Chironomus obtusidens

Author: Goetghebuer, 1921

Diagnosis (Specimens of clarus Michailova and Hirvenoja, 1995a (?nec clarus Hirvenoja, 1962) leg. M. Hirvenoja.)
Exuviae 9.2-10.6mm long (n=8).
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 140x104-192x136µm (n=5). Frontal setae 40-56µm long (n=4). Basal ring of thoracic horn 160-184x73-96µm; tracheal patch 112-136x73-96µm (n=5); 13-15 tracheoles across, 3-3.3µm in diameter. Tracheolar patch of thoracic horn without an "eye". Thoracic granulation anteriorly with great contrast between the large crowded granules towards the suture and the small granules further laterad; medially (between dorsocentral setae 1 and 2 and the anterior edge of the wing sheath) very distinctly small granulate right up to the suture (149f.jpg).
Abdomen: Hook row II entire, length of row 0.55, 0.58x width tergite (n=2); hooks 91-93 (n=3). Armament of tergites II-VI not strongly waisted and with the posterior transverse band not successively increasing in extent to tergite VI; usually reduced on VI. Armament of tergites far less extensive, 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. Points of tergites III and IV medially appearing dense: broader, with longer anterior 'tails' which overlap the points of the preceding row. Posterior points of tergites III and IV much larger than the median points on the same tergite. Points of tergite VIII mainly isolated and irregularly arranged. Lateral longitudinal shagreen bands of sternite IV extensive, similar to those on III. Parasternite II obviously shagreened. Pleura of segment IV spinulate, spinules 14µm long. Comb of segment VIII with 2-7 teeth, set on the end of an elongate ventral cuticular mound which exceeds appreciably the apico-lateral corner of the segment. Segment VIII with 5 lateral taeniae.
Anal segment: Anal lobes with brown colour confined posteriorly to the flattened margin. Anal lobes usually with only one taeniate dorsal seta; each lobe with 89-132 fringe taeniae (n=7).
(Linked adult male: Langton and Pinder, 2003a)

Species keys out at Page 197: Chironomini 94 Chironomus of the Text Key.

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