Micropsectra contracta

Author: Reiss, 1965

Exuviae 5.1-8.0mm long (m=6.0, n=22) (147-1.jpg).
Cephalothorax: Cephalic tubercles long conical (147d.jpg), 60-125µm long (n=4). Frontal setae 150, 180µm long (n=2). Antennal sheath base with a short rounded conical swelling. Thoracic horn 470-870µm long (m=654µm, n=18) (147b.jpg); ThR 6.2-13.7 (n=8). Thoracic horn setae from horn base, seta 200-257µm long (m=232µm, n=16), 0.26-0.49 of horn length (m=0.37, n=16). Posterior thoracic mounds strongly swollen. Pearl row absent.
Abdomen: Length hook row II 0.55-0.74x width tergite; hooks 171-200 (n=3). Tergite II without anterior point patches; armament with the lateral point bands completely fused anteriorly, leaving a longitudinally oval bare patch postero-medially. Tergite III with spines longer than 25µm (147c.jpg). Tergites IV and V with a pair of transverse, slightly oblique point patches. Lateral longitudinal bands of tergite IV with long spines, usually terminating at a half to three-quarters the length of the segment (147c.jpg); lateral longitudinal bands absent on tergite V. Tergites VII and VIII with very restricted armament or smooth. Pedes spurii B II well-developed. Comb of segment VIII 33-60µm wide (m=44.4µm, n=23); with 3-8 marginal teeth (m=5.6, n=22). Lateral taeniae of segments IV-VIII: 2(1),3,4,4(5),5.
Anal segment: Anal lobe ratio 1.1-1.4 (n=10). Fringe of anal lobe complete, with 34-60 taeniae (m=49, n=27) (147e.jpg).
(Linked adult male: Langton and Pinder, 2003a)

Note: Micropsectra apposita (Walker) and M. contracta are so far separable only as females. The possible distinction between the pupae given by Säwedal, 1976a (p. 111), anal fringe with 53-55 taeniae in apposita, 69-90 in contracta, has proved unreliable: in Britain the range so far for apposita is 34-51, and for contracta is 39-60.

Species keys out at Page 512: Tanytarsini 153 Micropsectra of the Text Key.

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

Ecological notes
In general contracta is a stagnant water species, but has occurred in a spring pool with a fast through-flow.