Key to the species of Hebridae from Argentina

(Modified from Konopko et al. 2009)

1- Antenna with segments robust and thick (Fig.7); segment IV subequal in length to segment I.......... Merragata hebroides

- Antenna with segments slender; segment IV longer than segment I (Figs. 4, 8)..................................... 2

2- Antennal segment IV without constriction (Fig. 8); male with a subapical spine on the posterior surface of the hind tibia..................................................................................... Lipogomphus lacuniferus

- Antennal IV segment with a constriction in the middle (false membranous articulation), so that the antenna appears to possess five segments (Fig. 4); male lacking a subapical spine on the posterior surface of the hind tibia ( Hebrus)................ 3

3- Body length approximately 3.00 mm; bucculae brownish, ventrally straight and subsequently slightly concave; clavus marked on each side with a small, basal, whitish spot adjacent to metanotal elevation and without pale spots on the membrane (Fig. 9). Metanotal elevation with lateral and hind margins carinate, with prominent median carina sharply obliquely narrowed on sides along apical two-fifths..................................................................... Hebrus engaeus

- Body length between 1.84 and 1.95 mm; bucculae yellowish, ventrally curved, posteriorly conical and slightly elevated; clavus with a pearl-white marking from the base until almost to the apex of the metanotal elevation (3/4 distance) and four distinct whitish spots on the membrane (Figs. 1, 2). Metanotal elevation with raised edges and strong, straight median carina, flanked by two submedial depressions....................................................... Hebrus alvearensis sp. nov.