Diamesa cinerella

Author: Meigen, 1835

Diagnosis (n=7, unless stated otherwise)
Exuviae 5.7-6.6mm long.
Note: Colour pattern well-marked: tergites along the edge of the lateral adhesion marks narrowly brown, anterior transverse apodeme dark golden brown, base of posterior teeth bright yellow, joined by a pale golden band, together giving a 'framed' appearance to the tergite, which is otherwise smudged with pale brown; paratergites almost colourless (except laterally, where yellowish) contrasting strongly with the brown margin of the tergites. Thoracic setae and lateral setae of abdomen grey.
Cephalothorax: Frontal setae 240-340µm long (n=2). Precorneal setae 1-3: 75-115; 245-327; 182-230µm long. Thorax granulate. Thoracic horn 350-500µm long; ThR 19-30.
Abdomen: Tergite II rarely with less than 7 teeth in tooth row; tergites VI and VII dorsally each with 4-10 teeth. Total dorsal teeth II-VIII 37+-62+ (n=7); best developed dorsal teeth about 100µm long, golden to brown. Total ventral teeth III-VII/VIII 57+-103+. Tergites with band of points behind tooth row. Tergite II with a band of dense points extending at least for half the width of the tergite and posteriorly at least as far as the anterior adhesion marks. Points of tergites III-VII spreading posteriorly outside the anterior adhesion marks, extending the point patch towards the postero-lateral corner, progressively more extensive on succeeding segments (031d.jpg). Shagreen points of tergite III 8µm long. Relative length segments IX:VIII:VII = 1.0:0.65-0.71:0.84-1.0 (n=5); relative width segments IX:VIII:VII = 1.0:1.2-1.3:1.5-1.6 (n=5). Segment VIII 2.6-2.8 (n=5) and segment VII 2.3-2.5 times as wide as long (n=4). Lateral setae of segments II-VII long; lateral setae 1-4 of segment III 110-160; 118-170; -- 130-163; 100µm long (n=5).
Anal segment: Anal lobe ratio 1.3-1.5 (n=5). Each anal lobe with 3 macrosetae; length macrosetae 0.7-0.8x lobe length (n=5).
(Linked adult male: Langton and Pinder, 2003a)

Species keys out at Page 581: Diamesinae 57 Diamesa of the Text Key.

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

Ecological notes
Cool streams.