Kneria rukwaensis Seegers, 1995
photo by Seegers, L.

Family:  Kneriidae (Shellears)
Max. size:  6.19 cm SL (male/unsexed)
Environment:  demersal; freshwater
Distribution:  Africa: restricted to the western drainage of the Lake Rukwa system and to the upper Kalambo drainage (Tanganyika basin) in Tanzania and Zambia (Ref. 26644).
Diagnosis:  Dorsal spines (total): -0; Dorsal soft rays (total): 8-11; Anal spines: -0; Anal soft rays: 9-11. Diagnosis: dorsal fin origin behind pelvic fin origin; 96-104 lateral line scales; preanal length 70.7-76.2% SL; prepelvic length 46.7-52.6% SL; 9-11 anal fin rays (Ref. 26644). Lower lobe of caudal fin longer and narrower than upper lobe in fully adult males (Ref. 26644, 27292), the upper lobe as long as the proximal part of the caudal fin (Ref. 27292). Opercular disc of males characteristic, its posterior margin broad, and postopercular apparatus well developed and pillow-like (Ref. 26644). Description: body slender, depth 5.1-7.3 times in standard length (SL); head short, 4.1-5.6 times in SL (Ref. 26644). Origin of dorsal fin nearer to end of snout than to base of caudal fin (Ref. 26644), in most cases clearly behind or nearly above pelvic fin origin (Ref. 26644, 27292). Pelvic fin long, 1.1-1.5 times in head length (HL); pectoral fin long, about 1.2-1.9 times in HL; snout short, about 3.1-4.0 times in HL and usually slightly longer than eye diameter, rarely shorter, about 0.8-1.1 its length; eye diameter 3.5-4.2 times in HL (Ref. 26644). Opercular organ in males present and heavily pigmented, large but shallow with a wide rim, the posterior part of the rim wider than its anterior part (Ref. 26644) and membraneous (Ref. 27292). Male postopercular organ pronounced with a series of about 24 oblique laminae, its upper part protruding, the lateral line running along the rim (Ref. 26644). Opercular organ only very rudimentary in females (Ref. 27292). Caudal peduncle long, 5.4-5.8 times in SL; scales small, numerous, difficult to count (Ref. 26644). Coloration: in life: ground color medium grey to brown; dark greyish band runs from opercular region straight to base of caudal fin; this band darker at dorsal edge and to posterior end and may end in a large dark spot; it is slightly bluish on posterior part of body and caudal peduncle; this band is dorsally accompagnied by a narrow lighter streak which is golden to brownish and contrasts with the dark band below; area above this streak dark brownish to greyish, speckled with many faint, dark, small, greyish spots reaching the lower flanks; these spots larger on posterior part of body and caudal peduncle; midlateral band at its lower margin not sharply defined, at least in its anterior part, but progressively lighter to the belly; belly whitish, base of pelvic fins with a dark spot; opercular organ heavily pigmented; postopercular organ dark especially in its upper parts (Ref. 26644). Fins (dark) greyish (Ref. 26644) to blackish at the base (Ref. 27292), otherwise slightly greyish along the rays (Ref. 27292) and hyaline (Ref. 26644, 27292). Alcohol preserved: generally same color as life specimens; ground color light greyish-brown; dark midlateral band more distinct; in most specimens it becomes more evident that the band is composed of spots which merge together (Ref. 26644). Females show the same color as males but juveniles are more or less uniformly greyish to brownish (Ref. 27292).
Biology:  Maximum total length recorded is 7.44cm TL (Ref. 26644). Mostly found in stagnant pools and moderately flowing streams, only rarely in fast flowing currents; omnivorous; a female of 6.55cm TL releases about 400-500 ripe eggs of a diameter of 1.2mm (Ref. 27292). Apparently no marked spawning period (Ref. 44637). Male reported to change its coloration at night, being very pale with dark spots along the midline of the body (Ref. 27292).
IUCN Red List Status: Least Concern (LC); Date assessed: 31 January 2006 Ref. (130435)
Threat to humans:  harmless

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