Heptageniidae of the World: Part II. Key to the Genera

Larval Diagnosis

Larvae of Leucrocuta can be distinguished from all other Ecdyonurinae genera except Ecdyogymnurus by the combination of having fimbriate setae on the ventral surface of the maxillae (as inFig. 51) and no interfacing setae on the caudal filaments (Fig. 101). Leucrocuta is Nearctic, and Ecdyogymnurus is Palearctic. Additionally, mature male larvae of Leucrocuta have widely separated eyes, whereas those of male Ecdyogymnurus are separated by a distance less than the width of the median ocellus. The presence of black spotting on the head capsule of Leucrocuta larvae is not a good characteristic for separating Leucrocuta from Nixe as nearly all North American Nixe have black spotting on the head capsule, although it is generally not as well developed as it in Leucrocuta, and larvae of some Leucrocuta lack the black spots.

Adult Diagnosis

The combination of the presence of ventral spines (as in Fig. 144) and large dorsolateral projections on the penes (Fig. 160, as in Fig. 146) and eyes separated by a distince much greater than the width of the medial ocellus will distinguish males of Leucrocuta. Females of all species except L. umbratica (McDunnough) differ from other North American Ecdyonurinae by having dark staining around the crossveins of the forewings (Fig. 184). Although we have not examined specimens, females of L. umbratica should differ from those of other Ecdyonurinae by having hyaline abdominal terga with large, very dark sublateral markings and black crossveins in the forewings.

Distribution

Nearctic (Fig. 231).

Figures