Solenopsis

Solenopsis Temporal range: 33.9–0 Ma K Pa Eo Ol Mi Pl Early Oligocene – Recent
Solenopsis geminata
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Myrmicinae
Tribe:	Solenopsidini
Genus:	Solenopsis Westwood, 1840
Type species
Solenopsis mandibularis (junior synonym of Solenopsis geminata)
Diversity
216 species 9 fossil species (Species Checklist, Species by Country) Solenopsis geminata Specimen Label
Synonyms
Bisolenopsis Kusnezov, 1953 Carebarella Emery, 1906 Carebarelloides Borgmeier, 1937 Diagyne Santschi, 1923 Diplorhoptrum Mayr, 1855 Euophthalma Creighton, 1930 Granisolenopsis Kusnezov, 1956 Labauchena Santschi, 1930 Lilidris Kusnezov, 1956 Octella Forel, 1915 Oedaleocerus Creighton, 1930 Paranamyrma Kusnezov, 1953 Synsolenopsis Forel, 1918

Evolutionary Relationships

Solenopsidini Stegomyrmex Dolopomyrmex Rogeria Bariamyrma Rogeria Solenopsis Kempfidris Tropidomyrmex Austromorium, Monomorium, Oxyepoecus Megalomyrmex Tyrannomyrmex some Monomorium Epelysidris Anillomyrma Myrmicaria Monomorium Syllophopsis Adelomyrmex, Baracidris, Cryptomyrmex

Based on Ward et al., 2014

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)

Photo Gallery

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  Solenopsis molesta worker. Image by Alex Wild.

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.

Keys including this Genus

• Key to Ant Genera of the Navajo Reservation
• Key to Australian Genera of Myrmicinae
• Key to North American Genera of Myrmicinae
• Key to Vietnamese Myrmicinae Genera
• Key to the Ant Genera of New Mexico

Keys to Subgenera or Species Groups in this Genus

• Key to New World Solenopsis Species Complexes

Keys to Species in this Genus

• Solenopsis brevicornis species complex
• Key to Solenopsis fugax species complex
• Solenopsis globularia species complex
• Solenopsis stricta species complex
• Key to Solenopsis molesta species complex
• Key to Solenopsis nigella species complex
• Key to Solenopsis pygmaea species complex
• Key to Solenopsis wasmannia species complex
• Clave a las obreras del complejo Solenopsis molesta
• Clave a las obreras del complejo Solenopsis nigella
• Clave a las obreras del complejo Solenopsis pygmaea
• Clave a las obreras del complejo Solenopsis wasmannii
• Key to Arabian Solenopsis
• Key to Solenopsis workers of Egypt
• Key to Solenopsis queens and males of Egypt
• Key to Solenopsis saevissima species group workers

Distribution

Fossils

Fossils are known from: Brunstatt, Haut-Rhin, France (Early Oligocene), Khronya Cape, Kerch, Crimea, Russian Federation (Sarmatian, Upper Miocene), Kleinkems, Germany (Early Oligocene).

Biology

Pitts et. al. (2018) - There are approximately 190 described species of Solenopsis worldwide (Bolton 1995). Most of these species are characterized by small, monomorphic workers that form small colonies and can display a lestobiotic lifestyle, living in the nest walls of other ant species from which they steal food and brood (Thompson 1980, 1989; Pacheco and Mackay 2013). These habits have earned such Solenopsis species the name “thief ants.” A smaller group composed of five species of Solenopsis are considered inquiline social parasites of other ant species. These inquiline social parasites live alongside the host queen, generally lack a worker caste, and their brood is made up only of sexuals (Buschinger 2009). Among the remaining Solenopsis are 20 New World species that differ greatly from the thief ants and social parasites in their biology. These species have larger, polymorphic workers, form enormously populous colonies, and are highly aggressive in their foraging and defensive habits. The painful sting wielded by the workers has earned such Solenopsis species the name “fire ants.” Most fire ant species are Neotropical, although five species are native to North America (Chialvo et al. 2018). One of these (Solenopsis geminata (Fabricius), the tropical fire ant) and two of the Neotropical species (Solenopsis invicta Buren, the red imported fire ant, and Solenopsis richteri Forel, the black imported fire ant) have been inadvertently introduced to locations far from their native ranges. Solenopsis geminata has been introduced throughout the tropics worldwide (Wetterer 2011, Gotzek et al. 2015), S. invicta has been introduced to the United States and several other Pacific Rim countries (Lofgren 1986, Callcott and Collins 1996, Henshaw et al. 2005, Ascunce et al. 2011, Wetterer 2013), and S. richteri has been introduced to the United States (Lofgren 1986).

Solenopsis invicta and S. richteri have become economically important pests in the United States, where they invade lawns, pastures, and roadsides, attacking and stinging native animals, livestock, and humans when colonies are disturbed, and evidently out-competing native ants for food and nesting habitat (Lofgren et al. 1975, Jouvenaz 1990, Guillebeau et al. 2002, Tschinkel 2006). Annual economic losses in the United States attributable to the imported fire ants are estimated at $6 billion (Lard et al. 2006). Although the pugnacious nature of these exotic ants makes them undesirable inhabitants of areas that they have newly colonized, they nonetheless have become premier objects of study for ecologists and evolutionary biologists. For instance, fire ants offer one of relatively few well-documented cases of the formation of a hybrid zone in historical times (Vander Meer et al. 1985, Ross et al. 1987a, Shoemaker et al. 1996), which makes them a rich source of information for genetic studies of speciation (Baack and Rieseberg 2007, Nolte and Tautz 2010). Fire ants also show variation in the social organization of their colonies, some of which appears to be under simple genetic control (Krieger and Ross 2002, Wang et al. 2013), making them important model systems in the study of social evolution (Gotzek and Ross 2007, Smith et al. 2008, Robinson et al. 2008, Fischman et al. 2011). The flexibility demonstrated by some species in having either a single egg-laying gyne (monogyny) or multiple egg-laying gynes (polygyny) in a single colony has sparked comparative ecological and evolutionary studies about the causes and consequences of such variation (Vargo and Fletcher 1987, Ross and Keller 1995, Porter et al. 1997, Gotzek and Ross 2007, Huang and Wang 2014). Solenopsis also includes several social parasites that use various ant species as their hosts (Calcaterra et al. 2000, Davis and Deyrup 2006, Deyrup and Prusak 2008), a characteristic that is of great interest for studies of social evolution as well as integrated pest management.

