Antenna 5 segmented, basal segment shorter than flagellum. Long blade arises on apex of segment 2, reaching subapex of flagellum, accessory blade much shorter. Lauterborn organs absent. Style on apex of 3rd segment. Antennal seta absent.
SI seta-like; SII long, blade-like, much longer than SI, SIII very small, seta-like; SIVa long, 3-segmented, SIVb not identified. No chaetae. Labral lamellae absent. Pecten epipharyngis a rounded plate with faint indication of division into 3 lobes. Premandible with 6 strong teeth progressively becoming smaller basally, brush absent.
Mandible lacking dorsal tooth, with elongate, apical tooth about as long as combined 2 pointed inner teeth. Seta subdentalis short, broad, distally rounded Seta interna 4 branched, finely serrate on one side only. Pecten mandibularis absent.
Mentum with pale rounded broad median area, flanked by 7 pairs of dark, obliquely-arranged lateral teeth. Ventromental plates each about as wide as mentum, tapering to point laterally. with faint, fine striae, with smooth anterior margin. Setae submenti simple.
The diagnosis is based on the one species known as larva, G. alboviridis, first described by Sæther (1976). This larva differs from other Chironomini in the combination of broad, pale median mental tooth flanked by several pairs of obliquely sloping, darker lateral teeth, small scale-like pecten epipharyngis, weakly divided into 3 shallow lobes and premandible with 6 slender teeth progressively diminishing in size proximally.
No information on the ecology of Gillotia is available.
Known from the Nearctic and Afrotropical regions, one species from each region. Unpublished adult from Australia. Only the Nearctic species, G. alboviridis, is known as a larva.