Acanthostichus skwarrae

Wheeler found the single known specimen, the worker holotype, running on the ground.

Identification
Mackay (1996) - Acanthostichus skwarrae is presently represented by a poorly preserved, headless lectotype worker. Fortunately good distinguishing characteristics are present on the specimen which allow recognition of the taxon as a valid species. It is obviously a member of the brevicornis species complex, as the petiole is elongate (PL = 0.44 mm, PW = 0.35 mm) and wider posteriorly (Fig. 39). It is strongly concave anteriorly and the subpetiolar process is formed into a large, rounded lobe (Fig. 40). The hind femur is moderately thickened (FL = 0.58, FW = 0.26). It is easily separated from most other species in the complex by the shape of the petiole (wider posteriorly than anteriorly), the large subpetiolar process (Fig. 40) and the smooth dorsum of the petiole. It is closely related to Acanthostichus quirozi, differing as it has very few erect hairs on the surfaces.

Key to Acanthostichus workers

Distribution based on Regional Taxon Lists
Neotropical Region: Mexico.

Nomenclature

 *  skwarrae. Acanthostichus skwarrae Wheeler, W.M. 1934g: 161 (w.) MEXICO. See also: Mackay, 1996: 167.

Description
Length about 4.2 mm.

Small and slender, resembling A. brevicornis Emery. Head similar, but somewhat shorter, though distinctly longer than broad, very slightly broader in front than behind, posterior border broadly excised, posterior angles narrow as in brevicornis, but the frontal carinae thicker and longer, extending as far back as the middle of the head. Antennae very much like those of brevicornis, scapes not reaching the median transverse diameter of the head, three and one-half times as broad as long, abruptly narrower at the base. Mandibles broad, with blunt tips, differing from those of all the other described species of the genus in having the external borders distinctly concave, instead of convex. Thorax very narrow, broader in front than behind, distinctly constricted laterally in the mesoepinotal region, less flattened dorsally than in brevicornis, kirbyi, serratulus and quadratus. Base of epinotum longer than broad and longer than the steeply sloping declivity, with somewhat rounded sides. Humeral angles and margination on the sides of the thorax rather blunt, less distinct even than in brevicornis. Petiolar node from above nearly one and one-half times as long as broad, narrowed anteriorly, its straight sides, and the anterior border especially, bluntly marginate. Postpetiole also trapezoidal, longer than broad, much narrower in front than behind, its sides straight, its ventral portion very convex and protruding. as in the other species. Gastric segments narrow. Legs stout, their femora and tibire distinctly incrassated.

Smooth and shining; dorsal surface of head, especially laterally, anterior and lateral borders of thoracic segments, anterior border of petiole and dorsal surface of postpetiole and gaster with a few large, very sparse, elongate, piligerous punctures or foveolae. Neck, epinotal declivity and anterior surface of petiolar node subopaque, punctate-rugulose, the rugules on the declivity and petiolar node longitudinal and radiating upward. Legs, especially the tibiae, with numerous small piligerous punctures.

Hairs pale yellowish, erect, very sparse and not very long on the body, shorter and more oblique on the legs; dense and numerous on the extensor surfaces of the middle and hind tibiae.

Head and thorax reddish castaneous; abdomen paler; legs yellow; clypeus dark brown; antenna> slightly paler than the head; tips of funiculi pale yellowish.

Type Material
A single specimen (No. 34) from Tamarindo, State of Vera Cruz, found running on the ground.

Mackay (1996) - Mexico, Veracruz. There are at least 17 localities named Tamarindo in Mexico, of which at least 4 are located in the state of Veracruz. Holotype worker (here designated) [seen] 234/SK; 3 - iv -29, Tamarindo (Ver.); MCZ Cotype 1,20335; (Type); Gift of W. M. Wheeler [headless].