Solenopsis basalis

AntWiki: The Ants --- Online
Solenopsis basalis
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Solenopsidini
Genus: Solenopsis
Species complex: molesta
Species: S. basalis
Binomial name
Solenopsis basalis
Forel, 1895

Solenopsis basalis urichi casent0104999 profile 1.jpg

Solenopsis basalis urichi casent0104999 dorsal 1.jpg

Specimen labels


Solenopsis basalis can be found in rainforests in Brazil and Argentina. Additionally, S. basalis was collected in litter from montane evergreen forest and litter at 2100 m in lower yungas in Bolivia. (Pacheco and Mackay 2013)


A New World thief ant that is a member of the molesta species complex. (Key to New World Solenopsis Species Complexes)

Pacheco and Mackay (2013) – Worker - This species is usually bicolored with a yellow body and a dark brown gaster, with fine punctures on the dorsum of the head. Often the gaster is only slightly darker than the mesosoma. The clypeus has two angular lateral teeth and two extralateral bumps. The propodeal spiracle is relatively large at 0.042 mm in diameter. A character to note on this species is the wide petiole when viewed in profile as compared to the postpetiole. Queen - The gyne is bicolored with golden brown body with dark brown gaster. The clypeal carinae are weakly defined with a small medial ocellus at 0.060 rom in diameter. The propodeal spiracle is large at 0.090 rom in diameter.

The workers of S. basalis resemble those of Solenopsis decipiens which it overlaps in distribution, but can be separated by the width of the petiole (more slender in S. decipiens). This species is also similar to Solenopsis clytemnestra (which is also overlaps in distribution) but can be distinguished by the fine punctures on the head (coarse on S. clytemnestra).

Forel (1912, 1913, 1919) named several varieties of this species. Solenopsis basalis is a highly variable species with a range in morphs in certain phenotypic characters. Forel (1912) stated that S. urichi has a narrower head and a darker gaster as compared to the nominal of this bicolored species. Solenopsis basalis urichi does have lateral clypeal teeth that are more developed, but this is a variable character in addition to the variation in color and thus is synonymized. Solenopsis basalis urichi was described from Trinidad near Guiana and Venezuela. Since it is found in Brazil one would expect its distribution to continue into these countries and Trinidad. Forel (1912) diagnosed S. basalis vittata as slightly more slender than the nominal species and with a yellow gaster with brown highlights at each segment. These are also variable characters.

Solenopsis basalis raptor, urichi, vittata and novemmaculata all have a similar clypeus (and poorly developed teeth), the same deep depression of the notopropodeal suture and the same wide petiole when viewed in profile as the nominal form; all these features are suggestive of a single species-level taxon without subspecies. Solenopsis basalis oculatior has the same characters and is only different in being concolorous orange, similarly part of the overall color variation within this species.

Keys including this Species


Latitudinal Distribution Pattern

Latitudinal Range: 10.495797° to -38°.

Tropical South

Distribution based on Regional Taxon Lists

Neotropical Region: Argentina (type locality), Bolivia (type locality), Brazil (type locality), Colombia, Lesser Antilles, Trinidad and Tobago (type locality).

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb

Countries Occupied

Number of countries occupied by this species based on AntWiki Regional Taxon Lists. In general, fewer countries occupied indicates a narrower range, while more countries indicates a more widespread species.

Estimated Abundance

Relative abundance based on number of AntMaps records per species (this species within the purple bar). Fewer records (to the left) indicates a less abundant/encountered species while more records (to the right) indicates more abundant/encountered species.




Images from AntWeb

Solenopsis basalis urichi casent0104998 head 1.jpgSolenopsis basalis urichi casent0104998 profile 1.jpgSolenopsis basalis urichi casent0104998 dorsal 1.jpgSolenopsis basalis urichi casent0104998 label 1.jpg
Queen (alate/dealate). Specimen code casent0104998. Photographer April Nobile, uploaded by California Academy of Sciences. Owned by MHNG, Geneva, Switzerland.


