chang (1971) described. In this article, we provide detailed color photographs and additional voucher specimens of D. similis to assist in its identification. 

Moreover, during our recent field investigations, an unknown species of Decalobanthus was found at the seashore in northern Taiwan. Of this taxon, the inflorescences corymbose cymes, sepals broadly ovate, equal, outer 2 yellowish pubescent on abaxial surface, and corolla yellow. After detailed study in its morphology and comparison with known literatures (Van Ooststroom and Hoogland, 1953; Fang and Staples, 1995; Simões et al., 2020), we identified this species as Decalobanthus boisianus (Gagnep.) A. R. Simões & Staples var. boisianus, which is native from southern China, northern Vietnam to Laos. In this article, we describe it as a newly naturalized plant in Taiwan and provide taxonomic description and detailed color photographs to assist in its identification. 

Taxonomic treatment 

1. Decalobanthus boisianus (Gagnep.) A. R. Simões & Staples var. boisianus, Bot. J. Linn. Soc. 183(4): 569. 2017. 

金鐘藤 Fig. 1 

Basionym: Ipomoea boisiana Gagnep., Notul. Syst. (Paris) 3: 141. 1915.

Type: VIETNAM. Montagnes du Caï Kunh, Bois 138 (syntype P, P00608899 image!); Mt. Cha- Pa, Lecomte et Finet s.n. (syntype P, P03536883 image!; syntype P, P03536884 image!). LAOS. near Ken-trap, Spire 1049 (syntype P, P03536873 image!). 

Liana, whole plants with white latex; stems dextrorsely twining, terete, glabrous; young stems fistulose and yellowish pubescent. Leaves alternate, ovate to nearly orbicular, 8–28 cm 

× 6.5–24.5 cm, base cordate, margins entire, apex caudate, glabrous on both surfaces, 7–9 pinnate lateral veins; petiole 2–11.5 cm long, glabrous. Corymbose cymes axillary, 5–16 cm long; bracts lanceolate or narrowly triangular, ca. 3 mm long, densely yellowish pubescent, fugacious; peduncles 2.5–10 cm long, pubescent or glabrous; pedicels 1–1.5 cm long, enlarged in fruit. Sepals broadly ovate or nearly orbicular, equal, 6–7 mm × 5–6 mm, apex mucronate; outer 2 yellowish pubescent on abaxial surface; inner 3 glabrous. Corolla yellow, campanulate, ca. 2 cm long, ca. 3 cm in diameter, midpetaline bands yellowish pubescent on abaxial surface, limb ondulate; stamens 5, included; filaments 1–1.1 cm long, inserted at the mouth of the tube, 4 mm long, with 2 longitudinal pubescent lines below insertion; anthers basifixed, ca. 3 mm long, twisted; pistil 1, included, 1.2 cm long; stigma capitate, 2-lobed, white; ovary conical, green, glabrous, 1 mm long, 2-loculed, 4-ovuled, base with annular disc. Capsule subglobose, 1–1.2 cm in diameter, glabrous. Seeds 4, broadly trigonous-ovoid, 5 mm long, densely scaly pubescent along angles. 

Specimens examined: TAIWAN. New Taipei City, Bali Dist., 21 October, 2021, S.-W. Chung & W.-J. Huang 14929 (TAIF); 21 October, 2021, Z.-X. Chang ZXC002691 (TAIF); 30 October, 2021, P.-H. Chen & A.-C. Chung 3429~ 3434 (TAIE).

2. Decalobanthus similis (Elmer) A. R. Simões & Staples, Bot. J. Linn. Soc. 183(4): 571. 

2017. 

Basionym: Merremia similis Elmer, Leafl. Philipp. Bot. 1: 335. 1908; Chang, Bull. Taiwan Prov. Ping. Inst. Agr. 12: 15. 1971; Chang, Fl. Taiwan 4: 385. 1978; Staples and Yang, Fl. Taiwan, 2nd ed 4: 379. 1998.

Type: PHILIPPINES. Leyte, Palo, A.D.E. Elmer 7341 (isotype E, E00273913 image!, isotype K000830840 image!, isotype NY, NY00336585 image!). 

