Macrognathus maculatus (Cuvier 1832)

Mastacembelus perakensis: Herre & Myers 1937: 74 (Bukit Merah reservoir).

Macrognathus maculatus: Ahmad et al., 2014: 21 (Sungkai Wildlife Reserve); Ahmad & Zakaria-Ismail, 2014: 415 (Sg. Ketir; Sg. Tiang); Shafiq et al., 2014: 826 (Sg. Ara); Authors' data (Jalong; Lata Ulu Chepor).

Remarks. Mastacembelus perakensis was first described by Herre & Myers (1937) as they observed their material was different from its closest congener M. maculatus (without vs. with preopercular spine). Subsequently, Sufi (1956) reported that the presence of a preopercular spine may be variable in some Mastacembelids and the spine can be pungent or hidden beneath the skin. Thereon Sufi (1956) treated M. perakensis as a doubtful species but he/ she did not examine the holotype. The holotype was eventually examined and confirmed to possess a preopercular spine by Roberts (1989) and it was synonymized with M. maculatus . We note that Kottelat (2013) lists M. perakensis as a valid species although no reference is provided. We therefore follow Roberts (1989) by treating M. perakensis as a junior synonym of M. maculatus .