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

  • basalis. Solenopsis basalis Forel, 1895j: 178 (w.) BRAZIL (Rio de Janeiro).
    • Type-material: lectotype worker (by designation of Pacheco & Mackay, 2013: 117), 1 paralectotype worker.
    • Type-locality: lectotype Brazil: Rio de Janeiro, Colonia Alpina, nr Theresopolis (A. Göldi); paralectotype with same data.
    • [Note: Pacheco & Mackay actually cite 6 specimens in MCZC; other original syntypes will certainly be in MHNG.]
    • Type-depository: MCZC.
    • Forel, 1913l: 219 (q.m.).
    • Status as species: Emery, 1906c: 123; Santschi, 1912e: 526; Forel, 1912g: 5; Forel, 1913l: 219; Bruch, 1914: 222; Bruch, 1915: 532; Emery, 1922e: 199; Wheeler, W.M. 1922c: 8; Borgmeier, 1927c: 102; Eidmann, 1936a: 45; Ettershank, 1966: 140; Kempf, 1972a: 233; Bolton, 1995b: 386; Pacheco & Mackay, 2013: 115 (redescription); Bezděčková, et al. 2015: 121; Fernández & Serna, 2019: 815.
    • Senior synonym of novemmaculata: Pacheco & Mackay, 2013: 115.
    • Senior synonym of oculatior: Pacheco & Mackay, 2013: 115.
    • Senior synonym of raptor: Pacheco & Mackay, 2013: 115.
    • Senior synonym of urichi: Pacheco & Mackay, 2013: 115.
    • Senior synonym of vittata: Pacheco & Mackay, 2013: 115.
    • Distribution: Argentina, Bolivia, Brazil, Colombia, Trinidad, St Vincent
  • novemmaculata. Solenopsis novemmaculata Wheeler, W.M. 1925a: 35 (w.) BOLIVIA.
    • Type-material: 3 syntype workers.
    • Type-locality: Bolivia: Mojos (N. Holmgren).
    • Type-depositories: MCZC, NHRS.
    • Status as species: Ettershank, 1966: 142; Kempf, 1972a: 238; Bolton, 1995b: 389.
    • Junior synonym of basalis: Pacheco & Mackay, 2013: 115.
  • oculatior. Solenopsis basalis r. oculatior Forel, 1913l: 220 (w.) ARGENTINA (Buenos Aires).
    • Type-material: syntype workers (number not stated).
    • Type-locality: Argentina: Tigre (Richter).
    • Type-depository: MHNG.
    • Subspecies of basalis: Bruch, 1914: 222; Forel, 1915c: 354; Santschi, 1916b: 510; Emery, 1922e: 199; Ettershank, 1966: 142; Kempf, 1972a: 233; Bolton, 1995b: 389.
    • Junior synonym of basalis: Pacheco & Mackay, 2013: 115.
  • raptor. Solenopsis basalis var. raptor Santschi, 1919f: 42 (w.) ARGENTINA (Buenos Aires).
    • Type-material: syntype workers (number not stated).
    • Type-locality: Argentina: Mar del Plata (von Steiger).
    • Type-depository: NHMB.
    • Subspecies of basalis: Ettershank, 1966: 143; Kempf, 1972a: 233; Bolton, 1995b: 390.
    • Junior synonym of basalis: Pacheco & Mackay, 2013: 115.
  • urichi. Solenopsis basalis var. urichi Forel, 1912g: 6 (w.q.) TRINIDAD, ST VINCENT & THE GRENADINES (St Vincent I.).
    • Type-material: syntype workers (number not stated), 1 syntype queen.
    • Type-localities: Trinidad: (no further data) (Urich), St Vincent & the Grenadines: St Vincent (no further data).
    • [Note: Pacheco & Mackay, 2013: 117, record both localities, 6 syntype workers.]
    • Type-depository: MHNG.
    • Subspecies of basalis: Wheeler, W.M. 1922c: 8; Emery, 1922e: 199; Ettershank, 1966: 144; Kempf, 1972a: 233; Bolton, 1995b: 391.
    • Junior synonym of basalis: Pacheco & Mackay, 2013: 115.
  • vittata. Solenopsis basalis var. vittata Forel, 1912g: 6 (w.) BRAZIL (Ceará).
    • Type-material: syntype workers (number not stated).
    • [Note: Pacheco & Mackay, 2013: 117, record 6 syntype workers.]
    • Type-locality: Brazil: Ceará (Diaz da Rocha).
    • Type-depository: MHNG.
    • [Solenopsis basalis var. vittata Forel, 1908e: 67. Nomen nudum.]
    • Subspecies of basalis: Emery, 1922e: 199; Borgmeier, 1927c: 102; Ettershank, 1966: 144; Kempf, 1972a: 233; Bolton, 1995b: 391.
    • Junior synonym of basalis: Pacheco & Mackay, 2013: 115.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.



