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Natural History: I have long suspected the small, yellowish P. tysoni lives a mainly subterranean existence, perhaps cultivating subterranean aphids or mealy bugs, and one observation in a sandy prairie in southwest Missouri supports this latter part. It has also been captured in buried, meat-baited traps in a sandy prairie in southwestern Missouri. On the other hand, Stefan Cover (in Wilson, 2003) reports it foraging and tending aphids above ground in Arizona.
types Mus. Hist. Nat. Geneve.
Etymology Named after "M. Tyson," whose farm was near the type locality.
Diagnosis A medium-sized yellow member of the flavensHNS 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 amabilisHNS, bolivianaHNS, melastomaeHNS, mixtecaHNS, scitulaHNS, and especially terresiHNS of Hispaniola. Most easily distinguished from the often sympatric Pheidole bicarinataHNS by the absence of sculpture on the sides of the propodeum in the minor. In bicarinataHNS 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.
Range P. tysoniHNS 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 Juarez, Chihuahua, Mexico, and New
Liberia, Louisiana, by William MacKay. The latter two records are somewhat anomalous in view of the otherwise montane and cooltemperate range of the species.
Biology In New York, Stefan Cover (unpublished field notes) encountered colonies of tysoniHNS in pure sandy soil of the Suffolk Co. pine barrens; in New York City, itself, he found a colony in the clayey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. According to Cover, seeds are occasionally found in the nest, and workers tend aphids and collect floral nectar on low, herbaceous plants.
FIGURE Upper: major. Lower: minor. TENNESSEE: Great Smoky Mountains National Park. (Type locality: at base of Mt. Mitchell, North Carolina, collected by Auguste Forel.) Scale bars = 1 mm.
Found most commonly in these habitats: 1 times found in riparian juniper woodland, 1 times found in city park, grass, sparse trees, 1 times found in pine/Yucca woodland, 1 times found in Kochia- elm- yucca, 1 times found in Mixed hardwood forest, 1 times found in on rock creek, 1 times found in city park, creosote mesquite.
Found most commonly in these microhabitats: 1 times nest in grass clump, 2 times at bait, 1 times in lawn near buildings and parking area, 1 times under stone, 1 times from malaise trap, 1 times roadside nest, 1 times on lawn.
Collected most commonly using these methods: 2 times search, 2 times bait, 1 times at bait.
Elevations: collected from 110 - 2420 meters, 1272 meters average