NATURE IN SINGAPORE 2017 10: 1–5 Date of Publication: 25 January 2017 © National University of Singapore

Rediscovery in Singapore of Calamus densiflorus Becc. (Arecaceae)

Adrian H. B. Loo*, Hock Keong Lua and Wee Foong Ang

National Parks Board HQ, National Parks Board, Singapore Botanic Gardens, 1 Cluny Road, Singapore 259569, Republic of Singapore; Email: [email protected] (*corresponding author)

Abstract. Calamus densiflorus is a new record for Singapore after its rediscovery in the Rifle Range Road area in 2016. Its description, distribution and distinct vegetative characters are provided.

Key words. Calamus densiflorus, new record, Singapore

INTRODUCTION

Calamus densiflorus Becc. is a clustering rattan palm of lowland forest and was Presumed Nationally Extinct in Singapore (Tan et al., 2008; Chong et al., 2009). This paper reports its rediscovery in the Rifle Range Road area in 2016 and reassigns it status in Singapore to “Critically Endangered” according to the categories defined in The Singapore Red Data Book (Davison et al., 2008).

Description. Calamus densiflorus is a dioecious clustering rattan palm, climbing to 40 m tall (Fig. 1, p. 2). It has stems enclosed in bright yellowish green sheaths up to 4 cm wide. The spines are hairy, dense and slightly reflexed (Fig. 1, p. 2), with swollen bases. The knee of the sheath is prominent and the flagellum is up to 3 m long. The leaf is ecirrate, and without a petiole in mature specimens. The leaves are arcuate, about 1 m long with regularly arranged leaflets that are bristly on both margins. The male inflorescence has slightly recurved rachillae and is branched to 3 orders (Fig. 1). The female inflorescence has second order branching and its rachillae are slightly recurved and up to 10 cm long. The fruit is scaly and ovoid, about 2 cm long and 1.2 cm wide.

Distribution. Calamus densiflorus is a rattan of the lowlands to hills up to 600 m altitude and is distributed in Singapore, Peninsular Malaysia, and Thailand (Dransfield, 1979). It avoids swamp forests but can be found on river banks.

Herbarium records for Singapore (Table 1, p. 2) show that it was last collected in 1903 by Henry Nicholas Ridley in Bukit Timah. Previous to this were also collections made by Ridley in the 1890s in Bukit Mandai and the Gardens’ Jungle at the Singapore Botanic Gardens.

A clump of the rattan with some expired infructescences was first rediscovered in the Rifle Range Road area (herbarium specimen SING 2016-107) and the species was later found to also occur in the Chestnut Area after surveying the Central Catchment Nature Reserve for this palm.

Comparisons with Calamus ridleyanus. Calamus densiflorus is very easily confused with Calamus ridleyanus Becc. (Furtado, 1956; Dransfield, 1979) shown in Fig. 2 (p. 4). Besides a few vegetative characters (Fig. 3, p. 5) that can provide a tentative distinction from Calamus ridleyanus, several reproductive characters such as the spiny rachillae bracts and reflexed recurving rachillae in Calamus ridleyanus are needed to differentiate the two (Furtado, 1956; Dransfield, 1979). The suite of key features that differentiate between the two congeners are listed in Table 2. Besides superficial similarities in terms of general habit that explain why Calamus densiflorus is overlooked in the field, rattans are generally disregarded by plant collectors as they are “viciously spiny” (Dransfield, 1979). This rediscovery, that for Salacca (Loo, 2011) and the new record of Plectocomiopsis (Tan et al., 2011) vindicates Dransfield’s observation made 37 years ago.

CONCLUSION

More field work is needed to ascertain the distribution of Calamus densiflorus and its morphologically similar congener in Singapore. While it is certainly rare to spot in the field, it is an overlooked palm that requires further field studies.

This rediscovery also highlights the importance of our remnant forest patches in Singapore as a source and refuge for native species. Many of these species are overlooked or only discovered as new areas of the forests are accessed and explored. There are many more vegetated areas here that need to be thoroughly surveyed and documented.

1 Loo et al.: Rediscovery of Calamus densiflorus in Singapore

Table 1. Singapore specimens of Calamus densiflorus Becc. in the Singapore Botanic Gardens’ Herbarium (SING).

S/No. Collector and Number Date Collected Location Accession No.

1. HN Ridley 11515 7 April 1903 Probably Bukit Timah Nature Reserve 0014613

2. HN Ridley 11050 1898 Gardens Jungle, Singapore Botanic Gardens 0090478

3. HN Ridley 6280 1891 Bukit Mandai 0090481

4. HN Ridley 10861 1890 Gardens Jungle, Singapore Botanic Gardens 0090479

5. HN Ridley 6280 1890 Gardens Jungle, Singapore Botanic Gardens 0090480

A B

C

Fig. 1. Calamus densiflorus. A, habit, note the ecirrate leaves of the species; B, stem showing the slightly recurved spines characteristic of the species. Note the absence of leaf stalks in this mature specimen; C, dried male inflorescences.

ACKNOWLEDGEMENTS

We thank John Dransfield for kindly verifying the identity of the rattan.

LITERATURE CITED

Chong KY, Tan HTW & Corlett RT (2009) A Checklist of the Total Vascular Plant Flora of Singapore: Native, Naturalised and Cultivated Species. Raffles Museum of Biodiversity Research, National University of Singapore, Singapore. 273 pp. http://rmbr.nus.edu.sg/raffles_museum_pub/flora_of_singapore_tc.pdf (Accessed September 2016). Davison GWH (2008) The Red List categories. In: Davison GWH, Ng PKL & Ho HC (eds.) The Singapore Red Data Book: Threatened Plants & Animals of Singapore. 2nd Edition. Nature Society (Singapore), Singapore, pp. 1−4.

2 NATURE IN SINGAPORE 2016

Dransfield J (1979) A Manual of the Rattans of the Malay Peninsula. Forest Department, Ministry of Primary Industries Malaysia, Malaysia, 270 pp. Furtado CX (1956) Palmae Malesicae, XIX—The Genus Calamus in the Malayan Peninsula. Gardens’ Bulletin Singapore, 15: 32–265. Loo AHB (2011) Rediscovery in Singapore of Salacca affinis Griff. (Arecaceae). Nature in Singapore, 4: 123–126. Tan HTW, Tan K-x, Ali bin Ibrahim, Chew PT, Chua KS, Duistermaat H, Ganesan SK, Goh MWK, Gwee AT, Kiew R, Lee SML, Leong P, Lim J, Lok AFSL, Loo AHB, Lum SKY, Morgany T, Saifuddin bin Suran, Sim S, Haji Samsuri bin Haji Ahmad, Wee YC, Yap KF, Yeo CK & Yong JWH (2008) Checklists of threatened species―Seed plants. In: Davison GWH, Ng PKL & Ho HC (eds.) The Singapore Red Data Book: Threatened Plants & Animals of Singapore. 2nd Edition. Nature Society (Singapore), Singapore, pp. 213–244. Tan LL, Lum SKY & Loo AHB (2011) Plectocomiopsis geminiflora (Griff.) Becc. (Arecaceae)—A new record for Singapore. Nature in Singapore, 4: 1–4.

Table 2. Characters that differentiate Calamus densiflorus from Calamus ridleyanus. adapted from Dransfield (1979).

Characteristics Calamus densiflorus Calamus ridleyanus

Stem width Stem with leaf sheaths to 4 cm wide. Stem with leaf sheaths to 2.5 cm wide.

Leaf sheath colour Sheaths bright to yellowish green, armed densely Sheaths dull green, rather densely armed with and spines with reflexed, blackish-brown spines; spine bases slightly upward pointing, hairy margined, pale- often joined by swollen ridges. based, brown spines; spine bases only slightly swollen.

Presence of cirrus Leaf ecirrate to 1.1 m long, in juvenile specimens Leaf subcirrate to about 1.3 m long with leaf stalk to and leaf stalk with leaf stalk to 20 cm long, in mature leaves 10 cm long in juvenile or mature leaves. usually with no leaf stalk.

Bristles on leaflets Leaflets conspicuously bristly on the 3 main veins Leaflets bristly along the mid-vein below, with no above, and on the mid-vein below, and along bristles on upper surface. margins.

Inflorescence Inflorescence with sparsely spiny bracts; female Inflorescence with spiny bracts; female rachillae rachillae slightly recurved. distinctly recurved.

3 Loo et al.: Rediscovery of Calamus densiflorus in Singapore

A B

C

Fig. 2. Calamus ridleyanus. A, Habit; B, Stem showing the slightly upward pointing spines characteristic of the species. Note the presence of the leaf stalk in this mature leaf. C, recurved rachillae. Note the spiny prophyll characteristic of the species.

4 NATURE IN SINGAPORE 2016

A B

C D

E F

Fig. 3. Comparisons between Calamus densiflorus (left column) and Calamus ridleyanus (right column). A, the slightly recurved spines of Calamus densiflorus; B, the slightly upward pointing spines of Calamus ridleyanus; C, ecirrate; versus D, subcirrate leaves; E, sparsely spiny inflorescence bracts; versus F, densely spiny inflorescence bracts.

5 NATURE IN SINGAPORE 2017 10: 7–24 Date of Publication: 29 May 2017 © National University of Singapore

The vascular plant flora and vegetation of the islands associated with Singapore’s first Marine Park (I): The Sisters’ Islands

Sherry M. X. Hung1*, K. Y. Chong1, Alex T. K. Yee1, Reuben C. J. Lim1, Jolyn W. Loh1, Louise Neo1, W. W. Seah1, S. Y. Tan1, Aloysius X. Y. Teo1, Karenne Tun2, Collin H. Y. Tong2, K. S. Koh2 and Hugh T. W. Tan1

1Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Republic of Singapore; Email: [email protected] (*corresponding author) 2Coastal and Marine Branch, National Biodiversity Centre Division, National Parks Board, Singapore Botanic Gardens, House 6, 1 Cluny Road, Singapore 259569, Republic of Singapore

Abstract. The Sisters’ Islands, consisting of Small Sister’s Island and Big Sister’s Island—officially known as Pulau Subar Darat and Pulau Subar Laut, respectively, support 144 vascular plant species from 59 families, of which 90 species are native, 34 are non-native, and 20 are cryptogenic weeds. The native species include 10 nationally Critically Endangered species, eight nationally Endangered species, 14 nationally Vulnerable species, and 58 species that are not nationally threatened. The 2.76-ha Small Sister’s Island has 0.94 ha of coastal forest, 1.80 ha of managed vegetation, and 0.02 ha of built-up structures. The 4.53-ha Big Sister’s Island has 1.67 ha of coastal forest, 2.84 ha of managed vegetation, and 0.02 ha of built-up structures.

Keywords. checklist, Pulau Subar Darat, Pulau Subar Laut, Singapore, Sisters’ Islands, vascular plants

INTRODUCTION

In July 2014, the Singapore government announced the establishment of Singapore’s first Marine Park. Located southeast of Sentosa in Singapore’s southern seas (Fig. 1), the Marine Park consists of Pulau Subar Darat and Pulau Subar Laut (unofficially and popularly known as Small Sister’s Island and Big Sister’s Island, respectively, and together as the Sisters’ Islands), and their surrounding waters, as well as the western coasts of both Pulau Tekukor and St. John’s Island (officially known as Pulau Sakijang Bendera) (Fig. 2). Altogether, the Marine Park consists of 40 ha of marine and terrestrial areas selected because of their diverse habitats, which include sandy shores, coral reefs, and sea grass beds. The main objectives of the park are conservation, research, education, and outreach, and conservation efforts will involve rare marine species, such as the Neptune cup sponge (Cliona patera), which was initially presumed to be globally extinct owing to overharvesting, but was rediscovered near the coast of St. John’s Island (Lim et al., 2012). The Marine Park also facilitates marine research in Singapore. For example, one of the on-going marine research projects plans to reintroduce the endangered giant clam underwater off Big Sister’s Island (M. L. Neo, pers. comm.).

Small Sister’s Island (1° 12′57.80″N, 103° 49′57.92″E) and Big Sister’s Island (1° 2′50.88″N, 103°50′05.40″E) are separated by a narrow channel. Reclamation works in the 1970s expanded Small Sister’s Island by 1.95 ha from 0.81 ha, and Big Sister’s Island by 2.91 ha from 1.62 ha, respectively (Ministry of Culture, 1971). Currently, Small Sister’s Island has a land area of 2.76 ha, while Big Sister’s Island is 4.53 ha. A study by Koh et al. (2002) found that Small Sister’s Island had the highest vascular plant taxon richness among the four islands surveyed. H. T. W. Tan and others also conducted floristic surveys on the islands in the 1990s and 2000s (unpublished data; see Appendix 2). The Sisters’ Islands are the only islands in Singapore listed as ‘Marine Nature Areas’ under the Parks and Waterbodies Plan (URA, 2014).

This study presents baseline information on the vascular plant flora and vegetation of the two islands. It was motivated by two questions—first, what vascular plant species are found on the islands? Second, what vegetation types occur on them? Floristic data are important for identifying important areas of high conservation value, especially where nationally threatened species are found. Vegetation maps display spatially explicit distribution information for the islands. Both kinds of information will be valuable for establishing conservation strategies, biodiversity loss mitigation efforts, monitoring of the islands’ biodiversity and habitats, and developing impact mitigation strategies for future development.

MATERIAL AND METHODS

A comprehensive checklist of all the vascular plant species presently and previously found on the two islands was compiled from this study’s floristic surveys, as well as data from previous floristic surveys by H. T. W. Tan et al. (unpublished data), Koh et al. (2002), and the records of the Singapore Botanic Gardens’ Herbarium (SING) and the Herbarium, Lee Kong Chian Natural History Museum, Faculty of Science, National University of Singapore (SINU) (Appendix 1). All plant species names and their respective authors were cross-checked with an online database, The Plant List (2013).

7 Hung et al.: The Vascular Plant Flora and Vegetation of the Sisters’ Islands

Fig. 1. Map of Singapore showing the location of the Marine Park.

Pulau Tekukor

Pulau Sakijang Bendera (St. John’s Island)

Pulau Subar Darat (Small Sister’s Island)

Pulau Subar Laut (Big Sister’s Island)

Fig. 2. Map of the Marine Park showing Pulau Subar Darat and Pulau Subar Laut (Sisters’ Islands), Pulau Tekukor, and Pulau Sakijang Bendera (St. John’s Island).

The national status of each species was retrieved from the checklist of Singapore’s vascular plant flora by Tan et al. (2008) and Chong et al. (2009).

The vegetation map was first drawn based on visual interpretation of two satellite images of 27 April 2010 and 22 April 2013 from Google Earth 7.1.2.2041 (Google Inc., 2013), which provided a relatively accurate portrayal of the distribution of the vegetation. The shoreline of the islands and boundaries of each area were traced at a map scale of 1: 2,000. Thereafter, the area of each vegetation type was calculated using ArcGIS®9 ArcMap™ Version 9.3.1 (ESRI, 2009), with

8 NATURE IN SINGAPORE 2017 the World Geodetic System 1984 (WGS84) and Universal Transverse Mercator Coordinate System, Zone 48 North (UTM48N) projections.

In the interpretation of the satellite images, preliminary classification was based on visual features of the vegetation type. For example, natural forests appear as areas with a dense canopy cover formed by large tree crowns. On the other hand, managed vegetation areas appear to be lighter coloured because of the sparser tree cover. Each vegetated area measured at least 10 × 10 m. Adjustments were subsequently made to the preliminary vegetation maps based on actual field observations during ground truthing.

Floristic surveys and ground truthing were conducted for all the accessible areas on the two islands between December 2014 and February 2015 with the aid of a Global Positioning System (GPS) receiver, the Garmin GPSMap® 62S, which records locations with ± 4 m accuracy. The main objective of the floristic surveys was to verify and supplement the list of vascular plant species recorded from the previous surveys, with the emphasis on native species. Additionally, the geographic coordinates of non-widespread, threatened plant species were recorded using the GPS receiver, and the localities were indicated on the vegetation map of each respective island. Voucher specimens were collected for plants that could not be identified with certainty in the field, or were not previously documented in the herbarium records of SING and SINU. The specimens were then matched with identified specimens in SING and/ or SINU.

OBSERVATIONS AND RESULTS

The vascular plant flora of the Sisters’ Islands consists of 18 species of ferns, two species of gymnosperms, and 124 species of angiosperms, so totaling 144 species belonging to 59 families, including the new records from this study’s floristic surveys (Appendix 1). Out of these, 90 species (62.5%) are native, of which 32 species (22.2%) are threatened, meaning that they are nationally classified as presumed nationally Extinct, Critically Endangered, Endangered, or Vulnerable (Table 1). Non-native or exotic species make up 23.6% or a total of 34 species (Table 1); however, this might be underestimated as we focused on verifying or adding to the list of native species. Owing to the differences in survey sampling efforts, some species that were found in this study’s floristic surveys were not previously recorded, and vice- versa (Appendix 2).

Table 1. National conservation status categories of the vascular flora of the Sisters’ Islands. Status category Number of species Percentage of species Native species 90 62.5% Presumed Nationally Extinct 0 0.0% Nationally Critically 10 6.9% Endangered Nationally Endangered 8 5.6% Nationally Vulnerable 14 9.7% Not nationally Threatened 58 40.3% Non-native species 34 23.6% Casual 4 2.8% Naturalised 25 17.4% Cultivated only 5 3.5% Cryptogenic weed species 20 13.9% Total 144 100.0%

Table 2 below lists the spatial extent of each vegetation type in the Sisters’ Islands. Altogether, natural vegetation covers 2.61 ha (35.8%) and managed vegetation 4.64 ha (63.6%) of the total land area of both islands (Table 2; Fig. 3). The natural vegetation is predominantly coastal forest.

Table 2. Area and percentage of each vegetation type. Island(s) Natural Vegetation Managed Vegetation Built-up Structures Total Big Sister’s Island 1.67 ha 36.9% 2.84 ha 62.7% 0.02 ha 0.4% 4.53 ha 100.0% Small Sister’s Island 0.94 ha 34.1% 1.80 ha 65.2% 0.02 ha 0.7% 2.76 ha 100.0% Both islands 2.61 ha 35.8% 4.64 ha 63.6% 0.04 ha 0.5% 7.29 ha 100.0%

9 Hung et al.: The Vascular Plant Flora and Vegetation of the Sisters’ Islands

Fig. 3. Vegetation map of the Sisters’ Islands. The numbers indicate the positions of individuals of non-widespread, nationally threatened species: 2 = Calophyllum inophyllum; 5 = Eurycoma longifolia; 8 = Ficus superba; 12 = Memecylon edule; 14 = Peltophorum pterocarpum; 15 = Pittosporum ferrugineum; 17 = Podocarpus polystachyus; 18 = Pongamia pinnata; 19 = Rapanea porteriana; 21 = Symplocos adenophylla; 22 = Syzygium claviflorum; 24 = Tarenna fragrans; 26 = Tristaniopsis whiteana.

The vascular flora on Big Sister’s Island consists of 96 species belonging to 46 families, of which 65 (67.7%) are native species and 26 (27.1%) are threatened in Singapore (Fig. 4, top; Appendix 1). Small Sister’s Island has slightly fewer species, with 93 unique vascular plant species from 45 families, of which 59 (63.4%) are native and 19 (20.4%) are threatened (Fig. 4, bottom; Appendix 1).

Numerous mature individuals and saplings of the nationally Critically Endangered Podocarpus polystachyus (Podocarpaceae) are thriving on Big Sister’s Island, with more than 20 mature trees and many saplings found on its hilltop, denoted by the ‘17s’ on the vegetation map (Figs. 3 & 5D). Two individuals of this species were observed on Small Sister’s Island. Large clumps of the nationally Endangered Memecylon edule (Melastomataceae), with many producing flowering buds, were also seen on both islands during surveys (Fig. 5A & 5B). However, it was also observed that the non-native tree, Alstonia macrophylla (Apocynaceae) is flourishing on Small Sister’s Island, along areas that fringe the natural forests. This observation was also made by Teo (2012) during his field survey in 2011, when there were likely more than 100 individuals on the island at the time of survey. Although few individuals of this naturalised species were found in the core of the coastal forests, which are relatively undisturbed, several mature individuals were found widely distributed along the areas surrounding the interior coastal hill forests.

DISCUSSION

Twenty-six nationally threatened species were found in abundance on the Sisters’ Islands. Although some have fairly large wild populations, attention should be paid to ensure the persistence of their native genetic stock. For example, Podocarpus polystachyus is a Nationally Critically Endangered species found thriving in the natural coastal forest of Big Sister’s Island. Many saplings were found growing close together in the understorey under large, mature trees.

10 NATURE IN SINGAPORE 2017

Fig. 4. Pie charts illustrating the number and proportion of species that belong to each national status group for the Sisters’ Islands.

11 Hung et al.: The Vascular Plant Flora and Vegetation of the Sisters’ Islands

A B

C D

Fig. 5. A, Fruiting and flowering branches of the nationally Endangered Memecylon edule on Big Sister’s Island; B, Inflorescences with flowers and buds of Memecylon edule on Small Sister’s Island; C, Flowers and flowering buds of Symplocos adenophylla, also nationally Endangered, on Big Sister’s Island; D, Saplings of the nationally Critically Endangered Podocarpus polystachyus at the foot of two adult trees on Big Sister’s Island . (Photographs A‒C by: Chong Kwek Yan; photograph D by: Sherry Hung Ming Xuan). Scale bars for A = 5 cm, B = 2 cm, C = 2 cm, and D = 5 cm.

As such, in the understorey environment where saplings of Podocarpus polystachyus were found in high density, overcrowding may limit the regeneration and growth of this species in the coastal forest of Big Sister’s Island. It is believed that there are less than 50 trees of this species left in the wild in Singapore (Tan, 2008). Hence, the removal of exotic trees would reduce direct competition over space and nutrients for the saplings to regenerate. Alternatively, the sapling s found in the understorey can be thinned out and transplanted to other areas to ensure a higher survival rate. Other ex-situ propagation methods could also be employed in the conservation of such threatened species on the islands and this species is very amenable to rooting by stem cuttings (Zhong et al., 2001).

The naturalised tree, Alstonia macrophylla was found to be thriving on the Small Sister’s Island. Several mature individuals have established themselves widely in disturbed areas that fringe the natural coastal forests. In 2012, the ecological study by Teo (2012) on Alstonia macrophylla recorded a high abundance of this naturalised species occurring on Small Sister’s Island, with 45 fruiting individuals and several more juveniles, and five individuals standing at 6 m, 7 m, 8 m, 1.2 m and 14 m tall on Big Sister’s Island during the time of survey. Two of the tallest trees on Big Sister’s Island were fruiting then.

