Acrochordus granulatus
Creators: name: Takata, Kento
name: Shen, Yanpeng
name: Nishikawa, Kanto
name: Motokawa, Masaharu
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Reptilia
Squamata
Acrochordidae
Acrochordus
Acrochordus granulatus

description: Acrochordus granulatus (Schneider, 1799)
[English name: Marine File Snake; Japanese name: Hime-yasuri-hebi] (Figs 1–3; Table 1)
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.
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).
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).
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.
description: Published as part of Takata, Kento, Shen, Yanpeng, Nishikawa, Kanto & Motokawa, Masaharu, 2023, First Record of the Marine File Snake Acrochordus granulatus (Squamata: Acrochordidae) from Japan Based on the Specimen of the Third Higher School, pp. 1-4 in Species Diversity 28 (1) on pages 1-2, DOI: 10.12782/specdiv.28.1, http://zenodo.org/record/7522788