Pinder, 1976
Body
Medium sized larvae 5.5 - 6.7 mm. Living larvae are orange. No lateral and ventral tubules. Procercus and anal tubules present (Wiederholm, 1983; Pinder, 1976).
Head
The clypeus is separate from the frontal apotome. A subapical pit is absent and labral sclerite 1 are absent.
Antenna
The antenna consists of 6 segments. The blade is subequal to the flagellum. Lauterborn organs alternate on the second and third segment Microt antenna.
Mentum
The mentum has 3 equally sized yellow median teeth and 6 pairs of brown lateral teeth Microt rydal mentum. The ventromental plates are narrow and strongly curved about 0.6-0.8x as wide as the mentum.
Labrum
SI is plumose on both sides and labral lamellae a single plate with approx. 14 distal teeth. The pecten epipharyngis with 9 teeth (Pinder, 1976).
Mandible
The mandible with a pale dorsal tooth, one apical and 3 inner teeth. The pecten mandibularis is present and seta interna with 4 toothed and plumose branches.
Differential characteristics
The combination of 2-3 mid-mental teeth Microt mentum, alternating Lauterborn organs Microt antenna and the absence of tubules on segment 10 is distinctive for the genus.
M. rydalensis differs from the other Microtendipes by the 3 equally sized large median teeth and the pecten epipharyngis with 9 teeth.