Chironomus pe28

new form

Exuviae 6.8-8.2mm long (n=7).
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 60x44-110x68µm (n=7). Frontal setae 40-50µm long (n=7). Basal ring of thoracic horn 110x50-124x60µm; tracheal patch 70x24-90x30µm (n=7); 12 tracheoles across, 2µm diameter (n=1). Tracheolar patch of thoracic horn without an "eye". Thorax extensively granulate, without large granules near suture anteriorly; medially (between dorsocentral setae 1 and 2 and the anterior edge of the wing sheath) very distinctly small granulate right up to the suture.
Abdomen: Hook row II entire, length of row 0.38-0.42x width tergite (n=5); hooks 45-52 (n=6). Armament of tergites reduced, 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. 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. 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. Sternites III and IV with lateral shagreen restricted to the anterolateral corners or extended for a short distance posteriad. Parasternite II obviously shagreened. Pleura of segment IV spinulate, spinules 12-18µm long. Comb of segment VIII with 3-6 elongate teeth (n=7), 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 usually with only one taeniate dorsal seta; each lobe with 66-79 fringe taeniae (n=7).
See Note under Chironomus longistylus.

Form keys out at Page 195: Chironomini 92 Chironomus of the Text Key.

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

Ecological notes
Shallow pool Bernese Alps.