Acanthostichus punctiscapus

The type collection of A. punctiscapus was taken from a nest of Pogonomyrmex desertorum at a depth of 70cm in an area of Larrea tridentata (creosotebush) Chihauhuan Desert scrub. A second collection was of two workers taken at a termite trap. Little else is known about this species or its biology.

Identification
Workers this species are easily recognized by the densely punctate scapes and dorsal surfaces of the head (less so), mesosoma (more so), petiole and gaster (MacKay 1996). In other species these regions are smooth and with at most a very few scattered punctures.

Identification Keys including this Taxon
Key to US Acanthostichus species

Distribution
United States: New Mexico (type collection) and Arizona (Pima Co., Tucson, foothills of Santa Catalina Mts., CASENT0173204). Mexico.

Distribution based on Regional Taxon Lists
Nearctic Region: United States. Neotropical Region: Mexico.



Habitat
Only known from desert habitat: the type locality (New Mexico) was reported as "Larrea tridentata (creosotebush) Chihauhuan Desert scrub" and while a collection in Arizona was "50' from wash in disturbed desert."

Abundance
With only two collections of this subterranean species known it is difficult to assess its potential abundance. This ant may rare or rarely detected.

Biology
The type series was collected in a nest of Pogonomyrmex desertorum at a depth of 70 cm. Only part of the nest was collected and no queen was found.

Castes
Known only from the worker caste.

Nomenclature

 *  punctiscapus. Acanthostichus punctiscapus Mackay, W.P., 1996: 160, figs. 12, 30, 31 (w.) U. S. A.

Worker
Mandible with tooth on median masticatory border, with larger apical angle; sides of head parallel, occiput somewhat concave; femur somewhat incrassate, concave ventrally; petiole strongly narrowed anteriorly, with large, ventrally directed tooth. Most of ant with distinct, dense, small punctures, including mandibles, scapes, head, dorsum of mesosoma, petiole and gaster.

Measurements: HL 0.83-0.86, HW 0.70-0.74, SL 0.39-0.40, WL 1.18-1.24, PW 0.39-0.40, PL 0.44-0.48, SI 45-48, CI 83-86, PI 113-123.

Type Material
New Mexico, Dona Ana Co.: Jornada LTER [National Science Foundation Long Term Ecologicial Research] site, 45 Km NE Las Cruces, 1.6 Km W of College Ranch Headquarters, about 150 m south of Jornado Playa; 17 July 1985, D. Lightfoot and S. Van Vactor collectors. Holotype (MCZ) and 38 Paratypes (AMNH, BMNH, CACS, CWEM, EMAU, FMNH, FSCA, IMLA, INPA, LACM, MACN, MCSN, MCZ, MIZA, MZSP, UAIC, UNAM, USNM).

Etymology
Morphology. The name is a reference to the densely punctate scapes.