Invasion by non-native species is a potential problem for the Sisters’ Islands. It may necessitate the deployment of strategic intervention in controlling, containing or eradicating the range of invasive species. Keeping the level of human disturbance low within the hill coastal forest could minimise the spread of Alstonia macrophylla into those areas since

12 NATURE IN SINGAPORE 2017 past and present empirical observations on Small Sister’s Island showed that saplings of this species tend to proliferate in areas adjacent to man-made structures. By preventing the introduction of habitat edge conditions into the forest interior, it would reduce further human-facilitated spread of such light-demanding pioneer species on the islands. Eradication methods should be employed to remove the species from all the southern islands and the south coast of the main island to further reduce its spread locally.

Future studies can further explore the potential problem of invasion on the islands, such as whether non-native species have become naturalised or invasive, the distribution of non-native species on the islands, and the rate of survival and growth in disturbed and natural sites. While the vegetation maps display explicit information of the distribution of vegetation, the state of vegetation cannot be rigorously assessed without detailed studies such as vegetation plots. Finally, effective management of the entire coastal landscape also requires an integrated approach involving both the terrestrial and marine habitats. Complementary studies of the marine habitats, such as water quality monitoring and coral cover, can be explored to better facilitate management of the coastal areas, especially with the long-term aim of protecting biodiversity and maintaining coastal stability of Singapore’s first Marine Park.

CONCLUSIONS

This study focused on obtaining baseline information of the vascular plant flora and vegetation in the form of compiled vascular plant species checklists and vegetation maps of the Sisters’ Islands. The compilation from past records and recent field surveys of both islands recorded 144 vascular plant species from 59 families, of which 90 are native and 32 are nationally threatened, i.e., Critically Endangered (10 spp.), Endangered (8 spp.), and Vulnerable (14 spp.). The islands host populations of several nationally threatened species, such as the Critically Endangered Podocarpus polystachyus, and the Endangered Memecylon edule and Symplocos adenophylla. The terrestrial areas are covered by nationally rare natural habitats such as coastal forest, sandy beach, and rocky shores.

ACKNOWLEDGEMENTS

We would like to express our gratitude to Serena Lee of the Singapore Botanic Gardens’ Herbarium (SING), and Chua Keng Soon of the Herbarium, Lee Kong Chian Natural History Museum, National University of Singapore (SINU) for supplying us with the herbarium records of the islands’ flora. We would also like to thank the National Parks Board for permission to access and make collections on the islands (permit no. NP/RP14-081), and Neo Mei Lin for additional information. Assistance from all the volunteers during fieldwork is also gratefully acknowledged.

LITERATURE CITED

Chong KY, Tan HTW & Corlett RT (2009) A Checklist of the Total Vascular Plant Flora of Singapore: Native, Naturalised and Cultivated Species. Raffles Museum of Biodiversity Research, National University of Singapore, Singapore, 273 pp. Uploaded 12 November 2009. http://lkcnhm.nus.edu.sg/nus/pdf/PUBLICATION/LKCNH%20Museum%20Books/LKCNHM%20Books/flora_of_ singapore_tc.pdf (Accessed 26 May 2015). ESRI Inc. (2009) ArcGIS®9 ArcMap™ Version 9.3.1. ESRI Inc., California. Google Inc. (2013) Google Earth 7.1.2.2041. Google Inc., California. Koh LP, Sodhi NS, Tan HTW & Peh KS-H (2002) Factors affecting the distribution of vascular plants, springtails, butterflies and birds on small tropical islands. Journal of Biography, 29: 93–108. Lim SC, Tun K & Goh E (2012) Rediscovery of the Neptune’s cup sponge in Singapore: Cliona or Poterion? Contributions to Marine Science 2012, 49–56. Ministry of Culture (1971) Singapore Facts and Pictures 1971. Ministry of Culture, Singapore, 115 pp. Tan HTW, Tan K-x, Ali bin Ibrahim, Chew PT, Chua KS, Duistermaat H, Ganesan SK, Goh MWK, Gwee AT, Kiew R, Lee SML, Leong P, Lim J, Lok AFSL, Loo AHB, Lum SKY, Morgany T, Saifuddin bin Suran, Sim S, Haji Samsuri bin Haji Ahmad, Wee YC, Yap KF, Yeo CK & Yong JWH (2008) Checklists of Threatened Species―Seed Plants. In: Davison GWH, Ng PKL & Ho HC (eds.) The Singapore Red Data Book: Threatened Plants & Animals of Singapore. 2nd Edition. The Nature Society (Singapore), Singapore. Pp. 213–244. Tan R (2008) Wild fact sheets. Sea Teak, Podocarpus polystachyus, Family Podocarpaceae. http://www.wildsingapore.com/wildfacts/plants/coastal/podocarpus/polystachyus.htm (Accessed on 30 March 2015). Teo AXY (2012) Ecology of Alstonia macrophylla: A potentially invasive tree in Singapore. B.Sc. Honours’ thesis, Department of Biological Sciences, National University of Singapore, Singapore, 70 pp. The Plant List (2013) A Working List of All Plant Species. Version 1.1. http://www.theplantlist.org/ (Accessed August 2014 to March 2015).

13 Hung et al.: The Vascular Plant Flora and Vegetation of the Sisters’ Islands

Urban Redevelopment Authority (URA), Singapore (2014) Parks and Waterbodies Plan. http://www.ura.gov.sg/maps/index.html?service=PWB. Urban Redevelopment Authority, Singapore. Last updated 28 August 2014. (Accessed 7 September 2014). Zhong OY, Choo SY & Fok WK (2001) Propagation of Endangered Sea Teak, Podocarpus polystachyus R.Br. ex Endl. (Podocarpaceae). Final-Year Project thesis, School of Chemical and Life Sciences, Singapore Polytechnic, Singapore,73 pp.

14 NATURE IN SINGAPORE 2017

APPENDIX 1

This is a checklist of all the vascular plants present (+) and absent (–) on the two Sisters’ Islands, divided into sections for ferns, gymnosperms, and angiosperms.

Status categories: CA = casual; CO = cultivated only; CR = Critically Endangered; CW = cryptogenic weed; EN = Endangered; NA = naturalised; NE = Presumed Nationally Extinct; NT = not threatened; VU = Vulnerable; UA = unassessed

Islands: BSI = Big Sister’s Island; SSI = Small Sister’s Island

S/No. Fern Species Family Status BSI SSI 1. Adiantum latifolium Lam. Pteridaceae NA − + 2. Asplenium nidus L. Aspleniaceae NT + + 3. Davallia denticulata (Burm.f.) Mett. ex Kuhn Davalliaceae NT − + 4. Dicranopteris linearis (Burm.f.) Underw. Gleicheniaceae NT + + 5. Lindsaea ensifolia Sw. Lindsaeaceae NT − + 6. Lygodium flexuosum (L.) Sw. Lygodiaceae NT − + 7. Lygodium longifolium (Willd.) Sw. Lygodiaceae VU − + 8. Lygodium microphyllum (Cav.) R.Br. Lygodiaceae NT − + 9. Microlepia speluncae (L.) T.Moore Dennstaedtiaceae NT − + 10. Nephrolepis biserrata (Sw.) Schott Nephrolepidaceae CW − + 11. Phymatosorus scolopendria (Burm.f.) Pic.Serm. Polypodiaceae NT − + 12. Pityrogramma calomelanos (L.) Link Pteridaceae NA − + 13. Pteris ensiformis Burm.f. Pteridaceae CW − + 14. Pteris semipinnata L. Pteridaceae VU + + 15. Pyrrosia longifolia (Burm.f.) C.V.Morton Polypodiaceae NT − + 16. Pyrrosia piloselloides (L.) M.G.Price Polypodiaceae NT − + 17. Stenochlaena palustris (Burm. f.) Bedd. Blechnaceae NT − + 18. Taenitis blechnoides (Willd.) Sw. Pteridaceae NT − +

S/No. Gymnosperm Species Family Status BSI SSI 1. Dacrycarpus imbricatus (Blume) de Laub. Podocarpaceae CO + − 2. Podocarpus polystachyus R.Br. ex Endl. Podocarpaceae CR + +

S/No. Angiosperm Species Family Status BSI SSI 1. Adenanthera pavonina L. Leguminosae NA + − 2. Adinandra dumosa Jack Pentaphylacaceae NT + − 3. Alstonia macrophylla Wall. ex G.Don Apocynaceae NA + + 4. Alysicarpus vaginalis (L.) DC. Leguminosae CW + − 5. Alyxia reinwardtii Blume Apocynaceae NT + + 6. Ardisia elliptica Thunb. Primulaceae EN + − 7. Asystasia gangetica (L.) T.Anderson subsp. gangetica Acanthaceae NA + + 8. Asystasia gangetica (L.) T.Anderson subsp. micrantha (Nees) Acanthaceae NA − + Ensermu 9. Axonopus compressus (Sw.) P.Beauv. Poaceae NA + + 10. Azadirachta indica A.Juss. Meliaceae CA + + 11. Barringtonia asiatica (L.) Kurz Lecythidaceae CR + − 12. Calophyllum inophyllum L. Clusiaceae CR + + 13. Cassytha filiformis L. Lauraceae NT + − 14. Casuarina equisetifolia L. Casuarinaceae NT + +

15 Hung et al.: The Vascular Plant Flora and Vegetation of the Sisters’ Islands

S/No. Angiosperm Species Family Status BSI SSI 15. Cereus repandus (L.) Mill. Cactaceae CA + − 16. Chrysopogon aciculatus (Retz.) Trin. Poaceae NT − + 17. Cissus hastata Miq. Vitaceae NT − + 18. Claoxylon indicum (Reinw. ex Blume) Hassk. Euphorbiaceae NT + − 19. Clidemia hirta (L.) D.Don Melastomataceae NA − + 20. Cocos nucifera L. Arecaceae NA + − 21. Commelina diffusa Burm.f. Commelinaceae CW − + 22. Commersonia bartramia (L.) Merr. Malvaceae NT + − 23. Cyanthillium cinereum (L.) H.Rob. Compositae CW − + 24. Dactyloctenium aegyptium (L.) Willd. Poaceae NT + + 25. Dalbergia candenatensis (Dennst.) Prain Leguminosae NT + − 26. Delonix regia (Hook.) Raf. Leguminosae CO + + 27. Dendrolobium umbellatum (L.) Benth. Leguminosae NT + − 28. Derris trifoliata Lour. Leguminosae NT + + 29. Dianella ensifolia (L.) DC. Xanthorrhoeaceae NT + + 30. Digitaria mollicoma (Kunth) Henrard Poaceae NT + − 31. Digitaria setigera Roth Poaceae CW + − 32. Dischidia major (Vahl) Merr. Apocynaceae NT + + 33. Dischidia nummularia R.Br. Apocynaceae NT − + 34. Elaeis guineensis Jacq. Arecaceae CA + − 35. Emilia sonchifolia (L.) DC. ex DC. Compositae CW − + 36. Eragrostis amabilis (L.) Wight & Arn. Poaceae CW − + 37. Euphorbia hirta L. Euphorbiaceae NA − + 38. Eurycoma longifolia Jack Simaroubaceae CR + + 39. Fagraea auriculata Jack Gentianaceae CR − + 40. Fagraea fragrans Roxb. Gentianaceae NT + + 41. Falcataria moluccana (Miq.) Barneby & J.W.Grimes Leguminosae NA + − 42. Ficus benjamina L. Moraceae CW + − 43. Ficus grossularioides Burm.f. Moraceae NT + − 44. Ficus microcarpa L.f. Moraceae NT + + 45. Ficus punctata Thunb. Moraceae NT + − 46. Ficus superba Miq. Moraceae EN + + 47. Ficus virens Aiton Moraceae CR − + 48. Garcinia cymosa (K.Schum.) I.M.Turner & P.F.Stevens Clusiaceae CO + − 49. Guettarda speciosa L. Rubiaceae EN + − 50. Guioa pleuropteris (Blume) Radlk. Sapindaceae VU + + 51. Guioa pubescens (Zoll. & Moritzi) Radlk. Sapindaceae VU + − 52. Gynochthodes sublanceolata Miq. Rubiaceae NT + + 53. Hoya verticillata (Vahl) G.Don Apocynaceae NT − + 54. Ipomoea pes−caprae (L.) R.Br. Convolvulaceae NT − + 55. Jatropha curcas L. Euphorbiaceae CO − + 56. Kyllinga nemoralis (J.R.Forst. & G.Forst.) Dandy ex Hutch. & Cyperaceae CW + + Dalziel 57. Lepturus repens (J.R.Forst.) R.Br. Poaceae NT + + 58. Licuala spinosa Wurmb Arecaceae VU + − 59. Lindernia ruellioides (Colsm.) Pennell Linderniaceae CW + − 60. Macaranga heynei I.M.Johnst. Euphorbiaceae NT + −

16 NATURE IN SINGAPORE 2017

S/No. Angiosperm Species Family Status BSI SSI 61. Macrosolen retusus Blume Loranthaceae NT + − 62. Melastoma malabathricum L. Melastomataceae NT + − 63. Memecylon edule Roxb. Melastomataceae EN + + 64. Mikania micrantha Kunth Compositae NA − + 65. Mimosa pudica L. Leguminosae NA + + 66. Morinda citrifolia L. Rubiaceae CW + − 67. Morinda umbellata L. Rubiaceae NT + + 68. Muntingia calabura L. Muntingiaceae NA + − 69. Myrica esculenta Buch.−Ham. ex D.Don Myricaceae NT + + 70. Nepenthes gracilis Korth. Nepenthaceae NT + − 71. Nepenthes rafflesiana Jack Nepenthaceae VU + − 72. Oldenlandia biflora L. Rubiaceae CW + + 73. Oldenlandia corymbosa L. Rubiaceae CW + − 74. Oxalis barrelieri L. Oxalidaceae NA + − 75. Oxalis corniculata L. Oxalidaceae NA + + 76. Palaquium obovatum (Griff.) Engl. Sapotaceae VU + − 77. Pandanus odorifer (Forssk.) Kuntze Pandanaceae NT + − 78. Passiflora laurifolia L. Passifloraceae NA + − 79. Passiflora suberosa L. Passifloraceae NA + + 80. Peltophorum pterocarpum (DC.) K.Heyne Leguminosae CR + + 81. Peperomia pellucida (L.) Kunth Piperaceae NA + − 82. Phyllanthus debilis Klein ex Willd. Phyllanthaceae NA − + 83. Pittosporum ferrugineum W.T.Aiton Pittosporaceae VU + − 84. Planchonella obovata (R.Br.) Pierre Sapotaceae VU + + 85. Polyscias diversifolia (Blume) Lowry & G.M.Plunkett Araliaceae NT + + 86. Pongamia pinnata (L.) Pierre Leguminosae EN + − 87. Premna serratifolia L. Lamiaceae VU − + 88. Rapanea porteriana (Wall. & A.DC.) Mez Primulaceae VU + + 89. Rhizophora stylosa Griff. Rhizophoraceae VU + − 90. Rhodamnia cinerea Jack Myrtaceae NT + − 91. Rhodomyrtus tomentosa (Aiton) Hassk. Myrtaceae NT + − 92. Rhynchospora colorata (L.) H.Pfeiff. Cyperaceae CW − + 93. Sauropus bacciformis (L.) Airy Shaw Phyllanthaceae CR − + 94. Scaevola taccada (Gaertn.) Roxb. Goodeniaceae NT + + 95. Scleria levis Retz. Cyperaceae CW − + 96. Scyphiphora hydrophylacea C.F.Gaertn. Rubiaceae NT − + 97. Senna sulfurea (Collad.) H.S.Irwin & Barneby Leguminosae CO + − 98. Sesuvium portulacastrum (L.) L. Aizoaceae NT − + 99. Sida acuta Burm.f. Malvaceae CW − + 100. Sida cordifolia L. Malvaceae NT + – 101. Sida rhombifolia L. Malvaceae CW + − 102. Spermacoce exilis (L.O.Williams) C.D.Adams ex W.C.Burger & Rubiaceae CW − + C.M.Taylor 103. Spermacoce ocymoides Burm.f. Rubiaceae NA + + 104. Spermacoce setidens (Miq.) Boerl. Rubiaceae CW + − 105. Sphagneticola trilobata (L.) Pruski Compositae NA − + 106. Symplocos adenophylla Wall. ex G.Don Symplocaceae EN + − 107. Synedrella nodiflora (L.) Gaertn. Compositae NA − +

17 Hung et al.: The Vascular Plant Flora and Vegetation of the Sisters’ Islands

S/No. Angiosperm Species Family Status BSI SSI 108. Syzygium claviflorum (Roxb.) Wall. ex A.M.Cowan & Cowan Myrtaceae CR + − 109. Syzygium palembanicum Miq. Myrtaceae VU + − 110. Syzygium polyanthum (Wight) Walp. Myrtaceae VU + + 111. Syzygium zeylanicum (L.) DC. Myrtaceae NT + + 112. Talipariti tiliaceum (L.) Fryxell Malvaceae NT + + 113. Tamarindus indica L. Leguminosae CA − + 114. Tarenna fragrans (Blume) Koord. & Valeton Rubiaceae EN + + 115. Terminalia catappa L. Combretaceae NT + + 116. Tetracera indica (Christm. & Panz.) Merr. Dilleniaceae NT + + 117. Thespesia populnea (L.) Sol. ex Corrêa Malvaceae NT + − 118. Thuarea involuta (G.Forst.) R.Br. ex Sm. Poaceae NT − + 119. Tridax procumbens (L.) L. Compositae NA − + 120. Tristaniopsis obovata (Benn.) Peter G.Wilson & J.T.Waterh. Myrtaceae CR + + 121. Tristaniopsis whiteana (Griff.) Peter G.Wilson & J.T.Waterh. Myrtaceae EN − + 122. Vitex pinnata L. Lamiaceae NT + + 123. Youngia japonica (L.) DC. Compositae NA − + 124. Zoysia matrella (L.) Merr. Poaceae NT − +

18 NATURE IN SINGAPORE 2017

APPENDIX 2

Individual checklists of all the vascular plants present on Small Sister’s Island and Big Sister’s Island compiled based on findings from the present floristic surveys, as well as data from previous floristic surveys by H. T. W. Tan et al. (unpublished data), Koh et al. (2002), and the herbarium records of the Singapore Botanic Gardens’ Herbarium (SING) and Herbarium, Lee Kong Chian Natural History Museum, Faculty of Science, National University of Singapore (SINU).

Status categories: CA = casual; CO = cultivated only; CR = Critically Endangered; CW = cryptogenic weed; EN = Endangered; NA = naturalised; NE = Presumed Nationally Extinct; NT = not threatened; VU = Vulnerable; UA = unassessed

Small Sister’s Island Previous records 2014/ S/No. Fern species Family Status SING SINU HTTW Koh 2015 1. Adiantum latifolium Lam. Pteridaceae NA – – – – + 2. Asplenium nidus L. Aspleniaceae NT – – – – + 3. Davallia denticulata (Burm. f.) Mett. ex Davalliaceae NT – – – – + Kuhn 4. Dicranopteris linearis (Burm. f.) Gleicheniaceae NT – – – + + Underw. 5. Lindsaea ensifolia Sw. Lindsaeaceae NT – – – + – 6. Lygodium flexuosum (L.) Sw. Lygodiaceae NT – – – + – 7. Lygodium longifolium (Willd.) Sw. Lygodiaceae VU – – – – + 8. Lygodium microphyllum (Cav.) R. Br. Lygodiaceae NT – – – – + 9. Microlepia speluncae (L.) T. Moore Dennstaedtiaceae NT – – – – + 10. Nephrolepis biserrata (Sw.) Schott Nephrolepidaceae CW – – – – + 11. Phymatosorus scolopendria (Burm. f.) Polypodiaceae NT + – – – – Pic. Serm. 12. Pityrogramma calomelanos (L.) Link Pteridaceae NA – – – + – 13. Pteris ensiformis Burm. f. Pteridaceae CW – – – – + 14. Pteris semipinnata L. Pteridaceae VU – – – – + 15. Pyrrosia longifolia (Burm. f.) C.V. Polypodiaceae NT – – – – + Morton 16. Pyrrosia piloselloides (L.) M.G. Price Polypodiaceae NT – – – – + 17. Stenochlaena palustris (Burm. f.) Bedd. Blechnaceae NT – – – – + 18. Taenitis blechnoides (Willd.) Sw. Pteridaceae NT – – – + –

Previous records 2014/ S/No. Gymnosperm species Family Status SING SINU HTTW Koh 2015 1. Podocarpus polystachyus R.Br. ex Endl. Podocarpaceae CR – – – – +

Previous records 2014/ S/No. Angiosperm species Family Status SING SINU HTTW Koh 2015 1. Alstonia macrophylla Wall. ex G.Don Apocynaceae NA – + + + + 2. Alyxia reinwardtii Blume Apocynaceae NT – + + – + 3. Asystasia gangetica (L.) T.Anderson Acanthaceae NA – – – + + 4. Asystasia nemorum Nees Acanthaceae UA – + + – – 5. Axonopus compressus (Sw.) P.Beauv. Poaceae NA – – – + – 6. Azadirachta indica A.Juss. Meliaceae CA – – – – + 7. Calophyllum inophyllum L. Clusiaceae CR – + + – – 8. Casuarina equisetifolia L. Casuarinaceae NT – + + + + 9. Chrysopogon aciculatus (Retz.) Trin. Poaceae NT – + – – – 10. Cissus hastata Miq. Vitaceae NT – – – – + 11. Clidemia hirta (L.) D. Don Melastomataceae NA – – – – + 12. Commelina diffusa Burm.f. Commelinaceae CW – + – – – 13. Cyanthillium cinereum (L.) H.Rob. Compositae CW – + + – – 14. Dactyloctenium aegyptium (L.) Willd. Poaceae NT – + – + – 15. Delonix regia (Hook.) Raf. Leguminosae CO – + + – + 16. Derris trifoliata Lour. Leguminosae NT – – – – + 17. Dianella ensifolia (L.) DC. Xanthorrhoeaceae NT – – – + + 18. Dischidia major (Vahl) Merr. Apocynaceae NT – + + + –

