Fordonia leucobalia (Schlegel, 1837)

Figueroa, Alex, Low, Martyn E. Y. & Lim, Kelvin K. P., 2023, Singapore’s herpetofauna: updated and annotated checklist, history, conservation, and distribution, Zootaxa 5287 (1), pp. 1-378 : 210-211

Fordonia leucobalia (Schlegel, 1837) — Native.

Homalopsis leucobalia Schlegel, 1837: 171 , 345–346, pl. 13, figs. 8, 9. Holotype: RMNH.RENA.1161, by original designation. Type locality: “ Timor ” (= Timor-Leste), Indonesia.

Crab-eating Water Snake

( Figure 24B )

Singapore records.

Hemiodontus chalybaeus Jan, 1863: 79 .— Jan & Sordelli, 1866 – 1870: pl. 28 VI 3.

Fordonia leucobalia —Sclater, 1891a: 55.— Flower, 1899: 679.—Ridley, 1899: 208.— Boulenger, 1912: 164.— Hanitsch, 1912b: 16.— de Rooij, 1917: 189.—Sworder, 1923: 66 (Kranji).— Smith, 1930: 62 (Changi).— de Haas, 1950: 578.—L.M. Chou et al., 1980: 71.—K. Lim, 1989h: 64 (Changi Central).—K.K.P. Lim & L.M. Chou, 1990: 54.—K.K.P. Lim & Subharaj, 1992: 7 (Sungei Buloh Nature Park [= SBWR]).—K.K.P. Lim & F.L.K. Lim, 1992: 147.—K.K.P. Lim, 1993b: 2 (Lim Chu Kang Mangroves).—L.M. Chou et al., 1994: 105.—J.K.Y. Low et al., 1994: 158.—K. Lim, 1995: 16 (Lim Chu Kang Mangroves).— David & Vogel, 1996: 119.— Manthey & Grossmann, 1997: 352.— Cox et al., 1998: 39.—Chan-ard et al., 1999: 33.— Iskandar & Colijn, 2001: 92.— Jayne et al., 2002: 143.— Karns et al., 2002: 488 (Pasir Ris Park Mangroves).—K.P. Lim & F.L.K. Lim, 2002: 147.—J.C. Murphy & Voris, 2002: 107.—Voris & J.C. Murphy, 2002: 1626 (“Pasar” Ris [PRPM]).— Anonymous, 2003: 92 (Sungei Buloh Wetland Reserve).— Karns et al., 2005: 86.—J.C. Murphy, 2007: 179.—N. Baker & K.P. Lim, 2008: 110, 161.—K.K.P. Lim et al., 2008: 265.—P.K.L. Ng et al., 2008: 165.—P.Z. Chen, 2010: 195.— Das, 2010: 329.—P.K.L. Ng et al., 2011: 502.—N. Baker & K.P. Lim, 2012: 110, 161.— Das, 2012a: 110.—Voris & J.C. Murphy, 2012: 194.—Huang & P. Lee, 2014: 259, 260 (Pasir Ris Park Mangroves).—J.C. Murphy & Voris, 2014: 20.—Wallach et al., 2014: 298.—Chan-ard et al., 2015: 245.—Serin, 2015c: 163 (Pasir Ris Park Mangroves).—T.L. Su & S.S. Lim, 2016: 227.— de Lang, 2017: 287.— Das, 2018: 128.—Jayne et al., 2018: 638.— Leviton et al., 2018: 416 .— Charlton, 2020: 99.— Figueroa & McCleary 2021: 1281 (Pasir Ris Park Mangroves).—W.L. Cheong & Z.A.Z.W Wee, 2023: 1 (Pasir Ris Park Mangroves).

Fordonia leucobalia var. D— Hanitsch, 1899: 12.

Enhydris plumbea —F.L.K. Lim & M.T.-M. Lee, 1989: 116 [= F. leucobalia, F.L.K. Lim pers. comm.].— F.L.K. Lim, 1991: 53.

