Medium-sized larvae, up to 9 mm long.
Antenna with 5 segments; segments consecutively shorter or segments 3-5 subequal in length. Ring organ on basal 1/4 of segment 1. Blade ending before apex of flagellum. Lauterborn organs large, at least 1/2 length of segment 3. Style as long as combined length of segments 3 and 4.
Labrum with single labral sclerite present. SI bifid; remaining S setae simple. Labral lamellae absent. Pecten epipharyngis consisting of 3 pointed scales. 6-7 pairs of chaetulae laterales; chaetulae basales present. Premandible simple or bifid; brush, if present, indistinct.
Apical tooth as long as or slightly longer than combined width of 3 inner teeth. Seta subdentalis straight, apically pointed. Seta interna with 5-6 simple branches.
Mentum with 1 median and 6 pairs of lateral teeth present; median tooth broad, low, dome-shaped and paler than lateral teeth. Ventromental plate narrow, elongate; beard present, sometimes indistinct.
Maxilla with palpiger and galea with triangular chaetulae and lamellae. Pecten galearis absent. Seta maxillaris simple.
Body with separate posterior parapods, each bearing an apical crown of claws. Procercus shorter than wide, bearing 6-7 anal setae; without spur. Anal tubules shorter than length of posterior parapods.
Among larvae with a bifid SI and ventromental beard, Paracladius larvae can be distinguished by the broad and dome shaped, lightly-coloured, median mental tooth.
Larval Paracladius occur in the northern Holarctic, in springs and all sizes of flowing and still water. Hirvenoja (1973) describes the larva. Saether et al (2000) list 4 species: akansextus, alpicola, conversus and quadrinosus.