Form described by Langton, 1984
Diagnosis
Exuviae 3.8-4.9mm long (4.4mm, n=37).
Colour: Pale yellow. (This is possibly only a colour variety of Orthocladius obumbratus.)
Cephalothorax: Thoracic horn 290-405µm long (m=363µm, n=19), coarsely toothed; ThR 5.3-9.6 (m=7.7, n=13). Four dorsocentral setae, the first, third and fourth thick, the second conspicuously thinner.
Abdomen: Hook row II a discrete pad or band of hooks, less than 0.34x width of segment II, usually of three or more transverse rows of hooks. Median point patches of tergites III-V usually completely fused to the posterior band to form a single trapezoidal patch, the points of median and posterior bands of about the same size and form. Points of the median patches on tergites III-V obviously demarcated from the antero-lateral shagreen where there is a sudden drop in point size. Posterior transverse point band on tergite III not extending further laterally than the apical band. No granulation present on tergites and sternites. Pedes spurii B on segment II conspicuous. Conjunctives without brown blotches. Forked or branched setae rare and usually confined to the apical sternites.
Anal segment: Anal lobe ratio 1.5-1.8 (m=1.6, n=7). Anal lobes without fringe. Apical teeth of anal lobes usually brown, sturdy and often fused at base; occasionally colourless, but always present. Length of anal macrosetae 0.49-0.85x length of the anal lobe (m=0.63, n=12).
Form keys out at Page 872: Orthocladiinae 283 Orthocladius of the Text Key.
Distribution
(For more information see module IdentifyIt – file: Orthocladiinae).
Ecological notes
A stream in Scotland, a pond in England.