Historically, Solenopsis has been a taxonomically difficult group (Creighton 1930, 1950; Wilson 1952; Buren 1972; Trager 1991; Pacheco and Mackay 2013). In South America, where species diversity is highest, distinguishing Solenopsis species is exceedingly difficult due to a paucity of reliable characters that are constant within putative species yet differ between them. Frustration with this situation prompted Carlo Emery to call the group the crux myrmecologorum (Creighton 1930).

The Solenopsis social parasites.— Because Labauchena and Paranamyrma were synonymized under Solenopsis (Ettershank 1966), Solenopsis now includes several species of social parasites. Two of these, Solenopsis daguerrei and Solenopsis hostilis, parasitize fire ants, whereas Solenopsis solenopsidis parasitizes thief ants (formerly Paranamyrma; Santschi 1930, Kusnezov 1954, Borgmeier 1959), and Solenopsis phoretica and Solenopsis enigmatica parasitize Pheidole. The social parasites lead an especially interesting life style when compared to other Solenopsis species, because the parasitic gyne enters a heterospecific colony and usurps the reproductive role of the host queen, rather than initiating her own colony or joining a conspecific one (as in the case of polygyne fire ants).

Solenopsis daguerrei, S. solenopsidis and, perhaps, S. hostilis exhibit permanent social parasitism. Solenopsis daguerrei has been reported to kill the host queen in laboratory studies (temporary social parasitism; Bruch 1930), but has been found to allow the host queen to live in field studies (permanent social parasitism; Silveira-Guido et al. 1965). It may be that under certain conditions S. daguerrei exhibit either form of social parasitism. This species is known to be a social parasite of Solenopsis invicta, S.richteri, Solenopsis macdonaghi, and Solenopsis quinquecuspis (Santschi 1930, Briano et al. 1997, Calcaterra et al. 2000). Borgmeier (1959) reported S. hostilis as a parasite of Solenopsis saevissima (Smith), but did not gather any natural history information for the species. Solenopsis solenopsidis is reported to be a permanent social parasite of Solenopsis clytemnestra Emery (Kusnezov 1954). Holldobler and Wilson (1990) reviewed social parasitism and included the known parasites and hosts of the Solenopsis social parasites.

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.

An apparently undescribed Solenopsis queen attached to a Pheidole tetra queen. Image by Alex Wild.

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.

Association with Other Organisms

Species Uncertain

An unknown species of Solenopsis is a host for the eucharitid wasp Orasema pireta (Varone et al., 2010; Baker et al., 2019).

