Acrochordus granulatus

CONSERVATION STATUS [IUCN]. — Least Concern [2016] ver. 3.1.

PHILIPPINE DISTRIBUTION (Map 2 A [p. 113]). — Bantanyan, Calamian Ids. (Calauit), Cebu, Guimaras, Luzon (Prov.: Batangas, Cavite, Ilocos Norte, Laguna, Manila, [Manila Bay], Quezon, Rizal), Masbate, Negros (Prov.: Negros Occidental, Negros Oriental), Palawan, Panay (Prov.: Iloilo), Siquijor. GENERAL DISTRIBUTION (OTHER THAN PHILIPPINES). — Coastal waters from west coast of India (as far north as Bombay), Sri Lanka, east coast of India, coasts of Myanmar, Malaysia, and east throught the Indonesian Archipelago to the north coast of Australia and the Solomon Islands.

TYPE LOCALITY AND TYPE SPECIMEN (S). — India (restricted by Smith [1943: 134]). Type un-known.

Marine File Snake; Little File Snake; Wart Snake

(Fig. 3 C, 11 B) Material: One adult, CSPT / S 75 from Port Blair, South Andaman. Morphology: Supralabials 14; infralabials 12; nasals in contact with each other, nostrils distinctly large; scales in 128 rows at midbody. Body with alternate grey and 67 white bands; ventrals small and indistinguishable from the rest of the scales. SVL 670 mm, TaL 80 mm, HL 14.5 mm, HW 12.5 mm, HD 11 mm, ED 1.5 mm, EN 3.5 mm, ES 4.0 mm. Distribution: One adult was recorded at Sippighat, Port Blair. Occurs throughout the coast of the Andaman Islands Status: Uncommon. Although only a single individual was recorded during the study, it is frequently encountered by fishermen (pers. comm.)

Remarks. Gray (1842 b) first reported A. granulatus in Singapore based on a museum specimen deposited at NHMUK by Hardwicke (Gray 1849). Gray (1849) later used the specimen as the type (syntype) specimen to describe Chersydrus annulatus (Table 1), a subjective synonym of A. granulatus. Additional early specimens include a specimen at ZSI (Sclater 1891 a), at SMF (Boettger 1898), one Ridley (1899) received that was collected from a road near SBG, and one Sworder (1924 a) collected at Pulau Sudong on 24 May 1923. The next report for A. granulatus comes 57 years later (Table 2) when Chou (1980) comments that it is found in mangroves. Concurrently, Voris and Jeffries collected numerous specimens from Jurong Prawn Pond, a kelong off Lim Chu Kang, and from Tuas during their sea snake study during the early 1980 s (see Elapidae below). Their data shows that A. granulatus is common in Singapore, having caught upwards of 22 specimens in one day. Primarily an occupant of marine habitats, freshwater populations exist in Singapore due to the creation of reservoirs (Ng 2011; Teo & Khoo 2016). A recently reported record documented mating behaviour of this species at Pasir Ris Beach on 15 August 2021 (Iesa 2021). Occurrence. Wide-ranging. Common.

Singapore conservation status. Near-Threatened. Conservation priority. Lowest. IUCN conservation status. Least Concern [2022]. LKCNHM & NHMUK Museum specimens. Singapore (no locality): BMNH 1946.1. 1.40 (no date [syntype of Chersydrus annulatus); Changi Beach: ZRC. 2.6081 (19 - Jan- 2004), ZRC. 2.7400 (04 - Jul- 2019); Kranji: ZRC. 2.2253 (25 - Mar- 1964); Kranji Mangroves: ZRC. 2.2252 (no date); Lim Chu Kang: ZRC. 2.5373 (30 - Mar- 1982); Lim Chu Kang Mangroves: ZRC. 2.3466 – ZRC. 2.3468 (27 - Dec- 1995); Lower Seletar Reservoir: ZRC. 2.6808 (25 - Feb- 2009); Mandai Mangroves: ZRC. 2.3278 (28 - Aug- 1991), ZRC. 2.7087 (05 - Jul- 2014) [mudflats]; Pulau Sudong: ZRC. 2.3120 (24 - May- 1923); Punggol: ZRC. 2.2254 (15 - Jan- 1982); Siglap: BMNH (no #) (no date), ZRC. 2.3115 – ZRC. 2.3117 (27 - Jun- 1933), ZRC. 2.3118 (1938); Simpang: ZRC. 2.6082 (13 - Aug- 2004); Sungei Buloh Wetland Reserve: ZRC. 2.6936 – ZRC. 2.6937 (20 - May- 2011); Tanjong Katong: ZRC. 2.3113 – ZRC. 2.3114 (03 - Nov- 1919); Telok Kurau: ZRC. 2.3119 (29 - Jun- 1933); Tuas: ZRC. 2.2183 – ZRC. 2.2190, ZRC. 2.2612 – ZRC. 2.2662 (20 - Mar- 1984). Additional Singapore museum specimens. Singapore (no locality): BPBM, FMNH, MCZ, NMW, QM, UMMZ; Siglap: CAS; Tuas: LSUMZ. Singapore localities. Changi Beach — Jurong Prawn Ponds — Kranji — Kranji Mangroves — Lim Chu Kang — Lim Chu Kang Mangroves — Lower Seletar Reservoir — Mandai Mangroves — Marina Reservoir — Pasir Ris Beach — Pasir Ris Park Mangroves — Pulau Semakau — Pulau Sudong — Pulau Ubin — Punggol — Sembawang Park — Siglap — Simpang — Singapore Botanic Gardens * — Sungei Buloh Wetland Reserve — Sungei Mandai Kechil — Tanjong Katong — Telok Kurau — Tuas — Yishun.

