Cyphomyrmex wheeleri

Unusual for the genus in its preference for arid habitats.

Identification
Kempf (1966) - C. wheeleri is closest to Cyphomyrmex costatus. Following are the main differences for the worker caste: Larger size (cf. measurements); body very sharply reticulate-punctate throughout; anterior clypeal border scarcely notched; carinae on vertex weak; postocular carina sharp, the supraocular tubercle lying below the carina; eyes larger with more facets; midpronotal denticles present; antero-inferior pronotal and epinotal teeth acute; petiole with a pair of postero-dorsal teeth; tergum I of gaster without four strongly raised longitudinal costae.

Identification Keys including this Taxon

 * Key to US Cyphomyrmex workers

Distribution
United States: known from California, Arizona and Texas. Mexico: Durango.

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



Habitat
Arid environments, desert shrublands and grasslands.

Biology
Mackay and Mackay (2002) - This species nests in the soil or under stones in creosote bush scrub. Nests consist of a few dozen workers and a single queen. Fungal gardens can be located a few centimeters under the soil surface in small chambers a few centimeters in diameter. Workers forage primarily at night or on moderately warm days in the spring and fall. They move slowly and feign death and are thus difficult to see. These ants are most commonly collected under stones or in pitfall traps. Males are attracted to lights.

Kempf (1966) reported:

C. wheeleri is more xerophilous than most species of the genus. According to Wheeler (1907: 765-8), whose field studies were made in the vicinity of Austin, it occurs only in arid regions. Nests were found principally on the higher and drier terraces of limestone hills, although a few nests were also discovered in the hard, pebbly soil of open wood at lower altitudes.

The hillside nests are invariably under large stones, which cover both horizontal and vertical galleries (the latter descending into the ground to a depth of 10-15 cm). One of the horizontal galleries communicates with the exterior at the edge of the stone. The entrance is sometimes marked by a small crater. The sessile fungus garden, having the size of pecan nut, is found at a particular widened portion of either the horizontal or the vertical galleries. The garden presents a flocculent appearance, and consists of small slivers of vegetable debris (probably entire sections of stems of herbaceous plants) bound together by the snow white mycelium. Skeletal parts of dead insects, principally fragments of coleopterous elytra, have been found inside the garden; they were probably added to the structure in order to give it consistency. The ants attach the refuse as a flat mass to the undersurface of the stone, or more rarely dump it outside the entrance.

The woodland nests were marked by craters of earth crumbs, around a small, circular opening of a vertical gallery, descending to appreciable depth into the soil. Wheeler was unable to unearth the fungus garden.

The colonies usually do not comprise more than a few dozen workers with a single queen. Their activity seems to be mainly nocturnal. Sexual forms appear in the nests ready for nuptial flight from early to late in June. As all other species of the present genus, the worker move slowly and "feign death" at the least disturbance.

Nomenclature

 *  wheeleri. Cyphomyrmex wheeleri Forel, 1900e: 282 (w.q.) U.S.A. Wheeler, W.M. 1907c: 726 (m.). See also: Kempf, 1966: 167.

Worker
Kempf (1966) - Total length 2.8-3.4 mm; head length 0.71-0.85 mm; head width 0.62-0.72 mm; thorax length 0.83-1.06 mm; hind femur length 0.64-0.78 mm. Light yellowish-brown; older specimens also darker. Integument very sharply reticulate-punctate, opaque. Mandibles and funiculi more superficially sculptured and somewhat shining.

Head (fig 7). Anterior apron of clypeus flattened, only vestigially notched on convex anterior border; lateral teeth, next to origin of frontal lobes, small and almost hidden by the latter. Frontal lobes elongate-rounded and flat, covering cheeks in full-face view. Frontal carinae moderately diverging caudad, straight. Occipital corners lobate, prominent, longitudinally carinate. Paired carinae on vertex feeble, short, scarcely diverging cephalad. Preocular carina fading out above eyes, not curving mesad. Postocular carina extending foreward from lateral face of occipital lobe, becoming obsolete just in front of posterior orbit of eyes, closing completely the antennal scrobe. Supraocular tumulus dentiform, situated below the postocular carina. Inferior border of sides of head carinate on posterior half. Eyes with 8-10 facets across greatest diameter. Scape strikingly attenuate at base, strongly incrassate apicad, not projecting beyond antennal scrobe. Funicular segments III-IX about as broad as long, I and X longer than broad.

