Chironomus brevidentatus

Author: Hirvenoja and Michailova, 1998

Diagnosis (Coll. M. Hirvenoja)
Exuviae 9.2-10.1mm long (n=5).
Colour: 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 170x70-200x72µm (n=5). Frontal setae 70-72µm long (n=4). Basal ring of thoracic horn 170x60µm. Tracheolar patch of thoracic horn without an "eye", patch 120x40µm (n=10); 19/22 tracheoles 3.3µm in diameter. Thorax less distinctly granulate: anteriorly the granules are small and distinct; medially most of the granules are somewhat flattened, producing an irregular reticulate pattern, or evanescent.
Abdomen: Hook row II entire, length of row 0.51x width tergite (n=1); hooks 82-105 (n=4). 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. Armament of tergites II-VI not so strongly waisted and with the posterior transverse band not successively increasing in extent to tergite VI; usually reduced on VI. Pleura of segment IV spinulate. 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. Parasternite II obviously shagreened. Both sternites III and IV with lateral longitudinal bands of shagreen, the lateral bands spreading inwards and only narrowly joined anteriorly. Sternite III with shagreen anteriorly and/or laterally which may be reduced to a small patch in mid-segment or at the anterolateral corner. Sternite IV with lateral shagreen bands reduced posteriorly, leaving a wide gap before the pedes spurii A, represented by a patch of spinous points (the enlarged posterior points of the lateral shagreen bands.) in the postero-lateral corners. Lateral setae long: on IV longest seta 150µm or longer, on V longest taenia at least 450µm long. Segment VIII with 5 lateral taeniae. Comb of segment VIII with 2-4 stout teeth with tips often split (n=4), comb on the end of an elongate ventral cuticular mound which exceeds appreciably the apico-lateral corner of the segment (100g.jpg , 100h.jpg).
Anal segment: Anal lobe with 74-95 fringe taeniae (n=5).

Species keys out at Page 204: Chironomini 101 Chironomus of the Text Key.

Northern Finland (Hirvenoja and Michailova, 1998a).
(For more information see module IdentifyIt – file: Chironominae).