Solenopsis xyloni
Solenopsis xyloni is native to North America and is not introduced or commonly intercepted. It is included in the Antkey classification because it is difficult to differentiate from S. geminata and to a lesser extent S. invicta.
Diagnosis of worker among Antkey species. Worker caste polymorphic. Total length > 2 mm. Head ovoid (minors) to rectangular (majors). Antenna 10-segmented. Antennal club 2-segmented. Antennal scapes not conspicuously short; easily extended beyond eye level. Antennal insertions at least partly covered by frontal lobes; not surrounded by a raised sharp-edged ridge. Antennal scrobe lacking. Posterolateral corners of head unarmed, without spines. Eyes medium to large (greater than 5 facets); distinctly less than half head length. Frontal lobes do not obscure face outline between mandible and eye. Anterior margin of clypeus with two lateral teeth but lacking median tooth. Mandibles triangular. Pronotal spines absent. Propodeum lacking spines or teeth. Petiole with peduncle; subpetiolar process well developed as a flange or lobe. Shiny yellowish to brownish red.
Solenopsis xyloni is easily separated from S. papuana by the polymorphic worker caste, the greater size (TL > 2.0 mm), and by the larger eye (> 5 facets). It is most reliably separated from S. invicta and S. richteri by the absence of a median tooth between the two lateral teeth on the anterior margin of the clypeus. This character is often difficult to see, and it is best to examine a moderate sample of specimens of different sizes before a confident determination can be made. Solenopsis xyloni is most easily distinguished from S. geminata, by the presence of a well-developed subpetiolar process that forms a flange or lobe.
