|Africa: Nsele River, a Malebo Pool tributary (Ref. 114247), up to Yangambi, Middle Congo River (Ref. 42033, 114247), including Ruki drainage (42033, 93897, 114247) and Kwilu (Ref. 114247), in Democratic Republic of the Congo, and Léfini River in Congo Republic (Ref. 122753).
Dorsal spines (total): 0-0; Dorsal soft rays (total): 11-11; Anal spines: 0-0; Anal soft rays: 8-8; Vertebrae: 35-36. Diagnosis: Clypeobarbus matthesi is unique among congeners in pigmentation patterning on dorsal fin in which proximal third to half is smoky black and distal half is creamy white in preservation, red in life, and eye form oval vs. rounded in congeners (Ref. 114247). It differs from all except C. bellcrossi, C. congicus and C. breviclipeus in possessing large pore-bearing scales in midlateral series below dorsal fin vs. greatly enlarged, high and narrow, shield-like scales in C. pleuropholis, C. bomokandi, C. hypsolepis, C. schoutedeni and C. pseudognathodon; it is readily distinguished from C. bellcrossi in lacking a series of discrete pigment dots midlaterally along body, and from C. congicus and C. breviclipeus in lateral-line scale counts, 26-28 vs. 20-22 and 23-24 respectively (Ref. 114247).
Description: Head dorsoventrally compressed and elongated; eyes oval, markedly so in larger specimens; mouth small and inferior; maxillary and mandibular barbels present but minuscule, often concealed beneath lachrymal skin fold (Ref. 114247). Mature individuals with prominent conical tubercles on snout and under eye, all with free neuromasts arranged in numerous sensory pit lines on cheek and dorsum of head (Ref. 114247). Occipital fontanel large, bordered laterally by frontal and parietal, and posteriorly by supraoccipital; five infraorbital bones: IO1 deepest of the series, IO2-4 almost completely reduced to infraorbital canal portion of bone, IO5 completely reduced; IO3 longest of series, almost twice the length of IO1 (Ref. 114247). Scales radially striated, 26-28 in lateral line, 3.5/1/2 body rows, 8-9 circumpeduncular rows, and 8-9 predorsal rows; lateral line complete, scales enlarged relative to those along impinging rows above and below; scale depth greatest below dorsal fin, but not markedly high, narrow and shield-like as in some congeners (Ref. 114247). Dorsal fin with 3 unbranched rays and 8 branched rays, positioned midway between snout and caudal-fin base, origin anterior to pelvic-fin insertion; last unbranched ray flexible, lacking serrations along posterior border; anal fin with 3 unbranched rays and 5 branhced rays; caudal fin strongly forked, 10-9 principal rays and 8-9+7-8 procurrent rays; pelvic fin with 1 unbranched ray and 8 branhced rays; pectoral fin with 1 unbranched ray and 13-14 branched rays (Ref. 114247). Total vertebrae 35-36, 19-20 abdominal and 16-17 caudal; 14 pairs of pleural ribs on vertebral centra number 5 to 8; four supraneurals, localed between neural spines of vertebral centra numbers 4 to 8; first dorsal-fin pterygiophore between neural spines of vertebral centra numbers 9 and 10, and first anal-fin pterygiophore between haemal spines of vertebral centra numbers 20-21; caudal-fin rays supported by neural and haemal spines of PU2-3, pleurostyle, single epural, parhypural and 7 hypural elements (Ref. 114247).
Colouration: In formalin preservation, base body colouration uniformly brownish yellow, somewhat paler ventrally and over belly and cheek; snout and dorsum of head, brown; faint blotch on mid-portion of opercle; well-marked cleithral streak passing anterodorsally to top of opercle; body scales bordered with thin margin of dark brown melanophores contrasting with scale centres, which mostly lack dark pigmentation; scale borders strongest along midline and on anterior borders of lateral-line scales, less clearly marked anterodorsally and ventrally; scales in region of caudal flexion darker than preceding scales and forming a faint caudal bar; proximal third to half of the dorsal fin smoky black, distal portion creamy white; dorsal-fin pigmentation most strongly marked in larger individuals; all other fins lack pigmentation and are colourless (Ref. 114247). Colouration in life: body silvery, with pearl blue and pink reflections, scales with dark bases; transverse black line behind opercle; lower jaw and snout orange-red, red eye in upper third, rest silvery white with a black lower border; paired fins reddish, anal slightly redder, caudal red at base; dorsal fin more or less darkened on lower half, rest bright red (Ref. 114247).