Kieffer in Thienemann and Kieffer, 1916
Body
Large larvae with a length up to 14 mm. Living larvae are red. Abdomen with a lateral fringe of swimming hairs (Wiederholm, 1983; Moller Pillot, 1984a).
Head
The head length is 0.9 - 1.25 mm, less than 1.5 times longer than wide with a cephalic ratio of 75 - 85% (Wiederholm, 1983; Moller Pillot, 1984a).
Antenna
The antennal segments are all yellow and the antennal ratio is 6 - 8. The ring organ is situated at 0.7 - 0.8 of the height of the first segment (Wiederholm, 1983; Moller Pillot, 1984a).
Mentum
Dorsomentum with 7-8 pair of teeth Macrop adaucta dorsomen (Wiederholm, 1983).
Ligula and paraligula
Ligula with 5 brown teeth in a strongly concave row. The inner tooth is curved outwards. Paraligula with a long outer and a much smaller inner tooth Mac adaucta ligula paraligula (Wiederholm, 1983; Moller Pillot, 1984a)
Mandible
The mandible has a large basal tooth.
Maxilla
The maxilla is short with an undivided basal segment Mac maxilla.
Anal tubules
4 anal tubules which are longer than wide.
Posterior parapods
All claws on posterior parapods are yellow. No teeth on their inner margin.
Differential characteristics
Within the Macropelopiini, Macropelopia differs in the shape of the ligula Mac nebul ligula paraligula from Procladius Pro ligula and Psectrotanypus Pse ligula dorsomentum . The 6 - 8 dorsomental separate Macropelopia Mac mentum from Anatopynia (13 - 14) Ana mentum9 and Apsectrotanypus (4 - 5) Aps mentum. M. adaucta differs from the other described species (M. nebulosa) by having a dorsomentum with 7-8 teeth Macrop adaucta dorsomen (8-9 teeth in M. nebulosa) and the inner tooth of the ligula is curved outwards Mac adaucta ligula paraligula (straight in M. nebulosa).