Remarks. When F. leucobalia was first reported from Singapore, it was described as a new species, Hemiodontus chalybaeus ( Table 1 ) from one specimen deposited at ZMH ( Jan 1863) that is no longer extant. Boulenger (1890a) later synonymised it with F. leucobalia noting that Jan (1863) recognised the specimen as a different species because it had the internasal scale missing. Following Jan (1863), F. leucobalia was also reported from specimens at ZSI (Sclater 1891a), a specimen purchased by Hanitsch in September 1898 ( Hanitsch 1899), two specimens collected by Sworder (1923) at Kranji, and one specimen at the Raffles Museum from 1927 from Changi (Smith 1930). Then, F. leucobalia went unreported for 62 years ( Table 2 ) until Lim (1989h) documented one found in a drain on reclaimed land at Changi Central on 15 October 1989. Next, a dead one was encountered in a disused prawn pond at SBWR on 15 August 1992 ( Lim & Subharaj 1992), and a live one was found at LCKNP on 28 September 1993 (Lim 1995). Most commonly seen at PRPM, surprisingly the population from there was not reported until Karns (2002). Several reported observations from PRPM involved F. leucobalia being predated upon. First was a Paradoxurus musangus sitting on a branch with a dead F. leucobalia on 6 September 2014 ( Huang & Lee 2014), followed by a Periophthalmodon schlosseri with a F. leucobalia in its mouth on 11 June 2015 (Serin 2015c), and a juvenile T. purpureomaculatus that was filmed feeding on a F. leucobalia ( Figueroa & McCleary 2021) . Periophthalmodon schlosseri appear to feed frequently on F. leucobalia , as one of us also witnessed a predation event at PRPM on 8 October 2015 (A. Figueroa pers. obs.). More recently, two F. leucobalia were observed engaging in courtship behaviour at PRPM on 8 October 2022 ( Cheong & Wee 2023). The photograph in Figure 24B was taken at PRPM on 12 November 2014 (A. Figueroa pers. obs.). LKCNHM has several specimens, mainly from after the 1990s.

Occurrence. Restricted to mangroves of LCKNP, PRPM, and SBWR. Uncommon.

Singapore conservation status. Endangered.

Conservation priority. Highest.

IUCN conservation status. Least Concern [2018].

LKCNHM & NHMUK Museum specimens. Singapore (no locality) : ZRC.2.3303 (no date), ZRC.2.3304 (29- Dec-1914) , ZRC.2.3931 (1986); Changi : BMNH 1968.792 (no date) , ZRC.2.3300 (1927); Changi Beach : ZRC.2.3489 (09-May-1996) ; Kranji: ZRC.2.3301 (29-Oct-1922) ; Kranji River : ZRC.2.3302 (20-Mar-1923) ; Lim Chu Kang: ZRC.2.5048 (19-Apr-2001) , ZRC.2.5045, ZRC.2.5047 (23-Apr-2001) ; Lim Chu Kang Mangroves: ZRC.2.3389 (28-Sep-1993) , ZRC.2.3462– ZRC.2.3465 (29-Dec-1995) , ZRC.2.3461 (16-Feb-1996) ; Pasir Ris: ZRC.2.5003 (03-Mar-2001) ; Pasir Ris Park Mangroves: ZRC.2.4578 (10- Jun-1999) , ZRC.2.4600 (15-Jul-1999) , ZRC.2.7094 (2011), ZRC.2.7092 (21-May-2011) , ZRC.2.7093 (02-Aug-2011) ; Seletar Reservoir: BMNH 1983.972 (no date); Serangoon Road : ZRC.2.3299 (16-Aug-1921) ; Sungei Buloh Wetland Reserve : ZRC.2.3366 (15-Aug-1992) , ZRC.2.6304 (23-Feb-2001) .

Additional Singapore museum specimens. Singapore (no locality): NMW, SAMA, ZMH, ZMUC ; West Coast Road Prawn Ponds [= Jurong Prawn Ponds]: BPBM.

Singapore localities. Changi—Changi Beach—Jurong Prawn Ponds—Kranji—Lim Chu Kang—Lim Chu Kang Nature Park—Pasir Ris (not specified)—Pasir Ris Park Mangroves—Seletar Reservoir*—Serangoon Road*—Sungei Buloh Wetland Reserve—Sungei Kranji.

Genus Gerarda Gray, 1849 (1 species)

Gerarda Gray, 1849: 39 , 77 (type species: Gerarda bicolor Gray, 1849 [= Coluber (Homalopsis) prevostianus Eydoux & Gervais, 1837 ], by monotypy; gender feminine).

Figures

FIGURE 24. A) Enhydris enhydris, B) Fordonia leucobalia, C) Gerarda prevostiana, D) Homalopsis buccata, E) Phytolopsis punctata, F) Raclitia indica, G) Psammodynastes pictus, and H) Asthenodipsas laevis. Photographs by: Joan Lee [A], Alex Figueroa [B–D], Holly Siow [E], Dennis Nathaniel Chan [F], Nick Baker [G], and Kelvin K.P. Lim [H].