(Figs. 18a–d)
[Key locator: Key to Group A species, couplet 25’]
Heteragrion brianmayi: Lencioni 2013: 15–16 (description of ♁ and ♀ from São Paulo state, Brazil; diagnosis, distribution and comparison with other species; figs. 27, 38d–f, 43a–c, 49a–b, 58b–c, 66–67, 76); Ávila-Jr. et al. 2017: 284 (comparison with H. cauei);— Lencioni 2017: 133–134 (general taxonomic information; distribution; figs. 60–61).
Material examined. 1♁ (HOLOTYPE) BRAZIL, São Paulo state, Caraguatatuba, Parque Estadual da Serra do Mar —Núcleo Caraguatatuba, 5.ii.2000, (-23.5933, -45.4186, 61 m asl), F.A.A. Lencioni leg., FAAL; 1♁ (PARATYPE) Ubatuba, 12.i.2011, F.A.A. Lencioni leg., FAAL.
Known distribution. Brazil (coastal areas of São Paulo state).
Diagnosis and remarks. The IUCN Red List has classified H. brianmayi as Data Deficient due to a paucity of information on its distribution and potential threats (Vilela & Guillermo-Ferreira 2021b). The species is close to H. itacolomii and can be distinguished from this and the remainder of Group A species by the following combination of characteristics: BP ventral concavity not greatly expanded (Figs. 18c–d); ML upper plate narrow, longer than wide, ridge centered (Fig. 18d).