Diagnosis of worker among Antkey species. Head shape triangular. Antenna 6-sgemented. Antennal club 2-segmented. Antennal scapes not conspicuously short; easily extended beyond eye level. Antennal insertions at least partly covered by frontal lobes. Eyes medium to large (greater than 5 facets); situated on lower margin of scrobe. Frontal lobes do not obscure face outline between mandible and eye. Posterolateral corners of head unarmed, without spines. Head lacking ventral notch anterior to eyes. Mandibles linear; armed with apical fork and 1 preapical tooth. Pronotal spines absent. Propodeum armed with spines or teeth. Waist 2-segmented. Postpetiole with distinct spongiform. Hairs on petiole, postpetiole and gaster spatulate. Appressed circular hairs do not cover face, mesosoma and waist segments.
Strumigenys silvestrii can be separated from other introduced and commonly intercepted Strumigenys species by the following combination of characters: (1) mandibles linear; (2) mandibles with apical fork and 1 preapical tooth; (3) head lacking ventral notch anterior to eyes; (4) hairs on petiole, postpetiole and gaster spatulate. Strumigenys silvestrii is similar to S. rogeri but can be separated by the 1 (versus 2) preapical tooth and the lack (verses presence) of a ventral notch anterior to the eyes.