Camponotus festinatus

This species has a tangled taxonomic history and is part of a species complex (see below).

Identification
This species is part of a complex that Snelling (2006) characterized as follows: defined by the following combination of features that will separate it from all other Nearctic species complexes: (1) the clypeus bears a well defined median ridge ("carina"); (2) the anterior margin of the clypeal median lobe is broadly transverse or shallowly concave; (3) the lateral margins of the head, as seen in full face view are evenly beset with short, stiff erect setae that extend from the base of the mandible to the posterolateral corner of the head (limited to the malar area in one species); (4) antennal scape shaft with at least a few erect setae, at least in major workers and queens; (5) side of pronotum of major workers often with standing setae above ventral margin; (6) appressed pubescence of gastral terga short and widely scattered, adjacent hairs separated by much more than their lengths; (7) head and body light yellowish brown with varying degrees of darker brownish infuscation.

See the nomenclature section below for details regarding how it may be possible to distinguish this ant from others in this complex.

Distribution
Snelling (2006) - Central Texas to the mountains of southern and central Arizona and adjacent States in northern Mexico. The extent of the southward distribution is unclear at this time. I have seen samples from as far south as the State of Jalisco that might prove to be C. festinatus when more adequate material becomes available. Westernmost records of C. festinatus are from central Arizona: Maricopa Co. (Mazatzal Mts.), Pinal Co. (Queen Creek Canyon) and Yavapai Co. (Lynx Lake).

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

Biology
Camponotus festinatus is a species primarily of oak woodlands. Nests are in soil, commonly beneath stones or other covering objects, most often on rocky hillsides.

Chemical Ecology
LeBrun et al. (2015) found a behaviour, first noted and resulting from interactions between Solenopsis invicta and Nylanderia fulva, that detoxifies fire ant venom is expressed widely across ants in the subfamily Formicinae. This behavior was also studied and shown in experiments with C. festinatus. See the biology section of the N. fulva page for a description of acidopore grooming and the use of formic acid for detoxification of a specific class of venoms that are produced by ants that may interact with formicines in the context of predation and food competition.

Nomenclature

 *  festinatus. Formica festinata Buckley, 1866: 164 (w.q.) U.S.A. Wheeler, W.M. 1910d: 312 (s.m.); Wheeler, G.C. & Wheeler, J. 1970: 651 (l.). Combination in Camponotus: Dalla Torre, 1893: 231; in C. (Myrmoturba): Wheeler, W.M. 1917a: 561; in C. (Tanaemyrmex): Emery, 1925b: 80. Subspecies of fumidus: Wheeler, W.M. 1902f: 22; Creighton, 1950a: 376. Revived status as species: Snelling, R.R. 1968b: 350. Senior synonym of pubicornis: Wheeler, W.M. 1910d: 312; of spurcus: Creighton, 1950a: 376; of †juliae: Snelling, R.R. (pers. comm., unpublished). See also: Snelling, R.R. 2006: 85.
 * pubicornis. Camponotus fumidus var. pubicornis Emery, 1893i: 670 (s.w.) U.S.A. Junior synonym of festinatus: Wheeler, W.M. 1910d: 312.
 * spurcus. Camponotus fumidus var. spurcus Wheeler, W.M. 1910d: 315 (s.w.q.) U.S.A. Combination in C. (Tanaemyrmex): Emery, 1925b: 80. Junior synonym of festinatus: Creighton, 1950a: 376.

Snelling in (2006) discussed some of the problems with this species name.....

Regarding Buckley's Formica festinata, Wheeler(1902) noted that this was "... recognizable with certainty as a variety of Camponotus fumidus of very common occurrence on the dry hill-slopes of Central Texas." Camponotus fumidus was described by Roger (1863) from a major worker from Venezuela. The type specimen apparently is no longer extant (F. Koch, pers. comm.) and there is no certainty now of its identity. By 1925 C. fumidus had acquired 13 subspecies / varieties, ranging from northern South America to the southwestern United States and the Antilles, from Dominica to the Bahamas (Emery 1925), even though there was never a clear concept of Roger's species. The situation has been further complicated by the existence of an additional related, if not synonymous, taxon, Camponotus picipes (Oliver 1792), with it's own accumulation of subspecies and / or varieties, eight in all, occupying much the same range as that of the protean C. fumidus. As in the case of C. fumidus, there is no clear concept of C. picipes nor have type specimens, if they still exist, been examined in recent years but that is a problem beyond the purview of the present paper. Snelling (1968) proposed that C. festinatus be elevated to full species, carrying with it those synonyms listed by Creighton (1950), but including also Camponotus fragilis Pergande, 1894. Two Antillean forms, Camponotus vittatus Forel, 1904, and Camponotus lucayanus Wheeler, 1905, were also recognized as full species.

Moving beyond the issues outlined above, Snelling then when on to detail what he felt were the species that C. festinata could be confused with......

The color of this species is subject to considerable variation. The basic pattern: a yellowish brown ant, with variable degrees of darker brownish infuscation, particularly on the head and gaster, each of which may be almost wholly brown. When the gaster is largely brown, there usually are distinct yellowish spots on lateral areas on the second and third terga as well as at the base of the first segment. Typically, too, the antennal scape and the tibiae are darker brownish. Specimens from the Chisos Mountains in western Texas are much lighter in color than the types, with almost no brownish infuscation, and thus are similar to Camponotus fragilis.

