Acanthostichus

In this Neotropical genus there are 22 valid extant species and one fossil species from Dominican amber.

Identification
The genus Acanthostichus is a member of the subfamily Cerapachyinae, which is a monophyletic group and should be considered distinct from subfamily Ponerinae. Acanthostichus can be defined by two synapomorphies in the workers and females: the presence of a metatibial gland, and the malar groove present below the eye. The functions of these two structures are unknown, and the groove has apparently been secondary lost in the female of A. quadratus. Males also possess the malar groove, although it is difficult to see in some species as the distance between the base of the mandible and the eye may be very short.

This genus can be separated from the closely related Cerapachys (which also has denticles on the pygidium of the worker) as it has a 12 segmented antenna (11 segmented in Cerapachys). (Mackay and Mackay 2002)

Biology
These subterranean ants are seldom collected and are presumed termite predators although some species may be predators on Pogonomyrmex and other ants. Mackay and Mackay (2002) stated, in the context of the North American ant fauna: collections of this genus are extremely rare, due to the subterranean habits of colonies. Males of this genus are commonly collected at lights in the tropics; males of North American species are either very rare or are not attracted to lights. The males and females are known for only one of the species that occurs in the United States: Acanthostichus texanus.

Nomenclature
The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants. Barry continually updates his Catalogue and thus the following information reflects an up-to-date accounting of ant taxonomy. We are indebted to Barry for making this information available.

Genus ACANTHOSTICHUS Acanthostichus Mayr, 1887: 549. Type-species: Typhlopone serratula, by monotypy. Taxonomic history Acanthostichus in Ponerinae: Dalla Torre, 1893: 16. Acanthostichus in Ponerinae, Cerapachyini: Forel, 1893a: 162; Forel, 1895b: 116; Wheeler, W.M. 1910g: 136 [subtribe Acanthostichini]. Acanthostichus in Dorylinae, Cerapachyini: Emery, 1895j: 765 [Cerapachyi]. Acanthostichus in Dorylinae, Acanthostichini: Emery, 1901a: 34. Acanthostichus in Dorylidae, Acanthostichinae: Ashmead, 1905b: 382; Ashmead, 1906: 29. Acanthostichus in Ponerinae, Acanthostichini: Emery, 1911d: 12; Forel, 1917: 239; Gallardo, 1918b: 7; Donisthorpe, 1943f: 619; Brown, 1975: 41; Dlussky & Fedoseeva, 1988: 79; Hölldobler & Wilson, 1990: 10. Acanthostichus in Cerapachyinae, Acanthostichini: Wheeler, W.M. 1902d: 184; Wheeler, W.M. 1922a: 640; Kempf, 1972a: 10; Bolton, 1990a: 67; Bolton, 1990c: 1357; Jaffe, 1993: 9; Bolton, 1994: 19; Bolton, 2003: 137.

Junior synonym of ACANTHOSTICHUS Ctenopyga Ashmead, 1906: 29. Type-species: Ctenopyga townsendi (junior synonym of Acanthostichus texanus), by original designation. Taxonomic history [Ctenopyga Ashmead, 1905b: 382 nomen nudum] Ctenopyga in Dorylidae, Acanthostichinae: Ashmead, 1906: 29. Ctenopyga in Ponerinae, Acanthostichini: Brown, 1975: 42; Hölldobler & Wilson, 1990: 10. Ctenopyga in Cerapachyinae, Acanthostichini: Bolton, 1990a: 67. Ctenopyga as subgenus of Acanthostichus: Emery, 1911d: 13; Forel, 1917: 239; Wheeler, W.M. 1922a: 640; Creighton, 1950a: 58. Ctenopyga as genus: Ashmead, 1906: 29; Brown, 1975: 42; Smith, D.R. 1979: 1333; Hölldobler & Wilson, 1990: 10; Bolton, 1990a: 67; Bolton, 1990c: 1357. Ctenopyga as junior synonym of Acanthostichus: Brown, 1973b: 179 [provisional]; Snelling, R.R. 1981: 389; Bolton, 1994: 19; Mackay, 1996: 132; Bolton, 2003: 138.

Additional References
MacKay, W.P. 1996. A revision of the ant genus Acanthostichus. Sociobiology 27: 129-179. 

Dalla Torre, 1893: 16 (catalogue); Emery, 1911d: 12 (diagnosis, catalogue); Emery, 1911d: 13 (A. (Ctenopyga) diagnosis, catalogue); Gallardo, 1918b: 8 (Argentina species key); Wheeler, W.M. 1922a: 640 (genera, key); Wheeler, W.M. 1934g: 162 (species key); Kusnezov, 1962a: 125 (species key); Kempf, 1972a: 10 (Neotropical catalogue); Brown, 1975: 39 (diagnosis, review of tribe and genus); Brown, 1975: 42 (review of Ctenopyga); Bolton, 1990a: 58 (abdominal morphology); Brandão, 1991: 322 (catalogue); Bolton, 1995a: 1047 (census); Bolton, 1995b: 54 (catalogue); Mackay, 1996: 129 (diagnosis, all species revision, key); Mackay & Mackay, 2002: 35 (U.S.A., New Mexico species key); Bolton, 2003: 33, 137 (diagnosis, synopsis).