Morphology Data of Enteromius thespesios
Identification keys
Main Ref. Katemo Manda, B., J. Snoeks, E. Decru, R. Bills and E. Vreven, 2020
Appearance refers to
Bones in OsteoBase

Sex attributes

Specialized organs
Different appearance different morphology during breeding season only
Different colors
Remarks During breeding season, head of mature males covered with conical tubercles; tubercles measure up to 0.50 mm of basal diameter and are most densely distributed above mouth, on tip of snout and area corresponding to lachrymal bone and evenly over central part and lateral sides of dorsum of head; tubercles with circular base, conical shape and tip usually situated directly over their centre; body scales with two to four submarginally situated small tubercles; furthermore, small tubercles also occur along pectoral, pelvic and anal fin rays but are lacking on dorsal and caudal fin rays; tubercles lacking all-together in females (Ref. 122753). Mature males differ from mature females in body and fin colouration; mature males during breeding season with bright yellow ground colouration, dorsal and, to a lesser degree, caudal fin both bright yellowish at base, black in middle and with red band towards their distal edge, although externally bordered by a narrow translucent band; body and fins of mature breeding females light yellow becoming silvery on belly (Ref. 122753). Furthermore, males and females also differ in fin proportions and shape, snout length and body proportion; in mature males, anal fin short and not reaching caudal-fin base, 22.5-23.7% of standard length, with straight distal margin vs. anal fin longer, reaching caudal-fin base, 25.6-27.2% of standard length, and with convex distal margin in mature females; in addition, snout longer, 36.8-39.2% of head length, in mature males than in mature females, 29.6-33.6% of head length; prepectoral distance longer, 26.3-31.6% of standard length, in mature males than in mature females, 25.0-26.7% of standard length; finally, pectoral fin long, 22.0-24.9% of standard length, reaching vertically to the anterior part of pelvic fin base in mature males while in mature females it is slightly shorter, 15.7-21.6% of standard length, reaching vertically up to about one scale row anterior to pelvic fin base (Ref. 122753).

Descriptive characteristics of juvenile and adult

Striking features
Body shape lateral fusiform / normal
Cross section
Dorsal head profile
Type of eyes
Type of mouth/snout
Position of mouth
Type of scales

Diagnosis: Enteromius thespesios belongs to the group of Enteromius species from the Congo basin of which the last unbranched dorsal-fin ray is weakly ossified, flexible and lacking serrations along its posterior edge (Ref. 122753). It can be easily distinguished from all other members of this group by the following unique combination of characters: two pairs of barbels vs. no barbels in Enteromius aspilus, E. baudoni, E. brazzai, E. carens, E. erythrozonus, E. haasianus, E. jae, E. stigmatopygus and E. toppini and a single pair of barbels in Enteromius brevidorsalis, E. candens, E. hulstaerti, E. nigrifilis, E. owenae, E. papilio and E. syntrechalepis; one prominent dark vertical bar situated behind gill-opening vs. a series of 10-15 black vertical bars on body in E. fasciolatus; no spots on flanks vs. well-defined spots on flanks in E. atromaculatus, E. barotseensis, E. camptacanthus, E. castrasibutum, E. collarti, E. lornae, E. lukusiensis, E. neefi, E. stanleyi, E. tetrastigma, E. trispilomimus and E. urostigma; a series of crescent-like spots along lateral line vs. a well-marked continuous black band running from snout to caudal fin base in E. ablabes, E. luluae, E. kessleri, E. lamani, E. macrops and E. radiatus; lateral line complete vs. lateral line incomplete in E. brachygramma and E. lujae; 23-26 lateral line scales vs. 21 in E. okae, 21-22 in E. pygmaeus, 20-22 in E. stigmasemion, 27-29 in E. bifrenatus, 30 in E. caudosignatus, 29-32 in E. cercops, 28 in E. citrinus, 32-33 in E. deguidei, 29-33 in E. innocens, 27-30 in E. kamolondoensis, 30-32 in E. lineomaculatus, 28-29 in E. marmoratus, 32-33 in E. mocoensis, 33-37 in E. motebensis, 31-33 in E. poechii, 27-30 in E. quadrilineatus, 27-29 in E. taeniopleura and 29-35 in E. unitaeniatus; and 11-12 circumpeduncular scales vs. 8-10 in E. amanpoae, 10 in E. humeralis and 8 in E. lufukiensis (Ref. 122753). Enteromius thespesios differs from E. tshopoensis by a long dorsal-fin length, 27.1-35.6% of standard length, vs. shorter, 22.3-24.0% of standard length, and by a large body depth, 29.4-34.1% of standard length, vs. smaller, 18.0-20.4% of standard length; it differs from E. validus by a dorsal fin without a conspicuous black tip vs. dorsal fin with a conspicuous black tip, a small eye diameter, 25.5-33.1% of head length, vs. larger, 37.2-46.9% of head length, and a small body depth, 22.2-24.6% of standard length, vs. larger, 26.3-35.5% of standard length (Ref. 122753). Finally, E. thespesios besides its high number of circumpeduncular scales, 11-12 vs. lower, 10, is further distinguished from E. humeralis by its small eye diameter, 25.5-33.1% of head length, vs. larger, 33.8-41.2% of head length; short anterior barbel length, 22.2-33.1% of head length, vs. longer, 35.1-45.0% of head length; short posterior barbel length, 25.9-32.0% of head length, vs. longer, 34.2-44.6% of head length, and its short, dorsal fin length, 22.3-24.0% of standard length, vs. 24.0-27.3% of head length (Ref. 122753).

