Chironomus aprilinus

Author: Meigen, 1830

Exuviae 7.5-10.8mm long (m=9.1mm, n=10) (100-1.jpg).
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 93x87-145x135µm (n=9); frontal setae 40-57µm long (n=5) (100f.jpg). Thoracic horn much branched; basal ring of thoracic horn 133-187x57-85µm; tracheal patch without an "eye", 100-135x27-35µm, 10-15 tracheoles across (n=10); 2µm in diameter. Thorax less distinctly granulate: anteriorly the granules are small and distinct as far as the dorsocentral setae; medially most of the granules are somewhat flattened, producing an irregular reticulate pattern, or evanescent.
Abdomen: Hook row II entire, length of row 0.51-0.57x width tergite (n=3); hooks 64-89 (n=9). Armament of tergites II-VI in the form of an undivided, more central patch of strong points, 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 (100b.jpg). The points in each segment increasing in size posteriorly; the point patches increase in extent from tergite II to V, but on VI the patch is more or less reduced. Pleura of segment IV extensively armed with relatively large spinules: about 20µm long, 1µm broad at base (100c.jpg). Conjunctival spinules IV/V and V/VI about 2.5µm long. Shagreen of sternite II, if present, with a definite gap between the points in the postero-lateral corner and those near seta V5 of the same size, if the central armament extends that far. Sternites III and IV without a complete anterior transverse band of shagreen. Parasternite II obviously shagreened; III without shagreen; IV may have a few minute points in posterior half. Comb of segment VIII with 1-3(4) stout teeth, comb on the end of an elongate ventral cuticular mound which exceeds appreciably the apico-lateral corner of the segment (100d.jpg). Lateral taeniae of segments V-VIII: 4,4,4,5.
Anal segment: Anal lobes weakly rounded (100e.jpg). Fringe of anal lobe with 94-147 taeniae (m=119, n=10).
Note: Agrees with Strenzke-reared Chironomus halophilus in coll. ZSM.

Species keys out at Page 200: Chironomini 97 Chironomus of the Text Key.

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

Ecological notes
Fresh- and brackish water.