Key to species of Messoracarus

1. Mesogynal shield absent or hidden by latigynal shields........................................................ 2

- Mesogynal shield present, but weakly developed............................. Leptantennus pendulipes (Berlese, 1916)

2. Posterior margin of idiosoma concave, shaped like an inverted heart; margins of metapodal shields with setae................................................................................. Messoracarus emarginatus (Banks, 1916)

- Posterior margin of idiosoma flat to slightly convex, subcircular in shape; margins of metapodal shields without setae...... 3

3. Ventral posteromarginal plate divided, forming two small plates immediately behind the ventrianal shield that are free from the lateral elements of the marginal shield....................................... Messoracarus mirandus Silvestri, 1912

- Ventral posteromarginal plate entire, forming a single plate immediately behind the ventrianal shield that is fused posteriorly to the lateral elements of the marginal shield.................................... Messoracarus schwendingeri sp. nov.