Epeorus Eaton 1881

Key to mature nymphs in Sapporo City and adjacent areas 1 Gill I anteriorly enlarged (Figs 16e, 17e, 24d, 25e); gill VII with longitudinal fold (Figs 17g, 25g); pronotum slightly projecting laterally (Figs 29b, d)................................................................................. 2 - Gill I not anteriorly enlarged (Figs 6d, 7e, 11d, 21d, 22e); gill VII without longitudinal fold (Figs 7h, 22g); pronotum roundly projecting laterally (Figs 29a, c)......................................................................... 3 2 Gill I strongly enlarged and meet at beneath mesothorax (Figs 15b, e, 16e, 17e); posterior margin of abdominal terga with sharp denticles (Figs 17j, 31c).................................................................. E. (C.) curvatulus - Gill I slightly enlarged and not meet at beneath mesothorax (Figs 23b, e, 24d, 25e); posterior margin of abdominal terga with blunt denticles (Figs 25j, 31e)................................................................ E. (I.) aesculus 3 Gills with dark-violet spots (Figs 6d, 11d); gills II–VII with anal proximal projections (Figs 6d, 11d); posterior margin of abdominal terga with sharp denticles (Figs 7k, 12g, 31a, b).................................................... 4 - Gills without dark-violet spots (Fig. 21d); gills II–VII with anal ribs (Fig. 21d); posterior margin of abdominal terga with blunt denticles (Figs 22j, 31d).................................................................. E. (P.) nipponicus 4 Outer margin of inner incisor of the left mandible with sharp serration (Fig. 7c)....................... E. (B.) latifolium - Outer margin of inner incisor of the left mandible without sharp serration (Figs 12c, f).................. E. (B.) L-nigrum Key to male imagines in Sapporo City and adjacent areas 1 Black markings on the base of veins of the forewing (Figs 8e, 13e, 18e).......................................... 2 - No markings on the base of veins of the forewing (Fig. 26e)................................................... 3 2 Penis with titillators (Figs 13f, 18f)....................................................................... 4 - Penis without titillators (Fig. 8f)............................................................. E. (B.) latifolium 3 Forceps base without projection, penis laterally expanded with spines (Fig. 26f)........................ E. (I.) aesculus - Forceps base with projection, penis laterally expanded without spines (following Ma et al. 2021: p. 1149, figs 12c, 13c).......................................................................................... E. (P.) nipponicus 4 Posterior margin of styliger plate triangular edged (Fig. 13f)....................................... E. (B.) L-nigrum - Posterior margin of styliger plate rounded (Fig. 18f)............................................ E. (C.) curvatulus