紅花金鐘藤Fig. 2 Specimens examined: TAIWAN. Pingtung County, Manzhou Township, Fenshuiling, 10 Dec., 1960, C.-E. Chang 2467 (PPI); 11 Jan, 1971, C.-E. Chang 6760 (PPI); 14 March, 1971, C.-E. Chang s.n. (PPI); 15 Dec., 2021, P.-H. Chen 3450 (TAIE); Z-X. Chang ZXC002831 (TAIF); 17 

Dec., 2021, S.-W. Chung 14949 (TAIF). 

Discussion 

Decalobanthus boisianus 

Decalobanthus boisianus has three varieties, including var. boisianus, var. fulvopilosus (Gagnep.) A. R. Simões & Staples distributed from southern China to northern Vietnam and var. sumatranus (Ooststr.) A. R. Simões & Staples distributed in Indonesia (Sumatra) (Simões et al., 2020). The branchlets, petioles, leaves, peduncles and pedicels are glabrous or yellowish pubescent in var. boisianus (Fang and Staples, 1995), namely the taxon naturalized in Taiwan, while being grayish-yellow tomentose or fulvous pubescent in the other two varieties (Van Ooststroom and Hoogland, 1953; Fang and Staples, 1995). The latter two varieties could be further distinguished from each other by the much longer hairs in var. fulvopilosa and the much shorter and less dense hairs in var. sumatranus (Van Ooststroom, 1939). 

Originally distributed in Hainan Island, the border of China and Vietnam to Laos, and Sarawak to east Kalimantan, D. boisianus var. boisianus had gradually spread out (Wang et al., 2005). It could reproduce both sexually and asexually, and is excellent in asexual reproduction (Lian et al., 2007). D. boisianus var. boisianus is a very aggressive species that grows fast and climbs strongly, covering the canopy of forest broadly, which could damage all the trees (Wu et al., 2007; Huang et al., 2013; Huang et al., 2015). Seeds of D. boisianus var. boisianus could germinate under the dense forest, but most of the seedlings fail to survive (Huang et al., 2013), thus it could be shade-intolerant. Seeds are able to drift and can be dispersed by seawater (Wu et al., 2007), thus this new population of D. boisianus var. boisianus probably arrived Taiwan through the ocean current. 

This population of D. boisianus var. boisianus in Taiwan was first recorded by the third author on 12 January 2019. Street view images available in Google Map (https://maps.google. com.tw; accessed 4 December 2021) revealed that the population had appeared and covered the canopy on roadside at least since 9 November 2019. In Taiwan, though it has been found only one location at the seashore of Bali, but it spread vastly and cover the bare ground, orchard, secondary forest, and alley trees. According to our filed survey, there is potential for D. boi- sianus var. boisianus to be seriously invasive in Taiwan because the habitat is almost covered by 

it (Fig.1A). It is important to continually monitor the expansion of D. boisianus var. boisianus 

population in Taiwan and to prevent it endangering the native plant communities. 

Decalobanthus similis 

Decalobanthus similis is distributed in Philippines (Leyte, Luzon, Mindanao, Panay, Samar, Sibuyan) and Taiwan (Staples, 2010). In Taiwan, there was only one record in Fenshuiling, Hengchun Peninsula from the first report (Chang, 1971), making it be suggested as Critically Endangered (CR) in the Red List of Taiwan Plants (Editorial Committee of the Red List of Taiwan Plants, 2017). It was not until this year that the population in Fenshuiling was rediscovered. Being a large liana, the stem diameter of D. similis could be up to 10 cm in the field, and its leaves could reach 25 cm in length, covering the canopy of the habitat (Fig.2A). While the plants seem to thrive in this area less than 0.2 ha, we did not find seedling regeneration of D. similis in the understory, but observed the capsules matured in last year, without seeds now and persistent at the branches. As for that, it is necessary to investigate nearby habitats to clarify the current situation of its population in Taiwan. 

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資料來源:

國立臺灣博物館學刊