Fittkau, 1962
Body
Medium sized larvae with a length up to 9-10 mm. Living larvae are yellowish with brown stains. Fringe of swimming hairs absent (Moller Pillot, 1984a).
Head
The head length is 0,9 - 1,1 mm, with a cephalic index of 50 - 60% (Moller Pillot, 1984a).
Antenna
The antennal ratio is 4 - 5,5. The ring organ is situated a little distally from the middle of the first segment (Moller Pillot, 1984a).
Mentum
Dorsomentum without teeth.
Ligula and paraligula
Ligula with 5 brown teeth in a concave row. Paraligula bifid almost half as long as the ligula Abl ligula paraligula (Wiederholm, 1983; Moller Pillot, 1984a).
Mandible
The mandible with a large basal tooth and a smaller tooth on its inside (Wiederholm, 1983; Moller Pillot, 1984a).
Maxilla
The basal segment is subdivided into 4 segments Abl longistyla maxilla (Moller Pillot, 1984a)
Anal tubules
4 anal tubules which are 4 - 5 x as long as wide.
Posterior parapods
Two anal claws are brown, the remainder are yellow. All claws without inner teeth (Moller Pillot, 1984a) Abl claw.
Differential characteristics
Within the tribe of the Pentaneurini, Ablabesmyia has a very long maxilla with a unique basal segment. A. longistyla differs from the other Ablabesmyia species by having the basal segment subdivided into 4 segments Abl longistyla maxilla.