Large larvae, up to 15 mm long. Body red. Head capsule long, conical; cephalic index about 0.7. Ventrally, VP posterolateral to very anterior S9 and S10, and anterolateral to quite retracted SSm; S10 close to and near directly posterior to S9. Dorsally DP is absent, S7, quite ventral and distant from S8 located far posterior; S5 far posterior to S7; S5, S7 and SSm multi-branched, S9, S10 long and simple.
Very long, up to 5x length of mandible. Antennal ratio >10 (11-16). Basal segment about 10x as long as basal width, with ring organ at 0.9; segment 2 weakly curved, about 6x as long as wide; segments 3 and 4 very short, together shorter than width of segment 2, shorter than peg sensilla and < 1/2 as long as style; apical segment somewhat shorter than segment 3. Blade large, extending beyond flagellum by about 1/4. Accessory blade somewhat longer or sometimes shorter than segment 2. Segment 2 and antennal blade somewhat recessed into segment 1.
Distal 1/3 hooked, curved through about 90° distal to ventrolateral setae 1 and 2. Apical tooth almost 3x as long as basal width. Inner margin with 2 adjacent, small teeth in proximal 1/4, then large tooth with apically-directed point in angle of hook, then 2 or 3 small adjacent teeth proximal to large tooth, enclosed by inner margin of mandible; seta subdentalis arises proximal to all inner teeth. Basal 1/2 of mandible expanded on inner side. Pecten mandibularis formed by row of about 13 narrow spines, on sloping ridge extending from base to dorsally-located and adjacent ventrolateral setae 1 and 2. Ventrolateral setae all simple; seta 1 short, 2 and 3 much longer; Ring organ retracted, close to seta 3.
Basal segment of palp very long, sclerotized, tapered in apical 1/2, 5x as long as maximum width and situated on tall pedestal; ring organ at 0.75.
With dense fringe of swim-setae. Four conical anal tubules and conical papilla, as high as wide, located between procerci. Procercus about 3x as long as wide, with about 14 anal setae. Claws of posterior parapod pale, about 16; some longer claws strongly pointed, inner and/or outer margins partially with slender teeth; smallest claws simple, weakly curved.
Clinotanypus is closely related to Coelotanypus, the pair occupying an isolated position within the Tanypodinae, in the tribe Coelotanypodini. The labrum, antenna, maxilla, hypopharynx and mental complex, as well as the mandibles, are very modified. The hooked mandible with several inner teeth but including one large one, and the absence of small sclerotised hooklets anterodorsally on abdominal segment 1 separate Clinotanypus from Coelotanypus. Larvae of the subgenus Aponteus, erected for the species Clinotanypus sabenis Roback (Roback 1971), are unknown.
Clinotanypus larvae prefer soft sediments of shallow, warm water bodies of all sizes, including ponds, lakes and slowly flowing streams and rivers, and of varying water quality. Larval Clinotanypus may be abundant in Asia in rice fields, ditches and pools in drying rivers, where they tolerate high organic loadings.
Clinotanypus pinguis is widely distributed particularly in the eastern United States, with 3 additional poorly-known species reported from Florida; the genus is almost unknown in the western states. Only Clinotanypus nervosus occurs in the temperate western Palaearctic (Vallenduuk and Moller-Pillot 2008). However, diversity in the eastern Palaearctic and Oriental region is high with at least 25 species described based on adults with characteristic pigment patterns (Ming and Wang, 2008), but unassociated sexual dimorphism may mask some synonymy. One species, Clinotanypus crux extends from India to Australia. Clinotanypus is reported as unspecified adults from Mexico and several species are known from the neotropics, at least as far south as the s.e. Brazilian wetlands. Dietary studies show high detritus content (da Silva et al., 2008), although undoubtedly predation occurs.