Solenopsis basalis

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)

Identification
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.

Distribution based on Regional Taxon Lists
Neotropical Region: Argentina, Bolivia , Brazil , Colombia, Lesser Antilles, Trinidad and Tobago.

Nomenclature

 *  basalis. Solenopsis basalis Forel, 1895j: 178 (w.) BRAZIL. Forel, 1913l: 219 (q.m.). Senior synonym of novemmaculata, oculatior, raptor, urichi, vittata: Pacheco & Mackay, 2013: 115.
 * novemmaculata. Solenopsis novemmaculata Wheeler, W.M. 1925a: 35 (w.) BOLIVIA. Junior synonym of basalis: Pacheco & Mackay, 2013: 115.
 * oculatior. Solenopsis basalis r. oculatior Forel, 1913l: 220 (w.) ARGENTINA. Junior synonym of basalis: Pacheco & Mackay, 2013: 115.
 * raptor. Solenopsis basalis var. raptor Santschi, 1919f: 42 (w.) ARGENTINA. Junior synonym of basalis: Pacheco & Mackay, 2013: 115.
 * urichi. Solenopsis basalis var. urichi Forel, 1912g: 6 (w.q.) TRINIDAD. Junior synonym of basalis: Pacheco & Mackay, 2013: 115.
 * vittata. Solenopsis basalis var. vittata Forel, 1912g: 6 (w.) BRAZIL. [Solenopsis basalis v. vittata Forel, 1908e: 67. Nomen nudum.] Junior synonym of basalis: Pacheco & Mackay, 2013: 115.

Worker
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.

Queen
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 ). S. basalis urichi, Trinidad, St. Vincent (Trenuvar) Urich 124; Typus, 6 workers ). S. basalis vittata, Typus, Brazil, Ceara, (Diaz Da Rocha) 47; Typus, 107, 6 workers ). 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 ). 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 ). S. novemmaculata, Bolivia, Mojos, N. Holmgren, (Cotype, Wm. M. Wheeler, M.C.Z. Cotype 1,20943, 3 queens, Huacapistana, Rio Tarma, Peru, 1.2. June 1920, J.C.B. #821, cotype, Wm. M. Wheeler, M.C.Z. Cotype 2-4, 20943 ; Cotypus, 1 worker, La Plata, les Bruch, 10.9.12, det. Forel, M.C.Z. Cotype 29400 ).

References based on Global Ant Biodiversity Informatics

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 * 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.