Solenopsis whitfordi

The only sample of 'Solenopsis whitfordi'' was collected from an extraction of soil in a creosotebush shrubland area.

Identification
A New World thief ant that is a member of the pygmaea species complex.

Pacheco and Mackay (2013) – Worker - This is a minute, concolorous pale yellow species. The head is elongate with coarse cephalic punctures. The eye is minute and appears to have only one ommatidium. The lateral clypeal teeth are well developed and the extralateral teeth are weakly developed. It is moderately hairy with erect and suberect hairs of various lengths on all body surfaces.

This species may be confused Solenopsis ocellata. The greater number of longer hairs present on the first tergum of the gaster of S. ocellata is the distinguishing feature. Solenopsis ocellata has more than 20 erect hairs (many over 0.05 mm) on the first tergum of the gaster, separating it from S. whitfordi, which usually has fewer than 20 hairs between 0.03-0.04 mm in total length. Solenopsis ocellata can further be separated from S. whitfordi in being consistently larger in total length and having striae on the mesopleuron, a feature absent in S. whitfordi.

Distribution
Known only from the type locality, the Jomada Experimental Range in New Mexico (45K NE of Las Cruces).

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

Castes
Known only from the worker caste.

Nomenclature

 *  whitfordi. Solenopsis whitfordi Mackay, Moreno, & Pacheco, in Pacheco & Mackay, 2013: 359, figs. 359-361, map 85 (w.) U.S.A.

Worker
Measurements (n=2). TL 1.26; HL 0.360; HW 0.270-0.288 (0.279); EL 0.018; ED 0.012; SL 0.192-0.198 (0.195); FSL 0.072; CI 75.0-80.0 (77.5); SI 53.3-55.0 (54.2); PL 0.072; PW 0.090; PI 80.0; PPL 0.078; PPW 0.096; PPI 81.3; WL 0.240; PSL 0.012; PSW 0.012.

Head elongate, with abundant coarse punctures, larger than hairs that originate from them, thickened viewed laterally (~0.180 mm dorsally-ventrally), dorsal and ventral surfaces of head flat, sides of head straight, posterior border slightly concave; predominately yellow, darker mandibles; lateral clypeal teeth well developed, medial tooth absent, extralateral bumps poorly developed, scape extends slightly more than half length of head; eye clearly visible, usually light brown, one ommatidium; mesosoma very straight in profile, punctures on mesosoma and gaster similar, surfaces between punctures smooth and glossy; petiole as in other members of complex.

Short (~0.030 mm), erect hairs sparse on head; mesosoma with erect and suberect hairs (0.03 mm); suberect hairs (0.040 mm) on first tergum of gaster.

Type Material
Holotype worker and 3 paratype workers (, MCZC), United States, New Mexico, Dona Ana Co., Jomada Range, 415 m N of Las Cruces, 5-x-1983, W. Mackay #1312; same locality, ll-ix-1983, W. Mackay #1112 (5 workers CWEM).

Etymology
This species is named to honor of our close friend and colleague, Walter G. Whitford, who has published numerous papers on the ants of the southwest USA.