19 Hung et al.: The Vascular Plant Flora and Vegetation of the Sisters’ Islands

Previous records 2014/ S/No. Angiosperm species Family Status SING SINU HTTW Koh 2015 19. Dischidia nummularia R.Br. Apocynaceae NT – + – – – 20. Emilia sonchifolia (L.) DC. ex DC. Compositae CW – + + – – 21. Eragrostis amabilis (L.) Wight & Arn. Poaceae CW – + – – – 22. Euphorbia hirta L. Euphorbiaceae NA – + + – – 23. Eurycoma longifolia Jack Simaroubaceae CR + + – + + 24. Fagraea auriculata Jack Gentianaceae CR – – – + – 25. Fagraea fragrans Roxb. Gentianaceae NT – + – – – 26. Ficus microcarpa L.f. Moraceae NT – – – – + 27. Ficus superba Miq. Moraceae EN – – – – + 28. Ficus virens Aiton Moraceae CR – – – – + 29. Guioa pleuropteris (Blume) Radlk. Sapindaceae VU + – – + + 30. Gynochthodes sublanceolata Miq. Rubiaceae NT – + – – – 31. Hoya parasitica Wall. ex Traill Apocynaceae NT – + – – – 32. Hoya verticillata (Vahl) G. Don Apocynaceae NT – – + – + 33. Ipomoea pes–caprae (L.) R. Br. Convolvulaceae NT – + + – + 34. Jatropha curcas L. Euphorbiaceae CO – – + – – 35. Kyllinga nemoralis (J.R.Forst. & Cyperaceae CW – + – + – G.Forst.) Dandy ex Hutch. & Dalziel 36. Lepturus repens (J.R.Forst.) R.Br. Poaceae NT + – – – – 37. Memecylon edule Roxb. Melastomataceae EN – – – + + 38. Mikania micrantha Kunth Compositae NA – – – – + 39. Mimosa pudica L. Leguminosae NA – + + + – 40. Morinda umbellata L. Rubiaceae NT – – – + + 41. Myrica esculenta Buch.–Ham. ex D. Myricaceae NT – + – – – Don 42. Oldenlandia biflora L. Rubiaceae CW – + – – – 43. Oxalis corniculata L. Oxalidaceae NA – + – + – 44. Passiflora suberosa L. Passifloraceae NA – – – – + 45. Peltophorum pterocarpum (DC.) Leguminosae CR – + + – + K.Heyne 46. Phyllanthus debilis Klein ex Willd. Phyllanthaceae NA – + + – – 47. Planchonella obovata (R.Br.) Pierre Sapotaceae VU – – – – + 48. Polyscias diversifolia (Blume) Lowry & Araliaceae NT – + + – – G.M.Plunkett 49. Premna serratifolia L. Lamiaceae VU + – – – + 50. Rapanea porteriana (Wall. & A. DC.) Primulaceae VU – – – – + Mez 51. Rhynchospora colorata (L.) H.Pfeiff. Cyperaceae UA – + – – – 52. Sauropus bacciformis (L.) Airy Shaw Phyllanthaceae CR – + – – – 53. Scaevola taccada (Gaertn.) Roxb. Goodeniaceae NT – + + – – 54. Scleria levis Retz. Cyperaceae CW – + – – – 55. Scyphiphora hydrophylacea C.F.Gaertn. Rubiaceae NT – + – – – 56. Sesuvium portulacastrum (L.) L. Aizoaceae NT – + + – – 57. Sida acuta Burm.f. Malvaceae CW – + – + – 58. Spermacoce exilis (L.O.Williams) Rubiaceae CW – + – + – C.D.Adams ex W.C.Burger & C.M.Taylor 59. Spermacoce ocymoides Burm.f. Rubiaceae NA – + – – – 60. Sphagneticola trilobata (L.) Pruski Compositae NA – + + – – 61. Synedrella nodiflora (L.) Gaertn. Compositae NA – + + – – 62. Syzygium polyanthum (Wight) Walp. Myrtaceae VU – + – – + 63. Syzygium zeylanicum (L.) DC. Myrtaceae NT – + – + + 64. Talipariti tiliaceum (L.) Fryxell Malvaceae NT – + – – – 65. Tamarindus indica L. Leguminosae CA – + + – + 66. Tarenna fragrans (Blume) Koord. & Rubiaceae EN – – – – + Valeton 67. Terminalia catappa L. Combretaceae NT – + + – + 68. Tetracera indica (Christm. & Panz.) Dilleniaceae NT – + + + – Merr.

20 NATURE IN SINGAPORE 2017

Previous records 2014/ S/No. Angiosperm species Family Status SING SINU HTTW Koh 2015 69. Thuarea involuta (G.Forst.) R.Br. ex Poaceae NT + – – – – Sm. 70. Tridax procumbens (L.) L. Compositae NA – + + – – 71. Tristaniopsis obovata (Benn.) Peter Myrtaceae CR – – – + – G.Wilson & J.T.Waterh. 72. Tristaniopsis whiteana (Griff.) Peter Myrtaceae EN + + – – + G.Wilson & J.T.Waterh. 73. Vitex pinnata L. Lamiaceae NT – – – – + 74. Youngia japonica (L.) DC. Compositae NA – + + – – 75. Zoysia matrella (L.) Merr. Poaceae NT – + – – –

21 Hung et al.: The Vascular Plant Flora and Vegetation of the Sisters’ Islands

Big Sister’s Island Previous records 2014/ S/No. Fern species Family Status SING SINU HTTW Koh 2015 1. Asplenium nidus L. Aspleniaceae NT – – – – + 2. Dicranopteris linearis (Burm. f.) Gleicheniaceae NT – – – – + Underw. 3. Pteris semipinnata L. Pteridaceae VU – – – – +

Previous records 2014/ S/No. Gymnosperm species Family Status SING SINU HTTW Koh 2015 1. Dacrycarpus imbricatus (Blume) de Podocarpaceae CO + – – – – Laub. 2. Podocarpus polystachyus R.Br. ex Podocarpaceae CR – – – – + Endl.

Previous records 2014/ S/No. Angiosperm species Family Status SING SINU HTTW Koh 2015 1. Adenanthera pavonina L. Leguminosae NA – + – – + 2. Adinandra dumosa Jack Pentaphylacaceae NT – + – – – 3. Alstonia macrophylla Wall. ex G.Don Apocynaceae NA – – – – + 4. Alysicarpus vaginalis (L.) DC. Leguminosae CW – + – – – 5. Alyxia reinwardtii Blume Apocynaceae NT – – – – + 6. Ardisia elliptica Thunb. Primulaceae EN – + – – – 7. Asystasia gangetica (L.) T.Anderson Acanthaceae NA – + – – + 8. Axonopus compressus (Sw.) P.Beauv. Poaceae NA – + – – – 9. Azadirachta indica A.Juss. Meliaceae CA – + – – + 10. Barringtonia asiatica (L.) Kurz Lecythidaceae CR – – – – + 11. Calophyllum inophyllum L. Clusiaceae CR – – – – + 12. Cassytha filiformis L. Lauraceae NT – – – – + 13. Casuarina equisetifolia L. Casuarinaceae NT – – – – + 14. Cereus repandus (L.) Mill. Cactaceae UA + – – – – 15. Claoxylon indicum (Reinw. ex Euphorbiaceae NT – – – – + Blume) Hassk. 16. Cocos nucifera L. Arecaceae NA – + – – + 17. Commersonia bartramia (L.) Merr. Malvaceae NT – + – – – 18. Dactyloctenium aegyptium (L.) Poaceae NT – + – – – Willd. 19. Dalbergia candenatensis (Dennst.) Leguminosae NT – + – – + Prain 20. Delonix regia (Hook.) Raf. Leguminosae CO – + – – – 21. Dendrolobium umbellatum (L.) Leguminosae NT – + – – + Benth. 22. Derris trifoliata Lour. Leguminosae NT – + – – + 23. Dianella ensifolia (L.) DC. Xanthorrhoeaceae NT – + – – + 24. Digitaria mollicoma (Kunth) Henrard Poaceae NT + – – – – 25. Digitaria setigera Roth Poaceae CW + – – – – 26. Dischidia major (Vahl) Merr. Apocynaceae NT – + – – – 27. Elaeis guineensis Jacq. Arecaceae CA – + – – – 28. Eurycoma longifolia Jack Simaroubaceae CR – + – – + 29. Fagraea fragrans Roxb. Gentianaceae NT – + – – + 30. Falcataria moluccana (Miq.) Leguminosae NA – + – – – Barneby & J.W.Grimes 31. Ficus benjamina L. Moraceae CW – + – – + 32. Ficus grossularioides Burm.f. Moraceae NT – + – – – 33. Ficus microcarpa L.f. Moraceae NT – – – – + 34. Ficus punctata Thunb. Moraceae NT – + – – + 35. Ficus superba Miq. Moraceae EN – + – – + 36. Garcinia cymosa (K.Schum.) Clusiaceae CO + – – – – I.M.Turner & P.F.Stevens 37. Guettarda speciosa L. Rubiaceae EN – – – – + 38. Guioa pleuropteris (Blume) Radlk. Sapindaceae VU – – – – + 39. Guioa pubescens (Zoll. & Moritzi) Sapindaceae VU – + – – – Radlk.

22 NATURE IN SINGAPORE 2017

Previous records 2014/ S/No. Angiosperm species Family Status SING SINU HTTW Koh 2015 40. Gynochthodes sublanceolata Miq. Rubiaceae NT + + – – + 41. Kyllinga nemoralis (J.R.Forst. & Cyperaceae CW – + – – – G.Forst.) Dandy ex Hutch. & Dalziel 42. Lepturus repens (J.R.Forst.) R.Br. Poaceae NT + – – – – 43. Licuala spinosa Wurmb Arecaceae VU – + – – – 44. Lindernia ruellioides (Colsm.) Linderniaceae CW – + – – – Pennell 45. Macaranga heynei I.M.Johnst. Euphorbiaceae NT – – – – + 46. Macrosolen retusus Blume Loranthaceae NT + – – – – 47. Melastoma malabathricum L. Melastomataceae NT – + – – – 48. Memecylon edule Roxb. Melastomataceae EN + + – – + 49. Mimosa pudica L. Leguminosae NA – + – – + 50. Morinda citrifolia L. Rubiaceae CW – + – – + 51. Morinda umbellata L. Rubiaceae NT – + – – + 52. Muntingia calabura L. Muntingiaceae NA – – – – + 53. Myrica esculenta Buch.–Ham. ex D. Myricaceae NT – + – – – Don 54. Nepenthes gracilis Korth. Nepenthaceae NT – + – – – 55. Nepenthes rafflesiana Jack Nepenthaceae VU – + – – – 56. Oldenlandia biflora L. Rubiaceae CW – + – – – 57. Oldenlandia corymbosa L. Rubiaceae CW – + – – – 58. Oxalis barrelieri L. Oxalidaceae NA – + – – – 59. Oxalis corniculata L. Oxalidaceae NA – + – – – 60. Palaquium obovatum (Griff.) Engl. Sapotaceae VU – + – – – 61. Pandanus odorifer (Forssk.) Kuntze Pandanaceae NT – + – – + 62. Passiflora laurifolia L. Passifloraceae NA – – – – + 63. Passiflora suberosa L. Passifloraceae NA – + – – + 64. Peltophorum pterocarpum (DC.) Leguminosae CR – – – – + K.Heyne 65. Peperomia pellucida (L.) Kunth Piperaceae NA – + – – – 66. Pittosporum ferrugineum W.T.Aiton Pittosporaceae VU – + – – + 67. Planchonella obovata (R.Br.) Pierre Sapotaceae VU – + – – + 68. Polyscias diversifolia (Blume) Lowry Araliaceae NT – – – – + & G.M.Plunkett 69. Pongamia pinnata (L.) Pierre Leguminosae EN – + – – + 70. Rapanea porteriana (Wall. & A. Primulaceae VU + + – – + DC.) Mez 71. Rhizophora stylosa Griff. Rhizophoraceae VU + – – – – 72. Rhodamnia cinerea Jack Myrtaceae NT – – – – + 73. Rhodomyrtus tomentosa (Aiton) Myrtaceae NT – + – – – Hassk. 74. Scaevola taccada (Gaertn.) Roxb. Goodeniaceae NT – – – – + 75. Senna sulfurea (Collad.) H.S.Irwin & Leguminosae CO – + – – – Barneby 76. Sida mysorensis Wight & Arn. Malvaceae UA – + – – – 77. Sida rhombifolia L. Malvaceae CW – + – – – 78. Spermacoce ocymoides Burm.f. Rubiaceae NA – + – – – 79. Spermacoce setidens (Miq.) Boerl. Rubiaceae CW – + – – – 80. Symplocos adenophylla Wall. ex G. Symplocaceae EN – + – – + Don 81. Syzygium claviflorum (Roxb.) Wall. Myrtaceae CR – + – – + ex A.M.Cowan & Cowan 82. Syzygium palembanicum Miq. Myrtaceae VU + – – – + 83. Syzygium polyanthum (Wight) Walp. Myrtaceae VU – – – – + 84. Syzygium zeylanicum (L.) DC. Myrtaceae NT – + – – + 85. Talipariti tiliaceum (L.) Fryxell Malvaceae NT – + – – + 86. Tarenna fragrans (Blume) Koord. & Rubiaceae EN + + – – + Valeton 87. Terminalia catappa L. Combretaceae NT – – – – + 88. Tetracera indica (Christm. & Panz.) Dilleniaceae NT – + – – + Merr.

23 Hung et al.: The Vascular Plant Flora and Vegetation of the Sisters’ Islands

Previous records 2014/ S/No. Angiosperm species Family Status SING SINU HTTW Koh 2015 89. Thespesia populnea (L.) Sol. ex Malvaceae NT – + – – – Corrêa 90. Tristaniopsis obovata (Benn.) Peter Myrtaceae CR – + – – – G.Wilson & J.T.Waterh. 91. Vitex pinnata L. Lamiaceae NT – + – – +

24 NATURE IN SINGAPORE 2017 10: 25–35 Date of Publication: 29 May 2017 © National University of Singapore

The vascular plant flora and vegetation of the islands associated with Singapore’s first Marine Park (II): Pulau Tekukor

Sherry M. X. Hung*, K. Y. Chong, Alex T. K. Yee, Reuben C. J. Lim, Jolyn W. Loh, Louise Neo, W. W. Seah, S. Y. Tan and Hugh T. W. Tan

Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Republic of Singapore; Email: [email protected] (*corresponding author)

Abstract. Pulau Tekukor has 151 vascular plant species from 61 families, of which 86 species are native, 44 are non- native, and 21 are cryptogenic weeds. The native species include one presumed nationally Extinct species, 10 nationally Critically Endangered species, four nationally Endangered species, seven nationally Vulnerable species, 63 species that are not nationally threatened, and one that has not been accessed. The 5.07-ha island consists of 4.01 ha of natural vegetation and 1.06 ha of other landscape features.

Key words. checklist, Pulau Tekukor, Marine Park, Singapore, vascular plants

INTRODUCTION

Pulau Tekukor (1°13′50.57″N, 103°50′16.07″E) is an island south of Singapore Island that used to be an ammunition storage site, and measures approximately 650 m long and 100 m wide. In 1980, reclamation projects at the western half of the island expanded it by 1.43 ha, from 3.64 ha to the current total land area of 5.07 ha (Ministry of Culture, 1971). Pulau Tekukor hosts a variety of natural habitats, such as rocky cliffs and sandy beaches (Fig. 1). It is also known to have healthy populations or large mature individuals of several locally rare plant species, such as Fagraea auriculata (Gentianaceae) and Tristaniopsis obovata (Myrtaceae) (Tan et al., 2007; Chong et al., 2009). A survey in 2005 found that the plant species richness on the island is relatively high, with approximately 110 species of vascular plants, of which at least 22 species are nationally threatened (Tan et al., 2007). While the southwestern coast of Pulau Tekukor will be conserved as part of the Marine Park, it is also necessary for the other terrestrial sites on the island with unique habitats or threatened species to be preserved as well. This study presents information on the vascular plant species found on Pulau Tekukor, and the vegetation types on the island. Such data will be useful in understanding the floristics and vegetation of the island for conservation purposes.

MATERIAL AND METHODS

A checklist of all the vascular plant species presently and previously found on Pulau Tekukor was compiled from four sources: present floristic surveys conducted in this study, previous floristic surveys by H. T. W. Tan et al. (unpublished data), and the herbarium records of the Singapore Botanic Gardens’ Herbarium (SING), and Herbarium, Lee Kong Chian Natural History Museum, Faculty of Science, National University of Singapore (SINU) (Appendix 1). All plant species names and their respective authorships were cross-checked with The Plant List (2013), an online plant species database. The national status of each species was retrieved from the Singapore Red Data Book (Tan et al., 2008) and the checklist of Singapore’s vascular plant flora by Chong et al. (2009).

A map illustrating the shoreline and vegetation types on Pulau Tekukor was drawn according to visual interpretation of two satellite images of 27 April 2007 and 22 April 2013 from Google Earth 7.1.2.2041 (Google Inc., 2013), at a map scale of 1:2000. Visual features of the vegetation types were used to aid classification. For example, natural forests have a dense canopy cover formed by large tree crowns, and appear as dark green vegetation on the satellite image. On the other hand, natural scrub areas appear lighter coloured owing to the less dense vegetation cover by smaller plants. The area of each vegetation type was then calculated using ArcGIS®9 ArcMap™ Version 9.3.1 (ESRI, 2009), with the World Geodetic System 1984 (WGS84) and Universal Transverse Mercator Coordinate System, Zone 48 North (UTM48N) projections.

Floristic surveys and ground truthing were conducted for all accessible areas on the island on two separate occasions on 5 November 2014 and 27 August 2015, with the aid of a Garmin GPSMap® 62S Global Positioning System (GPS) receiver, which records locations within ± 4 m of accuracy. The main objective of the floristic surveys was to verify and supplement the list of vascular plant species recorded from the previous surveys, with an emphasis on native species. Additionally, the geographic coordinates of nationally threatened plant species that were not widespread throughout the island were recorded using the GPS receiver, and the localities were indicated on the vegetation map. Plants that

25 Hung et al.: The Vascular Plant Flora and Vegetation of the Sisters’ Islands

Fig. 1. Natural coastal shoreline of Pulau Tekukor, showing a stretch of sandy beach, rocky shore, and a cliff covered by beach vegetation. (Photograph by: Sherry Hung Ming Xuan).

could not be identified with certainty in the field, or which were not previously documented in the records of SING and SINU, were collected as voucher specimens. These specimens were subsequently matched with identified specimens in SING and/or SINU.

OBSERVATIONS AND RESULTS

The vascular flora of Pulau Tekukor consists of one species of a fern ally (lycophyte), 15 species of ferns, and 135 species of angiosperms. In total, there are 151 species belonging to 61 families (Appendix 1). Out of these, 86 species (57.0%) are native, of which 22 species (14.6%) are threatened, meaning that they are nationally classified as presumed nationally Extinct, Critically Endangered, Endangered, or Vulnerable (Table 1; Fig. 2). There are 65 (43.0%) non-native or exotic species, but this figure may be an underestimate, as more attention was given to compiling the list of native species (Table 1; Fig. 2).

Within the natural forested area, an abundance of Tristaniopsis species (Myrtaceae) was found around the area marked as point 25 on the vegetation map (Fig. 3). As individuals could not be identified to species in the field, it was estimated that there are more than 20 mature individuals from the genus Tristaniopsis (Fig. 4A). Subsequent examination of the voucher specimens revealed that the Critically Endangered Tristaniopsis obovata and Endangered Tristaniopsis whiteana (Myrtaceae) are most likely the species that are highly abundant in the forest. Further north on a vertical cliff located within the coastal forest is a mature Fagraea auriculata tree, marked as point 6 on the vegetation map (Fig. 3). This is also a critically endangered species and several saplings were seen growing on the face of the cliff (Fig. 4B) and across the island.

Pulau Tekukor also hosts large populations of Nepenthes rafflesiana (Nepenthaceae), and one group of them was marked as point 13 on the vegetation map (Fig. 3). This vulnerable species was found to be widespread on the island, especially on the faces of the vertical cliffs exposed to strong winds from the sea that render the site only suitable for scrubby growth

26 NATURE IN SINGAPORE 2017

(Fig. 5A). The non-native species, Acacia auriculiformis (Leguminosae), is also relatively widespread on the island. This naturalised species was more common along the southwestern half of the island, around sites that had been subjected to human disturbance.

Table 1. National conservation status categories of the vascular flora of Pulau Tekukor. Status category Number of species Percentage of species Native species 86 57.0% Presumed nationally Extinct 1 0.7% Nationally Critically Endangered 10 6.6% Nationally Endangered 4 2.6% Nationally Vulnerable 7 4.6% Not nationally Threatened 63 41.7% Unassessed 1 0.7% Non-native species 44 29.1% Casual 4 2.6% Naturalised 30 19.9% Cultivated only 10 6.6% Cryptogenic weed species 21 13.9% Total 151 100.0%

Fig. 2. Pie chart illustrating the number and proportion of species that belong to each national conservation status category for Pulau Tekukor.

27 Hung et al.: The Vascular Plant Flora and Vegetation of the Sisters’ Islands

Pulau Tekukor is covered by mainly natural vegetation (4.01 ha, 79.1%; Table 2; Fig. 3).

Table 2. Area (ha) and proportion (%) for each vegetation type on Pulau Tekukor. Area (ha) Proportion (%) Natural vegetation 4.01 79.1 Coastal forest 1.70 33.5 Coastal scrub 2.31 45.6 Others 1.06 20.9 Bare ground 0.05 1.0 Built-up structures (buildings, roads) 1.01 19.9 Total 5.07 100.0

Fig. 3. Vegetation map of Pulau Tekukor. The numbers indicate the positions of individuals of non-widespread, nationally threatened species: 2 = Calophyllum inophyllum; 6 = Fagraea auriculata; 7 = Ficus kerkhovenii; 8 = Ficus superba; 13 = Nepenthes rafflesiana; 14 = Peltophorum pterocarpum; 16 = Planchonella obovata; 23 = Syzygium palembanicum; 25 = Tristaniopsis species.

28 NATURE IN SINGAPORE 2017

A B

Fig. 4. A, Two individuals of Tristaniopsis species found in abundance within the natural forested area. (Photograph by: Chong Kwek Yan); B, Several saplings of the Nationally Critically Endangered Fagraea auriculata growing on the face of the cliff below the mature tree. (Photograph by: Sherry Hung Ming Xuan).

