| Diagnosis: |
Dorsal spines (total): 0-0; Dorsal soft rays (total): 10-12; Anal spines: 0-0; Anal soft rays: 8-9. Diagnosis: Enteromius alberti belongs to the group of species of Enteromius with a flexible last unbranched dorsal fin ray that lacks serrations along its posterior edge (Ref. 127947). It can easily be distinguished from the other species of this group from the East Coast and Nilo-Sudan ichthyofaunal regions by the following combination of characteristics: a complete lateral line vs. an incomplete lateral line in E. atkinsoni, E. pumilus, E. serengetiensis, E. tongaensis and E. toppini; two pairs of barbels vs. one pair in E. pseudotoppini, and no barbels in E. anema and E. profundus; one to three dark spots on the flanks, which sometimes fuse into a mid-lateral line in preserved specimens, starting posterior to the operculum vs. a dark line running from the tip of the snout to the caudal fin base in E. bifrenatus and E. yongei, and a thin dark line from the beginning of the operculum to the caudal fin base in E. viviparus; 12 scales around the caudal peduncle, with one aberrant specimen with 16, vs. 8 in E. leonensis, 9-10 in E. venustus, and 10 in E. magdalenae and E. yeiensis; 4.5 scales between the dorsal fin base and the lateral line vs. 3.5 in E. radiatus, 5.5 in E. unitaeniatus, and 6 in E. usambarae; a dorsal fin length which is larger than the head length vs. a dorsal fin length equal to the headclength in E. innocens; a body depth which is larger than the head length vs. a body depth which is equal to the head length in E. nigeriensis and E. trispilopleura; a pectoral fin length which is 5/6 of the head length vs. 3/4 in E. lineomaculatus, and 2/3 to 3/4 in E. neglectus; a maximum caudal peduncle depth which is 3/5 of the head length vs. 2/5 in E. quadripunctatus (Ref. 127947). Enteromius alberti differs from E. perince by a combination of a smaller body depth, 21.7-31.2% of standard length vs. 33.8-37.5%; a smaller minimum caudal peduncle depth, 10.0-13.6% of standard length vs. 15.0-16.4%; and a smaller maximum caudal peduncle depth, 11.8-15.5% of standard length vs. 17.7-19.4%; it differs from E. stigmatopygus by a combination of a higher number of lateral line scales, 27-34 vs. 20.25; a smaller predorsal distance, 45.7-51.3% of standard length vs. 51.9-55.8%; and a smaller pre-occipital distance, 16.6-21.8% of standard length vs. 22.1-27.3%; it differs from E. mimus by a higher number of lateral line scales, 27-34 vs. 24-27; a smaller preanal distance, 65.1-73.0% of standard length vs. 68.4-74.8%; a larger post-anal distance, 16.3-24.2% of standard length vs. 16.3-19.3%; a smaller body depth, 21.7-31.2% of standard length vs. 26.5-34.3%; a smaller head depth, 15.1-19.0% of standard length vs. 17.8-21.8%; and a smaller pelvic fin length, 15.0-20.9% of standard length vs. 18.2-22.4% (Ref. 127947). Specimens of E. alberti differ from the population of E. cf. mimus from the Lake Edward system by a smaller head depth; in general, a specimen with a head depth smaller than 19% of the standard length can be assigned to E. alberti, specimens with a head depth larger than 19% of the standard length can be assigned to E. cf. mimus; other characters are the higher number of lateral line scales, 27-34 vs. 21-31, the smaller interorbital width, 5.8-8.3% of standard length vs. 6.9-9.9, the smaller pre-pelvic distance, 44.8-53.3% of standard length vs. 48.4-55.4%, the smaller body depth, 21.7-31.2% of standard length vs. 23.5-35.8%, the smaller maximum caudal peduncle depth, 11.8-15.5% of standard length vs. 8.7-19.0%, the smaller minimum caudal peduncle depth, 10.0-13.6% of standard length vs. 7.1-15.9%, and the smaller head width, 10.4-14.2% of standard length vs. 11.6-14.5% (Ref. 127947). Description: Body fusiform, largest depth anterior to dorsal fin; dorsal profile from tip of snout to origin of dorsal fin slightly convex, slightly tapering to base of caudal fin; ventral profile from operculum to origin of pelvic fin slightly convex, slightly tapering to posterior end of anal fin base, then slightly concave to caudal fin (Ref. 127947). Head small; eye large and round, located dorso-laterally, closer to tip of snout than to distal margin of operculum, interorbital profile slightly convex; snout rounded and mouth subterminal; two pairs of barbels, anterior barbel usually slightly shorter than posterior with anterior one usually reaching up to vertical through posterior margin of eye, while posterior one usually up to vertical through posterior margin of pre-operculum (Ref. 27628, 127947). Dorsal fin with 3 unbranched and 7-9 branched rays, distal margin straight to slightly concave, origin located slightly anterior, 1 or 2 lateral line scales, to vertical through pelvic fin insertion; first branched dorsal fin ray longest, posterior rays decreasing progressively in size; pectoral fin with 1 unbranched and 13-16 branched rays, distal profile straight to slightly convex, not reaching anterior base of pelvic fin; pelvic fin with 1 unbranched and 6-8 branched rays, distal margin slightly convex; anal fin with 3 unbranched and 5-6 branched fin rays, distal margin slightly concave; caudal fin forked with outer rays twice as long as median ones and both lobes rounded and of similar size; anus and urogenital opening situated immediately in front of anal fin base (Ref. 127947). Scales cycloid, rounded and radially striate; lateral line completely pored with many lateral line scales, 27-34, and gently curved downwards over abdomen but running straight along middle of caudal peduncle and ending at base of caudal fin; lateral-line scales smaller on caudal peduncle than below dorsal fin; scales between dorsal fin and lateral line 4.5-4.5; predorsal scales 9-13; circumpeduncular scales 12-16; scales between lateral line and pelvic fin 2-4; scales between lateral line and belly 3.5-5.5 (Ref. 27628, 127947). Colouration: No sexual dimorphism observed (Ref. 127947). In life, overall background colour of body silvery, darker toward dorsum and lighter towards belly; thick yellowish midlateral band, often with one to three darker spots; first black spot between operculum and dorsal-fin origin, the second under dorsal fin and the third just before caudal fin; all fins translucent (Ref. 27628, 127947). In preserved specimens, overall background colour of body yellowish, greyish dorsally; one to three dark spots on flanks on thick silvery midlateral band; spots fused into mid-lateral line in some specimens, overlying silvery band and starting posterior to operculum; first spot situated anterior to dorsal fin origin, median one below last ray of dorsal fin and last one at caudal fin base; specimens with more than three spots are rare (Ref. 104796, 127947). |