All Associate Records for Genus

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Taxon	Relationship	Associate Type	Associate Taxon	Associate Relationship	Locality	Source	Notes
Solenopsis	host	eucharitid wasp	Orasema pireta	parasite		Varone et al., 2010; Baker et al., 2019	primary host
Solenopsis carolinensis	host	fungus	Myrmicinosporidium durum	pathogen		Espadaler & Santamaria, 2012
Solenopsis carolinensis	host	microsporidian fungus	Kneallhazia carolinensae	pathogen		Valles et al., 2011
Solenopsis daguerrei	inquiline	ant	Solenopsis invicta	host		Santschi 1930; Briano et al. 1997; Calcaterra et al. 2000
Solenopsis daguerrei	inquiline	ant	Solenopsis macdonaghi	host		Santschi 1930; Briano et al. 1997; Calcaterra et al. 2000
Solenopsis daguerrei	inquiline	ant	Solenopsis quinquecuspis	host		Santschi 1930; Briano et al. 1997; Calcaterra et al. 2000
Solenopsis daguerrei	inquiline	ant	Solenopsis richteri	host		Santschi 1930; Briano et al. 1997; Calcaterra et al. 2000
Solenopsis fugax	host	fungus	Myrmicinosporidium durum	pathogen		Espadaler & Santamaria, 2012
Solenopsis gayi	host	phorid fly	Pseudacteon obtusus	parasite	Chile	Sanchez-Restrepo et al., 2020
Solenopsis geminata	host	cricket	Myrmecophilus quadrispinus	myrmecophile
Solenopsis geminata	host	eucharitid wasp	Orasema taii	parasite		Heraty, 1990; Chien & Heraty, 2018; Baker et al., 2019; Universal Chalcidoidea Database	primary host; ''Solenopsis geminata'' X ''xyloni'' hybrid
Solenopsis geminata	host	microsporidian fungus	Burenella dimorpha			Jouvenaz & Hazard, 1978; Sokolova & Fuxa, 2008
Solenopsis geminata	host	microsporidian fungus	Kneallhazia solenopsae			Ascunce et al. 2010
Solenopsis geminata	host	phorid fly	Pseudacteon arcuatus	parasite		Pereira et al. 2015
Solenopsis geminata	host	phorid fly	Pseudacteon bifidus	parasite		Porter et al. 2018
Solenopsis geminata	host	phorid fly	Pseudacteon pesqueroi	parasite		Pereira et al. 2015
Solenopsis geminata	host	phorid fly	Pseudacteon plowesi	parasite		Pereira et al. 2015
Solenopsis interrupta	host	phorid fly	Pseudacteon calderensis	parasite	Argentina	Sanchez-Restrepo et al., 2020
Solenopsis interrupta	host	phorid fly	Pseudacteon curvatus	parasite	Argentina, Bolivia	Sanchez-Restrepo et al., 2020
Solenopsis interrupta	host	phorid fly	Pseudacteon litoralis	parasite	Bolivia, Brazil	Sanchez-Restrepo et al., 2020
Solenopsis interrupta	host	phorid fly	Pseudacteon nocens	parasite	Bolivia	Sanchez-Restrepo et al., 2020
Solenopsis interrupta	host	phorid fly	Pseudacteon notocaudatus	parasite	Argentina, Bolivia	Sanchez-Restrepo et al., 2020
Solenopsis interrupta	host	phorid fly	Pseudacteon nudicornis	parasite	Argentina, Bolivia	Sanchez-Restrepo et al., 2020
Solenopsis interrupta	host	phorid fly	Pseudacteon obtusus	parasite	Argentina, Brazil	Sanchez-Restrepo et al., 2020
Solenopsis interrupta	host	phorid fly	Pseudacteon pradei	parasite	Bolivia	Sanchez-Restrepo et al., 2020
Solenopsis interrupta	host	phorid fly	Pseudacteon tricuspis	parasite	Argentina, Bolivia	Sanchez-Restrepo et al., 2020
Solenopsis invicta	host	beetle	Myrmecosaurus ferrugineus	myrmecophile	Mississippi, USA	MacGown, 2006
Solenopsis invicta	host	eucharitid wasp	Orasema salebrosa	parasite		Heraty et al., 1993; Varone et al., 2010; Baker et al., 2019; Universal Chalcidoidea Database	primary host
Solenopsis invicta	host	eucharitid wasp	Orasema simplex	parasite		Heraty et al., 1993; Varone et al., 2010; Baker et al., 2019; Universal Chalcidoidea Database	primary host
Solenopsis invicta	host	eucharitid wasp	Orasema sp.	parasite		Universal Chalcidoidea Database	associate, primary host
Solenopsis invicta	host	eucharitid wasp	Orasema xanthopus	parasite		Silveira-Guido et al., 1964; Heraty et al., 1993; Varone et al., 2010; Baker et al., 2019; Universal Chalcidoidea Database	primary host
Solenopsis invicta	host	fungus	Myrmicinosporidium durum	pathogen		Espadaler & Santamaria, 2012
Solenopsis invicta	host	microsporidian fungus	Kneallhazia solenopsae	pathogen		Ascunce et al. 2010
Solenopsis invicta	host	microsporidian fungus	Thelohania solenopsae	pathogen		Knell et al. 1977; Sokolova & Fuxa, 2008
Solenopsis invicta	host	microsporidian fungus	Vairimorpha invictae	pathogen		Jouvenaz & Ellis, 1986; Sokolova & Fuxa, 2008
Solenopsis invicta	host	nematode	Allomermis solenopsi	parasite	Argentina	Poinar et al., 2007
Solenopsis invicta	host	nematode	Steinernema carpocapsae	parasite		Poinar, 2012
Solenopsis invicta	host	nematode	Tetradonema solenopsis	parasite	Brazil	Nickle & Jouvenaz, 1987
Solenopsis invicta	host	phorid fly	Pseudacteon cultellatus	parasite	Argentina, Brazil	Sanchez-Restrepo et al., 2020
Solenopsis invicta	host	phorid fly	Pseudacteon curvatus	parasite	Argentina, Brazil	Sanchez-Restrepo et al., 2020
Solenopsis invicta	host	phorid fly	Pseudacteon litoralis	parasite	Argentina, Brazil, Paraguay	Sanchez-Restrepo et al., 2020
Solenopsis invicta	host	phorid fly	Pseudacteon nocens	parasite	Argentina, Brazil	Sanchez-Restrepo et al., 2020
Solenopsis invicta	host	phorid fly	Pseudacteon nudicornis	parasite	Argentina	Sanchez-Restrepo et al., 2020
Solenopsis invicta	host	phorid fly	Pseudacteon obtusitus	parasite	Argentina, Uruguay	Sanchez-Restrepo et al., 2020
Solenopsis invicta	host	phorid fly	Pseudacteon obtusus	parasite	Argentina	Sanchez-Restrepo et al., 2020
Solenopsis invicta	host	phorid fly	Pseudacteon pradei	parasite	Brazil	Sanchez-Restrepo et al., 2020
Solenopsis invicta	host	phorid fly	Pseudacteon solenopsidis	parasite	Argentina	Sanchez-Restrepo et al., 2020
Solenopsis invicta	host	phorid fly	Pseudacteon tricuspis	parasite	Argentina, Brazil	Sanchez-Restrepo et al., 2020
Solenopsis invicta	host	phorid fly	Pseudacteon wasmanni	parasite	Brazil	Sanchez-Restrepo et al., 2020
