Medium-sized to large larvae, body length up to 10 mm. Head pale through reddish to mid-brown; body pink-reddish in life, often with brownish mottling. Head capsule oval; cephalic index 0.64-75. Dorsally, S5 anterior to approximated S7, S8; DP more posterior, unaligned; ventrally SSm posteromedian to diagonally aligned SSm-S10-S9; VP posterolateral to S9, posterior to SSm. At least S7, S9 and S10 multibranched.
1.7-2X as long as mandible, about 1/3 head length. Flagellum angled relative to basal segment. Antennal ratio about 5.4. Basal segment 5-8x as long as basal width, with ring organ at about 0.60; segment 2 4.5-6x as long as wide; segment 3 about 4-5x as long as wide, 2.5x as long as terminal segment. Style extending to middle of terminal segment. Peg sensilla about as long as segment 4. Blade extending to terminal segment; accessory blade short, ending proximal to middle of blade.
Moderately curved, gradually narrowed towards apex. Apical tooth indistinctly delimited, 1/4 length of mandible. Mola non-protruding, bearing two separated ranks of many (at least 10) accessory teeth; short seta subdentalis arises at anterior end ranked teeth, not separated from apical mandibular tooth. Ventrolateral setae situated in proximal 1/2 of mandible; seta 1 simple, 2 and 3 simple to trifid, SI, SII and ring organ adjacent, forming triangle, separated from more posterior SIII.
Basal segment of palp 3-3.3x as long as basal width, apically narrowed; ring organ 0.75-0.8 from base.
With dense lateral fringe of swim-setae. Anal tubules conical, 1/2 as long as posterior parapod. Procercus 4.5x as long as wide with 8 apical setae. All claws of posterior parapod light; all large claws with fine points on inner side and some of large claws with very fine points on outer side; 4 small claws with several strong points on inner side.
Fittkauimyia differs strongly from all other Macropelopiini (and indeed all other Tanypodinae) in the structure of the dorsomentum, ligula and mandible. The tripartite, concave, continuous dorsomentum resembles that of Tanypus, but the complex structures laterally, comprising an inward and an outward-directed tooth are distinctive. The arrangement of mandibular teeth on the mola and the outer mandible is unique. In no other larvae is the inner tooth of the ligula inclined towards the middle tooth.
The larvae of Fittkauimyia live in rivers and the littoral region of lakes, generally in tropical and subtropical regions throughout the world. Larvae known from Florida [including sub Parapelopia (Roback 1971, 1982c)] west to Texas and north-central Oklahoma, and north to North Carolina, are likely to belong to Fittkauimyia serta. Either 1 or 2 species are known in all stages from Japan, from slow streams in Fukushima and Shizuoka Prefectures (Niitsuma, 2004) and a pond in Tsukuba, Ibaraki (Ueno et al., 2005).
The distribution of the type species F. disparipes, described from Singapore, includes Australia and the genus is known from Indonesia (including Sulawesi) and unreared larvae in Thailand. Fittkauimyia petersi is known from tropical African lakes including sub Kamelopelopia (Harrison, 1978) also from subfossil head capsules. Fittkauimyia is recorded in Central America from Costa Rica (Watson and Heyn, 1993) and Mexico (Andersen et al., 2000). In the Neotropical region F. crypta is described in all stages from Brazil: further immature material from Amazonian Brazil and Peru may belong to this or undescribed species.
The larvae are 'sit-and-wait’ predators, with a diet including oligochaetes.