Chironomus commutatus

Author: Keyl, 1960

Diagnosis (Specimens coll. Strenzke in coll. ZSM)
Exuviae 7.97-9.6mm long (n=4).
Colour: Exuviae golden-brown to dark brown. Contrast in colour between thorax and abdomen not so strongly marked: specimens dark anteriorly also have the abdomen infuscated; outer margin of the anal lobes coloured except at base.
Cephalothorax: Cephalic tubercles conical, LxB 125x100-165x125µm (n=5), gradually contracted to apex. Frontal setae 63-75µm long (n=3). Thoracic horn much branched, basal ring of horn 127x47-175x67µm. Tracheal patch of thoracic horn without an "eye", patch 88x23-125x30µm; 10-15 tracheoles across (n=5). Tracheoles of tracheal patch 2µm across. Thoracic granulation distinct and extensive.
Abdomen: Hook row II entire; 65-85 hooks (n=4). Armament of tergites II-VI in the form of an undivided patch of strong points, not strongly reduced anteriorly; point patches not strongly waisted and e.g. on tergite III extending laterally at most only as far as the inner edge of the lateral of the anterior adhesion marks and setae D4. The points in each segment increasing in size posteriorly; the posterior transverse band not successively increasing in extent to tergite VI; usually reduced on VI. On tergite IV seta D3 lies external to seta D4 (102a.jpg). Shagreen of sternite II extensive complete posteriorly. Lateral longitudinal shagreen bands of sternite III, and often IV, present. Sternite VI with anterior shagreen rather disorganized, not forming a distinct pattern (102b.jpg). Parasternite II obviously shagreened; III without shagreen; IV may have a few minute points in posterior half. Conjunctives IV/V and V/VI at most minutely "rough". Pleura IV sparsely spinulate. Comb of segment VIII with 2-4 elongate teeth (n=5) on the end of an elongate ventral cuticular mound which exceeds appreciably the apico-lateral corner of the segment. Lateral setae of anterior segments longer, e.g. on III over 100µm long. Lateral taeniae of segments V-VIII: 4,4,4,5.
Anal segment: Anal lobes weakly rounded. Each anal lobe with 92-111 fringe taeniae (n=5) and one dorsal taenia.

Species keys out at Page 212: Chironomini 109 Chironomus of the Text Key.

Widespread in Europe.
(For more information see module IdentifyIt – file: Chironominae).

Ecological notes
Lakes, reservoirs and their outfall streams.