|
Dorsal spines (total): 1. Diagnosis: adipose fin present (Ref. 43912, 81643) and fully developed (Ref. 81643). Inner side of pectoral fin spine weakly serrated (Ref. 43912, 81643). Barbels well developed (Ref. 81643), nasal barbels always extend beyond posterior edge of orbit (Ref. 43912, 81643) and may almost reach posterior edge of opercle (Ref. 81643). Maxillary barbel not reaching beyond head; eye diameter 26.2-30.5% HL (Ref. 43912). Posterior nostrils at same distance (Ref. 43912, 81643) or slightly closer to each other than are anterior ones (Ref. 81643). 43-51 branched anal fin rays (Ref. 43912, 81643). Lower jaw always shorter than upper jaw (Ref. 43912, 81643) and completely surrounded by upper lip when mouth is closed (Ref. 43912). Moderately sized species (less than 20 cm SL)(Ref. 81643). Colour pattern characterized by brown back and head, large dark brown stripe along lateral line and oblique brown stripe from below anterior part of lateral line to origin of anal fin (Ref. 43912).
Description: mouth subterminal (Ref. 81643). ii-iv + 44-51 anal fin rays; 42 non-fused vertebrae; 9-10 + 3-4 gill rakers on first branchial arch; 9 branchiostegal rays on one side of head; caudal peduncle somewhat deeper as long, or slightly longer than deep; barbels moderately developed; nasal barbel reaches at least to somewhat beyond orbit and at maximum to posterior border of opercle; maxillary barbel reaches to end of head; outer mandibular barbel never reaches beyond posterior border of opercle; inner mandibular barbel short, reaching to about midway of eye; vomerine and palatine bands narrow, as wide as premaxillary one and distinct from each other but contiguous (Ref. 43912). Schilbe djeremi is a peculiar species with a coloration characterized by a dark lateral line as in S. intermedius or as in some specimens of S. mandibularis and S. multitaeniatus; however it differs from S. intermedius by the lower jaw being shorter than the upper one, while it reaches slightly beyond the snout in S. intermedius, and an adipose fin that seems always present in S. djeremi while it is absent in numerous populations of S. intermedius, especially from occidental Africa; S. djeremi is distinguished from S. mandibularis and S. multitaeniatus by the configuration of the mouth, especially by the mutual position of both jaws; S. djeremi closely resembles S. zairensis from the Lower Zaire System, both species having very similar general morphologies and coloration patterns as well as rather similar meristic characters, however in S. zairensis the barbels are considerably longer, the number of branched anal fin rays is slightly inferior (38-44 versus 44-51 in S. djeremi) and the eye is somewhat smaller (23,5-27,1% HL versus 26,2-30,5% HL in S. djeremi)(Ref. 43912).
Coloration: preserved specimens: head and dorsum brownish, paler ventrally; wide median brown band along lateral line; oblique brown stripe passing from behind head to belly and continuing along anal base; fins generally colourless, caudal fin base and dorsal fin often somewhat darker than other fins (Ref. 43912, 81643). Holotype coloration: brown, variegated with dark brown as irregular marblings and overspread with brownish specks; a large dark blotch on each side above pectoral fin where swim-bladder lies close below skin; fins faintly speckled; barbels pale; however, it seems that the coloration of the holotype does not represent a realistic view of the colour pattern of this species and probably this type was preserved in the field when it was no longer alive (Ref. 43912). |