Pheidole soritis

In eastern Colorado, Gregg (1963) found P. soritis under rocks in the clay soil of cottonwood-willow woodland and shortgrass prairie, from 1000 to 1300 m. I encountered it near Datil, New Mexico, in open juniper woodland (Wilson 1957). A nuptial flight was observed in progress following rainfall on 9 August in an abandoned homesite clearing. The swarms of flying ants, which held resolutely to the clearings, consisted mostly of males. The aggregations were roughly circular in shape and hovered from about half a meter to nearly 2 meters above the surface, depending on wind conditions. Winged queens flew into the swarms and were quickly seized by a male, whereupon the pair spiraled to the ground together. After insemination, the queens shed their wings and ran off over the ground, evidently in search of a nest site. (Wilson 2003)

Identification
The major of this species is small (total length about 2 1/2 mm), the scapes expand about 1/2 way to the posterior lateral corners, the anterior 1/2 of the head is covered with fine, longitudinal rugae, the posterior half is roughly sculptured with longitudinal and transverse striae, the tops of the posterior lateral lobes have transverse striae. The humeral angles and lateral connules are poorly developed. The anterior part of pronotum is predominantly glossy, the posterior part is covered with transverse, but fine striae. The minor worker is a small black ant, in which most of the dorsum of the head is smooth and glossy, the side and top of the pronotum are smooth and glossy, the remainder of the mesosoma punctate. The hairs on the dorsum of the mesosoma are blunt tipped, but not clavate. The minors in our samples show considerable variation in the sculpturing of the head, and in the pronotal rugae, and some of them would key to Pheidole sitarches. (Mackay and Mackay 2002)

Also see the description in the nomenclature section.

Distribution
Mississippi west to Colorado, Texas, Arizona, and northern Mexico. (Wilson 2003)

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

98

Worker
Minor

Nomenclature

 * rufescens. Pheidole sitarches subsp. rufescens Wheeler, W.M. 1908e: 443 (s.w.q.) U.S.A. Junior synonym of campestris: Creighton, 1950a: 189; of soritis: Cole, 1953e: 298; of campestris: Gregg, 1959: 30. [Although both Creighton and Gregg give campestris as the senior name, rufescens has priority: Bolton, 1995b: 329.] Subspecies of sitarches: Bolton, 1995b: 329. Junior synonym of soritis: Wilson, 2003: 598.
 * sitarches. Pheidole sitarches Wheeler, W.M. 1908e: 440 (s.w.q.) U.S.A. Senior synonym of transvarians: Creighton, 1950a: 189; Gregg, 1959: 30. Junior synonym of soritis: Wilson, 2003: 598.
 *  soritis. Pheidole soritis Wheeler, W.M. 1908e: 439 (s.w.) U.S.A. Subspecies of sitarches: Creighton, 1950a: 190. Revived status as species: Cole, 1953e: 298. Junior synonym of sitarches: Cole, 1956c: 115. Revived from synonymy as subspecies of sitarches: Gregg, 1959: 30; Smith, D.R. 1979: 1373. Revived status as species and senior synonym of campestris, rufescens, sitarches, transvarians: Wilson, 2003: 598.
 * transvarians. Pheidole sitarches var. transvarians Wheeler, W.M. 1908e: 442 (s.w.) U.S.A. Junior synonym of sitarches: Creighton, 1950a: 189; Gregg, 1959: 30; of soritis: Wilson, 2003: 598.
 * campestris. Pheidole sitarches subsp. campestris Creighton, 1950a: 189 (s.w.) U.S.A. [First available use of Pheidole sitarches subsp. rufescens var. campestris Wheeler, W.M. 1908e: 443; unavailable name.] Taber & Cokendolpher, 1988: 95 (k.). Junior synonym of soritis: Cole, 1953e: 298. Revived from synonymy as subspecies of sitarches: Cole, 1956c: 115 (footnote); Gregg, 1959: 30. Synonym of rufescens: Creighton, 1950a: 189; Gregg, 1959: 30. [Both references give campestris as senior synonym, but rufescens has priority and is the first available name for this taxon: Bolton, 1995b: 318.] Junior synonym of soritis: Wilson, 2003: 598.

Type Material
NEW MEXICO: Albuquerque. and - as reported in Wilson (2003)

Description
From Wilson (2003): DIAGNOSIS A member of the “pilifera complex” of the larger pilifera group, comprising Pheidole calens, Pheidole californica, Pheidole carrolli, Pheidole cavigenis, Pheidole clementensis, Pheidole creightoni, Pheidole hoplitica, Pheidole littoralis, Pheidole micula, Pheidole pilifera, Pheidole polymorpha, Pheidole rugulosa, Pheidole senex, Pheidole soritis, Pheidole tepicana and Pheidole torosa, which complex is distinguished by the following traits. Major: dorsal head surface extensively sculptured; occipital lobe transversely rugulose (or, in carrolli smooth, in littoralis foveate, and in micula and soritis carinulate); postpetiole from above diamond-shaped, trapezoidal, or spinose. Minor: eye medium-sized to large.

P. soritis is distinguished within this complex by the following combination of traits.

Major: extensive transverse carinulae of occiput curve laterally and forward, with many reaching the anterior border of the head capsule; almost entire dorsal surface of head, including clypeus, carinulate; rugulae lacking on head; humerus low and smoothly convex; postpetiole seen from above laterally angulate; small denticle present on anterior ventral surface of postpetiole in side view.

Minor: dorsal profile of promesonotum lined solely with evenly spaced pairs of clavate hairs; similar hairs occur on the waist; eye very large. The tangled infraspecific nomenclature of this species has been built mostly on variation in the sculpturing of the minor’s head. From central Texas north and west, the posterior dorsal surface is foveolate and opaque (subsp. rufescens = subsp. campestris). To the south, into Mexico, it is smooth and shiny, as illustrated here (subsp. sitarches). Westward to Arizona and Utah it is carinulate (typical soritis). Whether this variation is truly geographic within a single species or reflects the existence of sibling species around sitarches sensu str., is a question that awaits closer field and museum research.

MEASUREMENTS (mm) Lectotype soritis major: HW 1.16, HL 1.22, SL 0.60, EL 0.20, PW 0.52. Syntype sitarches minor (no type soritis minors available): HW 0.46, HL 0.50, SL 0.48, EL 0.12, PW 0.30.

COLOR Major: head and appendages light reddish brown, body a slightly contrasting medium reddish brown.

Minor: body plain light brown, appendages brownish yellow.



'''Figure. Upper: syntype major of synonymous sitarches. Lower: syntype minor of synonymous sitarches. Scale bars = 1 mm.'''

Etymology
Unknown