Key to Typhlomyrmex workers (modified from Brown, 1965)

1. Clypeal dome with anterior face vertical or subvertical (head in side view); mandible shape elongated­subtriangular, their basal margins weakly convex, not reaching the anterior clypeal margin at full closure; anterior face of mesotibia with about 10 denticuliform erect setae......................................................................... 2

– Clypeal dome with anterior face sharply inclined posteriorly (head in side view); mandible shape triangular, their basal margins rectilinear or weakly concave, fitting tightly against clypeus at full closure; anterior face of mesotibia without denticuliform setae ...................................................................................................... 3

2. Antennae 12­segmented; clypeal margin straight and totally concealed by the clypeal dome in dorsal view ....................................................... T. clavicornis Emery

– Antennae 10­segmented; clypeal margin weakly convex medially and only partially concealed by the clypeal dome in dorsal view ........................ T. meire n. sp.

3. Petiole well pedunculate in lateral view; node poorly developed, longer than high, subconvex at its top and without a distinct posterior face; abdominal tergite III without obvious anterior face; size polymorphism marked ...... T. rogenhoferi Mayr

– Petiole weakly pedunculate in lateral view; node well developed, higher than long, well rounded at its top and with a distinct posterior face; abdominal tergite III with a distinct anterior face; monomorphic ................................................................... 4

4. Metafemora base (posterior view) sharply swollen ventrally, so that it forms a short vertical face at the base, joining the ventral face by an obtuse and rounded angle; head width> 0.55 mm ........................................................ T. major Santschi

– Metafemora base (posterior view) poorly swollen ventrally, so that it does not form an angle at its base; head width <0.55 mm .......................... T. pusillus Emery