Solenopsis validiuscula

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Solenopsis validiuscula
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Solenopsidini
Genus: Solenopsis
Species complex: molesta
Species: S. validiuscula
Binomial name
Solenopsis validiuscula
Emery, 1895

Solenopsis validiuscula hal5.jpg

Solenopsis validiuscula hal11-5.jpg

Solenopsis validiuscula had5.jpg

These ants nest under stones and occasionally under logs in sagebrush/weedy communities, pine/oak forests, pinyon juniper forests, grassy clearings in pine/fir forests and are most common in ponderosa pine forests (ranging from 1200-9000 m) and riparian pine forests. In New Mexico, they have been found nesting under rocks near Camponotus and Lasius and reproductive have been found in August and September (Mackay and Mackay 2001). Brood and sexuals were found in nests in July and August in Colorado. It was found together with Camponotus spp. (especially Camponotus vicinus) and Lasius niger in Colorado and Myrmica hamulata, Formica argentea, Lasius sitiens and Lasius pallitarsis in New Mexico. Gregg (1963) lists them from a number of Colorado plant communities, ranging from grasslands to shrub lands and deciduous and coniferous forests, with sexuals collected in nests from July to October. They feed on carrion. They are found in fine sand/clay, moist brown loam rocky clay soils, rocky light brown loam, and rocky sandy soils. (Pacheco and Mackay 2013)

At a Glance • Limited invasive  


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 - These are relatively large, typically dark brown ants with moderately coarse cephalic punctures. The space between the tips of the lateral clypeal teeth is wide at 0.09 mm. A well-developed tooth is present ventrally on the petiolar peduncle. Queen - The queens are easily recognized as medium brown ants with a small median ocellus (0.080 mm maximum diameter) and relatively large eyes (0.240 mm). The space between the tips of the lateral clypeal teeth is wide at 0.144 mm. The scape is long and reaches the posterior border of the head. Male - undescribed). The males are dark brown with a small medium ocellus (0.102 mm), separated from the lateral ocellus by about two diameters and large eyes (maximum diameter 0.32 mm). The scape is short, approximately as long as the first 1.5 funicular segments.

Solenopsis validiuscula is similar to Solenopsis molesta, but can be separated on the basis of color (as S. molesta workers are typically yellow), size (S. molesta workers are smaller, 1.5-1.7 mm total length) and cephalic punctures (S. molesta typically have fine cephalic punctures). Moreover, the space between the tips of the lateral clypeal teeth of the queens and workers of S. molesta is shorter compared to "S. validiuscula". This species does not appear to be a synonym of S. molesta, based on the above characteristics and as the queens are distinctly different, in size of the ocelli, cephalic punctures and in color. Solenopsis validiuscula has been listed as Solenopsis truncorum throughout the literature, based on the misidentification of this species by Creighton (1950). Actually S. truncorum is here considered to be a synonym of Solenopsis carolinensis.

Keys including this Species


USA: Arizona, California, Colorado and New Mexico. Mexico: Coahuila, Colima. Canada(?): British Columbia.

Latitudinal Distribution Pattern

Latitudinal Range: 48.63° to 31.38583333°.

Tropical South

Distribution based on Regional Taxon Lists

Nearctic Region: United States (type locality).
Neotropical Region: Mexico.

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.

Pacheco and Mackay (2013) - We collected an interesting series of workers and winged queens from Canada (British Columbia, Jasper National Park, 19.30k N Jasper, Moberly Homestead, 1013m, 26-vii-2011, W&E Mackay # 24858 (34 workers, 32 alate queens CWEM, nest in soil, spruce/aspen forest, rocky loam), which appear to be S. validiuscula, but differ in having the lateral clypeal teeth more closely spaced (0.066 - 0.078 mm apart) and with smaller eyes. They will tentatively be considered S. validiuscula, although they are far from the known distribution of the species.



Solenopsis validiuscula Qhef6-3.jpgSolenopsis validiuscula Qhal2.jpgSolenopsis-Qsp had2.jpg


