Pheidole tysoni

In New York, Stefan Cover (unpublished field notes) encountered colonies of P. tysoni in pure sandy soil of the Suffolk Co. pine barrens; in New York City itself, he found a colony in the clayey soil of a residential lawn. In southern Arizona, he encountered the species in open woodlands variously composed of combinations of oak and juniper, usually with a grassy cover; nests were usually in the shade, either under stones or in open soil with or without craters of excavated earth. The soil varied from loam to fine sand. A nest Cover found in the Davis Mts. of Texas was beneath a stone in open oak-juniper-pinyon woodland. In Hale Co., Texas, Moody and Francke (1982) found a colony in the open ground of a vacant lot, the entrance surrounded by a 55-mm-wide tumulus of excavated soil.

It is found in open areas such as fields, prairies, edges of cotton fields, open wooded areas in parks (somewhat xeric), open upland hardwood forests, on ridges in deciduous or mixed hardwood/pine forests with slightly sandy soils (fine sand), loess, sandy or cherty parts of glades, generally on poor soils, drier prairies, cedar glades, and similar habitats (Joe MacGown, James C. Trager). It is often found near Crematogaster minutissima missuriensis.

According to Cover, seeds are occasionally found in the nest, and workers tend aphids and collect floral nectar on low, herbaceous plants. (Wilson 2003)

Identification
See the description in the nomenclature section.

The minor workers are indeed very small. In fact, at first glance you might think they were thief ants.

Distribution
Pheidole tysoni appears to have a disjunct distribution. I have seen material from New York south to extreme northwest Georgia (Clayton, Rabun Co.) and westward through Tennessee and Kentucky to Barry Co., Kentucky. Stefan Cover has collected it in the Davis Mts. of western Texas at 1800 m, and at 1400–1800 m in the mountains of southern Arizona. Moody and Francke (1982) record a single colony found at 950 m in Hale Co., western Texas. Single series are recorded from near Juárez, Chihuahua, Mexico, and New Liberia, Louisiana, by William MacKay. The latter two records are somewhat anomalous in view of the otherwise montane and cool-temperate range of the species. (Wilson 2003)

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

Biology


Pheidole tysoni, the smallest species (major 2mm, minor 1.4mm) of the genus in the eastern USA, feeding on a scarab larva (James Trager).

Nomenclature

 *  tysoni. Pheidole tysoni Forel, 1901e: 348 (s.w.m.) U.S.A. See also: Wilson, 2003: 528.

From Wilson (2003): DIAGNOSIS A medium-sized yellow member of the flavens group distinguished by the nearly complete absence of sculpturing on the body, except for longitudinal carinulae on the anterior half of the head capsule of the major and minor, short and faint carinulae on the humerus of the major, and small patches of foveolae on the waist (major) or propodeal dorsum (minor). Propodeal spine short and suberect in both castes. Postpetiolar node of major broad and oval. Vertex of major (center of dorsum of head) with a faint circular brown spot.

Similar to Pheidole amabilis, Pheidole boliviana, Pheidole melastomae, Pheidole mixteca, Pheidole scitula, and especially Pheidole terresi'' of Hispaniola. Most easily distinguished from the often sympatric Pheidole bicarinata by the absence of sculpture on the sides of the propodeum in the minor. In bicarinata minors these are foveolate.

MEASUREMENTS (mm) Major (figured specimen above): HW 0.94, HL 1.10, SL 0.44, EL 0.12, PW 0.48.Minor (figured specimen above): HW 0.44, HL 0.48, SL 0.42, EL 0.06, PW 0.28.

COLOR Major and minor: concolorous clear medium yellow.

Minor head with a slightly reddish tinge.



'''Figure. Upper: major. Lower: minor. TENNESSEE: Great Smoky Mountains National Park. Scale bars = 1 mm.'''

Type Material
Base of Mt. Mitchell, North Carolina, col. Auguste Forel. - as reported in Wilson (2003)

Etymology
Named after “M. Tyson,” whose farm was near the type locality. (Wilson 2003)