Camponotus essigi

A common, arboreal species from western North American, C. essigi extends from Washington and Idaho, United States, through California to northern Baja California, Mexico. Habitats range from chaparral and oak woodlands to pine-fir forest. Although primarily associated with oaks (both in dead branches and cynipid galls), C. essigi has also been found nesting in pine, cottonwood, cedar, and manzanita. Shields (1973) reported this species (as C. nearcticus) tending larvae of the lycaenid on Eriogonum kearneyi var. kearneyi in Nevada. (Snelling, 1988)

Identification
Snelling (1988) - Because the mandibles are rather sparsely punctate in the major workers of C. essigi this species can be confused with Camponotus hyatti, but even in the largest majors, the punctures are mostly separated by less than a puncture diameter. The interspaces may be smooth or lightly roughened. The most conspicuous difference, however, is the presence of a distinct metanotal impression in C. hyatti (Fig. 27) so that the basal face of the propodeum is convex; C. essigi lacks a distinct metanotal impression and the base of the propodeum is flat or slightly concave (Fig. 26).

This species is highly variable in color. Samples from northern localities or those at high elevations may be largely or entirely black. Most commonly, the head and gaster are dark and the mesosoma reddish. Most samples from southern California are largely yellowish red with only the two or three apical gastral segments blackish or brownish.

Distribution
The occurrence of this species in Trinidad (the Caribbean nation, and listed as the type locality for the junior synonym C. pertusus) is apparently in error and the locality is actually Trinidad, Humboldt County, California (Snelling, 2000). Thus this species does not occur outside western North America and is not invasive in the Caribbean.

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

Biology
Nevada, Wheeler and Wheeler (1986) - We have 7 records from 6 localities: 6,000-7,800 ft. The 4 reported habitats were in the Coniferous Forest Biome. One nest was in a decaying pine stump; 1 was in firewood; 1 was in a house. The records are widely scattered except for a concentration near Lake Tahoe.

Nomenclature

 * . Camponotus caryae var. essigi Smith, M.R. 1923b: 306 (s.w.) U.S.A. (California).
 * Type-material: 7 syntype major and minor workers.
 * [Note: Snelling, R.R. 2000: 601, mentions a queen as type-material, but this caste was not included in the original description.]
 * Type-locality: U.S.A.: California, Lagunitas, 23.vi.1913 (E.O. Essig?).
 * Type-depositories: MCZC, USNM.
 * Combination in C. (Myrmentoma): Creighton, 1950a: 387.
 * Status as species: Creighton, 1950a: 387; Smith, M.R. 1951a: 844; Yensen, et al. 1977: 183; Wheeler, G.C. & Wheeler, J. 1978: 392; Smith, D.R. 1979: 1432; Allred, 1982: 454; Wheeler, G.C. & Wheeler, J. 1986g: 61; Snelling, R.R. 1988: 68; Bolton, 1995b: 98; Snelling, R.R. 2000: 601; Hansen & Klotz, 2005: 89; Ward, 2005: 63.
 * Senior synonym of nevadensis: Wheeler, G.C. & Wheeler, J. 1986g: 61; Snelling, R.R. 1988: 68; Bolton, 1995b: 98.
 * Senior synonym of pertusus: Snelling, R.R. 2000: 601.
 * Distribution: U.S.A.
 * nevadensis. Camponotus (Myrmentoma) nevadensis Gregg, R.E. 1973: 39, fig. 1A (s.w.m.) U.S.A. (Nevada).
 * Type-material: holotype major worker, 6 paratype major workers, 51 paratype minor workers, 12 paratype males.
 * Type-locality: holotype U.S.A.: Nevada, Washoe County, Fuller Lake, 3 mi. S Verdi, 6000 ft, 28.ix.1968 (G.C. & E.W. Wheeler); paratypes with same data.
 * Type-depositories: FMNH (holotype); DRIR, FMNH, LACM (paratypes).
 * Status as species: Smith, D.R. 1979: 1432.
 * Junior synonym of essigi: Wheeler, G.C. & Wheeler, J. 1986g: 61; Snelling, R.R. 1988: 68; Bolton, 1995b: 113.
 * pertusus. Camponotus pertusus Mackay, W.P., in Mackay & Mackay, 1997b: 330, figs 4, 5, 9 (w.) TRINIDAD.
 * Type-material: holotype workers, 2 paratype workers.
 * Type-locality: holotype Trinidad: (no further data), summer 1908 (O.W. Barrett); paratypes with same data.
 * Type-depositories: USNM (holotype); USNM, WEMC (paratypes).
 * Combination in C. (Myrmentoma): Mackay & Mackay, 1997b: 319.
 * Junior synonym of essigi: Snelling, R.R. 2000: 601.