Pacheco and Mackay (2013) - Measurements (n=27). TL 1.44-1.92 (1.69); HL 0.402-0.510 (0.439); HW 0.300-0.396 (0.368); EL 0.042-0.054 (0.051); ED 0.030-0.042 (0.037); SL 0.264-0.336 (0.296); FSL 0.084-0.132 (0.116); CI 68.5-89.6 (83.8); SI 58.8-82.1 (67.4); PL 0.066-0.078 (0.074); PW 0.090-0.126 (0.114); PI 55.0-86.7 (64.9); PPL 0.090-0.096 (0.091); PPW 0.102-0.144 (0.129); PPI 62.5-88.2 (70.8); WL 0.300-0.360 (0.316); PSL 0.030-0.054 (0.039); PSW 0.030-0.420 (0.055).

Bicolored with yellow head, mesosoma, dark brown (occasionally light brown) gaster, but at times concolorous yellow (as seen with some populations in Brazil, ex. vittata); eyes contain approximately six ommatidia; both lateral and extralateral teeth angular; clypeal carinae weakly defined; head quadrate with fine punctures; notopropodeal suture deeply depressed, groove breaks sculpture of mesosoma; metapleuron with horizontal striae; propodeal margin rounded, propodeal spiracle relatively large; petiole wide when viewed laterally, wider than postpetiole.

Hairy with erect and sub erect hairs covering all body surfaces; long erect hairs present at clypeal margin; antennae pilose, especially club; short suberect hairs present at posterior border of head; viewed in profile, mesosoma with erect hairs, several on pronotum, few on propodeum; petiole and postpetiole with suberect hairs that extend posteriorly; first tergite pilose with sub erect hairs that extend posteriorly.


Pacheco and Mackay (2013) - Measurements (n=4). TL 3.72-3.84 (3.78); HL 0.612-0.660 (0.641); HW 0.540-0.600 (0.578); EL 0.204-0.216 (0.210); ED 0.180; MOL 0.048-0.054 (0.051); MOD 0.054-0.060 (0.059); SL 0.420-0.480 (0.450); FSL 0.180-0.222 (0.209); CI 88.2-92.6 (90.1); SI 68.2-74.1 (70.2); PSL 0.078-0.090 (0.084); PSW 0.09-0.1 (0.095); PL 0.132-0.138 (0.135); PW 0.216-0.240 (0.228); PI 56.4-63.9 (59.3); PPL 0.168-0.210 (0.185); PPW 0.240-0.282 (0.270); PPI 63.8-74.5 (68.4); WL 0.840-0.960 (0.930).

Queen description (S. basalis urichi). Bicolored, golden yellow head and mesosoma, gaster brown; clypeal carinae weakly developed; lateral clypeal teeth angular, extralateral teeth absent; scape relatively long, but does not reach posterior border of head; medial ocellus relatively small (diameter 0.180 mm); eye extends past lateral margin of head by 0.060 mm, contains approximately 120-140 ommatidia; propodeal margin rounded with propodeal spiracle large; metapleuron with horizontal striae; petiole wider than postpetiole viewed laterally, petiole lacking subpeduncular process.

All body surfaces covered with erect and suberect hairs, majority approximately 0.120 mm in length.

