(Kieffer, 1918)
Body
Medium sized larvae up to 8.5 mm long. Living larvae red. Claws on the posterior parapods are simpel. No lateral and ventral tubules (Wiederholm, 1983; Moller Pillot, 1984a).
Head
Antenna
The antenna, on a broad pedestal, consists of 5 segments. The 2nd and 3d segment not clearly separated. The 2nd segment longer than the remaining segments. The blade longer than the flagellum. Lauterborn organs absent.
Mentum
The mentum has a trifid median tooth and 6 pairs of lateral teeth. The 4th pair is very small and the 5th lateral is larger than the neighbouring teeth Microch tener mentum. The ventromental plates are 0.7-0.9x as wide as the mentum.
Labrum
SI is simpel and labral lamellae are absent. The pecten epipharyngis is either a simpel plate or distally divided into 3 lobes. The premandible has 2 apical teeth.
Mandible
The mandible without a dorsal tooth, apical tooth and 2 flat inner teeth present Microch tener mandible. The pecten mandibularis is absent and seta interna with 4 branches.
Differential characteristics
The flat mentum with the 5th lateral tooth larger than the neighbouring teeth Microch tener mentum is distinctive for the genus.
M. tener differs from M. deribae by the trifid median mentum tooth, the flat inner mandibular teeth, the antennal blade longer than the flagellum and the occurrence in freshwater only.