DISCUSSION

There are many threatened species on the island, and as some of them have relatively large wild populations, attention should be paid to ensure the persistence of the native genetic stock. For example, several saplings of Fagraea auriculata, a Critically Endangered species, were found growing on a vertical cliff within the natural coastal forest of Pulau Tekukor (Fig. 4B), and this species may be propagated readily by air-layering. From our experience, it can also be easily propagated using root cuttings. Results from a study by Yeo et al. (2011) that examined the effectiveness of air-layering for the mass propagation of Fagraea auriculata revealed a high successful rooting rate, where 94.2% of the samples had signs of rooting, and rooted branches were subsequently planted at different sites in the Kent Ridge campus of the National University of Singapore (Yeo et al., 2011). Such experiments can be conducted on threatened species found on the islands in ex-situ conservation efforts. This strategy can be employed in the conservation of other species on the island, such as Rhodomyrtus tomentosa (Fig. 5B) and the highly abundant but threatened Tristaniopsis species. Further experiments can be conducted to examine the genetic variability of individuals in the wild populations and the native stock propagules, so that saplings can be harvested from an assemblage of genotypes. Resulting propagules would then be genetically diverse, thus increasing the species’ ability to adapt to changing environmental conditions (Reusch et al., 2005; Leger & Espeland, 2010).

As the demand increases for using plants of native provenance in horticultural landscaping, it is necessary for wild species populations to be conserved as sources of propagation. Doing so not only maintains a steady supply of native species available, but also ensures the long-term conservation of the species (Yeo et al., 2011). Therefore, a deeper understanding of the traits of threatened species and suitable propagation methods would enhance conservation efforts.

Readers should be aware that plants growing in such public parks maintained by the National Parks Board are protected. Any activities relating to “trees, plants, etc.” described in Section 8 of the Parks and Trees Act may not be conducted without permission from the Commissioner of Parks and Recreation (Tan & Tan, 2013).

29 Hung et al.: The Vascular Plant Flora and Vegetation of the Sisters’ Islands

A

B

Fig. 5. A, A large population of the nationally Vulnerable Nepenthes rafflesiana growing on the vertical face of the cliff facing the sea; B, A large shrub of Rhodomyrtus tomentosa along the road. (Photographs by: Chong Kwek Yan).

30 NATURE IN SINGAPORE 2017

CONCLUSIONS

The compilation from past records and recent field surveys found 151 vascular plant species belonging to 61 families, of which 86 species are native. Out of these, 22 species are threatened, i.e. presumed nationally Extinct (one species), nationally Critically Endangered (10 species), nationally Endangered (four species) and nationally Vulnerable (seven species). The locations of these threatened species and vegetation were also mapped. The island hosts several large populations of threatened species, such as Fagraea auriculata and Tristaniopsis species, and rare habitats such as coastal forest and coastal scrub (79.1% of total land area), as well as sandy beach and rocky shores. Several of the threatened species found on the island are potential sources of native propagules for conservation and reforestation.

ACKNOWLEDGEMENTS

We would like to express our gratitude to Serena Lee of the Singapore Botanic Gardens’ Herbarium (SING) and Chua Keng Soon of the Herbarium, Lee Kong Chian Natural History Museum, National University of Singapore (SINU) for supplying us with the herbarium records of the island’s flora, and the National Parks Board for granting us permits for collections on the islands (permit no. NP/RP14-081). We thank Karenne Tun, Collin Tong, and Koh Kwan Siong for discussion and advice, and Lam Weng Ngai for his help in obtaining the GPS coordinates for Ficus kerkhovenii.

LITERATURE CITED

Chong KY, Tan HTW & Corlett RT (2009) A Checklist of the Total Vascular Plant Flora of Singapore: Native, Naturalised and Cultivated Species. Raffles Museum of Biodiversity Research, National University of Singapore, Singapore, 273 pp. Uploaded 12 November 2009. http://lkcnhm.nus.edu.sg/nus/pdf/PUBLICATION/LKCNH%20Museum%20Books/LKCNHM%20Books/flora_of_ singapore_tc.pdf. (Accessed 14 October 2016). ESRI Inc. (2009) ArcGIS®9 ArcMap™ Version 9.3.1. ESRI Inc., California. Google Inc. (2013) Google Earth 7.1.2.2041. Google Inc., California. Leger EA & Espeland EK (2010) Coevolution between native and invasive plant competitors: Implications for invasive species management. Evolutionary Applications, 3: 169–178. Ministry of Culture (1971) Singapore Facts and Pictures 1971. Ministry of Culture, Singapore, 115 pp. Reusch TBH, Ehlers A, Hammerli A & Worm B (2005) Ecosystem recovery after climatic extremes enhanced by genotypic diversity. Proceedings of the National Academy of Sciences of the United States of America, 102: 2826– 2831. Tan HTW, Morgany T, Lim SW & Tan KW (2007) Pulau Tekukor. Nature Watch, 15: 10–16. Tan HTW, Tan K-x, Ali bin Ibrahim, Chew PT, Chua KS, Duistermaat H, Ganesan SK, Goh MWK, Gwee AT, Kiew R, Lee SML, Leong P, Lim J, Lok AFSL, Loo AHB, Lum SKY, Morgany T, Saifuddin bin Suran, Sim S, Haji Samsuri bin Haji Ahmad, Wee YC, Yap KF, Yeo CK & Yong JWH (2008) Checklists of threatened species―Seed plants. In: Davison GWH, Ng PKL & Ho HC (eds.) The Singapore Red Data Book: Threatened Plants & Animals of Singapore. 2nd Edition. Nature Society (Singapore), Singapore. Pp. 213–244. Tan MBN & Tan HTW (2013) The Laws Relating to Biodiversity in Singapore. Raffles Museum of Biodiversity Research, National University of Singapore, Singapore, 96 pp. Uploaded 23 May 2013. https://lkcnhm.nus.edu.sg/nus/pdf/PUBLICATION/LKCNH%20Museum%20Books/LKCNHM%20Books/biodlaw sgp.pdf. (Accessed 7 January 2016). The Plant List (2013) A Working List of All Plant Species. Version 1.1. http://www.theplantlist.org/ (Accessed from August 2014 to August 2015). Yeo CK, Ng BYQ, Ng PX, Chong KY, Lok AFSL, Ang WF, Tan SY & Tan HTW (2011) Air-layering: a suitable method for mass-propagating the nationally critically endangered Fagraea auriculatum Jack (Gentianaceae). Nature in Singapore, 4: 383–392.

31 Hung et al.: The Vascular Plant Flora and Vegetation of the Sisters’ Islands

APPENDIX 1

This is a checklist of all the vascular plants present on Pulau Tekukor, and divided into sections for fern allies, ferns, and angiosperms. It was compiled based on findings from the present floristic surveys, as well as data from previous floristic surveys by H. T. W. Tan et al. (unpublished data), and the herbarium records of the Singapore Botanic Gardens’ Herbarium (SING) and Herbarium, Lee Kong Chian Natural History Museum, Faculty of Science, National University of Singapore (SINU).

Status categories: CA = casual; CO = cultivated only; CR = Critically Endangered; CW = cryptogenic weed; EN = Endangered; NA = naturalised; NE = Presumed Nationally Extinct; NT = not threatened; VU = Vulnerable; UA = unassessed

Previous Records 2014/ S/No. Fern Ally Species Family Status SING SINU HTTW Koh 2015 1. Lycopodiella cernua (L.) Pic. Lycopodiaceae NT – – + – + Serm.

Previous Records 2014/ S/No. Fern species Family Status SING SINU HTTW Koh 2015 1. Amblovenatum opulentum J.P. Thelypteridaceae EN – – – – + Roux 2. Asplenium nidus L. Aspleniaceae NT – – + – + 3. Blechnum orientale L. Blechnaceae NT – – + – – 4. Davallia denticulata (Burm. Davalliaceae NT – – + – – f.) Mett. ex Kuhn 5. Dicranopteris linearis (Burm. Gleicheniaceae NT – – + – + f.) Underw. 6. Lygodium flexuosum (L.) Sw. Lygodiaceae NT – – + – – 7. Lygodium microphyllum Lygodiaceae NT – – – – + (Cav.) R. Br. 8. Nephrolepis auriculata Oleandraceae CW – – + – + Trimen 9. Nephrolepis biserrata (Sw.) Nephrolepidaceae CW – – – – + Schott 10. Phymatosorus scolopendria Polypodiaceae NT – – + – – (Burm. f.) Pic. Serm. 11. Pteris vittata L. Pteridaceae CW – – + – + 12. Pyrrosia piloselloides (L.) Polypodiaceae NT – – – – + M.G. Price 13. Stenochlaena palustris (Burm. Blechnaceae NT – – + – + f.) Bedd. 14. Taenitis blechnoides (Willd.) Pteridaceae NT – – + – – Sw. 15. Taenitis interrupta Hook. & Pteridaceae UA – – + – – Grev.

Previous Records 2014/ S/No. Angiosperm Species Family Status SING SINU HTTW Koh 2015 1. Acacia auriculiformis Benth. Leguminosae NA – – + – + 2. Adinandra dumosa Jack Pentaphylacaceae NT – – + – + 3. Alstonia angustifolia Wall. ex A.DC. Apocynaceae NT – – – – + 4. Alstonia angustiloba Miq. Apocynaceae NT – – + – + 5. Alstonia scholaris (L.) R. Br. Apocynaceae CO – – – – + 6. Asystasia gangetica (L.) T.Anderson Acanthaceae NA – – + – + 7. Asystasia nemorum Nees Acanthaceae UA – – + – – 8. Axonopus compressus (Sw.) Poaceae NA – – + – + P.Beauv. 9. Azadirachta indica A.Juss. Meliaceae CA – – + – + 10. Baphia nitida Lodd. Leguminosae CA – – – – + 11. Brachiaria mutica (Forssk.) Stapf Poaceae NA – – + – – 12. Bromheadia finlaysoniana (Lindl.) Orchidaceae NT – + + – – Miq. 13. Buchanania arborescens (Blume) Anacardiaceae NT – – + – + Blume

32 NATURE IN SINGAPORE 2017

Previous Records 2014/ S/No. Angiosperm Species Family Status SING SINU HTTW Koh 2015 14. Caesalpinia crista L. Leguminosae VU – – + – – 15. Calophyllum inophyllum L. Clusiaceae CR – – + – + 16. Caryota mitis Lour. Arecaceae NT – – + – + 17. Cassytha filiformis L. Lauraceae NT – – + – + 18. Casuarina equisetifolia L. Casuarinaceae NT – – + – + 19. Centrosema pubescens Benth. Leguminosae NA – – + – – 20. Chloris barbata Sw. Poaceae NA – – + – – 21. Citrus japonica Thunb. Rutaceae CO – – + – – 22. Cocos nucifera L. Arecaceae NA – – + – + 23. Commelina diffusa Burm.f. Commelinaceae CW – – + – – 24. Commersonia bartramia (L.) Merr. Malvaceae NT – – + – – 25. Cyanthillium cinereum (L.) H.Rob. Compositae CW – – + – + 26. Cyperus rotundus L. Cyperaceae CW – – + – – 27. Dactyloctenium aegyptium (L.) Poaceae NT – – + – – Willd. 28. Dalbergia candenatensis (Dennst.) Leguminosae NT – – + – – Prain 29. Dendrolobium umbellatum (L.) Leguminosae NT – – + – + Benth. 30. Desmodium heterophyllum (Willd.) Leguminosae CW – – + – + DC. 31. Desmodium triflorum (L.) DC. Leguminosae CW – – + – – 32. Dianella ensifolia (L.) DC. Xanthorrhoeaceae NT – – + – + 33. Digitaria radicosa (J.Presl) Miq. Poaceae CW – – + – – 34. Diospyros discolor Willd. Ebenaceae CO – – + – + 35. Duranta erecta L. Verbenaceae CO – – + – – 36. Elaeocarpus pedunculatus Wall. ex Elaeocarpaceae NT – – – – + Mast. 37. Emilia sonchifolia (L.) DC. ex DC. Compositae CW – – + – – 38. Eragrostis amabilis (L.) Wight & Poaceae CW – – + – – Arn. 39. Eriachne pallescens R.Br. Poaceae VU – – + – – 40. Eriochloa procera (Retz.) C.E.Hubb. Poaceae CW – – – – + 41. Erythroxylum cuneatum (Miq.) Kurz Erythroxylaceae NT – – + – + 42. Eulophia graminea Lindl. Orchidaceae CW – – + – – 43. Euphorbia hirta L. Euphorbiaceae NA – – + – – 44. Fagraea auriculata Jack Gentianaceae CR – – + – + 45. Fagraea fragrans Roxb. Gentianaceae NT – – + – + 46. Ficus benjamina L. Moraceae CW – – + – + 47. Ficus consociata Blume Moraceae CR – – + – – 48. Ficus grossularioides Burm.f. Moraceae NT – – + – + 49. Ficus kerkhovenii Koord. & Valeton Moraceae CR – – – – + 50. Ficus microcarpa L.f. Moraceae NT – – + – + 51. Ficus religiosa L. Moraceae NA – – + – + 52. Ficus superba Miq. Moraceae EN – – + – + 53. Fimbristylis cymosa R.Br. Cyperaceae NT – – + – – 54. Fimbristylis dichotoma (L.) Vahl Cyperaceae CW – – + – + 55. Guettarda speciosa L. Rubiaceae EN – – – – + 56. Gynochthodes sublanceolata Miq. Rubiaceae NT – – + – + 57. Halophila ovalis (R.Br.) Hook.f. Hydrocharitaceae NT + – – – – 58. Ilex cymosa Blume Aquifoliaceae NT – – + – + 59. Imperata cylindrica (L.) Raeusch. Poaceae CW – – + – + 60. Ipomoea pes–caprae (L.) R. Br. Convolvulaceae NT – – + – + 61. Ischaemum muticum L. Poaceae NT – + + – + 62. Ixora finlaysoniana Wall. ex G.Don Rubiaceae CO – – + – + 63. Kyllinga polyphylla Willd. ex Kunth Cyperaceae NA – – + – – 64. Lantana camara L. Verbenaceae NA – – + – + 65. Mangifera indica L. Anacardiaceae CA – – + – + 66. Melastoma malabathricum L. Melastomataceae NT – – + – + 67. Mimosa pudica L. Leguminosae NA – + + – +

33 Hung et al.: The Vascular Plant Flora and Vegetation of the Sisters’ Islands

Previous Records 2014/ S/No. Angiosperm Species Family Status SING SINU HTTW Koh 2015 68. Morinda citrifolia L. Rubiaceae CW – – + – + 69. Morinda umbellata L. Rubiaceae NT – – + – + 70. Moringa oleifera Lam. Moringaceae CO – – – – + 71. Moringa pterygosperma Gaertn. Moringaceae CO – – + – + 72. Muntingia calabura L. Muntingiaceae NA – – + – + 73. Myrica esculenta Buch.–Ham. ex D. Myricaceae NT – – + – + Don 74. Nepenthes rafflesiana Jack Nepenthaceae VU – + + – + 75. Oldenlandia corymbosa L. Rubiaceae CW – – + – + 76. Oncosperma tigillarium (Jack) Ridl. Arecaceae VU – – – – + 77. Oxalis barrelieri L. Oxalidaceae NA – – + – + 78. Paederia foetida L. Rubiaceae NT – – + – + 79. Pandanus odorifer (Forssk.) Kuntze Pandanaceae NT – – + – + 80. Pandanus amaryllifolius Roxb. Pandanaceae CA – – + – – 81. Pandanus singaporensis Kaneh. Pandanaceae CR – – – – + 82. Pandanus tectorius Parkinson ex Du Pandanaceae CO – – – – + Roi 83. Passiflora laurifolia L. Passifloraceae NA – – + – + 84. Passiflora suberosa L. Passifloraceae NA – – + – + 85. Peltophorum pterocarpum (DC.) Leguminosae CR – – + – + K.Heyne 86. Phyllanthus acidus (L.) Skeels Phyllanthaceae CO – – + – – 87. Phyllanthus urinaria L. Phyllanthaceae NA – – + – + 88. Pittosporum ferrugineum W.T.Aiton Pittosporaceae VU – – + – – 89. Planchonella obovata (R.Br.) Pierre Sapotaceae VU – – + – + 90. Ploiarium alternifolium (Vahl) Bonnetiaceae NT – – + – + Melch. 91. Pluchea indica (L.) Less. Compositae NT – – + – – 92. Plumeria rubra L. Apocynaceae CO – – – – + 93. Porophyllum ruderale (Jacq.) Cass. Compositae NA – – + – – 94. Proiphys amboinensis (L.) Herb. Amaryllidaceae CO – – + – – 95. Ptychosperma macarthurii Arecaceae NA – – + – + (H.Wendl. ex H.J.Veitch) H.Wendl. ex Hook.f. 96. Rhodamnia cinerea Jack Myrtaceae NT – – + – + 97. Rhodomyrtus tomentosa (Aiton) Myrtaceae NT – + + – + Hassk. 98. Scaevola taccada (Gaertn.) Roxb. Goodeniaceae NT – – + – + 99. Schizachyrium sanguineum (Retz.) Poaceae NE – – + – – Alston 100. Scleria levis Retz. Cyperaceae CW – – + – + 101. Scoparia dulcis L. Plantaginaceae NA – – + – – 102. Scyphiphora hydrophylacea Rubiaceae NT – – + – + C.F.Gaertn. 103. Spermacoce articularis L.f. Rubiaceae CW – – + – – 104. Spermacoce exilis (L.O.Williams) Rubiaceae CW – – + – – C.D.Adams ex W.C.Burger & C.M.Taylor 105. Spermacoce ocymoides Burm.f. Rubiaceae NA – – + – + 106. Sphagneticola trilobata (L.) Pruski Compositae NA – – + – + 107. Sporobolus fertilis (Steud.) Clayton Poaceae NT – – + – + 108. Sporobolus indicus (L.) R.Br. Poaceae NT – – + – – 109. Stachytarpheta indica (L.) Vahl Verbenaceae NA – – + – – 110. Synedrella nodiflora (L.) Gaertn. Compositae NA – – + – – 111. Syzygium cumini (L.) Skeels Myrtaceae NA – – – – + 112. Syzygium lineatum (DC.) Merr. & Myrtaceae NT – – – – + L.M.Perry 113. Syzygium palembanicum Miq. Myrtaceae VU – – + – + 114. Syzygium zeylanicum (L.) DC. Myrtaceae NT – – + – + 115. Talipariti tiliaceum (L.) Fryxell Malvaceae NT – – + – + 116. Terminalia catappa L. Combretaceae NT – – + – +

34 NATURE IN SINGAPORE 2017

Previous Records 2014/ S/No. Angiosperm Species Family Status SING SINU HTTW Koh 2015 117. Tetracera indica (Christm. & Panz.) Dilleniaceae NT – – – – + Merr. 118. Thalassia hemprichii (Ehrenb. ex Hydrocharitaceae CR + – – – – Solms) Asch. 119. Thunbergia alata Bojer ex Sims Acanthaceae NA – – + – – 120. Tridax procumbens (L.) L. Compositae NA – – + – + 121. Tristaniopsis obovata (Benn.) Peter Myrtaceae CR – – + – + G.Wilson & J.T.Waterh. 122. Tristaniopsis whiteana (Griff.) Peter Myrtaceae EN – – + – + G.Wilson & J.T.Waterh. 123. Tylophora flexuosa R. Br. Apocynaceae NT – – + – + 124. Vigna marina (Burm.) Merr. Leguminosae NT – – + – – 125. Vitex pinnata L. Lamiaceae NT – – + – + 126. Wollastonia biflora (L.) DC. Compositae NT – – + – – 127. Ximenia americana L. Olacaceae NT – – + – + 128. Xylocarpus granatum J.Koenig Meliaceae NT – – + – + 129. Xylocarpus rumphii (Kostel.) Mabb. Meliaceae CR – – + – – 130. Youngia japonica (L.) DC. Compositae NA – – + – – 131. Zoysia matrella (L.) Merr. Poaceae NT – – + – +

35 NATURE IN SINGAPORE 2017 10: 37–48 Date of Publication: 29 May 2017 © National University of Singapore

The vascular plant flora and vegetation of the islands associated with Singapore’s first Marine Park (III): St. John’s Island

Sherry M. X. Hung*, K. Y. Chong, Alex T. K. Yee, Reuben C. J. Lim, Jolyn W. Loh, Louise Neo, W. W. Seah, S. Y. Tan and Hugh T. W. Tan

Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Republic of Singapore; Email: [email protected] (*corresponding author)

Abstract. St. John’s Island, officially known as Pulau Sakijang Bendera, has 258 vascular plant species from 81 families, of which 154 species are native, 76 are non-native and 28 are cryptogenic weeds. The native species include 22 nationally Critically Endangered species, 15 nationally Endangered species, 20 nationally Vulnerable species, 96 species that are not nationally threatened and one that has not yet been assessed. The 41.23-ha island consists of 13.19 ha of coastal forest, 24.98 ha of managed vegetation, 2.94 ha of built-up structures, and a small 0.12-ha water body.

Keywords. checklist, St. John’s Island, Pulau Sakijang Bendera, Marine Park, Singapore, vascular plants

INTRODUCTION

At approximately 40 ha, St. John’s Island, officially known as Pulau Sakijang Bendera, (1°13′08.30″N, 103°50′53.88″E) has the largest land area among the four islands associated with Singapore’s first Marine Park. Initial re-development of the island started around mid-1975 (Sentosa Development Corporation, 1976, 1977), where reclamation works added 7.64 ha to the original 33.59 ha (Ministry of Culture, 1971) and largely transformed the island to host several recreational facilities. Part of the development package included landscaping works, where coastal vegetation and grasses were planted on the reclaimed lands (Sentosa Development Corporation, 1977, 1978). A previous study on the land use and vegetation by See (1993) found that the island consists largely of parkland vegetation, including planted ornamental trees and shrubs with turf. There were only a few remaining patches of secondary vegetation, secondary forest on cliffs, beach vegetation, and mangroves (See, 1993). As the island continues to provide recreational amenities for the public, it is important that the remaining natural areas are preserved. Thus, floristic and vegetation data from this study can be utilised in the management of this island.

MATERIAL AND METHODS

All the vascular plant species presently and previously found on St. John’s Island were compiled in a checklist from various sources, namely the present floristic surveys, data from previous floristic surveys by H. T. W. Tan et al. (unpublished data), and the herbarium records of the Singapore Botanic Gardens’ Herbarium (SING) and Herbarium, Lee Kong Chian Natural History Museum, Faculty of Science, National University of Singapore (SINU). All plant species names and their respective authors were cross-checked with The Plant List (2013). The national status of each species was retrieved from the checklists of Singapore’s vascular plant flora by Tan et al. (2008) and Chong et al. (2009).

