|
Dorsal spines (total): 0-0; Dorsal soft rays (total): 14-14; Anal spines: 0-0; Anal soft rays: 8-8; Vertebrae: 34-36. Diagnosis: Labeo latebra differs from all other Labeo species from the Nile in having only 12-13 scales around the caudal peduncle, vs. 16 in L. meroensis, 16-18 in L. forskalii and L. coubie, 16-20 in L. horie, and 18-22 in L. niloticus; it further differs from all other Labeo in the main Nile River except L. meroensis in having only 4.5-5.5 scales between lateral line and mid-dorsal line, vs. 6.5-7.5 in L. forskalii and L. coubie, 6.5-8.5 in L. horie, and 8.5-9.5 in L. niloticus; from L. meroensis it differs in having 34-37 scales in lateral line, vs. 39-41 (Ref. 116769). Labeo latebra shares 12 caudal peduncle scales with L. parvus and L. lukulae from the Congo basin, L. chariensis and L. djourae from the Chad basin, L. ogunensis and L. brachypoma from Nilo-Sudanic river basins west of the Niger Delta, and the Upper Guinean endemic L. obscurus, which is confined to the Konkouré River (Ref. 116769). Labeo latebra differs from L. ogunensis by having 3.5-4 scales between lateral line and ventral fin insertion, vs. 4.5; from L. parvus, L. obscurus and L. brachypoma in a higher lateral line scale count of 34-37, vs. 30-33; and finally from L. djourae, L. lukulae and L. chariensis in the poorly developed snout which lacks a prominent suckermouth vs. prominently swollen snout with well-developed sucker, the poorly developed ethmoid furrow vs. very prominent ethmoid furrow, and the small nub-like tubercles on the snout vs. usually prominent, acanthoid snout tubercles (Ref. 116769).
Description: A small-sized Labeo species belonging to the cylindriform L. forskalii group, which is characterised by its streamlined body, falciform dorsal fin and 9-10 branched dorsal fin rays (Ref. 116769). Body cylindriform and rather roundish with only slight lateral compression (Ref. 116769). Eyes medium-sized, in slight dorsolateral position, not visible if specimens are viewed ventrally; tube of anterior nasal opening poorly developed, snout only feebly swollen, ethmoid furrow absent or only weakly developed; tubercles if present small, restricted to dorsal snout and ethmoid furrow area, but absent from interorbital fields; rostral flap minute, closely adhering to upper lip except free distal lobes; mouth without prominent sucker, the two barbels proximal deeply embedded in lip fold but often with visible free distal tips, which reach beyond jaw articulation; inner upper labial fold with crenulated costae (Ref. 116769). Dorsal fin concave with two simple and 10 branched rays; two additional small supranumerary simple spines in front of dorsal fin only visible in X-rays; branched rays without filamentous extension; in smaller specimens dorsal fin slightly concave, changing to a more falciform contour in larger specimens; pectoral fins inserted rather low on body flanks, their free ends reach to level of the dorsal fin origin but rarely beyond and terminate well in front of pelvic fin base; pelvic fin insertion level with pectoral fins and situated below the anterior half of dorsal fin; pelvics reach exactly to the anus; anus and anal fin insertion separated by three to four scales, anal fin with two simple and five branched rays and an additional single small supranumerary simple spine; caudal fin deeply notched, lobes pointed with 10 principal rays on upper and 9-10 on lower lobe (Ref. 116769).
Colouration: Living specimens with light grey to olive-brownish back with silvery reflections; lateral band faintly visible, including first scale row above and below lateral line; prominent dark blotch with bright green iridescence directly behind operculum at same level of eye and of roughly the same height or smaller (Ref. 116769). Body colouration below lateral line gradually brightening to light beige or white; singla scales with prominent bright orange centres loosely scattered on body flanks, visibly especially in dead fishes; posterior rim of scales intensely pigmented and dark except for belly-scales and scales near anal fin base; scales on the caudal peduncle with dark margin pronouncing the contour of each scale; dorsal portion of the head yellowish-brown with greenish hue and similar green iridescence as on opercular series and cheek; transverse dark stripe connecting tip of snout and eye which exceeds beyond the lower rim of eye; a second parallel dark band is occasionally visible connecting the nasal openings; on the lower head dark colours of the dorsal part gradually fade to light beige or white; upper and caudal portions of iris prominent bright orange-red, ventrally blackish (Ref. 116769). All fins pale and translucent, grey markings near origin of dorsal fin rays, first pectoral and pelvic fin ray with whitish hue; fins in fresh dead specimens clearly reddish to orange superimposed with a rather dark grey colouration; caudal fin lobes of individual specimens with faint dark margin on upper and lower lobe of caudal fin (Ref. 116769). Preserved specimens dorsally brown, ventrally light beige; lateral band faintly visible, less pronounced as in Labeo parvus or L. ogunensis; fins pale whitish, but not translucent, with weak pigmentation between rays of unpaired fins; caudal fin lobes with dark margin, more pronounced on lower lobe (Ref. 116769). |