Solenopsis invicta	host	strepsipteran	Caenocholax fenyesi	parasite		Cook, 2019
Solenopsis macdonaghi	host	eucharitid wasp	Orasema salebrosa	parasite		Universal Chalcidoidea Database	primary host
Solenopsis macdonaghi	host	eucharitid wasp	Orasema simplex	parasite		Heraty et al., 1993; Varone et al., 2010; Baker et al., 2019
Solenopsis macdonaghi	host	phorid fly	Pseudacteon obtusus	parasite	Argentina	Sanchez-Restrepo et al., 2020
Solenopsis molesta	host	eucharitid wasp	Orasema coloradensis	parasite		Wheeler, 1907; Johnson et al., 1986; Baker et al., 2019; Universal Chalcidoidea Database	primary host
Solenopsis molesta	prey	tiger beetle	Tetracha virginica	predator	United States	Valenti & Gaimari, 2000; Polidori et al., 2020
Solenopsis picea	xenobiont	ant	Camponotus femoratus	host	British Guiana	Weber, 1943
Solenopsis picea	xenobiont	ant	Crematogaster carinata	host	British Guiana		Weber, 1943
Solenopsis quinquecuspis	host	eucharitid wasp	Orasema aenea	parasite		Universal Chalcidoidea Database	primary host
Solenopsis quinquecuspis	host	eucharitid wasp	Orasema freychei	parasite		Varone et al., 2010; Baker et al., 2019;
Solenopsis quinquecuspis	host	eucharitid wasp	Orasema simplex	parasite		Heraty et al., 1993; Varone et al., 2010; Baker et al., 2019;
Solenopsis quinquecuspis	host	eucharitid wasp	Orasema xanthopus	parasite		Silveira-Guido et al., 1964; Heraty et al., 1993; Varone et al., 2010; Baker et al., 2019	primary host
Solenopsis richteri	host	beetle	Myrmecosaurus ferrugineus	myrmecophile	Mississippi, USA	MacGown, 2006
Solenopsis richteri	host	diapriid wasp	Bruchopria hexatoma	parasite	Argentina	Loiacono, 2013; Gonzalez et al., 2016
Solenopsis richteri	host	diapriid wasp	Bruchopria pentatoma	parasite	Argentina	Loiacono, 2013; Gonzalez et al., 2016
Solenopsis richteri	host	diapriid wasp	Trichopria myrmecophila	parasite	Argentina	Loiacono, 2013; Gonzalez et al., 2016
Solenopsis richteri	host	eucharitid wasp	Orasema salebrosa	parasite		Heraty et al., 1993; Varone et al., 2010; Baker et al., 2019; Universal Chalcidoidea Database	primary host
Solenopsis richteri	host	eucharitid wasp	Orasema simplex	parasite		Heraty et al., 1993; Varone et al., 2010; Baker et al., 2019; Universal Chalcidoidea Database	primary host
Solenopsis richteri	host	eucharitid wasp	Orasema xanthopus	parasite		Silveira-Guido et al., 1964; Heraty et al., 1993; Varone et al. 2010; Baker et al., 2019; Universal Chalcidoidea Database	primary host
Solenopsis richteri	host	microsporidian fungus	Burenella dimorpha			Sokolova & Fuxa, 2008
Solenopsis richteri	host	microsporidian fungus	Kneallhazia solenopsae			Ascunce et al. 2010
Solenopsis richteri	host	microsporidian fungus	Vairimorpha invictae			Sokolova & Fuxa, 2008
Solenopsis richteri	host	nematode	Tetradonema solenopsis	parasite		Jouvenaz & Wojcik, 1990
Solenopsis richteri	host	phorid fly	Pseudacteon borgmeieri	parasite	Argentina	Sanchez-Restrepo et al., 2020
Solenopsis richteri	host	phorid fly	Pseudacteon cultellatus	parasite	Argentina	Sanchez-Restrepo et al., 2020
Solenopsis richteri	host	phorid fly	Pseudacteon curvatus	parasite	Argentina	Sanchez-Restrepo et al., 2020
Solenopsis richteri	host	phorid fly	Pseudacteon obtusus	parasite	Argentina	Sanchez-Restrepo et al., 2020
Solenopsis richteri	host	phorid fly	Pseudacteon tricuspis	parasite	Argentina	Sanchez-Restrepo et al., 2020
Solenopsis richteri	host	strepsipteran	Stichotrema beckeri	parasite		Cook, 2019
Solenopsis saevissima	host	diapriid wasp	Pentapria cf. nodicornis	parasite	Argentina	Loiacono, 2013; Gonzalez et al., 2016
Solenopsis saevissima	host	eucharitid wasp	Orasema xanthopus	parasite		Universal Chalcidoidea Database	associate, primary host
Solenopsis saevissima	host	phorid fly	Pseudacteon affinis	parasite	Brazil	Sanchez-Restrepo et al., 2020
Solenopsis saevissima	host	phorid fly	Pseudacteon cultellatus	parasite	Brazil	Sanchez-Restrepo et al., 2020
Solenopsis saevissima	host	phorid fly	Pseudacteon dentiger	parasite	Brazil	Sanchez-Restrepo et al., 2020
Solenopsis saevissima	host	phorid fly	Pseudacteon disneyi	parasite	Brazil	Sanchez-Restrepo et al., 2020
Solenopsis saevissima	host	phorid fly	Pseudacteon fowleri	parasite	Brazil	Pereira et al. 2015; Sanchez-Restrepo et al., 2020
Solenopsis saevissima	host	phorid fly	Pseudacteon lenkoi	parasite	Brazil	Sanchez-Restrepo et al., 2020
Solenopsis saevissima	host	phorid fly	Pseudacteon nudicornis	parasite	Brazil	Williams et al., 1973; Sanchez-Restrepo et al., 2020
Solenopsis saevissima	host	phorid fly	Pseudacteon pesqueroi	parasite		Pereira et al. 2015
Solenopsis saevissima	host	phorid fly	Pseudacteon pradei	parasite	Brazil	Williams et al., 1973; Pereira et al. 2015
Solenopsis saevissima	host	phorid fly	Pseudacteon solenopsidis	parasite	Brazil	Sanchez-Restrepo et al., 2020
Solenopsis saevissima	host	phorid fly	Pseudacteon tricuspis	parasite	Brazil	Williams et al., 1973
Solenopsis saevissima	host	phorid fly	Pseudacteon wasmanni	parasite	Brazil	Williams et al., 1973
Solenopsis tenuis	host	eucharitid wasp	Orasema sixaolae	parasite		Wheeler & Wheeler, 1937; Baker et al., 2019; Universal Chalcidoidea Database	primary host
Solenopsis xyloni	host	aphelinid wasp	Aphytis melinus	parasite		Universal Chalcidoidea Database	associate
Solenopsis xyloni	host	encyrtid wasp	Comperiella bifasciata	parasite		Universal Chalcidoidea Database	associate
Solenopsis xyloni	host	eucharitid wasp	Orasema taii	parasite		Heraty, 1990; Chien & Heraty, 2018; Baker et al., 2019; Universal Chalcidoidea Database	primary host; ''Solenopsis geminata'' X ''xyloni'' hybrid
Solenopsis xyloni	host	microsporidian fungus	Kneallhazia solenopsae			Ascunce et al. 2010	listed as ''S. geminata'' X ''S. xyloni'' hybrids

