Solenopsis

Solenopsis is a large, cosmopolitan, and taxonomically difficult genus of mostly minute, monomorphic, wholly subterranean species. These minute species frequently live as thief ants within the colonies of other larger species of ants or termites. Some New World species are larger and the workers are polymorphic. These species have colonies that can be very large and the workers are aggressive surface foragers. These ants are commonly referred to as "fire ants" because of the intense, burning sensation caused by their stings. The fire ants are important pest species. (Wheeler and Wheeler 1986)

Identification
Workers can be separated from similar genera such as Monomorium, Dolopomyrmex, Carebara by the ten segmented antenna and the two segmented antennal club. There are english and spanish keys for the New World thief ants.

Deyrup and Prusak (2008) - Members of the genus can usually be recogniszed by the following combination of character states: 2-segmeneted petiole, 2-segmented antennal club; propodeum lacking spines or angles; petiolar node well developed; head and body shining, localized striae; clypeus longitudinally carinate, with a median, apical marginal seta.

Biology
The thief ants were relatively recently revised (Pacheco and Mackay 2013). This work was an important step forward in our understanding of these small ants. Despite this recent revision there still remains many species that are known only from a few specimens or, if known from more material, are generally poorly known.

Pacheco and Mackay (2013) - The thief ants group of the genus Solenopsis is virtually cosmopolitan throughout the New World. The genus ranges from southern Canada to Argentina. The majority of the species can be found in tropical rain forests, especially in areas of thick leaf litter. Most colonies of the smaller species are found in the soil without an entrance hole, unless nuptial flights are occurring. Occasionally nests are discovered under stones, but are often found while one is excavating the nest of another ant species (Mackay and Mackay 2002). They are considered thief ants because they pilfer the nests of other ants, where they steal brood or food. Some species are considered pests, such as Solenopsis molesta, perhaps the most abundant of the "smaller species." It can be found in parks and residential areas and occasionally is a house pest. Many species can be collected with subterranean baited traps set at least 10 cm down in the soil column. The ecology of most species is virtually unknown.

Alex Wild (March, 2017) - As best as I can discern, this little Solenopsis is undescribed. She was clinging to the petiole of a Pheidole tetra queen at Brackenridge Field Lab, Texas, and remained firmly attached even in ethanol. While similar to Solenopsis phoretica, she differs in the structure of the petiolar process and in the pilosity.

