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Solenopsis pergandei Forel

Solenopsis pergandei, side view of a worker - MS specimen (click image to enlarge).
Solenopsis pergandei, full face view of a worker (click image to enlarge).
Photo courtesy of
Solenopsis pergandei, side view of a worker (click image to enlarge).
Photo courtesy of
Solenopsis pergandei queen - head
Solenopsis pergandei queen side view
Solenopsis pergandei, full face view of a queen - FL specimen (click image to enlarge).
Solenopsis pergandei, side view of a queen - FL specimen (click image to enlarge).
Solenopsis pergandei male - side view
Solenopsis pergandei, side view of a queen (click image to enlarge).
Photo courtesy of
Solenopsis pergandei, side view of a male - FL specimen (click image to enlarge).

The genus Solenopsis includes both the "fire ants", known for their aggressive nature and potent sting, and the minute "thief ants", many of which are lestobiotic subterranaen or arboreal species that are rarely collected. Many species may be polygynous.

Solenopsis pergandei is a relatively large, milky white colored, and relatively large species that appears to be confined to nesting in a variety of sand habitats int the Southeast.

Generic level identification of Solenopsis is relatively straight forward, although sizes are greatly variable ranging from approximately 1.0 mm to over 4.0 mm. The genus can be basically characterized by the following: mandible with four teeth (usually), bicarinate clypeus with 0-5 teeth, median part of clypeus with a pair of longitudinal carinae medially or at lateral edges, 10-segmented antennae that terminates in a distinctive 2-segmented club, overall shiny appearance and general lack of or reduced sculpture (when present usually restricted to rugulae or striae on the head, alitrunk, petiole, and postpetiole), lack of propodeal spines or other protuberances on the alitrunk, well developed petiole and postpetiole, and a well developed sting. Workers are either polymorphic (especially in the fire ant group) or monomorphic (especially thief ants). The thief ant group shares these characteristics, but workers are minute (usually under 2.0 mm in total length), usually have minute eyes (usually with only 1-5 ommatidia (rarely more than 18, except for S. globularia in our region), minor funicular segments 2-3 typically wider than long (usually longer than wide in the fire ant group).

Hybridization is not uncommon among the larger fire ant group, which can make identification of some species difficult. Identification of thief ants is perhaps even more challenging due to their minute size, similar appearance of workers of one species to another, taxonomic problems, and lack of knowledge of all castes.

Worker: SIze, minute, but relatively large compared to many thief ant species [1.74-1.86 mm in total length (measurements from Pacheco 2007)]. Concolorous light, milky white. Well developed lateral and extralateral teeth on the clypeus. The eyes are small with only 2 facets. Punctures on head are coarse and larger than the diameter of hairs which arise from them. Metanotal suture is deeply impressed. Postpetiole circular (in dorsal view).

Female: Relatively large, robust (approximately 5.3 mm in TL), yellowish orange, and opaque.

Male: Relatively large (about 4 mm in TL), yellowish orange, opaque.

This species is most similar to S. molesta, but workers can be distinguished by their pale yellow color, opaque appearance, and coarse punctures on the head.

Biology and Economic Importance
Solenopsis pergandei nests in the soil of sandy habitats such as drained scrub and dry oak-pine savannas. We have collected this species in sandy soil of a campsite near a lake in a mixed pine/hardwood forest (Tuscaloosa Co., AL), in sand chenier woodland (Hancock Co., MS), nesting in sand bar along a river running through a dolemite glade (Bibb Co, AL), in back dunes (Baldwin Co., AL), pine savannas (GA & FL), pine-oak scrub (GA & FL), soil and leaf litter from mixed pine/hardwood forest (Lauderdale Co., MS), in soil and humus at base of Fagus grandifolia in mixed forest (Lauderdale Co., AL), and in a mesic forest along the banks of the Chunky River (Lauderdale Co., MS). Alates have been collected flying in early August in northern Florida and southern Georgia.

AL, AR, FL, GA, LA, MS, NC, NM, SC, and TX.

Literature Cited
Pacheco, J. A. 2007. The New World ants of the genus Solenopsis (Hymenoptera: Formicidae). PhD dissertation, The University of Texas at El Paso. i-xxi +543 pp.


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