Diagnosis: single pair of mandibular barbels; 4-5 (exceptionally 6) branched dorsal fin rays; 30-54 branched anal fin rays; no dark oblique band (from posterior border of operculum to above anus), no dark spots on caudal lobes, dorsal dark band continues onto caudal fin (Ref. 43912, 81643). 7-8 (rarely 9) branchiostegal rays on one side of head; base of anal fin marked by small dark line (Ref. 43912).

Description: serrations on inner and outer side of pectoral (Ref. 81643) and dorsal spine (Ref. 43912). 7-9 (rarely 10) branched pectoral fin rays; 36-41 non-fused vertebrae; caudal peduncle in general somewhat longer than deep, sometimes slightly deeper than long; head rounded and rather narrow; snout reaching beyond lower jaw; nasal barbel reaching at least to middle of eye and at maximum to anterior border of operculum; maxillary barbel reaching to posterior border of opercle or beyond; mandibular barbels reaching at least to anterior border of opercle and at maximum to just beyond opercle; no trace of intermandibular barbels (Ref. 43912). Closely related to P. buffei from which it can be distinguished by its peculiar coloration; P. debauwi is also very similar to P. mandevillei but the latter has inner mental barbels which are always absent in P. debauwi (Ref. 43912).

Coloration: preserved specimens: broad mid-dorsal line present, continuing on upper half of caudal fin, sometimes somewhat bent downwards near posterior border of fin (Ref. 43912). Lateral line streak continues straight over caudal peduncle (Ref. 43912, 81643), generally slightly bent downwards on caudal fin and sometimes confluent with mid-dorsal line near posterior border of caudal fin (Ref. 43912). No spots on caudal fin lobes; anal fin base with a fine dark band (Ref. 43912, 81643). In life: silvery or whitish with lines grey-blue or grey-black (Ref. 43912, 81643).