Key to Females of Mesoleptobasis

1. Pronotum with projections (as in Fig. 4 a; Fig. 5 d) ............................................................................................. 2

1'. Pronotum lacking projections, its posterior margin slightly bi-or trilobate (Figs. 5 a, b, e, f) .................................... 3

2. Pronotal projections in dorsal view with a common stem and apices directed dorso-laterally (Fig. 5 d); Guyana and Saramacca and Marowijne Districts in Surinam (Fig. 21) ............................................................ M. cyanolineata

2'. Pronotal projections in dorsal view with no common stem, acuminate apices directed laterally (as in Fig. 4 a); Rondônia State in Brazil ............................................................................ M. sp. ( M. acuminata sensu Santos, 1961)

3. Costal side of FW pt shorter than basal side, its posterior margin convex (Fig. 12 a); posterior lobe of pronotum trilobate with medial lobe smoothly convex and extending posteriorly beyond level of lateral lobes (Fig. 5 a); Amazonian region of Peru (Fig. 21) ........................................................................................................ M. acuminata

3'. Costal side of FW pt subequal to longer than basal side, its posterior margin slightly convex (Figs. 12 b, 13b–c); posterior lobe of pronotum bi- or trilobate, in the latter case medial lobe reaching same level as lateral lobes posteriorly (Figs. 5 b, c, e–g).............................................................................................................................................. 4

4. FW CuA ending one or two cells proximal to vein descending from subnodus (Fig. 13 b); Para District in Surinam and Amazonas State in Brazil (Fig. 21) ............................................................................................. M. elongata

4'. FW CuA ending at or one or two cells distal to vein descending from subnodus (Fig. 12 b, 13c) ............................ 5

5. Middle lobe of hind margin of prothorax bent anteriorly (Figs. 5 f, g); ovipositor surpassing tip of cerci for a distance shorter than length of cerci (Fig. 16 e); Amazonas State in Venezuela and Amazonas and Rondônia States in Brazil (Fig. 21) ............................................................................................................................................... M. incus

5'. Middle lobe of hind margin of prothorax not bent anteriorly (Figs. 5 b, c); ovipositor surpassing tip of cerci for a distance subequal to length of cerci (Fig. 16 b); Amazonas and Rondônia States in Brazil (Fig. 21) .............. M. cantralli