(Egger, 1863)
Body
Medium sized larvae with a length up to 9-12 mm. Fringe of swimming hairs absent (Moller Pillot, 1984a).
Head
The head length is 1,2 - 1,5 mm, with a cephalic index of 48 - 56% (Moller Pillot, 1984a).
Antenna
The antennal ratio is 5,7 - 7. The ring organ is situated 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 (Moller Pillot, 1984a).
Mandible
The mandible with a large basal tooth and a smaller tooth inside (Moller Pillot, 1984a).
Maxilla
The basal segment is subdivided into 2 segments. Only the distal part is sclerotized Abl phatta 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 Abl claw (Moller Pillot, 1984a).
Differential characteristics
Within the tribe of the Pentaneurini, Ablabesmyia has a very long maxilla with a unique basal segment. A. phatta differs from the other 2 Ablabesmyia species by the large head (length 1,2 - 1,5 mm. The other species 0,9 - 1,1 mm).