The vegetation map of the island was first drawn based on visual interpretation of two satellite images of 27 April 2007 and 22 April 2013 from Google Earth 7.1.2.2041 (Google Inc., 2013). The shoreline of the island and boundaries of each vegetated patch that measured at least 10 × 10 m in area were traced at a map scale of 1: 2,000. In the preliminary classification, we recognised two main types of vegetation based on the image textures and colours. For example, natural forests were reflected as areas with dense canopy cover formed by large tree crowns. On the other hand, managed vegetation areas had smoother texture and were lighter in colour because of the more sparse vegetation cover by smaller plants.

Floristic surveys and ground truthing were conducted for all the accessible areas on the island on three separate occasions between September 2014 and January 2015 with the aid of a Garmin GPSMap® 62S Global Positioning System (GPS) receiver that records locations within ± 4 m of accuracy. The main objective of the floristic surveys was to verify and supplement the list of vascular plant species recorded from the previous surveys, with an emphasis on native species. Additionally, the geographic coordinates of non-widespread, nationally threatened plant species were marked down using the GPS receiver, and the localities were indicated on the vegetation map of the island. Voucher specimens were collected for plants that could not be identified with certainty in the field, or were not previously documented in the records of SING and SINU. The specimens were then matched with identified specimens in SING and/ or SINU.

37 Hung et al.: The Vascular Plant Flora and Vegetation of the Sisters’ Islands

Fig. 1. Map of St. John’s Island showing the area that was not ground-truthed in this study.

In addition, shores were preliminarily classified as either rocky or sandy. As various intermediates exist, e.g., a mix of rock and sandy shore, these were classified as ‘intermediate’. Adjustments were subsequently made to the preliminary classification based on actual field observations during ground truthing. Thereafter, the area of each vegetation type was calculated using ArcGIS®9 ArcMap™ Version 9.3.1 (ESRI, 2009), with the World Geodetic System 1984 (WGS84) and Universal Transverse Mercator Coordinate System, Zone 48 North (UTM48N) projections.

As some areas on St. John’s Island were not accessible to the public (Fig. 1), the vegetation of those areas was only visually interpreted from the two Google Earth 7.1.2.2041 satellite images.

OBSERVATIONS AND RESULTS

The vascular flora of St. John’s Island consists of two species of fern allies, 23 species of ferns, one species of gymnosperm, and 232 species of angiosperms, giving a total of 258 species belonging to 81 families (Appendix 1). Out

Table 1. National conservation status categories of the vascular flora of St. John’s Island.

Status category Number of Species Percentage of Species Native species 154 59.7% Presumed nationally Extinct 0 0% Nationally Critically Endangered 22 8.5% Nationally Endangered 15 5.8% Nationally Vulnerable 20 7.8% Not nationally Threatened 96 37.2% Unassessed 1 0.4% Non-native species 76 29.5% Casual 23 8.9% Naturalised 44 17.1% Cultivated only 9 3.5% Cryptogenic weed species 28 10.9% Total 258 100.0%

38 NATURE IN SINGAPORE 2017

Fig. 2. Pie chart illustrating the number and proportion of vascular plant species that belong to each national status group for St. John’s Island.

of these, 154 species (59.7%) are native, of which 57 species (22.1%) are threatened, meaning that they are nationally classified as Presumed nationally Extinct, Critically Endangered, Endangered, or Vulnerable (Table 1; Fig. 2). Non-native or exotic species make up 29.5% or a total of 76 species (Table 1; Fig. 2). This may be an underestimate as we focused on verifying or adding to the list of native species.

Altogether, natural vegetation comprises 13.19 ha (32.0%), while managed vegetation covers 24.98 ha (60.6%) of St. John’s Island (Table 2; Fig. 3). A small water body also takes up 0.3% of the total land area, i.e., 0.12 ha. The natural vegetation is predominantly coastal forest.

The majority of this island is covered by managed vegetation, which totals up to 24.98 ha (60.6%) of the land area. The natural vegetation includes a remnant patch of mangrove forest at the north-eastern part, as well as a thin stretch of coastal forest that runs adjacent to the natural sandy and rocky shores on the southwestern side of the island, both adding up to 13.19 ha (32.0%). The remaining land area is made up of managed vegetation and built-up structures, including large research facilities and several buildings (Fig. 3).

Along the narrow stretch of coastal forest that was surveyed, mature individuals of the Critically Endangered Calophyllum inophyllum (Clusiaceae) were found to be very widespread throughout the forest (Fig. 4A). Also, a grove of more than 50 mature individuals of Tristaniopsis species was found at the area indicated as point 25 on the vegetation map (Fig. 3). Examination of the voucher specimens showed that both Tristaniopsis obovata (Myrtaceae) and Tristaniopsis whiteana (Myrtaceae) (Fig. 4B) are thriving in the forest. The local conservation statuses of these two species are Critically Endangered and Endangered respectively (Appendix 1). Xylocarpus rumphii (Meliaceae), another Critically Endangered species, was also located along the forest fringe.

Table 2. Area (ha) and proportion (%) for each vegetation type.

Area (ha) Proportion (%) Natural vegetation 13.19 32.0 Managed vegetation 24.98 60.6 Man-made structures 2.94 7.1 Water body 0.12 0.3 Total 41.23 100.0

39 Hung et al.: The Vascular Plant Flora and Vegetation of the Sisters’ Islands

Fig. 3. Vegetation map of St. John’s Island. The numbers indicate the positions of individuals of non-widespread, nationally threatened species: 1 = Ardisia elliptica; 2 = Calophyllum inophyllum; 3 = Centotheca lappacea; 4 = Elaeocarpus floribundus; 7 = Ficus kerkhovenii; 8 = Ficus superba; 9 = Guettarda speciosa; 10 = Heritiera littoralis; 11 = Knema curtisii; 14 = Peltophorum pterocarpum; 17 = Podocarpus polystachyus; 20 = Streblus elongatus; 25 = Tristaniopsis species; 26 = Tristaniopsis whiteana; 27 = Xylocarpus rumphii.

Located at the interface between the coastal forest and urbanised areas are two mature trees of the Critically Endangered Ficus kerkhovenii (Moraceae) (Fig. 4C). Although most of the managed vegetation was not thoroughly surveyed, several other threatened species were found to be cultivated within the area, including the endangered Ficus superba (Moraceae) (Fig. 4D).

DISCUSSION

As the major vegetation type in St. John’s Island is managed vegetation, natural vegetation there has been largely cleared and replaced with cultivated and exotic species. Several research facilities have also been built on the island for on-going marine research in Singapore. The use of coastal ecosystems for other purposes, such as recreational development or urbanisation, compromises the ecosystem services they supply and threatens the delicate equilibrium of the coastal ecosystem (Botero et al., 2015). Thus, the remnant patch of natural forest on St John’s Island, especially the natural rocky shore coastal vegetation, has significant conservation potential that deserves to receive more attention since natural rocky shore coastal forest is uncommon in Singapore, and on Singapore Island, such natural rocky coastal forest is found only in the Labrador Nature Reserve.

Mature individuals of the Critically Endangered Calophyllum inophyllum were found to be very widespread throughout the natural coastal forest of St. John’s Island. Trees of this species attract many insects, owing to the sweet scent released by the flowers, and bats that disperse the fruits (Corner, 1988). Ecologically, this species can hence contribute to

40 NATURE IN SINGAPORE 2017

A B

C D

Fig. 4. A, A fruiting individual of the Critically Endangered Calophyllum inophyllum found within the natural coastal forest (Photograph by: Chong Kwek Yan); B, Flowers of the Endangered Tristaniopsis whiteana, also found within the natural coastal forest; C, A mature tree of the Critically Endangered Ficus kerkhovenii found at the interface between the coastal forest and urbanised areas; D, A mature tree of the Endangered Ficus superba growing next to a building within the managed vegetation area (Photographs B–D by: Sherry Hung Ming Xuan). Scale bars for A = 6 cm, B = 1 cm.

attracting biological diversity. Research has also found that some extracts in the stems and leaves of Calophyllum inophyllum display anti-HIV activity and anti-cancer properties (Li et al., 2010). Thus, ensuring the persistence of this and other threatened species, such as Xylocarpus rumphii, by conserving the natural forested areas could yield valuable ecosystem functions and services that benefit humans.

41 Hung et al.: The Vascular Plant Flora and Vegetation of the Sisters’ Islands

CONCLUSIONS

In this study, a compilation from past records and recent field surveys of Pulau Sakijang Bendera (St. John’s Island) recorded 258 vascular plant species from 81 families, of which 154 species are native and 57 are nationally threatened, i.e. 22 nationally Critically Endangered species, 15 nationally Endangered species, and 20 nationally Vulnerable species. The island hosts several nationally threatened species, such as Calophyllum inophyllum and the Tristaniopsis species. The land areas are also covered by unique habitats such as coastal forest, mangroves, as well as sandy beach and rocky shores.

ACKNOWLEDGEMENTS

We thank Serena Lee of the Singapore Botanic Gardens’ Herbarium (SING) and Chua Keng Soon of the Herbarium, Lee Kong Chian Natural History Museum, National University of Singapore (SINU) for supplying us with the herbarium records of the island’s flora. Help from Neo Mei Lin, Tan Koh Siang, Kam Pang Jen, and Mohamad Razali Bin Duriat of the Tropical Marine Science Institute (TMSI) in facilitating an overnight stay at TMSI and several boat rides to St. John’s Island (SJI) for fieldwork is gratefully acknowledged. We are also grateful to the National Parks Board for permission to access and make collections on the island (permit no. NP/RP14-081) and Goh Soon Huat from the Sentosa Development Corporation for granting permission for access to survey the campers’ dormitory areas on SJI. We thank all the volunteers who assisted us during fieldwork, and Karenne Tun, Collin Tong, and Koh Kwan Siong for their advice.

LITERATURE CITED

Botero C, Pereira C, Tosic M & Manjarrez G (2015) Design of an index for monitoring the environmental quality of tourist beaches from a holistic approach. Ocean & Coastal Management, 108: 65–73. Chong KY, Tan HTW & Corlett RT (2009) A Checklist of the Total Vascular Plant Flora of Singapore: Native, Naturalised and Cultivated Species. Raffles Museum of Biodiversity Research, National University of Singapore, Singapore, 273 pp. Uploaded 12 November 2009. http://lkcnhm.nus.edu.sg/nus/pdf/PUBLICATION/LKCNH%20Museum%20Books/LKCNHM%20Books/flora_of_ singapore_tc.pdf. (Accessed 26 May 2015). Corner EJH (1988) Wayside Trees of Malaya. Volume 1. 3rd Edition. Malayan Nature Society, Kuala Lumpur, xxii pp., Pp. 1−467, figs. 1−145, pls. 1−138. ESRI Inc. (2009) ArcGIS®9 ArcMap™ Version 9.3.1. ESRI Inc., California. Google Inc. (2013) Google Earth 7.1.2.2041. Google Inc., California. Li YZ, Li ZL, Yin SL, Shi G, Liu MS, Jing YK & Hua HM (2010) Triterpenoids from Calophyllum inophyllum and their growth inhibitory effects on human leukemia HL-60 cells. Fitoterapia, 81: 586–589. Ministry of Culture (1971) Singapore Facts and Pictures 1971. Ministry of Culture, Singapore, 115 pp.See RHH (1993) The Changing Physical Landscape of Three Southern Islands. B.Sc. Honours’ thesis, Department of Geography, National University of Singapore, Singapore. 194 pp. Sentosa Development Corporation (1976) Sentosa Development Corporation Annual Report for the Year Ended 31 March 1976. Publicity/ Promotion Department, Sentosa Development Corporation, Singapore, 17 pp. Sentosa Development Corporation (1977) Sentosa Development Corporation Annual Report for the Year Ended 31 March 1977. Publicity/ Promotion Unit, Sentosa Development Corporation, Singapore, 21 pp. Sentosa Development Corporation (1978) Sentosa Development Corporation Annual Report for the Year Ended 31 March 1978. Publicity/ Promotion Unit, Sentosa Development Corporation, Singapore, 25 pp. Tan HTW, Tan K-x, Ali bin Ibrahim, Chew PT, Chua KS, Duistermaat H, Ganesan SK, Goh MWK, Gwee AT, Kiew R, Lee SML, Leong P, Lim J, Lok AFSL, Loo AHB, Lum SKY, Morgany T, Saifuddin bin Suran, Sim S, Haji Samsuri bin Haji Ahmad, Wee YC, Yap KF, Yeo CK & Yong JWH (2008) Checklists of Threatened Species―Seed Plants. In: Davison GWH, Ng PKL & Ho HC (eds.) The Singapore Red Data Book: Threatened Plants & Animals of Singapore. 2nd Edition. The Nature Society (Singapore), Singapore. Pp. 213–244. The Plant List (2013) A Working List of All Plant Species. Version 1.1. http://www.theplantlist.org/ (Accessed from August 2014 to March 2015).

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APPENDIX 1

This is a checklist of all the vascular plants present on St. John’s Island, and divided into sections for fern allies, ferns, gymnosperms, and angiosperms. It was compiled based on findings from the present floristic surveys conducted in 2014/2015, data from previous floristic surveys by H. T. W. Tan et al. (unpublished data), and the herbarium records of the Singapore Botanic Gardens’ Herbarium (SING) and Herbarium, Lee Kong Chian Natural History Museum, Faculty of Science, National University of Singapore (SINU).

Status categories: CA = casual; CO = cultivated only; CR = Critically Endangered; CW = cryptogenic weed; EN = Endangered; NA = naturalised; NE = Presumed Nationally Extinct; NT = not threatened; VU = Vulnerable; UA = unassessed

Previous records S/No. Fern Ally Species Family Status SING SINU HTTW 2014/2015 1. Lycopodiella cernua (L.) Pic. Serm. Lycopodiaceae NT – – + – 2. Psilotum nudum (L.) P. Beauv. Psilotaceae NT – – + –

Previous records S/No. Fern Species Family Status SING SINU HTTW 2014/2015 1. Acrostichum aureum L. Pteridaceae NT – – + + 2. Acrostichum speciosum Willd. Pteridaceae NT – – + – 3. Asplenium nidus L. Aspleniaceae NT – – + + 4. Blechnum orientale L. Blechnaceae NT – – + – 5. Davallia denticulata (Burm. f.) Mett. ex Davalliaceae NT – – + – Kuhn 6. Davallia solida (G. Forst.) Sw. Davalliaceae VU – – + – 7. Dicranopteris linearis (Burm. f.) Gleicheniaceae NT – – + + Underw. 8. Drynaria quercifolia (L.) J. Sm. Polypodiaceae NT – – + – 9. Lindsaea ensifolia Sw. Lindsaeaceae NT – – + – 10. Lygodium circinatum (Burm. f.) Sw. Lygodiaceae VU – – + + 11. Lygodium flexuosum (L.) Sw. Lygodiaceae NT – – + + 12. Lygodium microphyllum (Cav.) R. Br. Lygodiaceae NT – – + – 13. Microsorum punctatum (L.) Copel. Polypodiaceae NT – – + – 14. Nephrolepis auriculata Trimen Oleandraceae CW – – + + 15. Phymatosorus scolopendria (Burm. f.) Polypodiaceae NT – – + – Pic. Serm. 16. Pteris ensiformis Burm. f. Pteridaceae CW – – + + 17. Pteris vittata L. Pteridaceae CW – – + – 18. Pyrrosia lanceolata (L.) Farw. Polypodiaceae NT – – + – 19. Pyrrosia longifolia (Burm. f.) C.V. Polypodiaceae NT – – + + Morton 20. Pyrrosia piloselloides (L.) M.G. Price Polypodiaceae NT – – + – 21. Stenochlaena palustris (Burm. f.) Bedd. Blechnaceae NT – – + – 22. Taenitis blechnoides (Willd.) Sw. Pteridaceae NT – – + – 23. Vittaria ensiformis Sw. Pteridaceae NT – – + –

Previous records S/No. Gymnosperm species Family Status SING SINU HTTW 2014/2015 1. Podocarpus polystachyus R.Br. ex Endl. Podocarpaceae CR – – + +

43 Hung et al.: The Vascular Plant Flora and Vegetation of the Sisters’ Islands

Previous records S/No. Angiosperm Species Family Status SING SINU HTTW 2014/2015 1. Acacia auriculiformis Benth. Leguminosae NA – + + + 2. Adenanthera pavonina L. Leguminosae NA – + + + 3. Adinandra dumosa Jack Pentaphylacaceae NT – + + + 4. Allophylus cobbe (L.) Raeusch. Sapindaceae NT + – – – 5. Alternanthera sessilis (L.) R.Br. ex DC. Amaranthaceae CW – + – – 6. Alysicarpus vaginalis (L.) DC. Leguminosae CW – + – – 7. Anacardium occidentale L. Anacardiaceae CA – + – – 8. Andrographis paniculata (Burm.f.) Nees Acanthaceae NA – – – + 9. Antigonon leptopus Hook. & Arn. Polygonaceae CA – – – + 10. Ardisia elliptica Thunb. Primulaceae EN – + + + 11. Ardisia teysmanniana Scheff. Primulaceae EN + – – – 12. Asystasia gangetica (L.) T.Anderson Acanthaceae NA – + + + 13. Avicennia marina (Forssk.) Vierh. Acanthaceae CR + + + – 14. Axonopus compressus (Sw.) P.Beauv. Poaceae NA – + + – 15. Azadirachta indica A.Juss. Meliaceae CA – + + – 16. Bambusa vulgaris Schrad. Poaceae CA – + + – 17. Baphia nitida Lodd. Leguminosae CA – + – – 18. Bauhinia purpurea L. Leguminosae CO – + – – 19. Bhesa robusta (Roxb.) Ding Hou Centroplacaceae VU + – + + 20. Bouea macrophylla Griff. Anacardiaceae CR – – + – 21. Breynia coronata Hook.f. Phyllanthaceae EN – – – + 22. Breynia racemosa (Blume) Müll.Arg. Phyllanthaceae NT + + + + 23. Bromheadia finlaysoniana (Lindl.) Miq. Orchidaceae NT – + + + 24. Bruguiera gymnorhiza (L.) Lam. Rhizophoraceae NT – + + – 25. Buchanania arborescens (Blume) Anacardiaceae NT – + + + Blume 26. Buchanania sessilifolia Blume Anacardiaceae VU – + + – 27. Callerya atropurpurea (Wall.) Schot Leguminosae CA – + + – 28. Calophyllum inophyllum L. Clusiaceae CR – + + + 29. Canavalia cathartica Thouars Leguminosae NT – – – + 30. Carica papaya L. Caricaceae CA – – – + 31. Caryota mitis Lour. Arecaceae NT – – + – 32. Cassytha filiformis L. Lauraceae NT – + + – 33. Casuarina equisetifolia L. Casuarinaceae NT – – + + 34. Casuarina glauca Sieber ex Spreng. Casuarinaceae UA + – + – 35. Centella asiatica (L.) Urb. Apiaceae NT – – + + 36. Centotheca lappacea (L.) Desv. Poaceae CR – + + + 37. Cerbera manghas L. Apocynaceae CR + + + + 38. Cerbera odollam Gaertn. Apocynaceae VU – – + + 39. Chloris barbata Sw. Poaceae NA – + – – 40. Chrysobalanus icaco L. Chrysobalanaceae NA – + + – 41. Cissus hastata Miq. Vitaceae NT – + + + 42. Claoxylon indicum (Reinw. ex Blume) Euphorbiaceae NT – – – + Hassk. 43. Clidemia hirta (L.) D. Don Melastomataceae NA – + + + 44. Coccinia grandis (L.) Voigt Cucurbitaceae NA – – – + 45. Coccoloba uvifera (L.) L. Polygonaceae CO – – – + 46. Cocos nucifera L. Arecaceae NA – + + + 47. Commelina diffusa Burm.f. Commelinaceae CW – + + – 48. Commersonia bartramia (L.) Merr. Malvaceae NT – + + + 49. Cordia cylindrostachya (Ruiz & Pav.) Boraginaceae NA + – + – Roem. & Schult. 50. Crotalaria saltiana Andrews Leguminosae NA – – + – 51. Cyanthillium cinereum (L.) H.Rob. Compositae CW – + + – 52. Cynodon dactylon (L.) Pers. Poaceae NT – + + –

44 NATURE IN SINGAPORE 2017

Previous records S/No. Angiosperm Species Family Status SING SINU HTTW 2014/2015 53. Cyperus rotundus L. Cyperaceae CW – + – – 54. Cyperus stoloniferus Retz. Cyperaceae NT – – + – 55. Dactyloctenium aegyptium (L.) Willd. Poaceae NT – + + – 56. Dalbergia candenatensis (Dennst.) Leguminosae NT + – + + Prain 57. Dalbergia junghuhnii Benth. Leguminosae CR – – + – 58. Dalbergia pseudo-sissoo Miq. Leguminosae NT – – + + 59. Delonix regia (Hook.) Raf. Leguminosae CO – + + – 60. Dendrobium crumenatum Sw. Orchidaceae NT – + + – 61. Dendrocalamus asper (Schult.) Backer Poaceae CA – – + – 62. Dendrophthoe pentandra (L.) Miq. Loranthaceae NT – + + + 63. Derris trifoliata Lour. Leguminosae NT – + + + 64. Desmodium heterocarpon (L.) DC. Leguminosae CW – + + – 65. Desmodium triflorum (L.) DC. Leguminosae CW – + + + 66. Dianella ensifolia (L.) DC. Xanthorrhoeaceae NT + + + + 67. Digitaria ciliaris (Retz.) Koeler Poaceae CW – + – – 68. Dillenia suffruticosa (Griff.) Martelli Dilleniaceae NT – + + – 69. Dischidia major (Vahl) Merr. Apocynaceae NT + + + + 70. Dischidia nummularia R.Br. Apocynaceae NT – + + – 71. Dracaena fragrans (L.) Ker Gawl. Asparagaceae CA – + – – 72. Dypsis decaryi (Jum.) Beentje & Arecaceae CO – + – – J.Dransf. 73. Eclipta prostrata (L.) L. Compositae NA – + – – 74. Elaeis guineensis Jacq. Arecaceae CA – + + + 75. Elaeocarpus floribundus Blume Elaeocarpaceae EN – + + + 76. Elaeocarpus pedunculatus Wall. ex Elaeocarpaceae NT + + + + Mast. 77. Elaeocarpus polystachyus Wall. ex Elaeocarpaceae VU – – + – Müll.Berol. 78. Elephantopus scaber L. Compositae CW – + + – 79. Eleusine indica (L.) Gaertn. Poaceae NA – + – – 80. Embelia ribes Burm.f. Primulaceae NT – – – + 81. Emilia sonchifolia (L.) DC. ex DC. Compositae CW – + + – 82. Epipremnum aureum (Linden & André) Araceae CA – – – + G.S.Bunting 83. Epipremnum pinnatum (L.) Engl. Araceae CR – + – – 84. Eragrostis amabilis (L.) Wight & Arn. Poaceae CW – + + – 85. Eriachne pallescens R.Br. Poaceae VU + + + – 86. Erythroxylum cuneatum (Miq.) Kurz Erythroxylaceae NT + + + + 87. Euphorbia hirta L. Euphorbiaceae NA – + – + 88. Eurycoma longifolia Jack Simaroubaceae CR – + + – 89. Fagraea fragrans Roxb. Gentianaceae NT – + + + 90. Falcataria moluccana (Miq.) Barneby Leguminosae NA – – + – & J.W.Grimes 91. Ficus benjamina L. Moraceae CW – + + + 92. Ficus consociata Blume Moraceae CR – + + – 93. Ficus grossularioides Burm.f. Moraceae NT – + + + 94. Ficus kerkhovenii Koord. & Valeton Moraceae CR – + + + 95. Ficus microcarpa L.f. Moraceae NT – + + – 96. Ficus punctata Thunb. Moraceae NT – + + + 97. Ficus religiosa L. Moraceae NA – + + + 98. Ficus subpisocarpa Gagnep. Moraceae EN + – – – 99. Ficus superba Miq. Moraceae EN – + + + 100. Ficus virens Aiton Moraceae CR – – – + 101. Gahnia tristis Nees Cyperaceae NT – + + – 102. Garcinia celebica L. Clusiaceae EN – – + + 103. Guettarda speciosa L. Rubiaceae EN – – + +

