Acanthostichus are subterranean, predaceous ants that are infrequently collected. Numerous species are only known from a single collection and/or from a single caste (worker, queen or male).
A few species have been found in association with termites or Pogonomyrmex ant colonies. The Acanthostichus were either directly preying upon or presumably raiding these other social insects.
> Acanthostichus Mayr, 1887: 549 [[ worker ]] [[ male ]]. Type: Acanthostichus serratulus
(= Typhlopone serratulus F. Smith ), monobasic.
> Acanthostichus : Emery, 1895 a: 748 - 752; pl. 14, fig. 5 a-d; pl. 16, fig. 5, 6; pl. 17, fig. 12, 13; [[ worker ]] [[ queen ]] [[ male ]]; 3 n. spp. described. ----- Emery, 1899: 4, pl. 2, fig. 5 a-d, larva. ----- G. C. Wheeler, 1950: 109, fig. 2, larva.
> Acanthostichus subgenus Acanthostichus : Emery, 1911: 13, pl. 1, fig. 4, 4 b, 5, [[ worker ]] [[ queen ]] [[ male ]] diagnoses, species list.
> Acanthostichus : Bruch, 1925: 110 - 114, pl., [[ worker ]] [[ male ]] larva, pupa. ----- Bruch, 1934. [[ worker ]] [[ queen ]] [[ male ]].
= Acanthostichus (s. str.): Kusnezov, 1962, synopsis. ----- Kempf, 1964 b, critique of Kusnezov synopsis. = Acanthostichus : Kempf, 1972: 10, species list. [[ ... ]] Typhlopone : F. Smith, 1858: 111, [[ worker ]].
The worker, queen, and male are characterized above under the tribe.
bionomics: The species of Acanthostichus , so far as known, are termite hunters. In keeping with the dichthadiiform queen known for some species, the behavior and raiding organization is very army-ant-like in at least some of the tropical forms. Karol Lenko and I found a column at midday raiding a termite nest in the floor of the forest near Benjamin Constant in Brasilian Amazonas. These were robust, dark brown ants of an undetermined species. The column moved mostly beneath the leaf litter and had made a substantial cache of dead worker termites beneath a piece of bark lying on the ground. From the cache, a column led to a crevice in the ground under the roots of a tree, and we could not reach the nest. We saw more than 50 workers, which were probably only a small part of the column. The workers move rapidly and remind one of army ants by the way they walk and use their antennae.
distribution: South America east of the Andes and south into northern Argentina; one doubtful species, skwarrae , in southern Mexico.
species-level taxonomy: Kusnezov (1962) gave a review of Acanthostichus with rather full notes on the biology of some species, a discussion of the taxonomy of certain forms, and a key to the species modified from an earlier one by Wheeler (1934: 162). Kusnezov's paper was published in Spanish in a journal not readily available to many potential users, but even so, I have not attempted to translate or revise the key here. In the first place, a later paper by Kempf (1964) criticized the Kusnezov review for accepting too readily the Wheeler key and the taxonomy on which it was based. Kempf also pointed out that some of Kusnezov's locality records were based on misdeterminations, and that a variety was doubtfully synonymized. Kempf himself did not attempt a revision of the genus because, as he, Kusnezov, Creighton, and others have all declared, the systematics of this group can only be clarified by the study of new material and the critical reexamination of the types of F. Smith, Emery, and Forel. In his Catalogo, Kempf (1972) listed the species of Acanthostichus s. str., excluding Ctenopyga because it came from outside the neotropical area proper.
I find that there is little I can do at this time to further the revision of Acanthostichus . Both Kempf and I have obtained a little more material during recent years, and I have been able to examine the types of A. serratulus and A. kirbyi and to compare them with other material, so that digms are available to the next reviser. But the considerable variation in color, sculpture, and size in the worker samples in collections is great enough to demand that still more material be gathered. The clarification of the species-level taxonomy probably will depend on the association of all the worker forms with their males, since the male genitalia seem to have good characters.
The one important revisionary move I feel should be made now is the separation of Ctenopyga from Acanthostichus . This is explained below under the Ctenopyga generic heading.
Acanthostichus is a predatory and predominantly subterranean genus of ant in the subfamily Dorylinae.[2][3] They are found in the New World, from the southern United States to Uruguay, Paraguay and northern Argentina.[4] They are probably common, but due to their subterranean nature, they are seldom collected or seen.[5]
Most species are very similar; the petiole is the most important feature in identifying species. Many are known only from a few collections, or even single specimen, which makes it hard to determine variability within species. For this reason, many described members of this genus may be synonyms.[5]
The genus currently contains 24 species:
Acanthostichus is a predatory and predominantly subterranean genus of ant in the subfamily Dorylinae. They are found in the New World, from the southern United States to Uruguay, Paraguay and northern Argentina. They are probably common, but due to their subterranean nature, they are seldom collected or seen.
Most species are very similar; the petiole is the most important feature in identifying species. Many are known only from a few collections, or even single specimen, which makes it hard to determine variability within species. For this reason, many described members of this genus may be synonyms.