Life History Traits

• Worker-produced males: absent (Goetsch (1953) cited in Fletcher and Ross (1985); Frumhoff & Ward, 1992) (worker ovaries reported to be vestigial or absent)

Castes

Morphology of Sexuals

Pitts et. al. (2018) - Creighton (1930, 1950) stated that both males and gynes of Solenopsis appear to offer better characters for specific determinations than do the workers. Because individuals of the sexual caste tend to be larger than the worker caste and have a less generalized and reduced anatomy, they could provide characters, such as those from male genitalia and wing venation, that are not obtainable from workers and are useful for identification purposes (Creighton 1930, 1950). This study found that the amount of intraspecific variation occurring in the adult males and gynes was equivalent to that of workers, making the taxonomic information gained from these castes no better than that obtained from workers. Furthermore, the morphometric measurements and indices of the adult males and gynes alone are inadequate for determining species. Given a choice, workers still offer the most reliable and numerous characters, and these characters alone usually are sufficient for making accurate species identifications. Even though the morphology and morphometrics of sexuals are of limited use alone, they greatly improve the accuracy of identifications of fire ants when used in concert with data for the workers.

Male Genitalia

Pitts et. al. (2018) - For many Hymenoptera, the male genitalia are of great diagnostic utility. Sexual selection is hypothesized to often drive the rapid divergence of the morphology of male genitalia once speciation occurs (Eberhard 1985). Also, because the male genitalia are structurally complex, the likelihood that related species would become similar in this structure through parallelism is low (Mayr 1969). Thus, genitalic characters are potentially useful for distinguishing even closely related species. This is not the case for Solenopsis. Although there are slight differences between the Solenopsis fugax species-group and several of the other fire ant species-groups, this study found that the male genitalia of the species within the S. saevissima species-group were relatively homogeneous and uninformative. After study of the genitalia of many Solenopsis exemplars, we also conclude that characters used by Baroni-Urbani (1968) to raise Diplorhoptrum to the generic level are not found in all of the species he placed in this taxon. Furthermore, Diplorhoptrum species such as Solenopsis tennesseensis and Solenopsis abdita have genitalia more closely resembling those of the fire ants than those of the European Diplorhoptrum species, S. fugax. This information provides additional support for the synonymy of Diplorhoptrum with Solenopsis, as proposed by Bolton (1987).

Wing Venation

Pitts et. al. (2018) - Although wing venation in Solenopsis may provide valuable data for inferring the higher-level phylogeny of the tribe Solenopsidini in the future, as proposed by Brown and Nutting (1950), it appears to be too conservative within the S. saevissima species-group to be phylogenetically informative (Pitts et al. 2005). Moreover, wing venation tends to be too similar across species and too variable within species to provide diagnostic information.

Although some slight differences exist, the wing venation of the S. saevissima species-group is remarkably similar to that of other groups, such as the S. geminata species-group, the S. tridens species-group, the Solenopsis globularia species-group, and some members of the Solenopsis molesta species-group. Furthermore, distantly related species such as Solenopsis gensterblumi, S. nr. nigella, and an unidentified Solenopsis species are similar in their venation as well. Some species in the S. molesta species-group have diagnostic wing venation, such as the reduction of the r-rs cross vein, but others do not. In general, wing venation provides few taxonomically informative characters for the genus.

Intraspecific variation and individual aberrations in wing venation were commonly observed, including: 1) swelling in the Rs+M vein in the radial cell of a Solenopsis pusillignis gyne and S. richteri gyne; 2) coarseness of the Rs vein and the veins delineating the radial cell in individuals of several species; 3) swellings on the Cu vein of a S. macdonaghi male; 4) swellings on the Rs+M vein in the median cell of a S. megergates gyne. These abnormalities are found in other species-groups and are probably characteristic of the genus Solenopsis as a whole (see also Ross and Robertson 1990). In some cases, certain veins are misplaced so that the venation looks unique, but usually the other wing on the same individual is normal. Such asymmetry has been documented for Oxyepoecus, a close relative of Solenopsis (Kempf 1974). This variation exists as well for both spectral and nebulous veins.

