(Goetghebuer, 1921)
Body
Small larvae up to 5 mm long. Living larvae red. No lateral and ventral tubules (Wiederholm, 1983; Moller Pillot, 1984a).
Head
The clypeus is separated from the frontal apotome by a small suture. Labral sclerite 1 is absent sclerite 2 is present.
Antenna
The antenna consists of 5 segments. The basal segment and blade are shorter than the flagellum. Lauterborn organs absent or distally on the second segment.
Mentum
The mentum is pale with four median teeth, the inner pair smaller than the outer pair and 6 pairs of lateral teeth Nil mentum. The ventromental plates 1.5x as wide as the mentum.
Labrum
SI is plumose only distally and labral lamellae consist of only 6 small teeth. The pecten epipharyngis with three toothlets with a common base. The premandible has three teeth.
Mandible
The mandible is distinctive. All teeth are pale, dorsal tooth broad. The apical tooth is very long and the four small inner teeth lined up straight Nil mandible. The pecten mandibularis and seta interna apparently absent.
Differential characteristics
The combination of 4 median mental teeth Nil mentum and 4 inner mandibular teeth Nil mandible separate Nilothauma and Sergentia from all other genera. The pale mandibular teeth in Nilothauma are in contrast with the dark teeth of Sergentia Serg mandible 8.