1. Operculate gills with outer branch of underlying soft gill portion (found below the dorsal gill plate) with upper lobes subequal in size to lower lobes*; submentian spines on abdominal tergum spines 7 relatively narrowly spaced compared to midlength of tergum. . (Fig.1.1). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Eurylophella temporalis
Operculate gills with outer branch of underlying soft gill portion with upper lobes absent or highly reduced compared to lower lobes (Fig.1.2); submedian spines on abdominal tergum 7 relatively widely spaced compared to midlength of termum (Fig.1.3). . . . . . . . . . . . . . 2
2. Operculate gills with outer branch of underlying soft gill portion with two to five dorsal lobes (Fig.1 4). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Operculate gills with outer branch of underlying soft gill portion with no dorsal lobes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Body brown dorsally with only faint if any coontrasting color pattern and no speckling; submedian pairs of spines on terta 1-4 relatively elongate with space between spines of each pair progressively increasing from tergum 1 to tergum 4. . .Eurylophella funeralis
Body dorsally with some form of speckling or well-contrasting color patterning; submedian pairs of spines on terga 1-4 short and blunt, and more equally spread. . . . . . . . . . . . . . 4
4. Head with dorsal pair of tubercles small to absent (Fig.1.10); spines on abdominal terga 6 and 7 emerging from ridges at base (Fig.1.11). . . . . . . . . . . . . Eurylophella lutulenta
Head with dorsal pair of tubercles developed; spines on abdominal terga 6 and 7 with relatively flat base. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Eurolophella enoensis
5. Head with dorsal pair of tubercles developed; mature body length always greater than 6.5 mm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Eurylophella verisimilis
Head with dorsal pair of tubercles barely detectable in males and minute in females; mature body length variable. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
6. Space between submedian spines on abdominal tergum 5 distinctly greater than space between submedian spines on tergum 4. . . . . . . . . . . . . . . . . . . . Eurylophella bicolor
Space between submedian spines on abdominal tergum 5 subequal to space between submedian spines on tergum 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
7. Posterolateral projections somewhat developed on abdominal tergum 2; mature body (prevelent in spring emergence time) usually greater than 7.5 mm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Eurylophella macdunnoughi
Posterolateral projections not developed on tergum 2, represented by small angle only; mature body (prevalent during summer emergence time) always less than 7.5 mm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Eurylophella minimella
*position the nymph on the side; either lift the gill cover to see the operculate gills, or dissect out the gill cover with operculate gills and separate the latter from the former.
Key to Ohio Eurylophella Nymph Species