45 Hung et al.: The Vascular Plant Flora and Vegetation of the Sisters’ Islands

Previous records S/No. Angiosperm Species Family Status SING SINU HTTW 2014/2015 104. Guioa pleuropteris (Blume) Radlk. Sapindaceae VU + + + + 105. Guioa pubescens (Zoll. & Moritzi) Sapindaceae VU – – + – Radlk. 106. Gynochthodes sublanceolata Miq. Rubiaceae NT – + + – 107. Gynura procumbens (Lour.) Merr. Compositae CR – + – – 108. Heritiera littoralis Aiton Malvaceae EN – + + + 109. Hevea brasiliensis (Willd. ex A.Juss.) Euphorbiaceae NA – + + + Müll.Arg. 110. Hydnophytum formicarum Jack Rubiaceae CR – – – + 111. Hymenocallis littoralis (Jacq.) Salisb. Amaryllidaceae CO – + – – 112. Ilex cymosa Blume Aquifoliaceae NT – – + – 113. Imperata cylindrica (L.) Raeusch. Poaceae CW – + + + 114. Ipomoea pes-caprae (L.) R. Br. Convolvulaceae NT – + + + 115. Ischaemum ciliare Retz. Poaceae CW – + – – 116. Ischaemum magnum Rendle Poaceae NT + – – – 117. Ischaemum muticum L. Poaceae NT – + + – 118. Ixonanthes reticulata Jack Ixonanthaceae NT – – + – 119. Ixora finlaysoniana Wall. ex G.Don Rubiaceae CO + + – – 120. Ixora javanica (Blume) DC. Rubiaceae CO – + – – 121. Knema curtisii Warb. Myristicaceae EN + – + + 122. Knema globularia (Lam.) Warb. Myristicaceae CR – – – + 123. Kyllinga melanosperma Nees Cyperaceae CW – + – – 124. Kyllinga nemoralis (J.R.Forst. & Cyperaceae CW – + + – G.Forst.) Dandy ex Hutch. & Dalziel 125. Kyllinga polyphylla Willd. ex Kunth Cyperaceae NA – + + – 126. Lablab purpureus (L.) Sweet Leguminosae UA + – – – 127. Lantana camara L. Verbenaceae NA – + + + 128. Legazpia polygonoides (Benth.) T. Linderniaceae CW – + + – Yamaz. 129. Leucaena leucocephala (Lam.) de Wit Leguminosae NA – + + + 130. Licuala spinosa Wurmb Arecaceae VU – + + + 131. Lindernia crustacea (L.) F.Muell. Linderniaceae CW – + – – 132. Lindernia nummulariifolia (D.Don) Linderniaceae NA – + + – Wettst. 133. Lumnitzera littorea (Jack) Voigt Combretaceae EN – + – – 134. Macaranga heynei I.M.Johnst. Euphorbiaceae NT – + + – 135. Macrosolen cochinchinensis (Lour.) Loranthaceae NT – + + – Tiegh. 136. Macrosolen retusus Blume Loranthaceae NT + – – – 137. Mangifera indica L. Anacardiaceae CA – + – – 138. Mangifera magnifica Kochummen Anacardiaceae CR + – – + 139. Maranthes corymbosa Blume Chrysobalanaceae EN – + – – 140. Melastoma malabathricum L. Melastomataceae NT – + + + 141. Melinis repens (Willd.) Zizka Poaceae NA – – – + 142. Microstachys chamaelea (L.) Müll.Arg. Euphorbiaceae CW – – + – 143. Mimosa pudica L. Leguminosae NA – + + + 144. Mischocarpus sundaicus Blume Sapindaceae VU + – – – 145. Morinda citrifolia L. Rubiaceae CW – – + + 146. Morinda umbellata L. Rubiaceae NT – + + + 147. Mukia maderaspatana (L.) M.Roem. Cucurbitaceae NA – – – + 148. Muntingia calabura L. Muntingiaceae NA – + + – 149. Myrica esculenta Buch.-Ham. ex D. Myricaceae NT – + + + Don 150. Nepenthes gracilis Korth. Nepenthaceae NT – + + + 151. Nepenthes hookeriana H.Low Nepenthaceae UA + – – – 152. Nepenthes rafflesiana Jack Nepenthaceae VU + + + + 153. Nypa fruticans Wurmb Arecaceae VU + – + –

46 NATURE IN SINGAPORE 2017

Previous records S/No. Angiosperm Species Family Status SING SINU HTTW 2014/2015 154. 155. Ochna kirkii Oliv. Ochnaceae CO – + – – 156. Oldenlandia biflora L. Rubiaceae CW – + – + 157. Oldenlandia corymbosa L. Rubiaceae CW – + + – 158. Oxalis barrelieri L. Oxalidaceae NA – + + – 159. Oxalis corniculata L. Oxalidaceae NA – + + – 160. Paederia foetida L. Rubiaceae NT – – – + 161. Palaquium obovatum (Griff.) Engl. Sapotaceae VU – + + + 162. Pandanus odorifer (Forssk.) Kuntze Pandanaceae NT + + + + 163. Panicum maximum Jacq. Poaceae NA – – – + 164. Panicum sarmentosum Roxb. Poaceae NT – + + – 165. Paspalum conjugatum P.J.Bergius Poaceae NA – – + – 166. Paspalum vaginatum Sw. Poaceae NT – – + – 167. Passiflora foetida L. Passifloraceae NA – + + – 168. Passiflora laurifolia L. Passifloraceae NA – + + – 169. Passiflora suberosa L. Passifloraceae NA – + + + 170. Peltophorum pterocarpum (DC.) Leguminosae CR – + + + K.Heyne 171. Peperomia pellucida (L.) Kunth Piperaceae NA – – + – 172. Phyllanthus debilis Klein ex Willd. Phyllanthaceae NA – + + – 173. Phyllanthus urinaria L. Phyllanthaceae NA – – + – 174. Piper sarmentosum Roxb. Piperaceae NT – – + – 175. Pithecellobium dulce (Roxb.) Benth. Leguminosae CA – – + + 176. Pittosporum ferrugineum W.T.Aiton Pittosporaceae VU – + + + 177. Planchonella obovata (R.Br.) Pierre Sapotaceae VU – + + + 178. Polyscias diversifolia (Blume) Lowry & Araliaceae NT – + + + G.M.Plunkett 179. Polyscias guilfoylei (W.Bull) Araliaceae UA – – + – L.H.Bailey 180. Pongamia pinnata (L.) Pierre Leguminosae EN – – + – 181. Premna serratifolia L. Lamiaceae VU – + + + 182. Prunus polystachya (Hook.f.) Kalkman Rosaceae NT + – – – 183. Pterocarpus indicus Willd. Leguminosae CA – + + – 184. Ptychosperma macarthurii (H.Wendl. Arecaceae NA – + + – ex H.J.Veitch) H.Wendl. ex Hook.f. 185. Rhizophora apiculata Blume Rhizophoraceae NT – + + – 186. Rhizophora mucronata Lam. Rhizophoraceae NT + + + + 187. Rhizophora stylosa Griff. Rhizophoraceae VU – + + – 188. Rhodamnia cinerea Jack Myrtaceae NT – + + + 189. Rhodomyrtus tomentosa (Aiton) Hassk. Myrtaceae NT – + + + 190. Scaevola taccada (Gaertn.) Roxb. Goodeniaceae NT – + + + 191. Schizostachyum zollingeri Steud. Poaceae CA + – – – 192. Scleria ciliaris Nees Cyperaceae NT – + + + 193. Scleria oblata S.T.Blake ex J.Kern Cyperaceae CW + – – – 194. Scyphiphora hydrophylacea C.F.Gaertn. Rubiaceae NT – + + – 195. Sida acuta Burm.f. Malvaceae CW – + + – 196. Sonneratia alba Sm. Lythraceae NT – + + – 197. Spermacoce exilis (L.O.Williams) Rubiaceae CW – + + – C.D.Adams ex W.C.Burger & C.M.Taylor 198. Spermacoce ocymoides Burm.f. Rubiaceae NA – + + – 199. Sporobolus indicus (L.) R.Br. Poaceae NT – + + + 200. Stachytarpheta indica (L.) Vahl Verbenaceae NA – + + – 201. Streblus elongatus (Miq.) Corner Moraceae VU – + + + 202. Stylosanthes hamata (L.) Taub. Leguminosae NA – – + + 203. Suregada multiflora (A.Juss.) Baill. Euphorbiaceae CR – – – +

47 Hung et al.: The Vascular Plant Flora and Vegetation of the Sisters’ Islands

Previous records S/No. Angiosperm Species Family Status SING SINU HTTW 2014/2015 204. Swietenia macrophylla King Meliaceae CA – – + – 205. Syzygium antisepticum (Blume) Merr. & Myrtaceae CO – – + – L.M.Perry 206. Syzygium cumini (L.) Skeels Myrtaceae NA – – + + 207. Syzygium lineatum (DC.) Merr. & Myrtaceae NT – + + + L.M.Perry 208. Syzygium zeylanicum (L.) DC. Myrtaceae NT + + + + 209. Talipariti tiliaceum (L.) Fryxell Malvaceae NT – + + + 210. Tamarindus indica L. Leguminosae CA – + + + 211. Tarenna fragrans (Blume) Koord. & Rubiaceae EN + – – – Valeton 212. Tarlmounia elliptica (DC.) "H.Rob., Compositae CA – + + – S.C.Keeley, Skvarla & R.Chan" 213. Tephrosia noctiflora Baker Leguminosae NA – + – – 214. Terminalia catappa L. Combretaceae NT – + + + 215. Tetracera indica (Christm. & Panz.) Dilleniaceae NT – + + + Merr. 216. Thalassia hemprichii (Ehrenb. ex Hydrocharitaceae CR – + – – Solms) Asch. 217. Themeda villosa (Lam.) A.Camus Poaceae NT – + + + 218. Thespesia populnea (L.) Sol. ex Corrêa Malvaceae NT – + + + 219. Thuarea involuta (G.Forst.) R.Br. ex Poaceae NT – + + – Sm. 220. Thyrsostachys siamensis Gamble Poaceae CA – + – – 221. Timonius finlaysonianus (Wall. ex Rubiaceae CR – – + – G.Don) Hook.f. 222. Tridax procumbens (L.) L. Compositae NA – + + + 223. Tristaniopsis obovata (Benn.) Peter Myrtaceae CR – – + + G.Wilson & J.T.Waterh. 224. Tristaniopsis whiteana (Griff.) Peter Myrtaceae EN – + – + G.Wilson & J.T.Waterh. 225. Turnera ulmifolia L. Passifloraceae NA – – + – 226. Vernonia arborea Buch.-Ham. Compositae VU – + – – 227. Viscum articulatum Burm. f. Santalaceae NT – + + – 228. Vitex pinnata L. Lamiaceae NT – + + + 229. Volkameria inermis L. Lamiaceae NT – – + + 230. Wollastonia biflora (L.) DC. Compositae NT – – + – 231. Ximenia americana L. Olacaceae NT – – + + 232. Xylocarpus granatum J.Koenig Meliaceae NT – + + + 233. Xylocarpus rumphii (Kostel.) Mabb. Meliaceae CR + + + + 234. Zoysia matrella (L.) Merr. Poaceae NT – + – –

48 NATURE IN SINGAPORE 2017 10: 49–53 Date of Publication: 13 June 2017 © National University of Singapore

Glochidion obscurum Bl. (Phyllanthaceae), a new record for Singapore

Edmund J. J. Chia1*, Z. Y. Ooi1, H. K. Lua1, Adrian H. B. Loo1, W. F. Ang1, K. H. Ong and K. M. Wong1

1National Parks Board, Singapore Botanic Gardens, 1 Cluny Road, Singapore 259569, Republic of Singapore; Email: [email protected] (*corresponding author)

Abstract. Widely distributed in the Indochinese and Sunda regions, and common throughout Peninsular Malaysia, Glochidion obscurum appears to be an overlooked native species in Singapore. We discuss this new finding, here documented as a new record for Singapore, where, based on its known distribution, it is considered a locally threatened species.

Keywords. Glochidion obscurum, Phyllanthaceae, Singapore, Mandai, new record

INTRODUCTION

Glochidion Forst. is a genus of over 200 species of shrubs or small trees found mainly from Indomalaya to Australia and the Pacific, as well as Madagascar and South America (van Welzen & Chayamarit, 2007). Placed in the tribe Phyllantheae, recent consensus (Jangid & Gupta, 2016) has continued to regard Glochidion as generically distinct despite possible phylogenetic considerations that broadly circumscribe Phyllanthus s.l. as including Glochidion and other related genera (Hoffmann et al., 2006).

In Singapore, there are 10 species of Glochidion recorded in Keng (1990), listed in Table 1.

Table 1. Glochidion species previously recorded in Singapore.

S/No. Accepted Name Name in Keng (1990) Localities Recorded

1. Glochidion borneense Boerl. Glochidion microbotrys Hook.f. Gardens Jungle, Reservoir Jungle, Chua Chu Kang, Changi, Pulau Ubin

2. Glochidion glomerulatum Boerl. Glochidion glomerulatum Boerl. None listed

3. Glochidion littorale Bl. Glochidion littorale Bl. Chua Chu Kang, Bukit Mandai

4. Glochidion lutescens Bl. Glochidion hypoleucum Boerl. Bukit Timah, Bukit Mandai, Tuas

5. Glochidion rubrum Bl. Glochidion rubrum Bl. Gardens Jungle, Seletar, Nee Soon

6. Glochidion sericeum Hook.f. Glochidion sericeum Hook.f. Bukit Mandai

7. Glochidion singaporense Gage Glochidion singaporense Gage Reservoir Jungle

8. Glochidion superbum Baill. Glochidion superbum Baill. Mandai

9. Glochidion wallichianum Müll.Arg. Glochidion wallichianum Müll.Arg. Tanglin, Bajau

10. Glochidion zeylanicum Juss. Glochidion brunneum Hook. f. Gardens Jungle, Bukit Timah, Balestier Road

Glochidion zeylanicum Juss. Cluny Road

DISCOVERY OF GLOCHIDION OBSCURUM IN SINGAPORE

Although a collection was made in 2003 and the species was featured on a web-blog in 2013 (Table 2), it was not realised that this could be a new record until now. In January 2017, two individuals of Glochidion obscurum were discovered along a stretch of disturbed scrubland vegetation bordering old-growth forest, which comprised a mixture of cultivated, primary and secondary rainforest species. The identification was subsequently confirmed with flowers as well as immature and ripe fruits.

49

Chia et al.: New record of Glochidion obscurum in Singapore

Description. Glochidion obscurum can grow to 15 m tall and bears distichously arranged simple leaves whose laminas are asymmetric with one base oblique and glaucous on the lower surface, as well as triangular stipules (Whitmore, 1973; van Welzen & Chayamarit, 2007; Fig. 1). Its stalked axillary flowers occur in fascicles of three that include a single pistillate flower, which later forms an obscurely 12- to 14-ribbed capsule that reveals red seeds upon ripening and dehiscence (Fig. 1). The staminate flowers have 4–5 stamens each, distally adnate via connective teeth.

Fig. 1. Glochidion obscurum. A, Habit; B, Fertile branch; C, Axillary fascicles each with a pair of staminate flowers and a fruit formed from a single pistillate flower; D, Leaf, adaxial view; E, Leaf, abaxial view; F, Close-up of flowers; G, Seed mass revealed (left) after dehiscence of the intact capsule (right). (Photographs by: Hock Keong Lua [A] and Wee Foong Ang [B–G]). Scale bar = 1 cm.

50

NATURE IN SINGAPORE 2017

PRESENT AND PAST RECORDS

Distribution. Glochidion obscurum is naturally distributed in Indochina, Peninsular Malaysia, Sumatra, Java and Borneo, so that Singapore is well within the geographical range of this species.

This species has not been recorded for Singapore in Ridley (1900, 1924) or Keng (1990), and an examination of past publication records of Glochidion obscurum and the specimen collections in the Singapore Herbarium confirmed the presence of only one previous collection from Singapore made in 2003. Table 2 chronologically summarises the relevant past literature, documented sightings and botanical collection pertaining to a possible Singapore occurrence for Glochidion obscurum.

Table 2. Records of Glochidion obscurum for Singapore.

Publication/Specimen Year Type of Record accession number/Website Author/Collector Localities mentioned

1900 Publication Handleiding tot de kennis der J. H. Boerlage “Malakka, Penang, Singapore, Sumatra, flora van Nederlandsch Indië Java” [Outline of the knowledge of the flora of the Dutch Indies]

1911 Publication An Account of an Expedition to H. N. Ridley “Malay peninsula and islands…” Lower Siam [A possibly overlooked entry because this species was not mentioned in Ridley (1900) and Ridley (1924).]

2003 Specimen SING 0047746 S. K. Ganesan 105 Gerald Drive, “adjacent to a piece of vacant state land”

2013 Documented http://www.natureloveyou.sg/Gl K. H. Ong Woodlands Town Park East Sightings ochidion%20obscurum/Main.ht Mandai Track 15 ml

2017 Specimen SING 2017-015 J. J. E. Chia, W. F. Mandai Ang, A. H. B. Loo & Z. Y Ooi

No known Singapore collections of Glochidion obscurum seem to have existed prior to 2003, and Boerlage (1900) serves as the only explicit record of this species occurring in Singapore, from his unfinished work on phanerograms of the Dutch Indies region. Boerlage worked mainly with the collections at the herbaria at Bogor (BZ) and Leiden (L), in which Singapore collections of this species are not found (Nicolien Sol & Ridha Mahyuni, pers. comm.). It is therefore assumed that Boerlage had presumed a distribution in Singapore as well because the species seemed common enough in surrounding territories. While this species is noted to have ethnobotanical uses (Burkill, 1930), it is not known to be cultivated and is unlikely to be of cultivated origin (Chong et al., 2009). Hence, the absence of Glochidion obscurum in Singapore records (Ridley, 1900; Ridley, 1924; Keng, 1990) between 1900 and 2003 suggests a potentially limited distribution within Singapore. Ridley (1930) notes that seeds of Glochidion species are dispersed by birds and although it can be speculated that the individual trees we have recorded could be dispersed from Peninsular Malaysia, there is no reason to doubt that Glochidion obscurum could have established in Singapore in the past, given the shared floristic similarities.

Most Glochidion species, and in fact many Phyllanthaceae (e.g., Breynia) are transient pioneers of open sites such as wasteland and forest fringes; the demise of a local population owing to successional development of a closed vegetation canopy or to land-use changes can normally be expected to be compensated for by other developing populations elsewhere. It is also plausible that Glochidion obscurum is uncommon in Singapore. Although common in open sites and forest fringes throughout Malaysia (Ridley, 1924; Corner, 1988), suitable habitat for this species in Singapore is likely to have become reduced as much of open sites are turned over to managed greenery, so that chances of this species maintaining a presence as metapopulations become diminished.

Each Glochidion species is half of an obligate, species-specific, pollination mutualism with a species of Epicephala moth (Kawakita & Kato, 2006), in which the moth larvae destroy some, but not all of the seeds. This is why there is rarely a compete circle of seeds in the mature fruit capsules. This relationship is analogous to the relationship between figs and their pollinating fig wasps, but has received much less study and the pollinator of Glochidion obscurum appears to be currently unknown.

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Chia et al.: New record of Glochidion obscurum in Singapore

CONCLUSIONS

Our findings indicate that even in a relatively well-botanised place like Singapore, there are still interesting species records to be made. Such new findings have continued to be reported from time to time since the reorganisation of botanical research following World War II, e.g., Sinclair (1953, 1956), Tan et al. (1992) and Turner et al. (1994, 1997), including after the turn of the century, e.g., Leong-Škorničková et al. (2014, 2015). Our particular example demonstrates that these could also include common or well-known species in the region, as has also been the case for new native species records for Singapore discovered in the past.

Although it could be considered that existing specimens of Glochidion obscurum are remnants of originally extant vegetation, it is more likely that these individuals have managed to persist because their immediate environment has not changed substantially.

Glochidion obscurum is a new species record for the Singapore native flora with known localities in Woodlands, Mandai and Yio Chu Kang. Presently known only from five individuals, this species should be assigned a threatened status until further reassessment.

ACKNOWLEDGEMENTS

The authors wish to thank Kenneth Er, CEO, and Leong Chee Chiew, Deputy CEO, of the National Parks Board, Singapore, for their interest and support in developing native plant documentation and conservation approaches. Serena Lee, Bazilah, Paul Leong, Koh Sin Lan, Ali Ibrahim, Lam Hui Ju, and Parusuraman Athen of the Singapore Herbarium are thanked for determinations and providing access to past specimens and records. Nicolien Sol (Naturalis Biodiversity Center), Ridha Mahyuni (Herbarium Bogoriense) and Chua Keng Soon (Herbarium, Lee Kong Chian Natural History Museum, National University of Singapore) very kindly ascertained that the holdings at Leiden, Bogor, and the National University of Singapore do not include any Singapore collections of Glochidion obscurum, respectively. We are grateful to Eslindah Ismail for further information on documented sightings, and Gwee Aik Teck for comments on the manuscript and additional opinion on specimen determinations.

