(Meigen, 1818)
Body
Medium sized larvae up to 8 mm long. Living larvae are pale sometimes with faint pale rings. The two posterior parapods bear rows of yellow-brown to brown claws. Procercus is well developed with an apical spur. The setae on the procercus are short, only twice as long as the procercus. Supra-anal seta short and two pairs of anal tubules present (Wiederholm, 1983; Moller Pillot, 1984b).
Head
The head is brown and 0.40 - 0.49 mm long. The eyes are fused, egg-shaped and difficult to distinguish the individual eyes Metr hirtic agg head lateral.
Antenna
The antenna consists of five segments. The first segment the antennal width. The blade is longer than the flagellum Metr fuscipes antenna.
Mentum
The mentum has two reduced median teeth with the first and second laterals projecting. Five pairs of lateral teeth present Metr fuscipes mentum. The ventromental plates are weak and the beard is absent.
Labrum
The pecten epipharyngis consists of three short scales, SI is simpel. Labral lamellae are present between the SI.
Differential characteristics
The eye of Metriocnemus is distinctive. The smaller and larger eye are merged into one egg-shaped eye Metr hirtic agg head lateral. In all other genera the smaller eye can be distinguished from the larger eye Limnophyes head lateral. Metriocnemus can be separated from all genera except Thienemannia by the mentum with 5 pair of lateral teeth and the weak ventromental plates Metr hirticollis agg mentum, antenna 5 segmented Metr hirtocollis agg antenna 8, plumose SI and labral lamellae Metr hirticollis agg labrum, mandible with 4-5 teeth Metr terrester mandible. Metriocnemus can be separated from Thiemannia Thienemannia gracilis anal seg by the well developed sclerotized procercus and the short seta on the procercus Metr scirpi anal segments.
M. fuscipes can be separated from the other species and Species-groups of Metriocnemus by the short first antennal segment Metr fuscipes antenna and the pale body, when preserved.