Linepithema iniquum
Diagnosis of worker among Antkey species. Antenna 12-segmented. Antennal scape length less than 1.5x head length. Eyes medium to large (greater than 6 facets); do not break outline of head; placed distinctly below midline of face. Antennal sockets and posterior clypeal margin separated by a distance less than the minimum width of antennal scape. Anterior clypeal margin variously produced, but never with one median and two lateral rounded projections. Mandible lacking distinct basal angle. Profile of mesosomal dorsum with three distinct convexities. Dorsum of mesosoma lacking a deep and broad concavity; lacking erect hairs. Promesonotum separated from propodeum by metanotal groove. Propodeum with dorsal surface not distinctly shorter than posterior face; globular, strongly and uniformly convex. Propodeum and petiolar node both lacking a pair of short teeth. Mesopleura and metapleural bulla lacking pubescence; surface glabrous. Propodeal spiracle distinctly anterior to posterior margin of propodeal profile. Waist 1-segmented. Petiole upright and not appearing flattened. Gaster armed with ventral slit. Erect hairs present on cephalic dorsum (above eye level), gastral tergites 1 and 2; often present on pronotum. Dull, not shining, and color uniformly light to dark brown. Measurements: head length (HL) 0.55–0.74 mm, head width (HW) 0.46–0.70 mm.
Among the species treated here, Linepithema iniquum is most easily confused with the Argentine Ant, L. humile. It can be separated from that species by the following characters: (1) the mesopleura and metapleural bulla lack pubescence and have a glabrous (versus dull) surface; (2) erect hairs are present (versus lacking) on cephalic dorsum (above eye level), gastral tergites 1 and 2, and often present on pronotum; (3) the profile of mesosomal dorsum has three (versus two) distinct convexities; (4) the propodeum is globular (versus angular) and is strongly and uniformly convex (versus with flat or weakly convex dorsal and posterior faces); and (5) the propodeal spiracle is distinctly anterior to (versus bordering) the posterior margin of propodeal profile.
Linepithema humile