Medium sized larvae, about 7 mm long, moderately slender; 9x longer than broad.
Antenna with distinct 5 segments; segment 3 annulated all over. Ring organ situated just at the base of the basal segment. Blade reaching middle of segment 3; accessory blade much shorter. Style nearly reaching tip of antenna.
Labrum with SI and SII on high, slender tubercles; SI with a brown sclerite, at the base with a short accessory seta on a tubercle; SIII represented by 2 slender setae situated close together between SII; SIV represented by 1 short seta on each side. Pecten epipharyngis forming a slender lamella, ending in 4 short and slender spines. Spinulae reduced.
Mandible with 6 teeth, 2 subapically on outer margin, 2 apical ones, and 2 on inner margin.
Mentum very distinctive by the strongly retracted median tooth and the first pair of lateral teeth; 12 lateral teeth present on each side.
Body with procercus comparatively short and stout; with 6 anal setae, the longest one somewhat longer than procercus. Spiracular rings on 11th body segment absent.
Trichotanypus is confined to the northern part of the Holarctic region. Of the five described species the pupae of two are known (Brundin 1966a; Wirth and Sublette, 1970a). The immature stages are cold-stenothermal and live in both stagnant and running waters.