Pheidole soritis Wheeler

Wilson, E. O., 2003, Pheidole in the New World. A dominant, hyperdiverse ant genus., Cambridge, MA: Harvard University Press : 598-599

Pheidole soritis Wheeler

Pheidole soritis Wheeler 1908h: 439. Syn.: Pheidole sitarches Wheeler 1908h: 440, n. syn. (see history of earlier synonymy and revival in Bolton 1995b: 330); Pheidole sitarches var. transvarians Wheeler 1908h: 442, synonymy by Creighton 1950a: 189; Pheidole sitarches subsp. rufescens Wheeler 1908h: 443, n. syn. (name takes precedence over campestris Wheeler , see below and Bolton 1995b: 318, 329).; Pheidole sitarches subsp. campestris Creighton 1950a: 189, n. syn. (first available name of Pheidole sitarches subsp. rufescens var. campestris Wheeler 1908h: 443, a quadrinomial not available for use; see further nomenclatural details in Bolton 1995b: 318, 329). Raised to species level in this monograph: cavigenis .

Types Mus. Comp. Zool. Harvard; Amer. Mus. Nat. Hist.

Etymology Unknown.

diagnosis A member of the " pilifera complex" of the larger pilifera group, comprising calens , californica , carrolli , cavigenis , clementensis , creightoni , hoplitica , littoralis , micula , pilifera , polymorpha , rugulosa , senex , soritis , tepicana , and 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.

Range Mississippi west to Colorado, Texas, Arizona, and northern Mexico.

Biology 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 1957c). 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.

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