Nomenclature

 *  SOLENOPSIS [Myrmicinae: Solenopsidini]
 * Solenopsis Westwood, 1840b: 86. Type-species: Solenopsis mandibularis (junior synonym of Atta geminata), by monotypy.
 * Solenopsis senior synonym of Diplorhoptrum: Mayr, 1862: 751 (see under Diplorhoptrum).
 * Solenopsis senior synonym of Bisolenopsis, Diagyne, Euophthalma, Granisolenopsis, Labauchena, Lilidris, Oedaleocerus, Paranamyrma, Synsolenopsis: Ettershank, 1966: 134.
 * Solenopsis senior synonym of Octella: Taylor, 1991b: 611.
 * BISOLENOPSIS [junior synonym of Solenopsis]
 * Bisolenopsis Kusnezov, 1953d: 9. Type-species: Bisolenopsis sea, by monotypy.
 * Bisolenopsis junior synonym of Solenopsis: Ettershank, 1966: 134.
 * CAREBARELLA [Myrmicinae: Solenopsidini]
 * Carebarella Emery, 1906c: 137. Type-species: Carebarella bicolor, by monotypy.
 * Carebarella senior synonym of Carebarelloides: Ettershank, 1966: 113.
 * Carebarella junior synonym of Solenopsis: implied in Pacheco & Mackay, 2013: 37, 119 (type-species of Carebarella (C. bicolor Emery, 1906c: 138) was transferred to Solenopsis, establishing Carebarella as a junior synonym of Solenopsis).
 * CAREBARELLOIDES [junior synonym of Carebarella]
 * Carebarelloides Borgmeier, 1937b: 236 [as subgenus of Carebarella]. Type-species: Carebarella (Carebarelloides) condei, by original designation.
 * Carebarelloides junior synonym of Carebarella: Ettershank, 1966: 113.
 *  DISOLENOPSIS [unavailable name]
 * Disolenopsis Snelling, R.R. 1981: 397, incorrect subsequent spelling of Bisolenopsis: Bolton, 1995b: 22.
 * DIAGYNE [junior synonym of Solenopsis]
 * Diagyne Santschi, 1923c: 268 [as subgenus of Solenopsis]. Type-species: Solenopsis succinea, by monotypy.
 * Diagyne junior synonym of Solenopsis: Ettershank, 1966: 134.
 * DIPLORHOPTRUM [junior synonym of Solenopsis]
 * Diplorhoptrum Mayr, 1855: 449. Type-species: Formica fugax, by monotypy.
 * Diplorhoptrum as genus: Baroni Urbani, 1968: 68; Kutter, 1977c: 98; Bernard, 1978a: 543; Arnol'di & Dlussky, 1978: 539; Collingwood, 1979: 64; Dlussky & Fedoseeva, 1988: 80; Kupyanskaya, 1990: 132; Atanasov & Dlussky, 1992: 167; Dlussky & Radchenko, 1994: 102.
 * Diplorhoptrum subgenus of Solenopsis: Creighton, 1930b: 43; Creighton, 1950a: 233; Smith, M.R. 1951a: 813; Kusnezov, 1956: 27; Kusnezov, 1957a: 273; Kusnezov, 1962b: 160; Smith, M.R. 1967: 358.
 * Diplorhoptrum junior synonym of Solenopsis: Mayr, 1862: 751; Roger, 1863b: 32; Mayr, 1863: 453; Emery & Forel, 1879: 464; Dalla Torre, 1893: 75; Forel, 1915d: 9; Emery, 1922e: 195; Wheeler, W.M. 1922a: 877; Ettershank, 1966: 134; Kempf, 1972a: 232; Bolton, 1987: 285; Bolton, 1994: 106; Bolton, 1995b: 27; Bolton, 2003: 218.
 * EUOPHTHALMA [junior synonym of Solenopsis]
 * Euophthalma Creighton, 1930b: 43 [as subgenus of Solenopsis]. Type-species: Myrmica globularia, by original designation.
 * Euophthalma junior synonym of Solenopsis: Ettershank, 1966: 134.
 * GRANISOLENOPSIS [junior synonym of Solenopsis]
 * Granisolenopsis Kusnezov, 1956: 26 [as subgenus of Solenopsis] (diagnosis in key). Type-species: Solenopsis (Granisolenopsis) granivora, by original designation.
 * [Granisolenopsis also described as new by Kusnezov, 1957a: 277.]
 * Granisolenopsis junior synonym of Solenopsis: Ettershank, 1966: 134.
 * LABAUCHENA [junior synonym of Solenopsis]
 * Labauchena Santschi, 1930d: 81. Type-species: Labauchena daguerrei, by monotypy.
 * Labauchena junior synonym of Solenopsis: Ettershank, 1966: 134.
 * LILIDRIS [junior synonym of Solenopsis]
 * Lilidris Kusnezov, 1956: 26 (diagnosis in key). Type-species: Lilidris metatarsalis, by original designation.
 * [Lilidris also described as new by Kusnezov, 1957a: 274 and Kusnezov, 1958b: 189.]
 * Lilidris junior synonym of Solenopsis: Ettershank, 1966: 134.
 * OCTELLA [junior synonym of Solenopsis]
 * Octella Forel, 1915b: 70 [as subgenus of Oligomyrmex]. Type-species: Oligomyrmex (Octella) pachycerus, by original designation.
 * Octella junior synonym of Oligomyrmex: Ettershank, 1966: 119.
 * Octella junior synonym of Solenopsis: Taylor, 1991b: 611.
 * OEDALEOCERUS [junior synonym of Solenopsis]
 * Oedaleocerus Creighton, 1930b: 43 [as subgenus of Solenopsis]. Type-species: Solenopsis angulata, by original designation.
 * Oedaleocerus raised to genus: Kusnezov, 1957a: 272.
 * Oedaleocerus junior synonym of Solenopsis: Ettershank, 1966: 134.
 * PARANAMYRMA [junior synonym of Solenopsis]
 * Paranamyrma Kusnezov, 1953d: 17. Type-species: Paranamyrma solenopsidis, by monotypy.
 * [Paranamyrma also described as new by Kusnezov, 1954a: 9.]
 * Paranamyrma junior synonym of Solenopsis: Ettershank, 1966: 134.
 * SYNSOLENOPSIS [junior synonym of Solenopsis]
 * Synsolenopsis Forel, 1918b: 155 [as subgenus of Solenopsis]. Type-species: Solenopsis (Synsolenopsis) bruchi (junior primary homonym in Solenopsis, replaced by Solenopsis bruchiella), by monotypy.
 * Synsolenopsis raised to genus: Kusnezov, 1953c: 341; Kusnezov, 1962b: 160.
 * Synsolenopsis junior synonym of Solenopsis: Ettershank, 1966: 134.