The lack of the m-cu cross vein for the gynes of S. metallica and the reduction of wing venation in S. daguerrei are constant for all specimens seen and are considered characters rather than abnormalities. The lack of the m-cu cross vein for S. metallica was observed in all four forewings of the two gynes from different nests examined. All specimens of S. daguerrei had reduced wing venation, albeit to various degrees.

Other observed morphological abnormalities are noted here. A single gyne of S. megergates had two median ocelli and had coarse striations throughout the ocellar triangle. These complete striations were seen only in this single atypical specimen. One gyne of S. quinquecuspis had four propodeal spiracles. These two specimens did not otherwise differ from the typical gynes of their species. Lastly, two gynandromorphs of S. quinquecuspis were discovered, as will be discussed elsewhere.

Larval Morphology

Pitts et. al. (2018) - Wheeler and Wheeler (1976, 1986, 1991) found that larval morphology could be used to differentiate ant genera and provided a generic key using larval characters. In some cases, higher level taxonomy of Formicidae has been redefined using larval morphology (Wheeler and Wheeler 1970). Many species-level larval descriptions have been published for Formicidae, but in only three cases has larval morphology been used for phylogenetic purposes (Wheeler and Wheeler 1970, Schultz and Meier 1995, Pitts et al. 2005).

The larval stages of ten species within the Solenopsis saevissima species-group are described in this study, eight for the first time. The morphology of these species is very similar, yet some variation occurs. Wheeler and Wheeler (1977) reported that S. invicta differed from S. richteri x invicta (described as S. richteri) in the number of setae on the dorsal side of the labrum and the number of sensilla on the ventral margin of the labrum. The present survey of many specimens and species revealed that minute features such as these are quite variable within species and thus are not very useful in species determinations. Mandibular dentition is of limited use due to varying degrees of wear resulting from feeding. Solenopsis saevissima species-group larvae are of little systematic significance because most larval features are broadly overlapping and continuous among species. However, two general groups of species can be defined on the basis of larval characters. One group includes those species with bifid setae dorsal to the antennal margin (S. metallica, n. sp., S. interrupta, S. invicta, S. pusillignis, S. saevissima), a condition termed the S. saevissima type. The other group contains those species with setae dorsal to the antennal margin that are usually simple or dentate (S. macdonaghi, S. megergates, S. quinquecuspis, and S. richteri), a condition termed the S. megergates type. This latter type appears on the basis of the inferred species phylogeny to be the apomorphic condition in the species-group (Pitts et al. 2005).

Morphology

Karyotype

Species Uncertain

• 2n = 38 (Malaysia) (Goni et al., 1982) (as Diplorhoptrum sp.).
• n = 11 (Australia) (Crozier, 1966).

All Karyotype Records for Genus

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Taxon	Haploid	Diploid	Karyotype	Locality	Source	Notes
Solenopsis		38		Malaysia	Goni et al., 1982	as ''Diplorhoptrum'' sp.
Solenopsis	11			Australia	Crozier, 1966
Solenopsis aurea	16	32		USA	Crozier, 1970b
Solenopsis fugax		22		Japan	Imai, 1969
Solenopsis fugax	11	22		Switzerland	Hauschteck, 1961
Solenopsis geminata		32	26M+6A	India	Imai et al., 1984
Solenopsis geminata	16	32		USA	Crozier, 1970b
Solenopsis geminata	16	32	14M+12SM+6ST	French Guiana	Aguiar et al., 2020
Solenopsis invicta	16	32		USA	Glancey et al., 1976
Solenopsis molesta	11	22		USA	Crozier, 1970b
Solenopsis richteri	16	32		USA	Glancey et al., 1976
Solenopsis saevissima	16	32	20M+10ST+2A	Uruguay	Goni et al., 1983
Solenopsis xyloni	16	32	28M+4A	USA	Taber & Cokendolpher, 1988

Nomenclature

The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

• 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.

Etymology

Mark Deyrup (2017) discovered the meaning and derivation of the genus name. Others had previously, and correctly, found the first part of the name was a derivation of the Greek Solon, which means "pipe or channel". Deyrup though was the first to realize the Greek word "opsis" can be translated as "face" and Solenopsis can be interpreted to mean "an ant with a groove on its face". Even though the heads of most Solenopsis species are not grooved, Deyrup had gone back to Westwood (1840), where the genus name was applied to the new species he named Solenopsis mandibularis. It turns out the name is based on features of the majors he examined. He noted "the toothless mandibles and the enlarged head divide into two lobes" and from this, the name was created "on account of (its) grooved face."

Beyond the name's derivation, it was subjected to an interesting twist of the rules of nomenclature. Solenopsis mandibularis is a synonym of Solenopsis geminata, an ant first described by Fabricius (1804) as Atta geminata. Thus mandibularis is no longer valid but Westwood's generic description is the first use of using a genus name other than Atta for a Solenopsis species.

