Contribution to the taxonomy of Eastern North American Epeorus Eaton (Ephemeroptera: Heptageniidae) Author Webb, J. M. Author Mccafferty, W. P. text Zootaxa 2006 1128 57 64 journal article 10.5281/zenodo.171850 76959d8e-e37e-487d-a58b-19a89411f4a5 1175­5326 171850 Key to known larvae of the eastern north American vitreus species group 1. Lamellae of first pair of gills each with large anterior expansion, usually meeting or nearly meeting ventrally ( Fig. 11 ) [lamellae of gills 1 of E. namatus only slightly expanded anteriorly ( Fig. 12 )]; subdorsal setae on femora pectinate; maxillae with more than one seta at base of apical tooth complex ( Fig. 14 ); dorsal projection at apex of femora blunt; lamellae of gills 7 usually with longitudinal fold................................. ................................................................................................ E. pleuralis species group ­ Lamellae of first pair of gills cordate, not expanded anteriorly ( Fig. 9 ); subdorsal setae of femora simple; maxillae with single fimbriate seta at base of apical tooth complex; dorsal projection at apices of femora blunt or sharp; lamellae of gills 7 usually without longitudinal fold .................................................................... E. vitreus species group, 2 2. Dorsal (outer) posterolateral projections of abdomen distinctly longer than ventral projections ( Fig. 13 ) .............................................................................................. E. vitreus ­ Dorsal (outer) posterolateral projections of abdomen subequal to or only slightly longer than ventral posterolateral projections ( Fig. 8 ) ................................................. 3 3. Abdominal terga each with small but distinct median protuberance on posterior margin, increasing in size posteriorly; head distinctly wider anteriorly ( Fig. 15 ) and nearly uniform brown; gills 7 with longitudinal fold .................................................. E. dispar ­ Abdominal terga without posterior median protuberances or terga 2 or 3–7 each with small median protuberance, decreasing in size posteriorly; head subrectangular ( Fig. 1 ), with four large pale markings; gills 7 without longitudinal fold ............................ 4 4. Dorsal projection at apex of hind femur sharply pointed ( Fig. 16 ); pronotum with small pair of tubercles ( Fig. 17 ); mature larvae>8.0 mm long ................ E. subpallidus ­ Dorsal projection at apex of hind femur bluntly pointed ( Fig. 7 ); pronotum without pair of small tubercles; mature larvae 6.0–8.0 mm long ............................. E. punctatus