(Meigen, 1818)
Body
Medium sized to large larvae up to 10 mm long. A very large hump is present on the 11th segment. The L2 setae on the abdomen are simpel Microps atr L2 pict. The posterior parapods bear 30 - 34 simpel claws Microps gr atrof claws. Supra-anal-setae are very fine and hardly visible at 80 x magnification (Klink, 1982a; Wiederholm, 1983).
Head
The headcapsule pale and the S3 is simpel.
Antenna
The antenna pale but occasionally. The antenna stands on a pronounced pedestal without an apical spur. The distance between the antennal pedestals at most 30 µm. The basal segment 220 - 280 µm long. Segment 2 is cylindrical and longer than the remaining segments. The small Lauterborn organs distally on segment 2 with a very long pedestal.
Mentum
The mentum has a crenate median tooth and 5 pairs of lateral teeth Micropsectra mentum. The ventromental plates are close together medially and wider than the mentum.
Labrum
SI is a comb, SII is serrate with numerous teeth and labral lamellae a single plate with 34 - 40 apical teeth. The pecten epipharyngis consists of 3 scales with distal teeth. The premandible with 2 teeth Mips labrum pe premandible.
Mandible
The mandible with a dorsal tooth, one apical tooth and 3 inner teeth all brown. The pecten mandibularis is present and seta interna with branches.
Differential characteristics
Distinctive for most species is the small apical spur on the antennal pedestal Mips small spur ant pedestal. M. bidentata with a large projection Mipsbi large distal proj ant p can be separated from Tanytarsus gr. brundini by the larger number of claws and Micropsectra fusca (with a bare pedestal and a distinct hump on the 11 segment) can be separated from Krenopsectra by its much larger size (10 mm vs 5 mm in Krenopsectra).
M. fusca can be separated from the other Micropsectra by missing the spur on the antennal pedestal and the large size. M. fusca can be separated from Tanytarsus by the large amout (30 - 34) of anal claws (except T. gracilentus which has a mandible with accessory dorsal plates Tanyt gracilentus mand and no dorsal hump on segment 11). Also the large dorsal hump is distinctive.