References

• Arnold, G. 1916. A monograph of the Formicidae of South Africa. Part II. Ponerinae, Dorylinae. Ann. S. Afr. Mus. 14: 159-270 (page 242, Solenopsis in Myrmicinae, Solenopsidini)
• Ashmead, W. H. 1905c. A skeleton of a new arrangement of the families, subfamilies, tribes and genera of the ants, or the superfamily Formicoidea. Can. Entomol. 37: 381-384 (page 383, Solenopsis in Myrmicinae, Solenopsidini)
• Baigorria, J.A., Rubio, G.D., Stolar, C.E., Oklander, L.I. 2021. Notes on the jumping spider Corythalia conferta (Araneae: Salticidae), a possible myrmecophagous specialist in Argentina. Peckhamia 230.1, 1-12.
• Baker, A.J., Heraty, J.M., Mottern, J., Hang, J.Z., Hines, H.M., Lemmon, A.R., Lemmon, E.M. 2019. Inverse dispersal patterns in a group of ant parasitoids (Hymenoptera: Eucharitidae: Oraseminae) and their ant hosts. Systematic Entomology 45: 1–19 (doi:10.1111/syen.12371).
• Bolton, B. 1987. A review of the Solenopsis genus-group and revision of Afrotropical Monomorium Mayr (Hymenoptera: Formicidae). Bull. Br. Mus. (Nat. Hist.) Entomol. 54: 263-452 (page 271, 285, Solenopsis in Myrmicinae, Solenopsis genus group; Solenopsis senior synonym of Diplorhoptrum)
• Bolton, B. 1994. Identification guide to the ant genera of the world. Cambridge, Mass.: Harvard University Press, 222 pp. (page 106, Solenopsis in Myrmicinae, Solenopsidini)
• Bolton, B. 2003. Synopsis and Classification of Formicidae. Mem. Am. Entomol. Inst. 71: 370pp (page 218, Solenopsis in Myrmicinae, Solenopsidini)
• Creighton, W. S. 1930b. The New World species of the genus Solenopsis (Hymenop. Formicidae). Proc. Am. Acad. Arts Sci. 66: 39-151 (page 39, Revision of New World species (out of date))
• Cresson, E. T. 1887. Synopsis of the families and genera of the Hymenoptera of America, north of Mexico, together with a catalogue of the described species, and bibliography. Trans. Am. Entomol. Soc., Suppl. Vol. 1887: 1-351 (page 262, Solenopsis in Myrmicidae)
• Dalla Torre, K. W. von. 1893. Catalogus Hymenopterorum hucusque descriptorum systematicus et synonymicus. Vol. 7. Formicidae (Heterogyna). Leipzig: W. Engelmann, 289 pp. (page 75, Solenopsis in Myrmicinae)
• Dlussky, G. M.; Fedoseeva, E. B. 1988. Origin and early stages of evolution in ants. Pp. 70-144 in: Ponomarenko, A. G. (ed.) Cretaceous biocenotic crisis and insect evolution. Moskva: Nauka, 232 pp. (page 80, Solenopsis in Myrmicinae, Solenopsidini)
• Emery, C. 1877b. Saggio di un ordinamento naturale dei Mirmicidei, e considerazioni sulla filogenesi delle formiche. Bull. Soc. Entomol. Ital. 9: 67-83 (page 81, Solenopsis in Myrmicidae, Pheidolidae)
• Emery, C. 1895l. Die Gattung Dorylus Fab. und die systematische Eintheilung der Formiciden. Zool. Jahrb. Abt. Syst. Geogr. Biol. Tiere 8: 685-778 (page 770, Solenopsis in Myrmicinae, Solenopsidini)
• Emery, C. 1914e. Intorno alla classificazione dei Myrmicinae. Rend. Sess. R. Accad. Sci. Ist. Bologna Cl. Sci. Fis. (n.s.) 18: 29-42 (page 41, Solenopsis in Myrmicinae, Solenopsidini)
• Emery, C. 1922c. Hymenoptera. Fam. Formicidae. Subfam. Myrmicinae. [part]. Genera Insectorum 174B: 95-206 (page 195, Solenopsis in Myrmicinae, Solenopsidini)
• Emery, C.; Forel, A. 1879. Catalogue des Formicides d'Europe. Mitt. Schweiz. Entomol. Ges. 5: 441-481 (page 464, Solenopsis in Myrmicinae [Myrmicidae])
• Ettershank, G. 1966. A generic revision of the world Myrmicinae related to Solenopsis and Pheidologeton (Hymenoptera: Formicidae). Aust. J. Zool. 14: 73-171 (page 81, Solenopsis in Myrmicinae, Solenopsis genus group; Solenopsis senior synonym of Bisolenopsis, Diagyne, Euophthalma, Granisolenopsis, Labauchena, Lildris, Oedalecerus, Paranamyrma and Synsolenopsis)
• Forel, A. 1893b. Sur la classification de la famille des Formicides, avec remarques synonymiques. Ann. Soc. Entomol. Belg. 37: 161-167 (page 164, Solenopsis in Myrmicinae, Solenopsidini)
• Forel, A. 1895b. A fauna das formigas do Brazil. Bol. Mus. Para. Hist. Nat. Ethnogr. 1: 89-139 (page 130, Solenopsis in Myrmicinae, Solenopsidini)
• Forel, A. 1899e. Formicidae. [part]. Biol. Cent.-Am. Hym. 3: 57-80 (page 79, Solenopsis in Myrmicinae, Solenopsidini)
• Forel, A. 1917. Cadre synoptique actuel de la faune universelle des fourmis. Bull. Soc. Vaudoise Sci. Nat. 51: 229-253 (page 243, Solenopsis in Myrmicinae, Solenopsidini)
• Hamilton, N., Jones, T.H., Shik, J.Z., Wall, B., Schultz, T.R., Blair, H.A., Adams, R.M.M. 2018. Context is everything: mapping Cyphomyrmex-derived compounds to the fungus-growing ant phylogeny. Chemoecology 28, 137–144. (doi:10.1007/S00049-018-0265-5).
