size 6 mm length
freshwater, little pond with filamentous algae
Tanytarsus is a Tanytarsini we can recognize immeidately
by larvae displaying antennae with a pedestal
eyes spots usually double
Body segments 5-9 of most Tanytarsini with characteristic, bifurcate setae (you could see its in the video clip)
...... YouTube Video
very strange antenna for Tanytarsus, usually the pedestals of the lauterborn organs (l.o.) are longer and the l.o. not that large and bulbous. l.o. looks more like Cladotanytarsus, but the antennal-segments doesn't fit. I will ask my colleagues about this one and keep you posted. Is your larvae from Brasil?
On second thought I'm almost certain that your larvae is a member of Paratanytarsus. Pecten epypharynx with (about) 3 lobes, antennal segment 2 not shorter than 3, pedestal of l.o. small: smaller than the length of 3, l.o. large, posterior claws not with secondary teeth, labial plates long and small, touching eachother medially, antennal base withouth spur or (comb of) teeth. So in my opinion Paratanytarsus is the only option. Stempellina, Stempellinella, Constempellina, Zavrelia, Thienemanniola have a shorter labial plates, Micropsectra, Parapsectra, Krenopsectra and Tanytarsus have smaller l.o. and a much longer pedestal; Cladotanytarsus has short second antennal segment and toothed posterior claws; Rheotanytarsus has a pedestal of the l.o. about the length of third antennal segment and a pecten epypharynx with 5 teeth.