Brummett, R., Mbe Tawe, A.N., Dening Touokong, C., Reid, G.M., Snoeks, J. Staissny, M., Moelants, T., Mamonekene, V., Ndodet, B., Ifuta, S.N.B., Chilala, A., Monsembula, R., Ibala Zamba, A., Opoye Itoua, O., Pouomogne, V., Darwall, W. & Smith, K.
Marcusenius macrophthalmus is only known from Tshikapa on the Kasa River, Central Congo River basin, Democratic Republic of the Congo. The species may be more widespread than is currently known. More information is needed on the species distribution before an assessment can be made.
Translation of original description in Pellegrin (1924):
Body depth goes 3 ¾ times in length (minus caudal), HL 4 ¾ times. The head is a little longer than deep, upper profile rounded. Eye is oval-shaped and enormous, its diameter almost double length of the snout and is 2/3 of the interorbital space and only goes 2 2/3 times in HL. Mouth opens at the lower boundary of the eye; its width equal to half the diameter of the latter. 3 slightly cleft teeth above, 5 truncated teeth below. Chin swelling rudimentary. Lateral line with 75 scales. 16 / 18 in transverse series, 14 / 14 between the origin of the dorsal and that of the anal, 12 around the caudal peduncle. Dorsal with 34 rays beginning above the 2nd or 3rd simple rays of the anal, which is to say at the same level; the length of its base is double the distance to the tip of the snout. The anal, situated at equal distance from the origin of the ventral fin and that of the caudal, has 28 rays. The pectoral is pointed and is equal to the HL and almost double the ventral, extending to its middle. Caudal peduncle length is 4 times its depth and equals the HL. Caudal is scaled at its base, with pointed lobes. Coloration is uniformly silvery with reflective steely blue on the head and back.
D. 34, A. 28, P. 11, V. 6, Scales 16/75/18.
One specimen from Tshikapa (Kasaï) (Dr. Schouteden).
Total length: 125 + 25 = 150 mm.
This species is remarkable above all by the extraordinary development of its eye which surpasses all others known in this genus, approaching most closely Gnathonemus greshoffi Schilthuis of the Congo, a species with analogous counts and in which the eye is also large, but which possesses a well developed chin appendage and in which the dorsal fin begins generally a little in advance of the anal.