Diamesa sp.

Namayandeh, Armin, Bilyj, Bohdan, Beresford, David V., Somers, Keith M. & Dillon, Peter J., 2012, 3324, Zootaxa 3324, pp. 1-65 : 14

Diamesa sp.

Figs 8A–F

Diagnosis. Head ( Fig. 8A) yellow-brown, posterior margin brownish. Labrum as in Fig. 8B, SI seta simple; SIII seta bifid; labral lamella with about 20 hooked spines, flanked by dentate plate; pecten epipharyngis with 5 fingerlike scales fused at the base; premandible ( Fig. 8C) with 6 teeth and branched lateral spine; antenna ( Fig. 8D) 5- segmented, 3 rd segment annulated, AR 1.9; mandible ( Fig. 8E) with thin apical tooth and 4 inner teeth, seta subdentalis reduced; mentum ( Fig. 8F) evenly arched with 19 teeth, median tooth about 1.5 as wide as 1 st lateral tooth; VM plate reduced; procercus indistinct, 4 apical setae plus 1 basolateral seta.

Notes. The larva keys to Diamesa sp. B in Epler (2001). It may in fact be the common eastern species Diamesa nivoriunda (Fitch) , although it has a characteristic dark brown head.

Ecology and habitat. Reported by Ward (1994), Diamesa larvae are the dominant Chironomidae species in cold upper reaches of alpine streams and spring brooks. In this study Diamesa was collected in cold intermittent headwater streams (mean monthly temperature ≤16°C).

Sampling sites. Killarney, Arrowhead and Algonquin Provincial Parks and Parry Sound District.

Nearctic distribution. Canada: Ontario.