Thorax (fig 25). Pronotum with a pair of small denticles on disc, the latter laterally marginate between the marked humeral angle and the strong lateral pronotal tooth; antero-inferior corner acutely dentate. Mesonotum forming a shallowly impressed oval disc, the borders of which are flanked by the pair of anterior and posterior carinate welts; the anterior pair separated from the posterior pair by a small impression. Mesoepinotal suture distinct on bottom of broadly and deeply impressed mesoepinotal groove. Basal face of epinotum transversely shallowly concave, sides somewhat diverging caudad, bordered by carinae, which become foliaceous in front of the compressed, lamellate, acute, epinotal tooth; infradental lamellae low, bordering the upper half of the declivous face. Epinotal spiracle small, situated on the vestigial oblique carinule. Femora, especiaIly hind femora, postero-ventrally crested and bearing on basal first a broader foliaceous lobe. Tibiae subprismatic.

Pedicel (fig 25, 37). Petiolar node trapezoidal in dorsal view, broadest just behind the obliquely truncate anterior corners, its dorsum flattened, oblique; posterior corners with a raised, strong tooth; posterior border likewise raised and lamelliform, connecting the teeth from base to tip. Postpetiole decidedly broader than long, its dorsum with a shaIlow median impression between a pair of low, longitudinal welts, the extremities of which are tumuliform. Posterior border moderately and evenly rounded. Gaster anteriorly truncate; tergum I with a short antero-median impression, its sides submarginate.

Pilosity scarce, inconspicuous, decumbent throughout; dorsum of head and gaster with small, whitish, scale-like hairs.

Queen
Wheeler (1907) - Length: 2.5-2.7 mm.

Very similar to the worker. Pronotum with prominent inferior and superior teeth, the former acute, the latter larger and blunt. Mesonotum prominent, flattened, with a faint median furrow anteriorly and a pair of broader Mayrian furrows. Scutellum with very broadly and faintly excised posterior border separating a pair of broad, acute teeth. Epinotum with the base convex and only about half as long as the abrupt concave declivity; spines similar to those of the worker but somewhat stouter.

Sculpture and pilosity as in the worker.

Color a little darker in old specimens. Wings opaque, infuscated; the membranes and veins in the anterobasal portion of both fore and hind wings fulvous.

Male
Wheeler (1907) - Length: 2.4-2.6 mm.

Head, without the mandibles and eyes, narrow, longer than broad, with straight posterior border. Mandibles like those of the worker but less distinctly denticulate. Frontal carinae with large, reflected lobes and strong, diverging posterior ridges reaching to the posterior corners where each terminates in a compressed, projecting tooth. Postorbital carinae absent. Antennae slender, scapes enlarged towards their tips which surpass the posterior corners of the head by about 1/3 of their length. Pronotum with indistinct inferior, but prominent and acute superior teeth. Mesonotum with distinct Mayrian furrows. Scutellum like that of the female, but with more deeply excised posterior border. Petiole and postpetiole like those of the worker and female. Gaster elliptical, convex above. Legs long and slender. Hind femora not angularly dilated below.

Opaque; very finely and densely punctate; gaster faintly shining or glossy.

Pilosity very similar to that of the worker and female.

Ferruginous; upper surface of head and the thoracic depressions blackish; basal segment of gaster dark brown above. Mandibles, antennae, legs and tip of gaster yellowish. Wings like those of the female.

Type Material
Kempf (1966) - Workers and a female collected by W. M. Wheeler in the environs of Austin, Texas, U.S.A.; three syntype or nidotype workers, received on exchange from the Museum of Comparative Zoology at Harvard College for my collection (WWK), were examined.