Camponotus quercicola

Camponotus quercicola is an arboreal species (Fisher, 1997) that nests in dead branches of the oak Quercus wislizenii and possibly other species of Quercus where it is probably polygynous (Gadau et al., 1999), and is primarily active at night. It is the dominant ant in many oak communities in California. It feeds on the exudates on the trees, although the nature of the exudates is unknown. Foragers are attracted to honey baits, and collect living insects and bird droppings. (Gadau et al., 1999; Mackay, 2019)

Compare with Camponotus americanus, Camponotus herculeanus, Camponotus laevigatus, Camponotus modoc, Camponotus novaeboracensis, Camponotus schaefferi, Camponotus texanus.

The major worker of C. quercicola is a predominantly black ant with most surfaces relatively smooth. The cheeks and malar area have numerous erect and suberect setae; the scape is without erect and suberect setae (except at the apex). Appressed pubescence is very sparse, short (> 0.01 mm) and obvious only on the side of the head and the dorsum of the gaster.

The minor worker is black, with dark brown appendages. Most surfaces are at least weakly shining, the side of the head and the side of the gaster are nearly glossy. The clypeus and the cheeks have several erect and suberect setae, erect and suberect setae are lacking on the scape and on the side of the head, there are few erect and suberect setae on the dorsum of the mesosoma, dorsum of the petiole, and all surfaces of the gaster. The head and the gaster have tiny appressed setae.

The female and male are unknown.

Comparisons
Camponotus quercicola majors could be easily confused with those of Camponotus laevigatus. They can be distinguished as the appressed setae on the dorsum of the gaster are easily seen, even under low magnification, whereas they cannot be seen on the dorsum of the gaster of C. laevigatus, even under high magnification (apparently are absent).

Major workers could also be confused with those of Camponotus modoc. They always have a few erect setae on the cheeks and malar area, whereas, C. modoc is without these setae.

Camponotus quercicola is very similar to Camponotus americanus (E USA, Oregon). It can be separated by color (entirely dark or black, C. americanus is in part yellow or brown) and by the western distribution (versus the primarily eastern distribution of C. americanus).

Smith (1953) compared C. quercicola to Camponotus novaeboracensis (S Canada, US, has not been reported in S CA), but separates it on the basis of color, by the coarse piligerous foveolae on the anterior part of the head and by other [not specified] characters. Camponotus quercicola can be easily separated from C. novaeboracensis on the basis of color and by the presence of erect and suberect setae on the cheeks and malar area in C. quercicola (absent in C. novaeboracensis). Smith (1953) noted that C. quercicola varies considerably in the numbers of erect and suberect setae on the mesosoma and the number and size of the foveolae on the cheeks.

Gadau et al. (1999) suggest that C. quercicola is not similar to Camponotus herculeanus (S Canada, US), based on the mitochondrial gene cytochrome oxidase I, and perhaps forms a group with Camponotus texanus (W TX) and Camponotus schaefferi (AZ, NM) and is part of the subgenus Camponotus clade. Camponotus quercicola can be separated from these other two species as it is nearly concolorous black, not medium brown to yellowish-red as in C. schaefferi nor bicolored as in C. texanus. Workers of C. schaefferi usually have a few erect setae along the shaft of the scape, which are also present in majors and minors of Camponotus quercicola, but absent in C. texanus (except at the apex of the scape), a few tiny setae elevated slightly from the shaft of the scape occur in C. texanus). It did not form a clade with the herculeanus group, based on mitochondrial gene cytochrome oxidase 1 (Gadau et al., 1999).

Camponotus quercicola has an intermediately developed clypeal notch, which prevents C. texanus (western Texas), C. schaefferi (New Mexico and Arizona) and C. quercicola from forming a separate species complex, based on morphology. The anterior clypeal border of the major and female of C. laevigatus looks concave, not weakly notched as in C. quercicola.

Camponotus quercicola is black, not bicolored as in Camponotus bellacolor (NE Mexico).

