Distinguished from its congeners in Lake Tanganyika by the following characters: short post-anal length 36.6-44.8% SL ( vs. 50.6-60.5 % SL in Mastacembelus ophidium and Mastacembelus polli); brown background color without or with only a limited and scattered dark brown reticulate pattern ( vs. yellow background color with a series of large, saddleshaped, dark brown spots on the dorso-lateral surface of head, body and tail region in Mastacembelus ellipsifer, Mastacembelus plagiostomus and Mastacembelus zebratus); higher number of dorsal spines 34-38 (vs. <30 in Mastacembelus platysoma, Mastacembelus cunningtoni and Mastacembelus moorii and similarly from Mastacembelus micropectus with 26-35 dorsal spines). Additional characters useful to separate from Mastacembelus micropectus include: pectoral-fin length 14.4-25.9% HL (vs. 4.8-22.8% HL); post-anal length 37.5-43.1% SL (vs. 43.9-49.0% HL); brown background color without or with only a limited and scattered dark brown reticulate pattern (vs. a unique color pattern characterized by a light or dark brown background color mostly with numerous tiny yellowish-white spots). Differs from Mastacembelus tanganicae by its lower number of dorsal spines 34-38 (vs. 38-43). In addition, Mastacembelus tanganicae has a unique colour pattern characterized by a

uniform light brown to yellowish background colour with dark brown to black spots on the head, body and tail region forming short zigzag lines on the tail region. This species can also be distinguished by color pattern from Mastacembelus flavidus, which has a uniform light brown to yellowish overall background colour with numerous small, dark brown spots mainly situated on the head, body (above the lateral line) and dorsal fin (Ref. 82667).