The red imported ant can be misidentified as the similar-looking "S. richteri". The two species can be distinguished from each other through morphological examinations of the head, thorax, and postpetiole. In "S. richteri", the sides of the head are broadly elliptical and the cordate shape seen in the red imported fire ant is absent. The region of the occipital lobes that are situated nearby the midline and occipital excision appear more crease-like in "S. richteri" than it does in the red imported fire ant. The scapes of "S. richteri" are longer than they are in the red imported fire ant, and the pronotum has strong angulate shoulders. Such character is almost absent in the red imported fire ant. A shallow but sunken area is only known in the larger workers of "S. richteri", which is located in the posterior region of the dorsum of the pronotum. This feature is completely absent in larger red imported fire ant workers. The red imported fire ant's promesonotum is strongly convex, whereas this feature is weakly convex in "S. richteri". Upon examination, the base of the propodeum is elongated and straight in "S. richteri", while convex and shorter in the red imported fire ant. It also has a wide postpetiole with either straight or diverging sides. The postpetiole in "S. richteri" is narrower with converging sides. In "S. richteri", the transverse impression on the posterodorsal portion of the postpetiole is strong, but weak or absent in the red imported fire ant. As well as that, "S. richteri" workers are 15% larger than red imported fire ant workers, are blackish-brown, and have a yellow stripe on the dorsal side of the gaster.