Diamesa hamaticornis

Author: Kieffer, 1924

Diagnosis (n=2, unless stated otherwise, material in coll. ZSM)
Exuviae 4.5, 6.2mm long.
Cephalothorax: Frontal setae 280µm long (n=1). Thoracic horn 233, 500µm long; ThR 18, 29. Precorneal setae1-3: 60; 205, 263; 130, 200µm long. Thorax granulate.
Abdomen: Armament of tergite II consists 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 10µm long. Rarely less than 7 teeth in tooth row of tergite II; tergites VI and VII each with 4-10 teeth. Total dorsal teeth II-VIII 46, 50. Best developed dorsal teeth brownish-gold, triangular, widening suddenly where it joins the distinct golden basal mound; best developed ventral teeth awl-shaped, gold. Total ventral teeth IV-VII/VIII 35, 72. Teeth of posterior rows of segments V-VII more numerous ventrally than dorsally. Relative length segments IX:VIII:VII = 1.0:0.55, 0.58:0.87, 0.98; relative width segments IX:VIII:VII = 1.0:1.24, 1.4:1.4, 1.5. Segment VIII very short: 3.4, 3.5 times as wide as long. Segment VII 2.2, 2.6 times as wide as long. Lateral setae of segments II-VII long; lateral setae 1-4 of segment III 120, 145; 110, 150; -- 143, 150; 75, 90µm long.
Note: Pale golden to golden yellow; tergites laterally brown, smudged inwards irregularly; anterior corners of tergites distinctly darkened. Anterior transverse apodeme well-developed, golden-brown. Teeth 60µm long.
Anal segment: Anal lobe ratio 1.2, 1.4. Each anal lobe with 3 macrosetae; length macrosetae 0.7x lobe length. (032b.jpg)

Species keys out at Page 577: Diamesinae 53 Diamesa of the Text Key.

SW-C Europe and NW Africa.
(For more information see module IdentifyIt – file: Other subfamilies).

Ecological notes
Montane streams above 500m asl.