(Walker, 1856)
Subgenus Caulochironomus
Body
Medium sized larvae, up to 10 mm long. No tubules present on the 11th segment (Vallenduuk, 1999).
Head
The head capsule is shining. Anterior margin of fronto-clypeal apotome concave. Both labral sclerites 1 and 2 are present. Sclerite 1 is arch shaped (subgenus Caulochironomus Caulochir frontoclypeus. No dark band along the border of the frontal apotome.
Antenna
The antenna consists of 5 segments. The blade is shorter than the flagellum. Lauterborn organs distally on the second segment.
Mentum
The mentum has a single median tooth with 6 pairs of lateral teeth. The 4th lateral is not reduced Glyp imbec ment pict 8.
Labrum
SI is plumose to toothed on both sides and labral lamellae are a toothed plate. The pecten epipharyngis with many unequal distal teeth and small points on the surface. The premandible has two apical teeth.
Mandible
The mandible with a dorsal tooth, one apical tooth and 3 inner teeth. The pecten mandibularis is present and seta interna with 4 toothed and plumose branches (Wiederholm, 1983).
Differential characteristics
The combination of dull headcapsule, simpel mid-mental tooth and 6 pairs of lateral teeth Glyp mentum are distinctive for subgenus Glyptotendipes. Subgenus Caulochironomus can be identified by shining headcapsule, frontoclypeal apotome with concave anterior margin, labral sclerites 1 and 2 present Caulochir frontoclypeus and three inner mandibular teeth. In subgenus Trichotendipes the combination of a subapical pit on the frontal apotome and clypeus separate from frontal apotome Glyp signatus frontoclypeus is distinctive.
G. imbecillis can be separated from the other species of subgenus Caulochironomus by the mentum with single median tooth and 6 pairs of lateral teeth with the 4th lateral as strong as the 5th. No tubules on the 11th segment.