• Hölldobler, B.; Wilson, E. O. 1990. The ants. Cambridge, Mass.: Harvard University Press, xii + 732 pp. (page 16, Solenopsis in Myrmicinae, Solenopsidini)
• Jaffe, K. 1993. El mundo de las hormigas. Baruta, Venezuela: Equinoccio (Ediciones de la Universidad Simón Bolívar), 188 pp. (page 10, Solenopsis in Myrmicinae, Solenopsidini)
• Kempf, W. W. 1972b. Catálogo abreviado das formigas da regia~o Neotropical. Stud. Entomol. 15: 3-344 (page 232, Solenopsis in Myrmicinae, Solenopsidini; Solenopsis senior synonym of Diplorhoptrum)
• Mayr, G. 1865. Formicidae. In: Reise der Österreichischen Fregatte "Novara" um die Erde in den Jahren 1857, 1858, 1859. Zoologischer Theil. Bd. II. Abt. 1. Wien: K. Gerold's Sohn, 119 pp. (page 24, Solenopsis in Myrmicinae [Myrmicidae])
• Mendoza-Penagos, C.C., Hessen, K.O.V., Almeida, R.P.S. 2020. Assessing sodium limitation as a resource for ground-dwelling ants (Hymenoptera: Formicidae) in an area of the Amazonian Terra Firme Forest. Boletim do Museu Paraense Emílio Goeldi - Ciências Naturais 15, 135–143 (doi:10.46357/bcnaturais.v15i1.269).
• Pacheco, J.A. & Mackay, W.P. 2013. The systematics and biology of the New World thief ants of the genus Solenopsis (Hymenoptera: Formicidae). Edwin Mellen Press, Lewiston, New York. 501 pp.
• Pérez‐Marcos, M., López‐Gallego, E., Arnaldos, M.I., Martínez‐Ibáñez, D., García, M.D. 2020. Formicidae (Hymenoptera) community in corpses at different altitudes in a semiarid wild environment in the southeast of the Iberian Peninsula. Entomological Science 23, 297–310 (doi:10.1111/ENS.12422).
• Pitts, J.P., Camacho, G.P., Gotzek, D., McHugh, J.V., Ross, K.G. 2018. Revision of the fire ants of the Solenopisis saevissima species group (Hymenoptera: Formicidae). Proceedings of the Entomological Society of Washington. 120:308–411.
• Smith, D. R. 1979. Superfamily Formicoidea. Pp. 1323-1467 in: Krombein, K. V., Hurd, P. D., Smith, D. R., Burks, B. D. (eds.) Catalog of Hymenoptera in America north of Mexico. Volume 2. Apocrita (Aculeata). Washington, D.C.: Smithsonian Institution Pr (page 1384, Solenopsis in Myrmicinae, Solenopsidini)
• Smith, F. 1858a. Catalogue of hymenopterous insects in the collection of the British Museum. Part VI. Formicidae. London: British Museum, 216 pp. (page 177, Solenopsis in Poneridae, Attidae)
• Smith, F. 1860a. Descriptions of new species of hymenopterous insects collected by Mr. A. R. Wallace at Celebes. J. Proc. Linn. Soc. Lond. Zool. 5(17b)(suppl. to vol. 4 4: 57-93 (page 74, Solenopsis in Attidae)
• Smith, F. 1861b. Catalogue of hymenopterous insects collected by Mr. A. R. Wallace in the islands of Ceram, Celebes, Ternate, and Gilolo. [part]. J. Proc. Linn. Soc. Lond. Zool. 6: 36-48 (page 48, Solenopsis in Attidae)
• Smith, F. 1871a. A catalogue of the Aculeate Hymenoptera and Ichneumonidae of India and the Eastern Archipelago. With introductory remarks by A. R. Wallace. [part]. J. Linn. Soc. Lond. Zool. 11: 285-348 (page 333, Solenopsis in Myrmicidae)
• Snelling, R. R. 1963. The United States species of fire ants of the genus Solenopsis, subgenus Solenopsis Westwood, with synonymy of Solenopsis aurea Wheeler (Hymenoptera: Formicidae). Calif. Dep. Agric. Bur. Entomol. Occ. Pap. 3: 1-15 (page 7, Junior synonym of aurea)
• Taylor, R. W. 1991b. Nomenclature and distribution of some Australasian ants of the Myrmicinae (Hymenoptera: Formicidae). Mem. Qld. Mus. 30: 599-614 (page 611, Solenopsis senior synonym of Octella)
• Trager, J. C. 1991. A revision of the fire ants, Solenopsis geminata group (Hymenoptera: Formicidae: Myrmicinae). J. N. Y. Entomol. Soc. 99: 141-198 (page 141, Revision of geminata-group)
• Westwood, J. O. 1840b. Observations on the genus Typhlopone, with descriptions of several exotic species of ants. Ann. Mag. Nat. Hist. 6: 81-89 (page 86, Solenopsis as genus)
• Wheeler, G. C. and J. Wheeler. 1986. The ants of Nevada. Natural History Museum of Los Angeles County, Los Angeles.
• Wheeler, W. M. 1910b. Ants: their structure, development and behavior. New York: Columbia University Press, xxv + 663 pp. (page 140, Solenopsis in Myrmicinae, Solenopsidini)
• Wheeler, W. M. 1922i. Ants of the American Museum Congo expedition. A contribution to the myrmecology of Africa. VII. Keys to the genera and subgenera of ants. Bull. Am. Mus. Nat. Hist. 45: 631-710 (page 663, Solenopsis in Myrmicinae, Solenopsidini)