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

  • validiuscula. Solenopsis molesta var. validiuscula Emery, 1895c: 278 (w.) U.S.A. (California).
    • Type-material: syntype workers (number not stated).
    • Type-localities: U.S.A.: California, San Jacinto (no collector’s name), California, Los Angeles (no collector’s name).
    • Type-depository: MSNG.
    • [Note: Pacheco & Mackay, 2013: 345, report that they could not find the type-material.]
    • Wheeler, G.C. & Wheeler, J. 1955c: 135 (l.); Pacheco & Mackay, 2013: 343 (q.m.).
    • Subspecies of molesta: Wheeler, W.M. 1908e: 430; Wheeler, W.M. 1910g: 563; Wheeler, W.M. 1917a: 501; Emery, 1922e: 200; Essig, 1926: 859; Cole, 1936a: 35; Cole, 1937a: 99; Cole, 1942: 361; Creighton, 1950a: 237; Smith, M.R. 1951a: 814; Smith, M.R. 1958c: 129; Cole, 1966: 17 (in key); Ettershank, 1966: 144; Beck, et al. 1967: 72; Smith, M.R. 1967: 358; Yensen, et al. 1977: 183; Bolton, 1995b: 391.
    • Junior synonym of molesta: Smith, D.R. 1979: 1387; Snelling, R.R. & George, 1979:138; Coovert, 2005: 67.
    • Status as species: Pacheco & Mackay, 2013: 343 (redescription); Deyrup, 2017: 114.
    • Distribution: Mexico, U.S.A.

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=5). TL 1.50-1.80 (1.64); HL 0.450-0.498 (0.475); HW 0.384-0.432 (0.407); EL 0.036-0.048 (0.042); ED 0.030-0.036 (0.032); SL 0.300-0.330 (0.318); FSL 0.138-0.150 (0.144); CI 82.5-87.5 (85.6); SI 62.5-70.7 (66.9); PL 0.078-0.096 (0.082); PW 0.090-0.132 (0.116); PI 65.0-86.7 (70.9); PPL 0.120; PPW 0.132-0.150 (0.138); PPI 80.0-90.9 (87.1); WL 0.300-0.360 (0.323); PSL 0.030-0.036 (0.031); PSW 0.030-0.036 (0.031).

Moderately large; concolorous dark brown; head longer than wide, finely punctate; lateral clypeal teeth angulate, extralateral teeth absent; clypeal carinae well defined; eyes small, 3-5 ommatidia; scape does not reach posterior border of head; minor funicular segments 3-8 long; pronotum punctate, smooth and shiny between punctures; mesopleuron smooth and shiny; posterior propodeal margin nearly flat; propodeal spiracle small, rounded; metapleuron horizontally striated; petiole and postpetiole similar in size viewed laterally; petiolar node rounded, peduncle with well-defined tooth ventrally, translucent basally; postpetiolar node oval.

Moderately hairy; pilosity yellow; erect and suberect hairs covering all body surfaces; longest hairs on mesosoma 0.120 mm; hairs on petiole, postpetiole and first tergum of gaster curve posteriorly.


Pacheco and Mackay (2013) - Measurements (n=3). TL 5.16-5.52 (5.36); HL 0.762-0.768 (0.766); HW 0.720; EL 0.222-0.240 (0.228); ED 0.162-0.180 (0.168); MOL 0.072-0.084 (0.078); MOD 0.078; SL 0.522-0.540 (0.534); FSL 0.288-0.300 (0.296); CI 93.8-94.5 (93.9); SI 67.9-70.9 (69.7); PSL 0.078-0.084 (0.080); PSW 0.054; PL 0.180; PW 0.360-0.420 (0.388); PI 42.9-50.0 (46.6); PPL 0.300; PPW 0.420; PPI 71.4; WL 1.08-1.20 (1.14).

Large, concolorous medium brown; head square, barely longer than wide, finely punctate; lateral clypeal teeth well developed; extralateral teeth absent; space between lateral clypeal teeth wide at 0.144 mm; clypeal carinae well defined; scapes long, nearly reaching posterior border of head; minor funicular segments 3-8 long; eyes black, large; medial ocellus small; pronotum punctate, smooth and shiny between punctures; metapleuron smooth and shiny; posterior propodeal margin rounded; metapleuron horizontally striated; petiole wider than postpetiole viewed laterally; petiolar peduncle with well-developed tooth ventrally; petiole and postpetiole horizontally striated.

Abundantly hairy; pilosity yellow; erect and suberect hairs covering all body surfaces; longest hairs on pronotum 0.240 mm; hairs on petiole and postpetiole curve posteriorly.


Pacheco and Mackay (2013) - Measurements (n=2). TL3.28-3.70; HL 0.468-0.516; HW 0.502-0.516; EL 0.276-0.288; ED 0.196-0.216; MOL 0.072-0.078; MOD 0.078-0.114; SL 0.114-0.120; FSL 0.710-0.720; CI 97.3-110.3; SI 14.0-25.6; PSL 0.066-0.084; PSW 0.066-0.072; PL 0.180-0.216; PW 0.252-0.264; PI 72.0-83.3; PPL 0.216-0.254; PPW 0.300-0.324; PPI 66.7-84.7; WL 1.284-1.428.

