Acanthostichus

Acanthostichus is a Neotropical genus that reaches the northern limit of its distribution in the southwestern USA and its southern limit in Paraguay, Uruguay and northern Argentina. There is also a single fossil species from Dominican amber. Suspected of being deeply subterranean, little is known of their habits. Specimens have been found under stones and wood, and collections have been made in association with nests of termites. These ants are rarely collected but may be much more common than their representative specimens suggest.

Identification
This genus is most likely to be confused with the closely related Cerapachys, which also has denticles on the pygidium of the worker. It can be distinguished by its 12-segmented antennae (11 segments in Cerapachys), the strongly flattened antennal scape and the lack of a prominent lateral carina bordering the antennal sockets.

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 Acanthostichus 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.

Identification Keys
Key to US Acanthostichus species

Species richness
Species richness by country based on regional taxon lists (countries with darker colours are more species-rich). View Data



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

 *  ACANTHOSTICHUS  [Dorylinae]
 * Acanthostichus Mayr, 1887: 549. Type-species: Typhlopone serratula, by monotypy.
 * Acanthostichus senior synonym of Ctenopyga: Mackay, 1996: 132.
 * CTENOPYGA [junior synonym of Acanthostichus]
 * Ctenopyga Ashmead, 1906: 29. Type-species: Ctenopyga townsendi (junior synonym of Acanthostichus texanus), by original designation.
 * [Ctenopyga Ashmead, 1905b: 382. Nomen nudum.]
 * Ctenopyga subgenus of Acanthostichus: Emery, 1911d: 13.
 * Ctenopyga revived status as genus: Brown, 1975: 42; Bolton, 1990a: 67; Bolton, 1990c: 1357.
 * Ctenopyga junior synonym of Acanthostichus: Snelling, R.R. 1981: 389; Bolton, 1994: 19; Mackay, 1996: 132.