Camponotus fragilis

This nocturnal species nests in soil, most commonly under a covering object.

Identification
Major worker similar to Camponotus absquatulator in color and stature but erect setae present along entire head margin; minor workers with at least a few setae along head margins; differs from Camponotus festinatus by its smaller size and, in the major worker, by the lack of standing setae on the side of the pronotum.

Distribution
United States, Mexico. Camponotus fragilis occurs over most of the Lower California peninsula as far north on the Gulf of California coast at least to Bahía de los Angeles and northwest into southern California via San Diego County. It is also present on most, if not all, the islands of the Gulf of California and in the State of Sonora and north into Arizona (Tempe, Maricopa Co., the easternmost record) in the United States; from Sonora it ranges south along the coast to Nayarit: specimens that I collected on the Tres Marías Islands apparently are referable to C. fragilis. In California C. fragilis appears to be uncommon and is replaced in the lower desert of Imperial and Riverside Counties by Camponotus absquatulator. It is present in chaparral habitat in San Diego County, north to Riverside County and is found at mid-elevation sites along the margins of the lower desert, extending north into the Mojave Desert at least as far as the Old Woman Mountains (1.2 km S Sunflower Springs, 945 m), San Bernardino County. (Snelling 2006)

Distribution based on Regional Taxon Lists
Nearctic Region: United States. Neotropical Region: Mexico.

Habitat
Creosote Scrub, Coastal Scrub, Chaparral, and Oak Woodland.

Nomenclature

 *  fragilis. Camponotus fragilis Pergande, 1893: 26 (s.w.) MEXICO. Combination in C. (Myrmoturba): Forel, 1914a: 267. Subspecies of fumidus: Emery, 1895c: 336. Junior synonym of festinatus: Snelling, R.R. 1968b: 351. Revived from synonymy: Snelling, R.R. 2006: 89.

Worker
Snelling (2006) – Major. (n=12). Measurements: HL 2.25-2.70; HW 1.95-2.58; EL 0.50-0.60; SL 2.00-2.45; ML 3.10-3.45. Indices: CI 87-96; HFI 87-123; OI 21-25; SI 83-98.

Head shape about as in Camponotus festinatus. Mandible moderately shiny and weakly microreticulate between sparse, mostly round punctures; with six teeth, innermost acute or subtruncate to weakly bifid; usually subtended by a small acute tooth on inner margin.

Cephalic sculpture about as in C. festinatus but a little finer; malar area with only scattered round punctures and longest hairs about 0.1 mm long and absent on posterior one-third to one-half.

Pilosity generally similar to C. festinatus; side of pronotum without standing setae above ventral margin. Standing yellowish setae present on indicated surfaces: dorsal face of scape shaft (7-11), ventral margin of profemur (5-9), pronotum (10-16), mesonotum (5-12), propodeum (6-8), petiole (6-8), disc of gastral tergum I (10-12), premarginal row on gastral tergum I (14-16).

Media and minor. (n=12). Measurements: HL 1.20-1.75; HW 0.90-1.25; EL 0.40-0.45; SL 1.40-2.10; ML 1.85-2.60. Indices: CI 63-79; HFI 158-206; OI 27-45; SI 117-129.

Pilosity similar to C. festinatus with standing yellowish setae present on indicated surfaces: dorsal face of scape shaft (1-4), ventral margin of profemur (2-6), pronotum (4-10), mesonotum (2-6), propodeum (2-4), petiole (4-6), disc of gastral tergum I (6-10), premarginal row on gastral tergum I (6-8).

Queen
Snelling (2006) - (n=7). Measurements: HL 2.20-2.35; HW 2.00-2.15; EL 0.65-0.70; HFL 2.20-2.45; SL 1.90-2.15; PW 1.80-1.95; ML 3.85-4.20. Indices: CI 89-91; HFI 109-119; OI 28-30; SI 86-93.

Similar to queens of C. festinatus but distinctly smaller (ML 3.85-4.20 vs. 4.51-4.92) and malar area with scattered obscure round to slightly elliptical punctures and longest setae about 0.10 mm long (vs. about 0.20 mm); ICD 0.67-0.71 × HW; EL 0.76-0.93 × OMD; IOD 2.85-3.17 and OOD 3.00-3.25 × OD. Differs from queens of C. absquatulator by presence of erect setae along entire head margin.

Type Material
Snelling (2006) - Lectotype, by present designation, major worker. Mexico, Baja California Sur: San Fernando (label reads "San Fernando Mex."). A paralectotype minor worker in very poor condition in.

References based on Global Ant Biodiversity Informatics

 * Cover S. P., and R. A. Johnson. 20011. Checklist of Arizona Ants. Downloaded on January 7th at http://www.asu.edu/clas/sirgtools/AZants-2011%20updatev2.pdf
 * Dattilo W. et al. 2019. MEXICO ANTS: incidence and abundance along the Nearctic-Neotropical interface. Ecology https://doi.org/10.1002/ecy.2944
 * Emery C. 1886. Saggio di un catalogo sistematico dei generi Camponotus, Polyrhachis e affini. Memorie della Reale Accademia delle Scienze dell'Istituto di Bologna 5: 363-382
 * Johnson R. Personnal Database. Accessed on February 5th 2014 at http://www.asu.edu/clas/sirgtools/resources.htm
 * Kempf, W.W. 1972. Catalago abreviado das formigas da regiao Neotropical (Hym. Formicidae) Studia Entomologica 15(1-4).
 * Miguelena J. G., and P. B. Baker. 2019. Effects of urbanization on the diversity, abundance, and composition of ant assemblages in an arid city. Environmental Entomology doi: 10.1093/ee/nvz069.
 * Snelling R. R. 2006. Taxonomy of the Camponotus festinatus complex in the United States of America (Hymenoptera: Formicidae). Myrmecologische Nachrichten 8: 83-97
 * Vásquez-Bolaños M. 2011. Lista de especies de hormigas (Hymenoptera: Formicidae) para México. Dugesiana 18: 95-133
 * Wheeler W. M. 1905. The ants of the Bahamas, with a list of the known West Indian species. Bulletin of the American Museum of Natural History 21: 79-135.
 * Wheeler W. M. 1910. The North American ants of the genus Camponotus Mayr. Annals of the New York Academy of Sciences 20: 295-354.
 * Wheeler W. M. 1917. The mountain ants of western North America. Proceedings of the American Academy of Arts and Sciences 52: 457-569.