Description: Rather small-sized species of Enteromius, with a maximum recorded size of 62.3 mm standard length for females and 60.7 mm standard length for males (Ref. 122753). General body shape fusiform; body depth greatest anterior to dorsal fin; profile of predorsal region of body slightly convex (Ref. 122753). Mouth subterminal; eyes relatively small, located laterally, that is, visible from both above and below, closer to tip of snout than to the posterior region of operculum; interorbital profile flat (Ref. 122753). Anterior barbel usually slightly shorter than posterior barbel with anterior one reaching up to anterior border of eye while posterior one up to centre of eye (Ref. 122753). Dorsal-fin origin located at midbody and slightly anterior, 1 or 2 lateral line scales, to vertical through pelvic-fin insertion; distal margin of dorsal fin straight; first branched dorsal-fin ray longest, posterior rays decreasing progressively in size; distal profile of pectoral fin straight to slightly convex, not reaching anterior base of pelvic fin; distal profile of pelvic fin convex; distinct axillary pelvic scale pointed; caudal fin forked with outer rays twice as long as median ones and both lobes rounded and of similar size; anus and genital opening situated immediately in front of anal-fin base; size and shape of anal fin and pelvic fins sexually dimorphic (Ref. 122753). Scales cycloid, rounded and radially striate; lateral line 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 (Ref. 122753).

Colouration: In life, overall background body colouration variable and seemingly different between sexes; in general, background body colouration yellowish, darker towards dorsal midline and lighter towards belly; snout, upper jaw and dorsal part of head dark brownish while remaining part of head bright yellow; scales of lateral line and above with distinct black melanin mark covering 1/3rd of its proximal base; at level of lateral-line scales, inconspicuous black band in male specimens or silver band in female specimens runs from upper end of operculum to centre of caudal-fin base; all fins yellowish with white translucent distal margin (Ref. 122753). However, background body colouration more intense in mature breeding males than in mature breeding females; in addition, dorsal and caudal fins of males yellowish near ray insertions, followed by black band and red band toward their distal edge, bordered by a narrow translucent band (Ref. 122753). In preserved specimens, ground colour greyish dorsally and whitish ventrally and laterally below the lateral line; all red and yellowish colouration gradually disappears but the traces of the black band persist on the dorsal and caudal fins; a well-marked, black, mid-lateral band along lateral line becomes apparent; all fins whitish; black band on dorsal fin persists only on specimens freshly preserved in alcohol (Ref. 122753).

Ease of Identification

Meristic characteristics of Enteromius thespesios

Lateral Lines Interrupted: No
Scales on lateral line 23 - 26
Pored lateral line scales
Scales in lateral series
Scale rows above lateral line 3 - 4
Scale rows below lateral line 2 - 2
Scales around caudal peduncle 11 - 12
Barbels 4
Gill clefts (sharks/rays only)
Gill rakers
on lower limb
on upper limb
total 34 - 34


Dorsal fin(s)

Attributes no striking attributes
Fins number 1
Finlets No. Dorsal   
Spines total 0 - 0
Soft-rays total 11 - 11
Adipose fin absent

Caudal fin

Attributes forked; more or less normal

Anal fin(s)

Fins number 1
Spines total 0 - 0
Soft-rays total 8 - 8

Paired fins

Pectoral Attributes  more or less normal
Spines     0
Soft-rays   14 - 16
Pelvics Attributes  more or less normal
Position    abdominal  behind origin of D1
Spines     0
Soft-rays   8 - 8
Main Ref. (e.g. 9948)
Glossary ( e.g. cephalopods )
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