Type Material

Pacheco and Mackay (2013) - (lectotype worker and 1 paralectotype worker [here designated]; Typus, 6 workers Museum of Comparative Zoology). S. basalis urichi, Trinidad, St. Vincent (Trenuvar) Urich 124; Typus, 6 workers Musee d'Histoire Naturelle Genève). S. basalis vittata, Typus, Brazil, Ceara, (Diaz Da Rocha) 47; Typus, 107, 6 workers Musee d'Histoire Naturelle Genève). S. basalis oculatior worker type, Argentina, Buenos Aires, 190, C. Bruch, 788, Mar de del Plata v. Steiger, Tigre (Richter leg.) Argentine unter Baumrinde (Type, 2 workers Musee d'Histoire Naturelle Genève). S. basalis raptor Type, Sammlung Dr. F. Santschi Kairouan; peru, Huacapistana, Rio Tarma, 1.2. June 1920, J.C.B. #821, cotypes, Wm. M. Wheeler, M.C.Z. Cotype 9-12, 20934 (5 workers Museum of Comparative Zoology). S. novemmaculata, Bolivia, Mojos, N. Holmgren, (Cotype, Wm. M. Wheeler, M.C.Z. Cotype 1,20943, 3 queens Museum of Comparative Zoology, Huacapistana, Rio Tarma, Peru, 1.2. June 1920, J.C.B. #821, cotype, Wm. M. Wheeler, M.C.Z. Cotype 2-4, 20943 Museum of Comparative Zoology; Cotypus, 1 worker, La Plata, les Bruch, 10.9.12, det. Forel, M.C.Z. Cotype 29400 Museum of Comparative Zoology).


References based on Global Ant Biodiversity Informatics

  • Bruch C. 1914. Catálogo sistemático de los formícidos argentinos. Revista del Museo de La Plata 19: 211-234.
  • Ettershank G. 1966. A generic revision of the world Myrmicinae related to Solenopsis and Pheidologeton (Hymenoptera: Formicidae). Aust. J. Zool. 14: 73-171.
  • Fernández, F. and S. Sendoya. 2004. Lista de las hormigas neotropicales. Biota Colombiana Volume 5, Number 1.
  • Forel A. 1908. Catálogo systemático da collecção de formigas do Ceará. Boletim do Museu Rocha 1(1): 62-69.
  • Forel A. 1912. Formicides néotropiques. Part IV. 3me sous-famille Myrmicinae Lep. (suite). Mémoires de la Société Entomologique de Belgique. 20: 1-32.
  • Forel A. 1913. Fourmis d'Argentine, du Brésil, du Guatémala & de Cuba reçues de M. M. Bruch, Prof. v. Ihering, Mlle Baez, M. Peper et M. Rovereto. Bulletin de la Société Vaudoise des Sciences Naturelles. 49: 203-250.
  • Huong N. T. T., P. V. Sang, and B. T. Viet. 2015. A preliminary study on diversity of ants (Hymenoptera: Formicidae) at Hon Ba Nature Reserve. Environmental Scientific Conference 7: 614-620.
  • Kempf, W.W. 1972. Catalago abreviado das formigas da regiao Neotropical (Hym. Formicidae) Studia Entomologica 15(1-4).
  • Kusnezov N. 1953. La fauna mirmecológica de Bolivia. Folia Universitaria. Cochabamba 6: 211-229.
  • Pacheco J. A., and W. P. Mackay. 2013. The systematics and biology of the New World thief ants of the genus Solenopsis (Hymenoptera: Formicidae). Lewiston, New York: Edwin Mellen Press, 501 pp.
  • Rosa da Silva R. 1999. Formigas (Hymenoptera: Formicidae) do oeste de Santa Catarina: historico das coletas e lista atualizada das especies do Estado de Santa Catarina. Biotemas 12(2): 75-100.
  • Santschi F. 1916. Descriptions de fourmis nouvelles d'Afrique et d'Amérique. Annales de la Société Entomologique de France 84: 497-513.
  • Wheeler W. M. 1922. The ants of Trinidad. American Museum Novitates 45: 1-16.
  • Wheeler W. M. 1925. Neotropical ants in the collections of the Royal Museum of Stockholm. Arkiv för Zoologi 17A(8): 1-55.