Acanthostichus kirbyi

Mackay (1996) - This is one of the most widely distributed, commonly collected species in the genus.This species has been collected with termites. They capture termites and act like Eciton sp. the termites escape in circular files (Willink. per. comm.). Brown (1975) gives a description of the foraging behavior of A. kirbyi. He and Karol Lenko found a column at midday raiding a termite nest on the floor of the forest near Benjamin Constant. The column moved mostly beneath leaf litter and collected a cache of dead termites beneath a piece of bark. A column led from the cache to a crevice in the ground under the roots of a tree, but they could not reach the nest. They saw about 50 workers which they estimated to be only a small part of the column. The workers moved rapidly and reminded them of army ants by the way they walked and moved their antennae.

Identification
Mackay (1996) - This species is closely related to Acanthostichus serratulus, but can be distinguished by the well developed lateral teeth on the clypeus (poorly developed in A. serratulus), in addition to other characteristics including a more quadrate head in A. serratulus (sides almost parallel), the petiole of A. serratulus is parallel sided and somewhat concave anteriorly, that of A. kirbyi is wider posteriorly and not noticeably concave, the dorsum of the petiole of A. serratulus is somewhat smoother than that of A. kirbyi (which is lightly punctate and roughened) and the sides of the petiole of A. serratulus have well developed carinae that are lacking in A. kirbyi. It differs from Acanthostichus brevicornis in that the posterior femur is rarely incrassate and that the dorsum of the petiole is roughened and often has longitudinal troughs. It differs from Acanthostichus quadratus and Acanthostichus lattkei in that the node of the petiole is longer than broad (Fig. 24) and the longitudinal troughs are not as deep and the sides are not parallel as they are in these other two species. The clypeus is narrower and the two lateral teeth are usually well developed, but only somewhat developed in A. quadratus and A. lattkei. This species is often misidentified in collections. For example, Kusnezov identified it as A. brevicornis (based on figures in his revision (1962), and specimens #8926 and #9142 in the USNM and IMLA, collected primarily by Kusnezov and with his identification labels). The male is similar to that of A. serratulus, but can be distinguished by the shape of the petiole (see A. serratulus discussion).

Distribution based on Regional Taxon Lists
Neotropical Region: Argentina, Bolivia, Brazil, Paraguay, Peru.

Nomenclature

 *  kirbyi. Acanthostichus kirbyi Emery, 1895j: 751, fig. OO.B (w.) PARAGUAY. See also: Mackay, 1996: 155.

Worker
Mackay (1996) - HL 1.05-1.41, HW 0.83-1.30, SL 0.48-0.68, SW 0.19-0.28. WL 1.26-1.93. PW 0.39-0.55, PL 0.45-0.69. FL 0.70-1.10, FW 0.26-0.39, SI 45-49, CI 79-92, PI 116-128, FI 2.64-2.84, SL/SW 2.41-2.53. Median and lateral clypeal teeth well developed; mandible often with small denticles on masticatory border (especially in larger workers); promesonotal suture poorly marked; petiole longer than wide. subpetiolar process consisting of a large lobe, usually with a posteriorly directed tooth.

Type Material
Mackay (1996) - Worker (Fig. 00B), BRAZIL: Mato Grosso [seen]. Lectotype worker (here designated), (MCSN) [seen], one probable cotype worker, Mato Grosso, Germain; Typus; Acanthosnchus kirbyi Em. Part of type series from Paraguay not found and apparently lost.