Heterotrissocladius grimshawi

Author: (Edwards, 1929)

Exuviae 4.0-5.3mm long (m=4.4mm, n=17).
Cephalothorax: Cephalic tubercles absent. Thoracic horn 360-405µm long (m=377µm, n=13), small-toothed; ThR 5.5-8.2 (m=6.6, n=12). Wing sheaths without pearl row.
Abdomen: Tergites without a median transverse row of strong points. Points on tergites recurrent for a short distance (gradually a little larger posteriorly) giving a streaked appearance (039i.jpg). Postero-lateral corner of segment VII rounded. Sternite of male armed with a posterior band of conspicuous points along the evenly curved posterior margin; of female with a pair of triangular projections, each stiffened with an embedded spine (039h.jpg). Pedes spurii B of segment II well-developed, much wider than high. Pedes spurii A present on segment VII, but may be composed of very small spinules. Three or four lateral setae on segments II-VI, not taeniate; 3 taeniae and 1 seta laterally on segment VII (the seta is the most posterior and is occasionally developed as a small taenia), 4 lateral taeniae on segment VIII.
Anal segment: Anal lobe ratio 1.5-1.8 (m=1.6, n=13). Fringe of anal lobe with 17-23 taeniae (m=21.2, n=17).
(Linked adult male: Langton and Pinder, 2003a)

Species keys out at Page 628: Orthocladiinae 40 Heterotrissocladius of the Text Key.

NW+C Europe.
(For more information see module IdentifyIt – file: Orthocladiinae).

Ecological notes
Northern and montane lakes and streams.