Key to species of the M. spicata species-group 1. Disc, rim and fringe of setae of upper and lower calypters white; anterior spiracle yellowish. Male with short posterior projections medially on ST5 (Fig. 245); epandrium, cerci and surstyli distinctive, as in Figs 27–28; female terminalia distinctive, as in Fig. 289.......................................................................... M. mexicana sp. nov. - Discs of upper and lower calypters light tan to brown with dark rim and brown fringe; anterior spiracle brown [M. spicata] or yellow [M. guaramacalensis]. Male with long projections medially on ST5 [M. spicata], [condition unknown in M. guaramacalensis]; female terminalia distinctive, Figs. 288, 290........................................................ 2 2 Anterior thoracic spiracle brown; T4 without marginal row of stout setae in both sexes; male with the rear margin of ST5 with pair of long projections midway (Figs. 12, 246); female T6 of RV shape................................... M. spicata - Anterior thoracic spiracle yellow; T4 with marginal row of stout setae; [condition of ST 5 in male unknown]; female terminalia distinctive; T6 of WU shape (Fig. 288).............................................. M. guaramacalensis sp. nov.

Published as part of Whitworth, Terry L. & Yusseff-Vanegas, Sohath, 2019, A revision of the genera and species of the Neotropical family Mesembrinellidae (Diptera: Oestroidea), pp. 1-146 in Zootaxa 4659 (1) on page 49, DOI: 10.11646/zootaxa.4659.1.1, http://zenodo.org/record/3377239