Enhydris enhydris (Schneider, 1799) — Native. Hydrus Enhydris Schneider, 1799: 245–246. Lectotype: specimen described and illustrated by Russell (1796: 35, pl. 30), designated by Wallach et al. (2014: 270). Type locality: “Indiae orientalis” (= East India, i.e., Southeast Asia); later restricted to “lake of Ankapilly, coast of Coromandel, India ” via lectotype designation. Rainbow Water Snake (Figure 24A; Sungei Kadut Drive) Singapore records. Hypsirhina enhydris — Boulenger, 1896: 7.— Flower, 1896: 887.— Flower, 1899: 676.—Ridley, 1899: 208.— Boulenger, 1912: 160.— de Rooij, 1917: 181. Enhydris enhydris —Sworder, 1923: 66.—Tweedie, 1953: 83.—Tweedie, 1961: 86.— Gyi, 1970: 92.— Tweedie, 1983: 99.—F.L.K. Lim & M.T.-M. Lee, 1989: 73, 116.—F.L.K. Lim, 1991: 72.—K.K.P. Lim & F.L.K. Lim, 1992: 147.— David & Vogel, 1996: 116.— Cox et al., 1998: 40.— Iskandar & Colijn, 2001: 90.—K.P. Lim & F.L.K. Lim, 2002: 147.— de Lang & Vogel, 2005: 251.—J.C. Murphy, 2007: 238.—N. Baker & K.P. Lim, 2008: 169.—F.L.K. Lim, 2009: 464.—K.K.P. Lim & D’Rozario, 2009: 9–11 (Neo Tiew Road [LCK]; Sungei Buloh Wetland Reserve).— Das, 2010: 326.—L.L. Grismer, 2011a: 195.—P.K.L. Ng et al., 2011: 502.—N. Baker & K.P. Lim, 2012: 169.— Das, 2012a: 107.—N. Baker & Thomas, 2013: 47 (Kranji Marshes).—Thomas et al., 2014: 309.—Wallach et al., 2014: 269.—Chan-ard et al., 2015: 239.— Kwan & Pascoe, 2015: 102, 103 (Sungei Buloh Wetland Reserve).— de Lang, 2017: 284.— Das, 2018: 125.—Serin & R. Subaraj, 2018: 35 (Sungei Buloh Wetland Reserve).— Charlton, 2020: 98.— Leo et al., 2020: 257.— Figueroa et al., 2022: 1 (Kranji Way).— Kurniawan et al., 2022: 113. Enhydris enhydris enhydris — de Haas, 1950: 576. Xenopeltis unicolor —E.K. Chua, 2010: 101 [misidentified E. enhydris] (Sungei Buloh Wetland Reserve). Remarks. In a note documenting the first record of reproduction of E. enhydris in Singapore, Figueroa et al. (2022) discussed the status of this species in Singapore. Considered non-native (Lim & D’Rozario 2009; Baker & Lim 2012; Charlton 2020), Figueroa et al. (2022) asserted that E. enhydris is most likely native to Singapore. Lim & D’Rozario (2009) reported a dead individual found on Neo Tiew Road on 13 April 2008, and a live specimen seen at SBWR on 13 September 2008. The only record before this is an early specimen (BMNH 1870.1.14.4) collected prior to 1896 (Boulenger 1896). Given the long absence between these records, and that northwestern Singapore is dedicated to agrotechnological farming, Lim & D’Rozario (2009) suggest that E. enhydris was introduced into Singapore with imported aquatic plants. However, E. enhydris inhabits stagnant and slow-moving aquatic habitats such as rice paddies, canals, ditches, lakes, and rivers, including degraded areas and urban areas (Murphy 2007), making the wetlands, freshwater marshes, ponds, and farms found around northwestern Singapore ideal habitat. Thus, given this information and that E. enhydris ranges widely from Sri Lanka north along eastern India to Nepal, east to southeastern China, and south through Peninsular Malaysia to Indonesia, including Sumatra, Borneo, Java, and Sulawesi (Murphy 2007), Figueroa et al. (2022) reasoned that it is a native species that is rare in Singapore. Including the record of Figueroa et al. (2022), there are nine published records of E. enhydris from Singapore. In addition, one of us (A. Figueroa pers. obs.) observed one in a drain along Sungei Kadut Drive on 17 December 2020 (Fig. 24A) bringing the total to 10. We follow Figueroa et al. (2022) and designate E. enhydris as native. Intensive surveys are needed to better understand the occurrence of E. enhydris in Singapore. Occurrence. Restricted to Choa Chu Kang and Kranji. Rare. Singapore conservation status. Not Evaluated. Conservation priority. Highest. IUCN conservation status. Least Concern [2010]. LKCNHM & NHMUK Museum specimens. Singapore (no locality): BMNH 1870.1.14.4 (no date); Kranji Reservoir: ZRC.2.7337 (29-Nov-2018); Sungei Buloh Wetland Reserve: ZRC.2.7088 (14-Nov-2014). Additional Singapore museum specimens. No specimens. Singapore localities. Kranji Marshes—Kranji Reservoir—Kranji Way—Lim Chu Kang—Nee Soon Swamp Forest—Sungei Buloh Wetland Reserve—Sungei Kadut Drive. Genus Fordonia Gray, 1842 (1 species)

Published as part of Figueroa, Alex, Low, Martyn E. Y. & Lim, Kelvin K. P., 2023, Singapore's herpetofauna: updated and annotated checklist, history, conservation, and distribution, pp. 1-378 in Zootaxa 5287 (1) on pages 208-210, DOI: 10.11646/zootaxa.5287.1.1, http://zenodo.org/record/7960319