Moderate-sized to large larvae, up to 10 mm long.
Antenna with segment 3 subequal to or shorter than 2 and 5 subequal to 4. 3rd segment annulate. Ring organs basal on 1st segment. Style short; Lauterborn organs seemingly absent.
Labrum with all S setae simple; SII with scale at base, SIII very weak, SIVa and b short. Labral lamellae consisting of 2 pairs of pectinate lobes (distinguish from SI setae). Chaetae simple. Pecten epipharyngis consisting of 7 elongate scales. Ungula broadly U-shaped; basal sclerite squat. Premandible with 3, 4 or 5 teeth; lateral spine absent.
Mandible with apical tooth slightly shorter than first (of 4) inner tooth. Seta interna with 17-35 weakly serrate branches.
Mentum with one median and 8-9 pairs of lateral teeth (9th very small and appressed to next); median tooth ranges in width from equal to first laterals to wider than first 2-3 lateral teeth. Ventromental plate small. Setae submenti long, arising closer to mentum than to postoccipital margin.
Maxilla squat with palp covered with small pegs, chaetulae of palpiger and lamellae of galea apparently simple. Setae maxillaris simple.
Body with anterior and posterior parapods separate, each bearing an apical crown of claws, anterior claws with inner teeth. Procercus longer than wide with posteroapical rounded sub-basal spur; bearing 7-9 anal and 2 subapical setae. Body setae pale.
Makarchenko & Kerkis (1991) key larvae of 3 Holarctic species, and 4th species has been described since.
All species are found in or close to cold flowing water in the Holarctic region.