LITERATURE CITED

Boerlage JG (1900) Handleiding tot de kennis der flora van Nederlandsch Indië [Outline of the knowledge of the flora of the Dutch Indies], Volume 3. E.J. Brill, Leiden, 448 pp. [In Dutch] Burkill IM (1930) Malay village medicine: Prescriptions collected by I. H. Burkill and Mohamed Haniff. Gardens’ Bulletin, 6: 165–273. Chong KY, Tan HTW & Corlett RT (2009) A Checklist of the Total Vascular Plant Flora of Singapore: Native, Naturalised and Cultivated Species. Raffles Museum of Biodiversity Research, National University of Singapore, Singapore. 273 pp. Uploaded 12 Nov 2009. http://rmbr.nus.edu.sg/raffles_museum_pub/flora_of_singapore_tc.pdf (Accessed 23 Jan 2017). Corner EJH (1988) Wayside Trees of Malaya, 3rd Edition, Volume 1. Malayan Nature Society, Kuala Lumpur, xxii pp., pp. 1–476, figs. 1–145, pls. 1–138. Hoffmann P, Kathriarachchi H & Wurdack KJ (2006) A phylogenetic classification of Phyllanthaceae (Malpighiales; Euphorbiaceae sensu lato). Kew Bulletin, 61: 37–53. Jangid PP & Gupta S (2016) Systematic wood anatomy of the tribe Phyllantheae (Phyllanthaceae, Euphorbiaceae s.l.) from India: Implication in reinstatement of Phyllanthus, Glochidion and allies. Nordic Journal of Botany, 34: 496– 512. Kawakita M & Kato M (2006) Assessment of the diversity and species specificity of the mutualistic association between Epicephala moths and Glochidion trees. Molecular Ecology, 15: 3567–3581. Keng H (1990) The Concise Flora of Singapore: Gymnosperms and Dicotyledons. Singapore University Press, National University of Singapore, Singapore, 222 pp. Leong-Škorničková J, Thame A & Chew PT (2014) Notes on Singapore native Zingiberales I: A new species of Zingiber and notes on the identities of two further Zingiber taxa. Gardens’ Bulletin, Singapore, 66: 153–167. Leong-Škorničková J & Boyce PC (2015) Hanguana in Singapore demystified: An overview with descriptions of three new species and a new record. Gardens’ Bulletin, Singapore, 67: 1–28. Ong KH (2013) Glochidion obscurum. http://natureloveyou.sg/Glochidion%20obscurum/Main.html (Accessed 20 Jan 2017). Ridley HN (1900) The flora of Singapore. Journal of the Straits Branch of the Royal Asiatic Society, 33: 27–196. Ridley HN (1911) An account of a botanical expedition to Lower Siam. Journal of the Straits Branch of the Royal Asiatic Society, 59: 27–234. Ridley HN (1924) The Flora of the Malay Peninsula, Volume 3: Apetalae. L. Reeve & Co Ltd., London, 406 pp.

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Ridley HN (1930) The Dispersal of Plants throughout the World. L. Reeve & Co. Ltd., Ashford, Kent, xx + 744 pp., xxii pls. Sinclair J (1953) Additions to the flora of Singapore and new localities in Singapore for some plants thought to be extinct —Part I. Gardens’ Bulletin, Singapore, 14: 30–39. Sinclair J (1956) Additions to the flora of Singapore and new localities in Singapore for some plants thought to be extinct —Part II. Gardens’ Bulletin, Singapore, 15: 22–30. Tan HTW, Ali bin Ibrahim, Chua KS, Turner IM, Wee YC & Chew PT (1992) Additions to the flora of Singapore, I. Gardens’ Bulletin, 44: 127–133. Turner IM, Tan HTW & Chua KS (1994) Additions to the flora of Singapore, II. Gardens’ Bulletin, Singapore, 46: 131– 135. Turner IM, Tan HTW, Seah EEL, Loo AHB & Ali bin Ibrahim (1997) Additions to the flora of Singapore, III. Gardens Bulletin, Singapore, 49: 1–5. van Welzen PC & Chayamarit K (2007) Euphorbiaceae: Glochidion obscurum. Flora of Thailand, 8(2): 305–626. Whitmore TC (1973) Tree Flora of Malaya: A Manual for Foresters, 2: 34–136.

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NATURE IN SINGAPORE 2017 10: 55–66 Date of Publication: 4 July 2017 © National University of Singapore

A preliminary checklist of the ant genera of Pulau Ubin, Singapore, from rapid opportunistic sampling (Hymenoptera: Formicidae)

Gordon W. J. Yong1*, Mark K. L. Wong2,3 and Eunice J. Y. Soh3

1Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Republic of Singapore; Email: [email protected] (*corresponding author) 2National Parks Board, Singapore Botanic Gardens, 1 Cluny Road, Singapore 259569, Republic of Singapore 3Entomological Network of Singapore

Abstract. A preliminary checklist is provided for the ant genera of Pulau Ubin, the second largest offshore island of Singapore. Thirty-five genera representing seven subfamilies were collected on the island using rapid opportunistic hand sampling. This unexpected diversity on an island may reflect the high ant diversity in the tropics in general. The samples comprised both tramp and native species associated with the island’s habitat matrix of urban vegetation and secondary forest. Four native ant genera (Buniapone, Liomyrmex, Myopopone, and Proceratium) rarely collected on Singapore Island and with scarce collections globally were found on Pulau Ubin. This indicates that secondary forests on offshore islands can support rare ant fauna.

Key words. ant, diversity, island, Singapore, Pulau Ubin

INTRODUCTION

Ants (Hymenoptera: Formicidae) are a speciose and morphologically diverse group of insects with 15,217 valid species and subspecies, classified into 334 genera and 17 subfamilies (Bolton, 2016). The ubiquity of ants and the many ecosystem functions they support, such as bioturbation and insect predation (Philpott & Armbrecht, 2006; Del Toro et al., 2012), make them important components of the many habitats in which they occur.

On the global scale, ant diversity has been shown to decrease with increasing latitude (Guénard, 2013), making equatorial Singapore a potential hotspot for ants. This is further supported by records of high ant diversity in surrounding regions, e.g., Sumatra, 547 species; Java, 446 species; Thailand, 423 species (Janicki et al., 2016); and Borneo, 711 species (Pfeiffer, 2011). However, there is a dearth of published research on ants in Singapore in general; the only and last extensive collection was made by Hans Friedrich Overbeck prior to 1913, cumulating in Viehmeyer (1916) and Overbeck (1924) (AntWiki, 2013). Although the country’s landscape has been largely urbanised (Brook et al., 2003), remnant old- growth forests in several nature reserves and even disturbed patches of vegetation may still harbour speciose native ant assemblages.

Despite an overall lack of consistent long-term sampling efforts in Singapore, new ant species continue to be discovered in this miniature metropolis. For example, a colony of the rarely collected Tyrannomyrmex rex was recently discovered near the Central Catchment Nature Reserve (Wong & Yong, 2017), and a new species of the rare hypogaeic ant genus Leptanilla was described from a similar locality (Wong & Guénard, 2016a). Furthermore, another new species, Myrmecina magnificens, was also recently discovered and reported to occur in considerable densities at the CCNR (Wong & Guénard, 2016b). The recent spate of new species discoveries highlight the fact that very little is known about ant diversity of Singapore’s forests.

With an approximate area of 1,000 hectares, Pulau Ubin is the second largest offshore island in Singapore (Cornelius- Takahama, 2004). The shortest distances of Pulau Ubin from Singapore Island and Johor, Peninsular Malaysia are 1.2 km and 560 m, respectively (Google Earth, 2016). Pulau Ubin was previously a granite quarry in the early 20th century (Cornelius-Takahama, 2004) and is now predominantly secondary forest. To date, there has been no inventory published for the ant fauna in Pulau Ubin. In 2016, the ‘Ubin BioBlitz’, an initiative by the National Parks Board, permitted a rapid preliminary census of the ant communities on the island within a single morning. Based on the findings of the ‘Ubin BioBlitz’ as well as a recent prior instance of opportunistic hand sampling on Pulau Ubin, this paper aims to highlight the considerable diversity of ants found with limited sampling on this offshore island. It is also the first report on Pulau Ubin’s ant fauna. While this preliminary report only identifies the ants to generic level, it is still notable owing to the sheer diversity and rarity of some of the genera encountered.

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Yong et al.: A preliminary checklist of the ant genera of Pulau Ubin, Singapore

MATERIAL & METHODS

Sampling locality and dates. Ants were sampled from multiple sites in Pulau Ubin on two separate occasions in 2016 (Fig. 1). On 15 October 2016 between 0900–1300 hours, the secondary forest at Jalan Ubin (JU) and Jalan Sam Heng (JS) were sampled; only individuals found in nesting colonies were collected, so as to meet the aims of an unrelated study (P. Escoubas, pers. comm.). On 4 December 2016 between 0800–1100 hours, three additional sites were sampled: the urban Assembly Area (AA), a garden on Butterfly Hill (BH), and a secondary forest in the Outward Bound School’s premises (OB). As part of the National Parks Board’s ‘Ubin BioBlitz’ event, all ants encountered were collected. Sampling details are summarised in Table 1.

Sampling method. All of the ants incorporated into the present generic list (see Appendix) were collected via opportunistic hand sampling on the two dates described above, with the exception of an Echinopla specimen collected by Zestin Soh at Chek Jawa in 2016. Opportunistic hand sampling refers to manually searching all locations that are accessible to a person walking through a site, and using a pair of hand-held forceps to retrieve any ants encountered into tubes containing 70% ethanol (v/v). One tube was used per site per collector. In forested areas, this included lifting and dismantling small rotting logs on the forest floor, as well as displacing leaf-litter to search for ants on the exposed soil surface.

Identification and repository. Sampled specimens of each tube were sorted to morphospecies. Then, one individual of each morphospecies from every sampling tube was mounted and examined using a Leica MZ16 stereomicroscope. All mounted specimens were identified to genus using the Southeast Asian taxonomic keys (Eguchi et al., 2011, 2014). These were subsequently sorted to final morphospecies. Selected genera were imaged with Dun IncTM Passport II macrophotography imaging system using a Canon MP-E 65 mm lens. A synoptic and representative collection was deposited in the Zoological Reference Collection (ZRC) of the Lee Kong Chian Natural History Museum at the National University of Singapore.

Table 1. Breakdown of sampling effort by opportunistic hand sampling at five sites of varying habitat in Pulau Ubin. Site Habitat Duration (H) N Personnel Effort (Man-Hours) Assembly Area (AA) Urban 0.5 1 0.5 Butterfly Hill (BH) Managed garden 0.5 2 1 Jalan Ubin (JU) Secondary forest 1 2 2 Jalan Sam Heng (JS) Secondary forest 1 2 2 OBS Grounds (OB) Secondary forest 2 2 4 Total 9.5

Fig. 1 Sampling sites. AA = Assembly Area, BH = Butterfly Hill, JU = Jalan Ubin, JS = Jalan Sam Heng, OB = Outward Bound Singapore. Source: © OpenStreetMap contributors.

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Reference material used for identification. A preliminary generic checklist largely based on data sampled from Pulau Ubin was compiled to which we referenced to existing Singaporean records (see Appendix). These records were obtained from 1) authoritative catalogues, i.e., Bolton (2007) of all ants and Chapman & Capco (1951) of Asian ants; 2) more recent specimens uploaded on Ant Web and consolidated on the Singapore page (Antweb, 2016a), including records from other published material (Taylor, 1968; Moffet, 1986; Rigato & Bolton, 2001; Davison et al., 2008; Tan, 2010; Jacqueminn et al., 2015; Wong & Guénard, 2016a, b; Williams & La Polla, 2016); and 3) personal observations from prior ant surveys by EJYS of which samples are now based at the ZRC.

RESULTS & DISCUSSION

High diversity. In total, 36 genera were sampled on Pulau Ubin (see Appendix). Of these, 35 genera were sampled within a total of 9.5 man-hours across two sampling dates, each involving two persons (see Table 1). The generic diversity recorded at Pulau Ubin represents almost half of the genera known from Singapore (84 genera, with at least 235 species). Pulau Ubin is a non-pristine, secondary forest habitat on an offshore island roughly 1.6% the area of mainland Singapore (Turner & Tan, 1991). The high generic diversity of ants observed on Pulau Ubin suggests a high diversity of Singapore ants in general, indicating strong potential for more species waiting to be discovered. This can be compared to just 17 species and 13 genera found on tropical Santa Cruz Island, Galápagos (98,600 ha) using baited traps and similar hand collection methods (Clark et al., 1982) as well as 27 species and 15 genera collected using leaf litter sifting at the Yasawa islands in Fiji (Ward & Beggs, 2007).

The high diversity of ants may be attributed to the high diversity of habitats of the island. The surveys were conducted in open habitats of urban and managed greenery (BH, AA) as well as the secondary forest (JS, JU, OB). Thus, both urban- adapted tramp species (e.g., Anoplolepis gracilipes, Paratrechina longicornis, Tapinoma melanocephalum) (Silverman, 2005) and forest-associated genera (e.g., Myopopone, Proceratium, Strumigenys) were collected (see Appendix). Although sampling at Pulau Ubin’s mangrove and coastal areas would have likely yielded additional species, these have yet to be surveyed.

Uncommon genera. Four ant genera (discussed below) collected by hand from the brief opportunistic sampling in Pulau Ubin were seldom encountered in previous systematic sampling efforts, involving a variety of methods such as hand collection, leaf litter sampling, and pitfall traps, by the authors on Singapore Island (Yong, G. W. J., Wong, M. K. L., and Soh, E. J. Y., unpublished data). This is potentially owing to their patchy distribution and small colony sizes. The scarcity of collections for these ants may impede revisionary taxonomic work that includes molecular data. Short generic accounts on the biology and local records of the four uncommon genera are given below with accompanying images.

Subfamily Amblyoponinae

Myopopone Roger, 1861 (Fig. 2)

Myopopone is a monotypic genus with only one species, Myopopone castanea Smith, 1860. Previous local records of Myopopone castanea include individuals collected from Bukit Timah on Singapore Island in 1968 by D. H. Murphy under a rotten log, based on specimens deposited at the Australian National Insect Collection (ANIC) (AntWeb, 2016b). At a secondary forest in Pulau Ubin, a partial colony (workers and larvae) was found in a rotting log with abundant Scarabaeidae beetle larva, which is consistent with the known nesting habits and specific prey of this species (Ito, 2010). Like other amblyoponine ants, Myopopone castanea workers are also known to feed off the haemolymph of their own larvae (Ito, 2010).

Subfamily Myrmicinae

Liomyrmex Mayr, 1865 (Fig. 3)

The species collected at Pulau Ubin is identified as Liomyrmex gestroi (Emery, 1887), which is the sole species in this monotypic genus. Liomyrmex gestroi is rarely collected in its natural range (Oriental and Indo-Australia regions), as well as in Singapore. The only known local record for this species was by S. K. Yamane without a collection date cited in the paper (Rigato & Bolton, 2001). This ant, typically found under rotting wood, is reported to be associated with termites (Wheeler & Morton, 1914). At Pulau Ubin, Liomyrmex gestroi was found nesting in a dead log that was shared by termites, concurring with previous observations. However, the nature of the interspecific relationship between Liomyrmex gestroi and termites remains unknown (Rigato & Bolton, 2001).

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Yong et al.: A preliminary checklist of the ant genera of Pulau Ubin, Singapore

Fig. 2. Myopopone castanea. (a) lateral, (b) full-face, and (c) dorsal. Scale bar = 1 mm.

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Fig. 3. Liomyrmex gestroi. (a) lateral, (b) full-face, and (c) dorsal. Scale bar = 1 mm.

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Yong et al.: A preliminary checklist of the ant genera of Pulau Ubin, Singapore

Fig. 4. Buniapone amblyops. (a) lateral, (b) full-face, and (c) dorsal. Scale bar = 1 mm.

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Fig. 5. Proceratium sp. (a) lateral, (b) full-face, and (c) dorsal. Scale bar = 1 mm.

Subfamily Ponerinae

Buniapone Schmidt & Shattuck, 2014 (Fig. 4)

The species collected at Pulau Ubin is identified as Buniapone amblyops Emery, 1887, which is the sole species in the monotypic genus Buniapone. These ants are restricted to Southern and Southeast Asia. Buniapone ants are predominantly hypogaeic, and in Singapore B. amblyops was last collected in 1967 by D. H. Murphy under stones at Bukit Timah, based on a specimen at the ANIC (Ant Web, 2016c). The single worker specimen from Pulau Ubin was also found in soil below a resting stone at the OB site. Little is known about the biology of this genus.

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Yong et al.: A preliminary checklist of the ant genera of Pulau Ubin, Singapore

Subfamily Proceratiinae

Proceratium Roger, 1863 (Fig. 5)

The individual collected at Pulau Ubin is a female gyne collected from rotting wood at the OB site. Proceratium ants are considered to be rarely collected, although they are a diverse (> 70 described species), cosmopolitan genus found in both tropical and temperate regions (Baroni Urbani & de Andrade, 2003). They nest in rotten wood or soil, have relatively small colonies of up to 200 individuals (Baroni Urbani & de Andrade, 2003) and are likely to be specialist predators of spider eggs (Brown, 1980). While the genus has been revised (see Baroni Urbani & de Andrade, 2003), determination of species for the specimen collected is not straightforward as the taxonomic key is based on the worker caste. However, descriptions and available Antweb images of Proceratium deelemani, which was previously recorded in Singapore, do not match the specimen we collected from Pulau Ubin.

The microhabitat and life history of the four uncommon genera found at Pulau Ubin corroborates with observations recorded by past collectors such as D. H. Murphy in the late 1960s. Most of these ants are associated with soil, leaf litter or rotting wood; a lack of comprehensive sampling in these microhabitats may explain the apparent scarcity of collection records for these genera. Furthermore, the ants’ association with these specific microhabitats suggests that they require relatively undisturbed forest, where loose soil, humus layers, and dead woody debris are allowed to accumulate. Our results show that fragments of secondary forest may still be a refuge for uncommon ants when such attributes are present.

CONCLUSIONS

Given the sheer diversity of ants in Singapore, it is envisaged that more resources, sampling and taxonomic expertise will be required in order to systematically document the country’s native ant assemblages. In addition, conservation strategies should incorporate safeguards for secondary forests due to their potential for supporting uncommon and understudied invertebrate faunas.

ACKNOWLEDGEMENTS

We thank the National Parks Board for the opportunity to sample ants during the ‘Ubin BioBlitz’ and for the provision of research permits (reference numbers: NP/RP15-030-1 and NP/RP15-011-2a). We are also grateful to Pulau Ubin managers Noel Thomas and Justin Tan, as well as Sean Yap and Veron Pwa for their assistance with the fieldwork, Zestin Soh for the specimen contribution, and John S. Ascher for the use of laboratory and imaging facilities. Gordon W. J. Yong (GWJY) and Mark K. L. Wong (MKLW) did ant sampling; GWJY, MKLW, Eunice Soh (EJYS) did specimen processing; GWJY did the imaging; EJYS compiled the generic list; all authors contributed to the writing of the manuscript.

LITERATURE CITED

AntWeb (2016a) Singapore Ants (Genera). https://www.antweb.org/taxonomicPage.do?rank=genus&countryName=Sin gapore (Accessed 15 December 2016) AntWeb (2016b) Browsing species Myopopone castanea. https://www.antweb.org/browse.do?rank=species&genus=my opopone&name=castanea (Accessed 15 December 2016) AntWeb (2016c) Browsing species Buniapone amblyops. https://www.antweb.org/browse.do?rank=species&genus=bun iapone&name=amblyops (Accessed 15 December 2016) AntWiki (2013) Overbeck, Hans Friedrich (1882–1942). http://www.antwiki.org/wiki/Overbeck,_Hans_Friedrich_ (1882-1942) (Accessed 17 December 2016). Urbani CB & Andrade MLD (2003) The ant genus Proceratium in the extant and fossil record (Hymenoptera: Formicidae). Museo Regionale di Scienze Naturali Torino, Monografie: 1–492. Bolton B, Alpert G, Ward PS & Naskrecki P (2007) Bolton’s Catalogue of the Ants of the World 1758–2005 CD-ROM. Harvard University Press, Cambridge, USA. Bolton B (2016) An online catalog of the ants of the world. http://www.antcat.org/. (Accessed 15 December 2016). Brook BW, Sodhi NS & Ng PKL (2003) Catastrophic extinctions follow deforestation in Singapore. Nature, 424: 420– 426. Brown WL (1979) A Remarkable New Species of Proceratium, With Dietary and Other Notes on the Genus (Hymenoptera: Formicidae). Psyche, 86: 337–346. Chapman JW & Capco SR (1951) Check list of the ants (Hymenoptera: Formicidae) of Asia. Monographs of the Institute of Science and Technology, 1: 1–327. Clark DB, Guayasamin C, Pazmino O, Donoso C & de Villacis YP (1982) The tramp ant Wasmannia auropunctata: Autecology and effects on ant diversity and distribution on Santa Cruz Island, Galapagos. Biotropica, 14: 196–207.

