Ambassis macracanthus Bleeker, 1849

Zainal Abidin, Danial Hariz, Lavoué, Sébastien, Mohd Abu Hassan Alshari, Norli Fauzani, Mohd. Nor, Siti Azizah, A. Rahim, Masazurah & Mohammed Akib, Noor Adelyna, 2021, Ichthyofauna of Sungai Merbok Mangrove Forest Reserve, northwest Peninsular Malaysia, and its adjacent marine waters, Check List 17 (2), pp. 601-631 : 623

Ambassis macracanthus Bleeker, 1849

Figure 3O

Material examined. MALAYSIA • 2, 96– 102 mm TL; Kedah State, Kampung Batu Lintang, Pompang Batu Lintang ; 05.624°N, 100.395°E; 19 Apr. 2019; Danial H. Zainal Abidin, Norli F.M.A.H. Alshari leg.; USMFC (30) 00005 . • 1, 71 mm TL; Kedah State, Merbok, Pompang Sungai Merbok ; 05.664°N, 100.381°E; 6 Dec. 2018; Danial H. Zainal Abidin, Norli F.M.A.H. Alshari leg.; USMFC (30) 00004 . • 2, 70– 72 mm TL; Kedah

State, Kampung Batu Lintang, Pompang Batu Lintang; 05.624°N, 100.395°E; 19 Apr. 2019; Danial H. Zainal Abidin, Norli F.M.A.H. Alshari leg.; USMFC (30) 00007. Identification. A moderate-sized species of Ambassis (maximum TL about 10 cm); body relatively deep, laterally compressed; mouth terminal; continuous lateral line; eye diameter larger than snout length; only 1 supraorbital spine; nasal spine absent; single dorsal fin deeply notched; dorsal fin spines 7; anal fin spines 3; caudal fin deeply forked; body uniformly pale greyish with scattered melanophores; fins mostly translucent, first 2 or 3 dorsal fin spines blackish.

Ambassis macracanthus can easily be distinguished from the two other species of Ambassidae occurring in the Merbok river estuary by the unique combination of two characters: continuous lateral line and only one supraorbital spine. Ambassis macracanthus is a brackish species and it occurs in other brackish environments in this region (e.g., Tongnuinui et al. 2002). Its exact distribution in the Indo-West Pacific region is still unknown.