Description. Table 1 shows the measurement. Measurements shown in Table 1. Total length, 571 mm; tail length, 68 mm. Head short and rounded, with same width as neck; eyes small; nostrils tubular (Fig. 2). Skin of both body and venter with folds; no enlarged scales on venter; entire body covered with fine scales of about same size (Fig. 3); 156 mid-body scales; 10 scales eye – eye; 5 scales eye – lip on each side; 5 / 6 (left / right) scales naris – eye; 14 supralabial scales on each side; 18 infralabial scales on each side. Multiple tumors on body surface. Head dark brown with pale yellow spots (Fig. 2); body to tail alternating blackish-brown and pale yellow bands; dark brown bands longer at dorsal midline than toward venter (Fig. 3).

[English name: Marine File Snake; Japanese name: Hime-yasuri-hebi] (Figs 1 – 3; Table 1)

Remarks. This specimen agrees well with the morphological characteristics of A. granulatus described by Sanders et al. (2010) (Table 1). It was identified as “ Sea snake ” (including Laticauda) and as H. annandalei in the past. However, the sea snakes including H. annandalei are usually characterized by a flat tail and a head covered with relatively large scales (Stuebing et al. 2014), which do not correspond to the characteristics of the specimen. This misidentification may be due to the absence of occurrence records of file snakes in Japan, and also their similarity to sea snakes in both body coloration and habitat. Acrochordus granulatus is known to have ecologically adapted to shallow water habitats such as mangrove areas (Lillywhite 2020), while they were reported to be captured as far as 10 km from the coast (Voris and Glodek 1980). It is quite possible that the natural dispersal by the Kuroshio Current carried this species to Amamioshima Island. The nearest habitat of this species from Japan is the Philippine Islands or Hainan Island (Huang 1963; Dunson and Minton 1978; Bernstein and Bautista 2020). However, since there is only one record from Hainan Island (Huang 1963; Shi et al. 2011), it is more likely that this individual came from a larger and more stable population in the Philippines. In addition, since many typhoons in June track toward Japan after approaching the Philippines (Japan Metrological Agency 2022), it is possible that a typhoon carried this specimen from the Philippines to Amamioshima Island. On the other hand, A. javanicus, a closely related species of A. granulatus, has been reported to have been accidentally transported to Japan by hiding in wood from Indonesia (Kagei and Shogaki 1977), so we could not rule out the possibility that this individual was artificially transported to Japan. In either case, there are no solid records of A. granulatus in Japan from 1938 to the present. Thus, it is highly likely that A. granulatus is very rare in Japan, and it would be difficult to establish a stable population in the archipelago.

Distribution. Acrochordus granulatus is distributed in northern Australia (Cogger 2014), continental coastal areas from the Indian Peninsula to the Malay Peninsula and Indochina Peninsula (Cox et al. 1998; Nguyen et al. 2009; Murthy 2010), Hainan Island (Huang 1963), the Sunda Islands (de Rooij 1917; Stuebing et al. 2014) and the Philippine Islands (Dunson and Minton 1978; Bernstein and Bautista 2020).

Materials examined. Third Higher School collection at KUM (No. 3250 of Biological Laboratory, Yoshida College, Kyoto University), collected from Amamioshima Island, Kagoshima Prefecture, Japan in June 1938. Formalin-preserved specimens. Collector: unknown; preparing specimen: Niki Biological Institute.