Medium-sized larvae, up to 11.5 mm long.
Dorsal surface of head with frontoclypeolabral apotome.
Antenna with 5 segments; segment 3 longer than segment 4. Ring organ at about middle of basal segment. Blade shorter than flagellum. Lauterborn organs shorter than segment 3.
SI to SIV single, slender. Labral lamellae, chaetae and spinulae all absent. Pecten epipharyngis consisting of 3 spines with rounded base and pointed apex. Chaetulae laterales (about 5 pairs) and chaetulae basales smooth, simple. Premandible with 4 teeth; brush absent.
Apical tooth longer than combined width of 3 inner teeth. Seta subdentalis pointed. Seta interna absent.
Mentum with 4 equal median teeth and 5 pairs of lateral teeth; median teeth paler than lateral teeth and easily worn down to apparent broad, single median tooth. Ventromental plate weak; beard absent.
Anterior lacinial chaeta broad-based and pointed. Pecten galearis absent.
Body with short parapods; anterior parapods joined at base. Medium-sized claws of anterior parapods with teeth or serrations, others smooth. Procercus reduced; with 7 anal setae. Supraanal seta short. Anal tubules short, thick, and rounded, shorter than short posterior prolegs. Body segments with single setae shorter than 1/3 the length of corresponding segments.
Larvae of Dratnalia potamophylaxi, the only known species, live within larval and pupal tubes of Potamophylax spp. (Trichoptera: Limnephilidae) on the ventral part of the first abdominal segments. They have been found in streams, rivers and springs (Dratnal, 1979a) in central Europe (Poland, Czech Republic and central Germany).