Key to male Minagrion (adapted from Vilela et al. 2020)

1. Larger species (54–61 mm total length), abdomen 2x longer than Fw length........................ M. mecistogastrum

1’. Medium species (31–44 mm total length), abdomen less than 2x the length of Fw.................................. 2

2. Dorsal plate of cercus broad; ventrobasal portion only 1/5 of the cercus length; tubercle digit-like with a rounded apex..... 3

2’. Dorsal plate of cercus narrow; ventrobasal portion at least 1/2 of cercus length; tubercle never digit-like or with rounded apex ................................................................................................... 4

3. Cercus less forcipate, with ventral margin mostly linear (Figs. 4e, 5b).................................... M. waltheri

3’. Cercus markedly forcipate, with the ventral margin deeply concave (Figs. 4b, 5c).......................... M. veredae

4. Longitudinal ridge of cercus not entire (i.e., disrupted along its length) forming a basal and an apical ridge, more pronounced on the distal 1/2; sclerotized apex of cercus globose with no apparent teeth; tubercle quadrangular with a slightly concave apex......................................................................................... M. canaanense

4’. Longitudinal ridge of cercus entire (i.e., a continuous ridge along its length); sclerotized apex of cercus not globose, with evident teeth; tubercle not as above....................................................................... 5

5. Cercus shorter than S 10 in lateral view, and with acute sclerotized apex, with one strong tooth; tubercle triangular with acute apex........................................................................................ M. ribeiroi

5’. Cercus subequal in length to S 10 in lateral view, rounded sclerotized apex, with one strong tooth; dorsal portion of cercus broad at basal half, narrowing towards the base, ventrobasal portion roughly quadrangular, reaching 1/2 of cercus; tubercle quadrangular, with the excavated “beak-like” apex; genital ligula with a small inner fold at the flexure in lateral view, a pair of lateral sclerotized processes, and entire apex....................................................... M. caldense