Asthenopus

Molineri, Carlos, Cruz, Paulo Vilela & Emmerich, Daniel, 2011, A new species of Asthenopus (Ephemeroptera: Polymitarcyidae: Asthenopodinae) from Brazil and Colombia, Zootaxa 2750, pp. 33-38 : 37

Key to the male imagos of Asthenopus

1 Fore legs 0.73 × or less the length of forewings; penes broad at base, sometimes narrowing apically.................... 2

- Fore legs 0.8 × or more the length of forewings; penes slender from base to apex................................... 3

2(1) Fore legs of male 0.50–0.55 × the length of forewings; marginal intercalary veins of fore wings usually as long as or longer than distance between longitudinal veins..................................................... Asthenopus gilliesi

- Fore legs of male 0.60–0.73 × the length of forewings; marginal intercalary veins of fore wings usually shorter than distance between longitudinal veins................................................................ Asthenopus curtus

3(1) Medium sized species (forewing 12 mm); penes without apical crenulations........................ Asthenopus pictecti

- Small species (forewing 7.5–8.6 mm); penes with subapical crenulations......................... Asthenopus crenulatus