Parachironomus biannulatus

Author: (Staeger, 1839)

Exuviae 7.1-9.7mm long (n=4) (110-2.jpg).
Cephalothorax: Cephalic tubercles 85µm long, 85µm wide (n=1) (110f.jpg). Thoracic horn much branched. Thoracic granulation gradually increasing in size to suture, but no conspicuously outstanding granules near suture. Posterior thoracic mound swollen hemispherically anteriorly and posteriorly.
Abdomen: Tergite armament of Parachironomus-pattern. Length hook row II 0.32, 0.33x width tergite (n=3). Tergite II without armament (though occasionally represented by a short posterior band of small points). Sternite I with two large antero-lateral humps on each side, both usually armed with short teeth (sometimes the outer hump is smooth). Sternite II without transverse spine bands. Vortex present. Comb of segment VIII of 3-9 small colourless spines in the apico-lateral corner near the bases of the fourth and fifth lateral taeniae (n=8). Lateral taeniae of segments V-VIII: 4,4,4,5.
Anal segment: Fringe of anal lobe with 100-137 taeniae (n=4) (110h.jpg).
(Linked adult male: Langton and Pinder, 2003a)

Species keys out at Page 245: Chironomini 142 Parachironomus of the Text Key.

Palaearctic species: northwest Europe.
(For more information see module IdentifyIt – file: Chironominae).

Ecological notes
Lakes and their outflow streams.