Nylanderia flavipes (Smith, F. 1874)

Diagnosis of worker among Antkey species. Worker caste monomorphic. Antenna 12-segmented. Antennal club indistinct. Antennal scape length less than 1.5x head length. Antennal scapes with less than 10 erect hairs. Eyes medium to large (greater than 6 facets); do not break outline of head. Three ocelli usually present. Posteromedian portion of head densely covered in pubescence, such that the space between hairs is often less than the length of the hairs. Dorsum of mesosoma with weakly impressed metanotal groove, but never with a deep and broad concavity; shiny with sparse pubescence that rarely overlaps. Propodeum and petiolar node both lacking a pair of short teeth. Propodeum lacking posteriorly projecting protrusion. Mesopleuron shiny, not dulled by dense pubescence (less than 25 hairs). Metapleuron with a distinct gland orifice. Middle and hind coxae same color as mesosoma, not a strongly contrasting pale white. Waist 1-segmented (may be hidden by gaster). Petiole upright and not appearing flattened. Gaster armed with acidopore. Distinct constriction not visible between abdominal segments 3+4. Gaster (especially first segment) with sparse pilosity, giving it a shiny appearance. Hairs long thick and produced in pairs. Macrosetae on mesosoma of moderate length, thick and stout, weakly tapering to a blunt tip. Body color shiny reddish brown, first gastral segment often lighter than remaining segments.

Among other introduced and commonly intercepted Nylanderia species, N. flavipes can be distinguished from N. bourbonica, N. fulva and N. steinhelli by its shinier appearance caused by sparse pubescence, which is especially noticeable on the mesosomal dorsum, mesopleuron and first gastral segment. It can be separated from N. guatemalensis and N. vaga by the antennal scapes, which have less than 10 erect hairs. Nylanderia flavipes can be separated from N. vividula (and its nearly identical and native North American relative, N. terricola) by the posteromedian portion of head which is densely covered in pubescence, such that the space between hairs is often less than the length of the hairs, the presence of three ocelli, and the first gastral segment which is usually a more pale yellow than the remaining segments.