| Diagnosis: |
Dorsal spines (total): 0-0; Dorsal soft rays (total): 11-11; Anal spines: 0-0; Anal soft rays: 8-8; Vertebrae: 39-39. Diagnosis: This species differs from all other small species of African barbs by its very slender caudal peduncle; it is distinguished from the great majority of small African barbs by its exceptionally well developed sensory papillae or pitline organelles which cover most of the head in both sexes; similar pit lines occur on the scales covering the body; males differ from those of most other species of African barbs of similar size in having the rostrum and dorsal surface of the head covered with numerous breeding tubercles (Ref. 85567).
Description: Body subcylindrical, laterally compressed, terete; head moderately large and pointed; snout narrow when viewed from the side, but short and blunt viewed from above; dorsal profile of head evenly convex; no nuchal hump; ventral profile of head from tip of lower jaw to angle of preopercle very straight (Ref. 85567). Mouth termino-inferior, small, rictus of jaws lying anterior to a vertical through from margin of eye (Ref. 85567). Eyes large, oval, dorsally inclined; orbital length more than one-third head length; nostrils moderately large, lying entirely on half of snout nearest eye (Ref. 85567). Rostral and mandibular barbels well developed, rostral barbels slightly longer than maxillary barbels, about equal to eye diameter; rostral barbels originating almost at tip of snout, extending posteriorly to just beyond origin of maxillary barbels; maxillary barbels extending posteriorly from below middle of eyes to slightly beyond them, their anterior halves when adpressed accommodated by deep postlabial groove (Ref. 85567). Lateral line complete, nearly straight, slightly curved downwards anteriorly; scales in lateral line series 33-35, each with single small lateral line canal pore near middle of its exposed portion; scales of entire body nearly uniform in size and shape, with radiate striae; scales of lateral line series slightly enlarged; posterior scale margin semicircular or very slightly arched; predorsal scales 9; scales absent on ventral body surface behind head, including isthmus, to slightly beyond bases of pectoral fins; median abdominal scale rows, from just behind pectoral fin bases to pelvic fin bases, 9; transverse scale rows 5/1/2-3; circumpeduncular scales 9 (Ref. 85567). Dorsal fin very slightly falcate, with 3 simple and 8 branched rays; simple rays very slender and flexible, last simple ray not serrated; dorsal fin origin well in advance of vertical line drawn through pelvic fin origins; anal fin noticeably more falcate than dorsal fin, with 3 simple and 5 branched rays; pectoral fins with one simple and 12-15 branched rays; pelvic fins with one simple and 7 branched rays (Ref. 85567). Body depth declining more or less regularly from its maximum near dorsal fin origin to end of anal fin base, then evening out; hence transition to slender caudal peduncle very abrupt; caudal peduncle elongate and slender, its length 2.6-2.8 times its least depth; caudal peduncle depth 13.4 times in standard length; caudal fin forked, with ovate lobes; principal caudal fin rays 10/9 (Ref. 85567).
Colouration: In life, white or silvery laterally and ventrally with strong bluish reflections; no evident markings on head, body or fins; fins colourless; no sexual dichromatism observed (Ref. 85567). In preservation: head, body and fins without any distinction or striking marks, melanophores on fins hardly visible to unaided eye; head below middle of eye and body below lateral line scales row without any marks and almost devoid of melanophores; numerous fin melanophores on dorsum of snout and near nostrils, on posterior part of cranial roof over expanded portion of brain, and on opercular insertion; fine melanophores along occipital margin where anteriormost scales insert; fine melanophores forming thin mid-dorsal stripe between occiput and dorsal fin origin; fine melanophores in elliptic or crescentic patch covering posterior half of exposed part of each scale above lateral line scale row; very few much larger melanophores confined to small area near anteriormost exposed part of each scale or to larger area of each scale; faint midlateral longitudinal stripe closely associated with lateral line canal for its entire length composed of few large melanophores just above and below canal on anterior half of body; then same number or slightly more melanophores more evenly distributed over and near canal on its posterior half; triangular base of caudal fin overlying hypural fan covered with fine melanophores (Ref. 85567). Dorsal fin with wmall patch of larger melanophores just in front of and beside its origin; dorsal fin rays with small melanophores along anterior and posterior margins of branched and unbranched portions, dorsal fin interradial margins otherwise without melanophores; anal fin pigmentless except for few melanophores; paired fins devoid or almost devoid of melanophores; few tiny melanophores along inner margin of outermost pectoral fin ray, pectoral fins otherwise without melanophores; pelvic fins pigmentless; caudal fin with fine melanophores on edges of rays, sometimes also on lepidotrichial joints, rendering them more conspicious (Ref. 85567). |