Small to medium-sized larvae, to 5 mm long.
Antenna with 5 segments on a short pedestal lacking any basal tooth or spur. Antennal ratio around 1.0. Ring organ proximal on 1st antennal segment. Seta well developed. Lauterborn organs large, on short broad stems, opposite on apex of wedge-shaped 2nd segment. 3rd segment usually longer than 2nd. Antennal blade usually not extending to flagellum apex, accessory blade short. Style on apex of 2nd segment, shorter than segment 3.
SI seta comb-like, fused at bases, SII on large pedestal, distally plumose, SIII short, simple, SIVa present. Labral lamellae well developed. Pecten epipharyngis 3 distally serrate scales. Premandible with 4 or 5 apical teeth, brush strong; seta premandibularis simple.
Mandible with pale dorsal tooth, apical tooth and 3 pointed inner teeth dark. Seta subdentalis long, curved, reaching beyond base of apical tooth. Seta interna of 4 plumose branches. Pecten mandibularis well developed with many branched lamellae.
Mentum with broad median tooth often notched with outer toothlets variable in size and degree of fusion, 5 pair of laterals, regularly decreasing in size or 2nd lateral much smaller than remainder. Ventromental plates close together medially, a little wider than mentum, with fine striae.
Without tubules. Some claws of posterior parapod with finely serrate margins.
Cladotanytarsus larvae differ from all other Tanytarsini in that some of the curved claws of the posterior parapods are finely serrated along the inner margin. In addition the short, wedge shaped antennal segment 2, bearing large Lauterborn organs on short pedicels, in combination with wide ventromental plates, which are very close together medially are quite characteristic.
Species groups of Cladotanytarsus
- 1. First pair of lateral teeth of mentum very small and close to median tooth; thus mentum appears to consist of a compound median tooth and 4 pairs of separate lateral teeth ... Species group A
- -- First pair of lateral teeth well developed, mentum not as above ... 2
- 2. Mental teeth progressively diminishing in size laterally ... vanderwulpi group
- -- Second pair of lateral teeth much smaller than adjacent teeth ... mancus group
The genus is eurytopic. Larvae have been found in streams and larger rivers, lakes and ponds, as well as brackish waters and hot springs. Worldwide distribution, with at least 16 described species from the Holarctic, most of which are not described, or inadequately described, as larvae.