1. Anal prolegs each with free basoventral hook (Fig. 1.1). . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Anal prolegs without free basoventral hooks (Fig. 1.2). . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42. Anal claws without ventral teeth (Fig. 1.3). . . . . . . . . . . . . . . . . . . . . . . Rhyacophila minor
Anal claws with ventral teeth (Fig. 1.4). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Frontoclypeus with distinct dark "V" posteriorly; mandibles apically edentate (Fig. 1.5). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Rhyacophila torva
Frontoclypeus without distinct "V"; mandibles toothed apicaly (Fig. 1.6). Rhyacophila lobifera
4. Anal claws without ventral teeth (Fig. 1.7). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Anal claws with ventral teeth (Fig. 1.8). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5. Second segment of each maxillary palpus subequal to first (Fig. 1.9). Rhyacophila glaberrima
Second segment of each maxillary palpus longer than first. (Fig. 1.10). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Rhyacophila invaria Complex
6. Head with distinct pattern of infuscations and muscle scars (Fig. 1.11). . Rhyacophila fenestra or R. ledra (R. fenestra reported in south-western and south central Ohio; R. ledra is scattered throughtout the state)
Head completely or mostly concolorous (Fig. 1.12). . . . . . . . . . . . . . . . Rhyacophila carolina
Key to Rhyacophila Nymph Species
