Orthocladius (Mesorthocladius) frigidus Zetterstedt, 1838 (Fig. 56)

This is a new morphotype, not listed in Brooks et al. (2007).

Head capsule brown with black occipital margin. Mentum with single median tooth and 6 pairs of lateral teeth, all black. Median and first lateral tooth rounded, median and first laterals are subequal. Seta submenti is located between the narrow ventromental plates, very close to them; 2 setal pores present above each other, a bigger anterior and smaller posterior. Outer margin of mandible crenulated.