(Figs. 47a–e)
[Key locator: Key to Group B species, couplet 21’]
Heteragrion majus: Selys 1886: 62–63 (description of ♁ from Panama; comparison with H. aequatoriale);— Calvert 1901: 62–63 (remarks; fig. 6);— Calvert 1909: 108 (comparison with H. aequatoriale);— Ris 1918: 86–87 (additions to original description; description of ♀; comparison with H. erythrogastrum);— Williamson 1919: 35 (key to species, ♁ in couplet f1, ♀ in couplet d1; comparison with H. albifrons; figs. 42–43, 62, 67, 91–92, 106, 129–130, 156–157);— Paulson 1981: 303 (comparison of coloration patterns with other Heteragrion species);— Garrison et al. 2010: 88, 91 (list of Heteragrion species; fig. 395);— Garrison & von Ellenrieder 2013: 15, 23 (list of species from Costa Rica; fig. 20);— Ramírez & Gutiérrez-Fonseca 2013: 97–100 (description of F0 larvae; key to larvae known to Costa Rica, couplet 2);— Molinar et al. 2015: 87 (list of species from Panama).
Material examined. 1♁, 1♀ COSTA RICA, San Jose, Hacienda Zurqui, 16.viii.1979, (1500m asl), R.W. & J.A. Garrison leg., ABMM.
Known distribution. Costa Rica, Panama.
Diagnosis and remarks. The following character combination distinguishes this species from the remainder of Group B species: BP with a nearly straight margin, bearing no swelling or convexity (Figs. 47c–e); MP the shortest portion of cercus in length (Figs. 47c–e); ridge above ML formed by spaced and very strong teeth (Figs. 47c–e), 2–3 strong teeth on its apex (Fig. 47e); ML apex acute (Figs. 47c–e).