(Van der Wulp. 1874)
Body
Large larvae. Living larvae red. No lateral and ventral tubules (Wiederholm, 1983; Moller Pillot, 1984a).
Head
The head capsule is shining and 550 - 600 µm long. The gula is pale. Anterior margin of frontal apotome is straight without a subapical pit, but with anterio-lateral lobes on which the S3 is inserted. Labral sclerite 1 absent, sclerite 2 present.
Antenna
The antenna consists of 5 segments. Segments 2 - 4 are subequal. Lauterborn organs on the apex of the 2nd antennal segment. The blade reaches to the distal half of the 4 th segment (Moller Pillot, 1984a).
Mentum
The mentum has 2 median teeth and 7 pairs of lateral teeth. The median teeth are larger than the laterals Pol sordens mentum 2. The ventromantal plates are wider than the mentum.
Labrum
SI is plumose on both sides and labral lamellae a single plate with numerous distal teeth. The pecten epipharyngis with 3 small plates with distal teeth Pol pecten epiph. The premandible has three teeth.
Mandible
The mandible without a dorsal tooth, one apical tooth and 3 inner teeth Pol sordens mandible. The pecten mandibularis is present and seta interna with plumose branches.
Differential characteristics
Two median and 7 pairs of lateral teeth on the mentum Pol g nub mentum 8, with Lauterborn organs on the second segment and shining dorsal headcapsule will separate Polypedilum from all other genera except from Parachironomus which however has a completely different mentum Parach arc mentum.
P. sordens can be separated from the other Polypedilum by the size of the head (length 550 - 600 µm). Also the mentum with the large median teeth and normal first lateral tooth are distinctive.