Heterotrissocladius marcidus (Walker)

Namayandeh, Armin, Bilyj, Bohdan, Beresford, David V., Somers, Keith M. & Dillon, Peter J., 2012, 3324, Zootaxa 3324, pp. 1-65 : 30-31

Heterotrissocladius marcidus (Walker)

Figs 23A–C

Diagnosis. Head yellowish brown with contrasting dark brown submentum ( Fig. 23C). SI seta, pecten epipharyngis and antenna (see Fig. 23A) as described for H. changi , basal antennal segment 78–82 µm long; mentum ( Fig. 23B) with pair of median teeth; VM plates broad, V/M 1.3.

Notes. Keys out to couplet 10 in Saether (1975), ending as, either H. marcidus or H. latilaminus Saether. The characters given to separate the two species may not hold up given the range of variation in the pigmentation of the submentum and width of SSm setae (pers. observ.). In this case, the larvae inhabiting a lotic environment and its eastern locality favour H. marcidus as the most likely choice.

Ecology and habitat. The species is found in springs, streams, rivers and littoral zones of lakes, usually restricted to cold waters never exceeding 18°C throughout the year ( Saether 1975). We found the larvae in almost all headwater stream sites fed mainly by catchment.

Sampling sites. We found the larvae inhabiting streams in all the provincial parks and districts located in our study area.

Nearctic distribution. Canada: British Columbia, Ontario and Québec. USA: North and South Carolina, Michigan, New York State.