Camponotus quercicola is found in oak woodlands (Gadau et al., 1999) and also in Jeffrey pine forests.

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

Biology
The Argentine ant, Linepithema humile, has a negative impact on C. quercicola in northern California riparian woodlands (Holway, 1998). It is the host of Wolbachia bacteria (Wernegreen et al., 2009).

Nomenclature

 * . Camponotus (Camponotus) quercicola Smith, M.R. 1954b: 211 (w.) U.S.A. (California).
 * Gadau, et al. 1999: 516 (q.m.)
 * Status as species: Smith, M.R. 1958c: 143; Smith, D.R. 1979: 1427; Wheeler, G.C. & Wheeler, J. 1986g: 60 (in key); Bolton, 1995b: 119; Gadau, et al. 1999: 514 (redescription); Ward, 2005: 63; Mackay, 2019: 320 (redescription).

Description
Major worker measurements (mm): HL 3.16 - 3.30, HW 3.12 - 3.20, SL 2.92, EL 0.73 - 0.74, CL 1.08 - 1.15, CW 1.26 - 1.30, WL 4.20 - 4.36, FFL 2.60 - 2.66, FFW 0.84 - 0.90. Indices: CI 97 - 99, SI 88 - 92, CLI 113 - 117, FFI 32 - 34.

Mandible with 5 teeth; anterior border of clypeus concave, crenulated with small lateral teeth or angles; head narrowed anteriorly, sides of head convex, posterior margin concave; eyes failing to reach sides of head by about ½ minimum diameter; scape extending 2 funicular segments past posterior lateral corner of head; propodeum angulate between 2 faces of equal length, spiracle elongate; petiole narrow in profile, apex convex as seen from front.

Erect and suberect setae sparse, present on clypeus, including disc, on cheeks, on area along frontal carinae, near posterior margin of head, ventral surface of head, few setae on mesosoma, except present on angle between 2 faces of propodeum, present on petiole and gaster, absent on sides of head near eyes, on posterior lateral corners of head, scapes (except at apex), absent on tibiae, except for 1 - 2 rows of bristles on flexor surface of distal third of posterior tibia.

Head densely punctate, with scattered larger punctures, posterior half of head coriaceous, mesosoma coriaceous, gaster finely transversely striolate, most surfaces at least weakly shining, side of head strongly shining dorsum of gaster strongly shining.

Concolorous black.

Minor worker measurements (mm): HL 2.64 - 2.66, HW 1.92 - 2.30, SL 2.68, EL 0.64 - 0.65, CL 0.85 - 0.86, CW 1.08 - 1.10, WL 3.76 - 3.86, FFL 2.40 - 2.44, FFW 0.78. Indices: CI 73 - 86, SI 101 - 102, CLI 125 - 129, FFI 32.

Minor worker similar to major worker, except head elongate, sides of head nearly straight, almost parallel, posterior margin straight, eyes failing to reach sides of head by about ¼ minimum diameter; scapes extending 2 - 3 funicular segments past posterior lateral corner of head; propodeum angulate between 2 faces of equal length, posteropropodeum concave.

Pilosity, sculpture and color as in major worker.

References based on Global Ant Biodiversity Informatics

 * 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.
 * Gadau J., Brady S. G. and Ward P. S. 1999. Systematics, distribution and ecology of an endemic California Camponotus quercicola (Hymenoptera: Formicidae). Annals of the Entomological Society of America 92: 514-522
 * 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
 * Smith M. R. 1954. A new Camponotus in California apparently inhabiting live oak, Quercus sp. (Hymenoptera, Formicidae). Journal of the New York Entomological Society 61: 211-214.
 * Vásquez-Bolaños M. 2011. Lista de especies de hormigas (Hymenoptera: Formicidae) para México. Dugesiana 18: 95-133
 * Ward P. S. 2005. A synoptic review of the ants of California (Hymenoptera: Formicidae). Zootaxa 936: 1-68.