Taxonomic Notes
Snelling (2000) - Camponotus pertusus was described from three major workers from an un­specified locality in Trinidad, in the West Indies. In the discussion following the description of C. pertusus the MacKays noted that this ant is "very closely related to C. essigi" and distinguished between the two by means of trivial differences in the lengths of the appressed gastral pubescence. Camponotus essigi is a common and well-known species in the western United States (Snelling 1988) and that it should be closely related to a species found in Trinidad seemed unlikely to me. I have examined the type and one paratype of C. pertusus and find that this taxon is conspecific with C. essigi (new synonymy), and is apparently not from the island of Trinidad.

The label on the type specimens reads merely "Trinidad / summer 1907 / 0. W. Barrett" (the label clearly gives the year as 1907, not 1908 as stated by the MacKays in their paper). The only Trinidad that I can locate in the western United States is Trinidad, Humboldt County, California; C. essigi occurs in this area. While I have examined no other specimens collected by 0. W. Barrett, it is certainly arguable that Trinidad refers to this community rather than the South American Island, where no species belonging to the subgenus Myrmentoma is known to exist. This would appear to be the correct type locality for C. pertusus.

References based on Global Ant Biodiversity Informatics

 * Allred D. M. 1982. Ants of Utah. The Great Basin Naturalist 42: 415-511.
 * Allred, D.M. 1982. The ants of Utah. Great Basin Naturalist 42:415-511.
 * Dattilo W. et al. 2019. MEXICO ANTS: incidence and abundance along the Nearctic-Neotropical interface. Ecology https://doi.org/10.1002/ecy.2944
 * Des Lauriers J., and D. Ikeda. 2017. The ants (Hymenoptera: Formicidae) of the San Gabriel Mountains of Southern California, USA with an annotated list. In: Reynolds R. E. (Ed.) Desert Studies Symposium. California State University Desert Studies Consortium, 342 pp. Pages 264-277.
 * Fernández, F. and S. Sendoya. 2004. Lista de las hormigas neotropicales. Biota Colombiana Volume 5, Number 1.
 * Fisher B. L. 1997. A comparison of ant assemblages (Hymenoptera, Formicidae) on serpentine and non-serpentine soils in northern California. Insectes Sociaux 44: 23-33
 * Gregg R. E. 1973. A new species of Camponotus (Hymenoptera: Formicidae) from Nevada. The Southwestern Naturalist 18: 39-43.
 * Hoey-Chamberlain R. V., L. D. Hansen, J. H. Klotz and C. McNeeley. 2010. A survey of the ants of Washington and Surrounding areas in Idaho and Oregon focusing on disturbed sites (Hymenoptera: Formicidae). Sociobiology. 56: 195-207
 * Holway D.A. 1998. Effect of Argentine ant invasions on ground-dwelling arthropods in northern California riparian woodlands. Oecologia. 116: 252-258
 * Johnson, R.A. and P.S. Ward. 2002. Biogeography and endemism of ants (Hymenoptera: Formicidae) in Baja California, Mexico: a first overview. Journal of Biogeography 29:10091026/
 * Longino, J.T. 2010. Personal Communication. Longino Collection Database
 * Mackay, W.P. and E.E. Mackay. 1997. A revision of the Neotropical ants of the montivagus species complex, genus Camponotus, subgenus Myrmentoma (Hymenoptera: Formicidae). Sociobiology 30(3):319-333
 * Parson G. L., G Cassis, A. R. Moldenke, J. D. Lattin, N. H. Anderson, J. C. Miller, P. Hammond, T. Schowalter. 1991. Invertebrates of the H.J. Andrews Experimental Forest, western Cascade Range, Oregon. V: An annotated list of insects and other arthropods. Gen. Tech. Rep. PNW-GTR-290. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 168 p.
 * Ratchford, J.S., S.E. Wittman, E.S. Jules, A.M. Ellison, N.J. Gotelli and N.J. Sanders. 2005. The effects of fire, local environment and time on ant assemblages in fens and forests. Diversity and Distributions 11:487-497.
 * Snelling, R.R. 1988. Taxonomic notes on Nearctic species of Camponotus, subgenus Myrmentoma (Hymenoptera: Formicidae). pages 55-XX in J. Trager, editor, Advances in Myrmecology
 * Vásquez-Bolaños M. 2011. Lista de especies de hormigas (Hymenoptera: Formicidae) para México. Dugesiana 18: 95-133
 * Ward P. S. 1987. Distribution of the introduced Argentine ant (Iridomyrmex humilis) in natural habitats of the lower Sacramento Valley and its effects on the indigenous ant fauna. Hilgardia 55: 1-16
 * Wheeler G. C., and J. Wheeler. 1986. The ants of Nevada. Los Angeles: Natural History Museum of Los Angeles County, vii + 138 pp.
 * Wheeler, G.C. and J. Wheeler. 1978. Mountain ants of Nevada. Great Basin Naturalist 35(4):379-396
 * Yensen, N.P., W.H. Clark and A. Francoeur. 1977. A checklist of Idaho Ants. The Pan-Pacific Entomologist 53:181-187