Moderate sized, brown; head narrowed posteriorly, mostly smooth and shining; clypeal teeth absent, clypeal carinae absent; scapes short; minor funicular segments long; eyes black, large; pronotum shiny, mesopleuron and metapleuron smooth; scutum and scutellum smooth and glossy; posterior propodeal margin rounded; petiole longer than postpetiole (side view); petiolar peduncle with small ventral tooth; side of petiole finely punctated, side of postpetiole mostly shining.

Abundantly hairy, especially head, dorsum of mesosoma, petiole and postpetiole and gaster.


References based on Global Ant Biodiversity Informatics

  • Beck D. E., D. M. Allred, W. J. Despain. 1967. Predaceous-scavenger ants in Utah. Great Basin Naturalist 27: 67-78
  • Borchert, H.F. and N.L. Anderson. 1973. The Ants of the Bearpaw Mountains of Montana (Hymenoptera: Formicidae). Journal of the Kansas Entomological Society 46(2):200-224
  • Cole A. C., Jr. 1934. An annotated list of the ants of the Snake River Plains, Idaho (Hymenoptera: Formicidae). Psyche (Cambridge) 41: 221-227.
  • Cole A. C., Jr. 1936. An annotated list of the ants of Idaho (Hymenoptera: Formicidae). Canadian Entomologist 68: 34-39.
  • Cole A. C., Jr. 1937. An annotated list of the ants of Arizona (Hymen.: Formicidae). [part]. Entomological News 48: 97-101.
  • Cole A. C., Jr. 1953. Studies of New Mexico ants. VI. The genera Monomorium, Solenopsis, Myrmecina, and Trachymyrmex (Hymenoptera: Formicidae). [part]. Journal of the Tennessee Academy of Science 28: 299-300.
  • Cole, A.C. 1936. An annotated list of the ants of Idaho (Hymenoptera; Formicidae). Canadian Entomologist 68(2):34-39
  • Emery C. 1895. Beiträge zur Kenntniss der nordamerikanischen Ameisenfauna. (Schluss). Zoologische Jahrbücher. Abteilung für Systematik, Geographie und Biologie der Tiere 8: 257-360.
  • Gregg, R.T. 1963. The Ants of Colorado.
  • Johnson R. Personnal Database. Accessed on February 5th 2014 at
  • Knowlton G. F. 1970. Ants of Curlew Valley. Proceedings of the Utah Academy of Sciences, Arts and Letters 47(1): 208-212.
  • La Rivers I. 1968. A first listing of the ants of Nevada. Biological Society of Nevada, Occasional Papers 17: 1-12.
  • Lavigne R., and T. J. Tepedino. 1976. Checklist of the insects in Wyoming. I. Hymenoptera. Agric. Exp. Sta., Univ. Wyoming Res. J. 106: 24-26.
  • Mackay W. P., and E. E. Mackay. 2002. The ants of New Mexico (Hymenoptera: Formicidae). Lewiston, New York: Edwin Mellen Press, 400 pp.
  • Mallis A. 1941. A list of the ants of California with notes on their habits and distribution. Bulletin of the Southern California Academy of Sciences 40: 61-100. 
  • 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.
  • Rees D. M., and A. W. Grundmann. 1940. A preliminary list of the ants of Utah. Bulletin of the University of Utah, 31(5): 1-12.
  • Smith F. 1941. A list of the ants of Washington State. The Pan-Pacific Entomologist 17(1): 23-28.
  • Vasquez-Bolanos M. 2015. Taxonomia de Formicidae (Hymenoptera) para Mexico. Métodos en Ecología y Sistemática 10(1): 1. 53 pages.
  • Wenner A. M. 1959. The ants of Bidwell Park, Chico, California. American Midland Naturalist 62: 174-183
  • Wheeler W. M. 1901. The compound and mixed nests of American ants. Part II. The known cases of social symbiosis among American ants. American Naturalist. 35: 513-539.
  • Wheeler W. M. 1908. The ants of Texas, New Mexico and Arizona. (Part I.). Bulletin of the American Museum of Natural History 24: 399-485.
  • Wheeler W. M. 1917. The mountain ants of western North America. Proceedings of the American Academy of Arts and Sciences 52: 457-569.
  • Yensen, N.P., W.H. Clark and A. Francoeur. 1977. A checklist of Idaho Ants. The Pan-Pacific Entomologist 53:181-187