The following key to Australian Diacamma is based on Shattuck (2008).
- Dorsal surfaces of pronotum and head with at most very fine, indistinct sculpturing (Northern Territory) => Diacamma leve
- Dorsal surfaces of pronotum and head with distinct rugae (Queensland) => 2
- First gastral tergite with distinct arched rugae; the dorsal spines relatively widely spaced; anterior face of petiolar node shorter than dorsal face and separated from it by a distinct angle => Diacamma australe
- First gastral tergite weakly and indistinctly sculptured; the dorsal spines relatively narrowly spaced; anterior and dorsal faces of petiolar node similar in length and separated by a broad, rounded angle (however dorsal face longer in some northern samples) => 3
- Smaller species (head length less than 2.8 mm, mesosomal length less than 4.1 mm); entire mandible (except along mandibular teeth) finely striate, occasionally with small scattered fovea (north of Townsville) => Diacamma schoedli
- Larger species (head length greater than 2.8 mm, mesosomal length greater than 4.1 mm); anterior region of mandible mainly smooth, basal region weakly striate, elongate fovea present on entire surface (south of MacKay) => Diacamma colosseense