Acanthostichus species groups

The information below is based on Mackay, W.P. 1996. A revision of the ant genus Acanthostichus. Sociobiology 27:129-179..

brevicornis species complex

Head elongate; frontal carinae closely placed, exposing basal condyle and base of scape; anterior face of scape convex, rarely slightly concave and with angle near apex present or absent; masticatory border of mandible without teeth, (except at apex) or with a single tooth (A. punctiscapus and A. arizonensis); lateral and medial clypeal teeth not developed; petiole often somewhat elongate, wider posteriorly than anteriorly, usually with strongly concave anterior face, subpetiolar process consisting of a broadly rounded lobe, rudimentary in A. arizonensis and consisting of a ventrally directed, sharp tooth in A. punctiscapus. The femur is often incrassate, at least in the larger workers. Not strongly polymorphic as in members of the serratulus species complex. The females of this species complex are unknown. The males can be distinguished from those of the other species complexes as the petiole is subquadrate (at least in two species) and the teeth of the subgenital process are long and thin.

serratulus species complex

Frontal carinae wide, covering at least part of the basal condyle and often part of the base of scape; anterior face of scape concave with well defined angle near apex; masticatory border of mandible without teeth, or occasionally with several small denticles; petiole usually subquadrate (or slightly longer than broad) with weakly concave anterior face; subpetiolar process consisting of a large lobe which is sharply angulate (with a posteriorly directed tooth) or truncate ventrally; femur is never incrassate (except occasionally in smaller workers); workers are strongly polymorphic, smallest workers often bearing little resemblance to larger workers, and appearing in some ways similar to those of the brevicornis species complex. The females of two of the species are subdichthadiiform; the others are unknown. The males of this species complex can be distinguished as the petiole is elongated, much longer than broad.

texanus species complex

Large species with relatively well developed eyes; no median tooth on mandibles; hind femora not incrassated; petiole elongated, wider posteriorly; ventral process of petiole angulate posteriorly. Acanthostichus texanus and A. emmae are the only known members of the complex and are the only species known to have winged females. The male of A. texanusis similar to that of other species in most respects, although the genitalia are quite different (see A. texanus).