Chironomus crassimanus

Author: Strenzke, 1959

Diagnosis (True description in preparation.)
(Specimens coll. Strenzke in coll. ZSM. Further material leg. Rodrigues)
Exuviae 6.7-7.6mm long (n=3).
Colour: Exuviae golden-brown to 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 83x55, 113x67µm (n=2). Frontal setae 38, 40µm long (n=2). Thoracic horn much branched, basal ring 100-120x40-50µm. Tracheal patch of thoracic horn without an "eye", patch 70-85x15-23µm (n=3). Tracheal patch at the origin of the thoracic horn only about 80µm long by 20µm wide, of relatively few tracheoles: about 8 tracheoles across the anterior lobe. Anterior thorax more sparsely granulate; granulation grading into reticulation sooner: above the oblique hinge line towards scutal hump evanescent and below, reticulate.
Abdomen: Hook row II entire, length of row 0.41x width tergite (n=1); hooks 42-66 (n=3). Armament of tergites II-VI in the form of an undivided patch of strong points, 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 posterior transverse band not successively increasing in extent to tergite VI; usually reduced on VI, the most posterior points of tergites IV and V short. Shagreen of sternite II continuous from postero-lateral corner to seta V5, the region between containing points of similar size to those on each side. Lateral shagreen bands of sternite III long and spread inwards anteriorly. Parasternite II obviously shagreened; III without shagreen; IV may have a few minute points in posterior half. Conjunctives IV/V and V/VI less strongly armed, rarely the points spinulate. Pleura of segment IV extensively armed with relatively large spinules: about 20µm long, 1µm broad at base (100c.jpg). Comb of segment VIII with 1, 2 stout teeth (n=3), set on the end of an elongate ventral cuticular mound which exceeds appreciably the apico-lateral corner of the segment. Lateral taeniae of segments V-VIII: 4,4,4,5.
Anal segment: Anal lobes weakly rounded. Fringe of anal lobe with 67-80 taeniae (n=3). Fringe of anal lobes with fewer than 90 taeniae.

Species keys out at Page 206: Chironomini 103 Chironomus of the Text Key.

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

Ecological notes
Stagnant water of very low pH, Germany.