62 NATURE IN SINGAPORE 2017

Cornelius-Takahama V (2004) Pulau Ubin. http://eresources.nlb.gov.sg/infopedia/articles/SIP_219_2004-12-13.html (Accessed 6 December 2016). Davison GWH, Ng PKL & Ho HC (2008) The Singapore Red Data Book: Threatened Plants and Animals of Singapore, 2nd Edition. The Nature Society (Singapore), Singapore, 285 pp. Del Toro I, Ribbons RR & Pelini SL (2012) The little things that run the world revisited: A review of ant-mediated ecosystem services and disservices (Hymenoptera: Formicidae). Myrmecological News, 17: 133–146. Eguchi K, Bui TV & Yamane S (2011) Generic synopsis of the Formicidae of Vietnam (Insecta: Hymenoptera), Part I— Myrmicinae and Pseudomyrmecinae. Zootaxa, 2878: 1–61. Eguchi K, Bui TV & Yamane S (2014) Generic synopsis of the Formicidae of Vietnam (Insecta: Hymenoptera), Part II— Cerapachyinae, Aenictinae, Dorylinae, Leptanillinae, Amblyoponinae, Ponerinae, Ectatomminae and Proceratiinae. Zootaxa, 3860: 1–46. Google Earth (2016) Pulau Ubin 1.412592°N, 103.957908°E. http://www.earth.google.com (Accessed 8 February 2017). Guénard B (2013) An overview of the species and ecological diversity of ants. eLS, DOI: 10.1002/9780470015902.a00 2359 (Accessed 31 March 2017). Ito F (2010) Notes on the biology of the oriental amblyoponine ant Myopopone castanea: Queenworker dimorphism, worker polymorphism and larval hemolymph feeding by workers (Hymenoptera: Formicidae). Entomological Science, 13: 199–204. Janicki J, Narula N, Ziegler M, Guénard B & Economo EP (2016) Visualizing and interacting with large-volume biodiversity data using client–server web-mapping applications: The design and implementation of antmaps.org. Ecological Informatics, 32: 185–193. Moffett MW (1986) Behaviour of the group-predatory ant Proatta butteli (Hymenoptera: Formicidae): An old world relative of the attine ants. Insect Sociaux, 33: 444–457. Overbeck H (1924) A list of ants from Singapore and neighbouring places. Journal of the Malayan Branch of the Royal Asiatic Society, 2: 25–40. Pfeiffer M, Mezger D, Hosoishi S, Bakhtiar EY, & Kohout RJ (2011) The Formicidae of Borneo (Insecta: Hymenoptera): A preliminary species list. Asian Myrmecology, 4: 9–58. Philpott SM & Armbrecht I (2006) Biodiversity in tropical agroforests and the ecological role of ants and ant diversity in predatory function. Ecological Entomology, 31: 369–377. Rigato F & Bolton B (2001) The ant genus Liomyrmex: A review (Hymenoptera Formicidae). Bollettino della Societa Entomologica Italiana, 133: 247–256. Schmidt CA & Shattuck SO (2014) The higher classification of the ant subfamily Ponerinae (Hymenoptera: Formicidae), with a review of Ponerine ecology and behavior. Zootaxa, 3817: 1–242. Silverman J (2005) Why do certain ants thrive in the urban environment? In: Lee CY & Robinson WH (eds.) Proceedings of the Fifth International Conference on Urban Pests, Singapore. International Conference on Urban Pests. Pp. 29– 31. Tan CKW & Corlett RT (2012) Scavenging of dead invertebrates along an urbanisation gradient in Singapore. Insect Conservation and Diversity, 5: 138–145. Taylor RW (1968) Notes on the Indo-Australian Basicerotine ants (Hymenoptera: Formicidae). Australian Journal of Zoology, 16: 333–348. Turner IM & Tan HTW (1991) Habitat-related variation in tree leaf form in four tropical forest types on Pulau Ubin, Singapore. Journal of Vegetation Science, 2: 691–698. Viehmeyer H (1916) Ameisen von Singapore. Beobachtet und gesammelt von H. Overbeck. Archiv für Naturgeschichte, 81: 108–168. Ward D & Beggs J (2007) Coexistence, habitat patterns and the assembly of ant communities in the Yasawa islands, Fiji. Acta Oecologica, 32: 215–223. Wheeler WM (1914) Note on the Habits of Liomyrmex. Psyche, 21: 75–76. Williams JL & LaPolla JS (2016) Taxonomic revision and phylogeny of the ant genus Prenolepis (Hymenoptera: Formicidae). Zootaxa, 4200: 201–258. Ward PS, Blaimer BB & Fisher BL (2016) A revised phylogenetic classification of the ant subfamily Formicinae (Hymenoptera: Formicidae), with resurrection of the genera Colobopsis and Dinomyrmex. Zootaxa, 4072: 343–357. Wong MKL & Guénard B (2016a) Leptanilla hypodracos sp. n., a new species of the cryptic ant genus Leptanilla (Hymenoptera, Formicidae) from Singapore, with new distribution data and an updated key to Oriental Leptanilla species. ZooKeys, 551: 129–144. Wong MKL & Guénard B (2016b) First confirmed record of the ant genus Myrmecina (Hymenoptera, Formicidae) from the Malay Peninsula: Description of a new species and a key to Myrmecina species from Sundaland. Journal of Hymenoptera Research, 50: 129–140. Wong MKL & Yong GWJ (2017) Notes on the habitat and biology of the rare ant genus Tyrannomyrmex (Fernández, 2003). Asian Myrmecology, 9: e009007 (1–4).

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APPENDIX

A list of ant genera recorded from Singapore and Pulau Ubin, based on material from published catalogues, papers and collections.

The respective abbreviations refer to:  Under ‘Singapore’, representing number of species obtained from: B—Bolton (2005); C—Chapman & Capco (1951); O—Other references, as cited in the next column ‘Reference’; N—number of species from literature records (first three columns); A— AntWeb records; N+ —number of species from literature records and AntWeb.  Under ‘Pulau Ubin’, with × representing the localities to which the ants were found: JS—Jalan Sam Heng (15 October 2016); JU—Jalan Ubin (15 October 2016); AA—Assembly Area (4 December 2016); BH—Butterfly Hill (4 December 2016); OB—Outward Bound Singapore (5 December 2016); N—total number of species from the two sampling events; O—number of species from other recent records at Pulau Ubin.

Singapore Pulau Ubin Genus B C O1 Reference N A N+ JS JU AA BH OB N O2 Subfamily

Amblyoponinae Myopopone 1 1 × 1 Mystrium 1 1 Stigmatomma 1 2 2

Subfamily Dolichoderinae Dolichoderus 2 2 5 5 × × × 2 Iridomyrmex 1 1 Philidris 1 1 1 × 1 Tapinoma 2 1 2 2 2 × × 1 Technomyrmex 3 5 6 7

Subfamily Dorylinae Cerapachys 2 2 2 2 2 Simopone 1 1 1 1 1

Subfamily Ectatomminae Gnamptogenys 3 3 4 4

Subfamily Formicinae Acropyga 2 2 2 2 Anoplolepis 1 1 1 1 × × 1 Camponotus 12 13 17 19 22 × × 2 Colobopsis 4 4 4 1 4 × 2 Dinomyrmex 1 1 1 1 Echinopla 1 2 2 2 2 Z(1) Euprenolepis * Lepisiota 1 1 1 1 1 Myrmoteras 1 2 2 Nylanderia 1 1 × × 2 Oecophylla 1 1 1 × × 1 Overbeckia 1 1 1 1 Paraparatrechina 1 1 1 1 × 1 Paratrechina 1 Tan, 2010 1 1 1 × 1 Plagiolepis * Polyrhachis 12 25 27 19 31 × 2 Williams & Prenolepis 1 LaPolla, 1 1 2016 Pseudolasius 3 3 3 3 3

Subfamily Leptanillinae Wong & Leptanilla 1 1 1 Guenard, 2 1 2 2016a Protanilla 1 1 1 1

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Singapore Pulau Ubin Genus B C O1 Reference N A N+ JS JU AA BH OB N O2 Subfamily

Amblyoponinae

Subfamily Myrmicinae Aphaenogaster * Calyptomyrmex 1 1 1 1 1 Cardiocondyla 1 1 1 1 1 Carebara3 4 1 3 Tan, 2010 5 2 2 × × 2 Cataulacus 1 2 3 4 4 Hoisoishi Crematogaster 9 4 2 & Ogata, 11 12 14 × × × 4 2009 Dilobocondyla 1 1 1 1 1 Eurhopalothrix 1 1 1 Rigato & Liomyrmex 1 Bolton, 1 1 × 1 2001 Mayriella 1 1 1 1 Meranoplus 1 1 2 1 2 × 1 Monomorium 4 3 5 5 6 × Wong & Myrmecina 1 Guenard, 1 1 2016b Myrmicaria 1 2 1 × 1 Paratopula 1 1 Pheidole 4 5 6 Tan, 2010 12 7 15 × × × × 5 Pristomyrmex 3 3 3 3 × 1 Moffet, Proatta 1 1 1 1 × × 1 1986 Rhopalomastix 1 1 2 1 Rostromyrmex 1 1 Rotastruma 1 1 1 Solenopsis 1 1 1 1 1 Taylor, Strumigenys 10 1 10 10 10 × 1 1968 Syllophopsis 1 1 Tetramorium 3 4 1 Tan, 2010 5 4 6 × × × × 4 Trichomyrmex 1 1 Jacquemin Tyrannomyrmex 1 1 1 et al., 2015 Vollenhovia 1 2 2 2 2 × × 2

Subfamily Ponerinae Anochetus 1 1 1 5 5 × 1 Bothroponera 1 1 Brachyponera × 1 Buniapone 1 1 1 1 × 1 Centromyrmex 1 1 1 1 Cryptopone 1 1 Diacamma 2 1 3 1 3 × × 2 Ectomomyrmex 1 2 2 1 2 × 1 Euponera 1 1 1 1 1 Davison et Harpegnathos 1 1 1 al., 2008 Hypoponera 1 1 1 2 1 × × ? Leptogenys 3 3 2 5 × 1 Mesoponera 1 2 2 2 3 × Neoponera 1 1 Odontomachus 1 1 1 2 2 × × × 2 Odontoponera 1 1 1 2 2 × 1 Parvaponera 1 1 1 Platythyrea 1 2 2 1 2 × 1 Pseudoneoponera 1 1 1 1 1

Subfamily Proceratiinae Discothyrea * 1 1

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Yong et al.: A preliminary checklist of the ant genera of Pulau Ubin, Singapore

Singapore Pulau Ubin Genus B C O1 Reference N A N+ JS JU AA BH OB N O2 Subfamily

Amblyoponinae Probolomyrmex 1 1 1 2 Proceratium 1 1 1 1 × 1

Subfamily Pseudomyrmicinae Tetraponera 6 6 9 9 9 × 1 84 genera Total spp. 190 184 235 53 1 Total genera 68 68 80 35 1

1* indicates that the specimen was obtained from prior ant collecting by ES and specimens are currently based at ZRC but not formally catalogued with the collection. 2numbers in brackets indicate the number of morphospecies; Z refers to a specimen contributed by Zestin Soh collected on 10 September 2016 at Chek Jawa. 3Pheidologeton is synonymised under Carebara.

66 NATURE IN SINGAPORE 2017 10: 67–71 Date of Publication: 29 August 2017 © National University of Singapore

Pinalia floribunda (Lindl.) Kuntze (Orchidaceae): Rediscovery and conservation of a species thought extinct in Singapore

Paul K. F. Leong, Clayton Lee, Felicia E. L. Tay, Peter Ang and Tim W. Yam*

National Parks Board, 1 Cluny Road, Singapore 259569, Republic of Singapore; Email: [email protected] (*corresponding author)

Abstract. Until recently, the last local herbarium collection for Pinalia floridunda, a Singapore native species, was made 125 years ago in 1892. In November 2012, a small clump of this orchid was found among the debris of a fallen tree in Bukit Timah Nature Reserve. It was collected and grown in the Singapore Botanic Gardens and its identity confirmed when it flowered in February 2013. Since then, this species has been sighted growing epiphytically on several trees in Nee Soon Swamp Forest. In 2016, a large clump about 90 cm in diameter was sighted growing on a tall tree (Pentace triptera), some 20 m above ground, deep within this swamp forest. A portion of this was collected for propagation and future reintroduction. This species is thus documented as a rediscovery and considered as nationally Critically Endangered owing to its rarity here.

Key words. Orchidaceae, Pinalia floribunda, Eria, Nee Soon Swamp Forest, rediscovery, conservation

INTRODUCTION

This paper documents the rediscovery and conservation of Pinalia floribunda (Fig. 1) in Singapore. John Lindley established the genus Pinalia (Lindley, 1826) but subsequently in 1830 decided to reduce it to a section of Eria (Lindley, 1830), a genus he established in 1825 (Lindley, 1825). He later described the species Eria floribunda in the Edwards’s Botanical Register (Lindley, 1843). Kuntze restored Pinalia to generic status in 1891 and transferred the species Eria floribunda into Pinalia (Kuntze, 1891). However, his treatment was not widely used and the name Eria floribunda continued to be generally accepted. The genus Eria sensu lato was confirmed to be polyphyletic as evidenced in molecular analyses of Ng (2002), and as a result, Pinalia was restored to generic status in the subtribe Eriinae in Genera Orchidacearum (Pridgeon et. al., 2005).

DESCRIPTION

Pinalia floribunda is an epiphytic orchid, forming a clump, usually small to about 90 cm across, with many closely clustered, erect, stem-like, yellowish-green pseudobulbs. These are covered by thin reddish-brown, translucent sheaths with distinct venation that turn pale translucent and tattered with age. Each pseudobulb is about 4050 cm long and about 1 cm across, slightly flattened when young, maturing cylindrical and fleshy with about 10 nodes along its length. Leaves are sessile, 46, narrow elliptic to elliptic, crowded at the apex of the pseudobulb, bright pale green and soft, mid-green above and slightly paler below, maturing coriaceous, 4.625 cm long and 1.53.1 cm wide. Inflorescences are axillary, 514.2 cm long, arising within a sheath near the nodes on the upper part of the pseudobulb (leaving a pit on the pseudobulb when shed), with about 27 inflorescences per pseudobulb with several at the same developmental stage, racemose, with about 3650 flowers per inflorescence, and the flowers lax to dense. The inflorescences develop from the leafy zone or the upper part of the pseudobulb below the insertion of the leaves, and are almost horizontal and arching slightly downwards to being pendent. The peduncle is up to 1 cm long and subtended by pale brown bracts. The bracteole of each flower is ovate and brown. Each flower is about 5 mm long and 7 mm across and covered with sparse maroon hairs outside. The pedicel is about 4 mm long. Sepals are white, and the petals white but sometimes tinged pinkish at the margins. The lip is white but suffused pink near the side lobes, and the column is maroon at its apex and whitish to pinkish below, and at the foot. The flowers are very faintly scented.

PAST AND PRESENT RECORDS

Distribution. Pinalia floribunda is distributed from Myanmar to Vietnam in the north, to Thailand, Peninsular Malaysia, the Riau Islands, and Singapore in the south, from the Philippines, Sabah, and Sarawak in the east to Sumatra and the Mentawai Islands in the west and is found in the lowlands, from mangrove to freshwater swamp forests, and lowland dipterocarp forest to hill forest, and up to montane forest at more than 2,000 m at Gunung Tahan (Ridley, 1908; Seidenfaden & Smitinand, 1959; Holttum, 1964; Wood & Cribb, 1994; Comber, 2001; Cootes, 2011).

67 Leong et al.: Rediscovery and conservation of Pinalia floribunda

Fig. 1. A, cutting from the orchid clump; B, inflorescences of one pseudobulb; C, inflorescence with ruler; D, inflorescence close up; E, front view of the flower; F, side view of the flower; G, side view of the flower with a petal removed to show the lip attachment to the column with the column foot. (Photographs by: Felicia E. L. Tay [EG], Paul K. F. Leong [A & C], and Tim W. Yam [B & D]).

68 NATURE IN SINGAPORE 2017

Table 1. Previous Singapore collections of Pinalia floribunda (Lindl.) Kuntz deposited in the Herbarium, Singapore Botanic Gardens (SING). S/No. Bar Code No. Collector Collector’s No. Date Collected Locality 1. SING 0010751 H.N. Ridley s.n. 26 February 1889 Kranji 2. SING 0010753 H.N. Ridley 1634 9 January 1890 Sungei Buloh 3. SING 0010752 H.N. Ridley 8928 1892 Seletar 4. SING 0010749 J.S. Goodenough s.n. 13 January 1892 Chan Chu Kang Forest Reserve 5. SING 0010750 J.S. Goodenough s.n. 18 September 1892 Sungei Murai 6. SING 0205850 N.N.H. Faizu SING 2012-518 November 2012 Bukit Timah Nature Reserve 7. In process C. Lee et. al. SING 2016-135 26 February 2016 Nee Soon Freshwater Swamp Forest

Records of the Singapore Botanic Gardens’ Herbarium (SING) showed that the species was collected five times in Singapore in the 19th century (Table 1). The first was from Kranji by H. N. Ridley in 1889. The second was collected from Sungei Buloh by H. N. Ridley in 1890. It was collected three times in 1892 by H.N. Ridley (Seletar) and J. S. Goodenough (Chan Chu Kang and Sungei Murai). Since then, it was thought to be presumed nationally extinct as it has not been encountered again by 2008, when the 2nd Edition of the Singapore Red Data Book (Tan et al., 2008) was published.

A small clump of Pinalia floribunda was found growing epiphytically on a fallen tree in Fern Valley, Bukit Timah Nature Reserve in November 2012. It was collected and brought to the Singapore Botanic Gardens for cultivation and its identity was confirmed when it flowered in February 2013. It was lodged as herbarium specimen, N. N. H. Faizu SING 2012-518.

During a field survey on 26 February 2016 at the Nee Soon Swamp Forest, we encountered this orchid species again. Several plants were seen on smaller trees within the swamp forest perched on branch forks of trees in bright but filtered light. A large clump was found growing on a 30-m tall tree, Pentace triptera (Malvaceae) (Figs. 24), incidentally, the same species of tree that fell in the Fern Valley, where the orchid was first rediscovered.

The Nee Soon Swamp Forest is a freshwater swamp forest area of around 80 ha, consisting of a mixture of old secondary and primary forests, with the Nee Soon Stream running through it. The area where the species was found is about 10 m above sea level and generally flat with thick leaf litter, but surface water was visible within gaps in the root mat. Most of the trees within the area had trunk girths of around 3060 cm, and an average height of around 30 m. The tree canopy coverage was around 50%, offering bright light to filter in. There were epiphytes such as ferns and another orchid species, Cymbidium finlaysonianum, as well as Freycinetia and Korthalsia climbers that are typical of the primary freshwater swamp forest flora.

CONSERVATION

The specimen collected is now growing in Singapore Botanic Gardens’ orchid nursery. The plant has been divided into cuttings consisting of five to six pseudobulbs each. The cuttings were planted in a growing medium consisting of charcoal

Fig. 2. A large clump of Pinalia floribunda was found growing on a 30-m tall Pentace triptera (Malvaceae) tree. (Photograph by: Clayton Lee).

69 Leong et al.: Rediscovery and conservation of Pinalia floribunda

Fig. 3. Crown of the tree in the Nee Soon Swamp Forest where Pinalia floribunda was rediscovered. (Photograph by: Paul K.F. Leong).

Fig. 4. Clayton Lee collecting the rediscovered Pinalia floribunda from the Pentace triptera tree. (Photograph by: Tim W. Yam).

70 NATURE IN SINGAPORE 2017 and coconut husk in 6-inch plastic pots. All the cuttings are growing well, with new shoots emerging. Four inflorescences began to appear in late June and flowered on 21 July 2016.

Since only one specimen was collected and there were no seed capsules on the plant, we can only propagate the plant by division. We would like to expedite the propagation so that reintroduction of this species back to our forests can be carried out in a few years’ time.

Besides conservation, the species is also a very attractive plant for horticulture (Hawkes, 1965). A well-grown mature plant is rather compact in size and produces numerous sprays of attractive, slightly scented flowers. In the 2016 Singapore Orchid Show, a beautiful Pinalia floribunda won the trophy for the best species and the Reserve Champion of the show!

ACKNOWLEDGEMENTS

We would like to thank the staff from the Conservation Division, National Parks Board, especially William Ng, Ngon Soon Kong, Toh Yuet Hsin, Derek Liew, and Hassan Ibrahim for their support during the field surveys and the staff of the Orchid Nursery, Singapore Botanic Gardens, Whang Lay Keng, Mark Choo and Kee Kai Ying for growing the species. Also, we would like to thank the Singapore Botanic Gardens’ Herbarium and Library for access to the herbarium specimens and reference books, respectively, and in particular to Ho Boon Chuan and Hubert Kurzweil for their assistance in deciphering the old literature as well as Aung Thame for collecting the inflorescences when the Bukit Timah Nature Reserve plant flowered during the Chinese New Year holiday period.

LITERATURE CITED

Comber JB (2001) Orchids of Sumatra. Natural History Publications (Borneo) in association with The Royal Botanic Gardens, Kew, 1,026 pp. Cootes J (2011) Philippines Native Orchid Species. Katha Publishing, Quezon City, 288 pp. Hawkes AD (1965) Encyclopedia of Cultivated Orchids. Faber & Faber, 602 pp. Holttum RE (1964) A Revised Flora of Malaya. Volume I, Orchids of Malaya, 3rd Edition. Government Printing Office, Singapore, 759 pp. Kuntze O (1891) Revisio generum plantarum, 2: 375–1011. Lindley J (1825) The botanical register, 11: 868–955, 88 colour pls. Lindley J (1826) Orchidearum Sceletos. Typis Ricardi Taylor, London, England, 27 pp. Lindley J (1830) The Genera and Species of Orchidaceous Plants. Ridgways, London, 544 pp. Lindley J (1843) Edwards’s Botanical Register, 29: 1–66, 65 colour pls. Ng YP (2002) Molecular Systematics and Evolution of Eria (Orchidaceae). Unpublished PhD Thesis, Birkbeck College, University of London, London, 111 pp. Pridgeon AM, Cribb PJ, Chase MW & Rasmussen FN (2005) Genera Orchidacearum Vol. 4 Epidendroideae (Part One). Oxford University Press, Oxford, UK, 672 pp. Ridley HN (1908) Materials for a Flora of the Malayan Peninsula, Part I. Printed at the Methodist Publishing House, Singapore, 233 pp. Seidenfaden G & Smitinand T (1959) The Orchids of Thailand: A Preliminary List. Parts I and II. Siam Society, Bangkok, 186 pp. Tan HTW, Tan K-x, Ali bin Ibrahim, Chew PT, Chua KS, Duistermaat H, Ganesan SK, Goh MWK, Gwee AT, Kiew R, Lee SML, Leong P, Lim J, Lok AFSL, Loo AHB, Lum SKY, Morgany T, Saifuddin bin Suran, Sim S, Haji Samsuri bin Haji Ahmad, Wee YC, Yap KF, Yeo CK & Yong JWH (2008) Checklists of Threatened Species―Seed Plants. In: Davison GWH, Ng PKL & Ho HC (eds.) The Singapore Red Data Book: Threatened Plants & Animals of Singapore. 2nd Edition. The Nature Society (Singapore), Singapore. Pp. 213–244. Wood JJ & Cribb PJ (1994) A Checklist of the Orchids of Borneo. Royal Botanic Gardens, Kew, UK, 409 pp.

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