Heteragrion gracile Machado, 2006

(Figs. 37a–d)

[Key locator: Key to Group A species, couplet 17 (15’)]

Heteragrion gracile: Machado 2006: 1065 (description and diagnosis of ♁; figs. 3, 7, 11, 15–16);— Garrison et al. 2010: 88 (list of Heteragrion species);— Lencioni 2013: 9–10 (information on types, distribution, diagnosis; figs. 16, 31a–c, 52c, 74);— Lencioni 2017: 147–148 (general taxonomic information; distribution; figs. 71–72);—Ávila-Jr. et al. 2021: 3 (list of species for Rio das Velhas, Minas Gerais state).

Material examined. 1♁ (HOLOTYPE) BRAZIL, Minas Gerais state, Carmo do Rio Claro, 15.ix.1984, J. Augusto leg., ABMM (abdomen placed in a diferent envelope); 1 ♁ Espírito Santo State, Reserva Biológica Augusto Ruschi, 21.xii.2001, K.S. Furieri leg., FAAL .

Known distribution. Brazil (states of Minas Gerais, Espírito Santo and São Paulo).

Diagnosis and remarks. The following character combination distinguishes this species from the remainder of Group A species: ML with two parallel ridges on its medial space (unique to the genus, Fig. 37d), plus an additional basal ridge (Fig. 37c); ML apex undulate (Figs. 37c–d).