Most similar in stature and color to Camponotus festinatus is Camponotus pudorosus, a species that ranges from the Mexican State of Hidalgo north to the mountains of southern Arizona. The two differ in the pilosity of the scape. In C. pudorosus there is a mixture of subdecumbent to erect setae that are quite variable in length with the shortest setae far more abundant. In contrast the scape of C. festinatus has scattered appressed fine pubescence and sparse longer erect setae in the major worker and queen, and few or no standing setae of any inclination in the media and minor workers.

The range of C. festinatus overlaps that of Camponotus microps in the mountains of southern Arizona, but that species, as the name implies, has distinctly smaller eyes. Also generally sympatric is Camponotus vafer, known from only a few collections in the mountains of southwestern New Mexico, southern Arizona and northeastern Sonora, Mexico. Unlike C. festinatus and other members of the festinatus complex, C. vafer nests in dead branches of live oaks, rather than in the ground. In C. vafer major workers and queens, the anterior margin of the clypeus is most often slightly incurved (transverse in C. festinatus) and in the minor workers there are usually 6 - 14 fully erect setae along the mesial and dorsal faces of the antennal scape (absent in most minor workers in any nest population in C. festinatus).

Two smaller species in this complex are found at lower elevations west of the range of C. festinatus: Camponotus fragilis and Camponotus absquatulator. The latter is limited to the Sonoran Desert portions of southern California. In major workers there are no erect setae along the head margins posterior to the anterior margin of the compound eyes. The setae on the malar area are shorter and sparser than in C. festinatus. Minor workers, too, lack marginal setae posterior to the anterior eye margins and often none along the outer margin of the malar area.

Camponotus fragilis is similar to Camponotus absquatulator in color and stature, but does possess erect setae along the entire head margin; in minor workers these setae may be sparse, but there are always at least 2 or 3 between the level of the eyes and the posterolateral angles of the head. Separation of C. festinatus and C. fragilis is no easy matter as the two are distressingly similar in virtually every feature. Furthermore, since C. fragilis is allopatric to C. festinatus, the two species hypothesis has not the benefit of the test of sympatry that so usefully distinguishes C. festinatus from such species as Camponotus microps, Camponotus pudorosus, and Camponotus vafer. Comparative genetic and molecular studies, such as those that separate C. festinatus from its sympatric relatives, are not yet available. Until such data become available the distinctions between C. festinatus and C. fragilis will be a bit uncertain. For the present I have relied upon the larger size of C. festinatus and the presence of standing setae on the side of the pronotum above the ventral margin to distinguish between the two. The latter feature is limited to the major workers.

Worker
Snelling (2006) Mandible of major worker microreticulate on basal half between scattered piligerous punctures; anterior half of malar area with numerous coarse elongate punctures; scape of major worker with a variable number of fully erect setae, but pubescence fully appressed, that of minor worker with fewer than 3 fine suberect setae (usually none) and pubescence fully appressed; both subcastes with suberect to erect setae along entire head margin in frontal view.

major (n = 12). Measurements (mm): HL 2.75 - 3.00; HW 2.45 - 2.75; EL 0.60 - 0.70; SL 2.50 - 2.70; ML 3.55 - 3.85. Indices: CI 84 - 93; HFI 109 - 116; OI 22 - 24; SI 88 - 95.

Medium-sized species in the C. festinatus complex. Head wedge-shaped, broadest at or slightly above level of eyes, evenly tapering to base of mandibles. Mandible microreticulate basad, becoming smoother and shinier apicad, with scattered piligerous punctures, rarely with a few weak longitudinal rugae near base; masticatory margin with six teeth, the first five (counting from apex) acute; proximal tooth larger than preceding teeth and slightly offset, acute to truncate or weakly bifid; subtended by an offset small tooth on inner basal margin (sometimes sufficiently strong that mandible appears to be seven-toothed). Head at least slightly longer than broad, sides weakly convex and divergent behind and broadly rounded into concave posterior (preoccipital) margin. EL about one-quarter of HL; in frontal view outer margin of eye separated from head margin by about 0.50 × EW; ICD 0.58 - 0.63 × HW. Disc of clypeus distinctly subangulate along midline; anterior margin truncate, transverse to very weakly concave in middle. Scape long, its apex distinctly surpassing posterolateral angles of head; scape base subcylindrical. Frontal carinae separated anteriorly by about one-fifth HW, flaring out posteriorly to about one-third HW. Entire head slightly shiny and coarsely microreticulate between sparse piligerous punctures; anterior half of malar area with coarser elongate punctures; gena slightly shiny below eye, coarsely microreticulate between mostly elliptical piligerous punctures. Mesosomal dorsum moderately convex in profile; metanotum usually distinctly defined by anterior and posterior unimpressed lines (mesometanotal line sometimes weakly impressed); dorsal face of propodeum broadly rounded into declivitous face and about one-third longer than declivitous face.

Petiole simple, scale-like in profile and summit distinctly convex in posterior view. Legs relatively short, metatibia 2.75 - 3.20 mm long.

Body moderately shiny and weakly microreticulate; head duller and more strongly microreticulate; with sparse to scattered moderately coarse piligerous punctures; anterior malar area with conspicuous coarse elongate punctures.

Pilosity moderately abundant on dorsal surfaces of head and body, setae apically acute and yellowish; malar area and margins of head with numerous short standing setae, longest setae c. 0.20 mm long; underside of head with numerous standing setae, ranging from 0.13 - 0.30 mm long; side of pronotum with several standing setae above ventral margin; the following numbers of medium length to long standing setae present on indicated structures: scape shaft (15+), ventral margin of profemur (10 - 19), pronotum (18 - 26), mesonotum (9 - 14), propodeum (10 - 16), petiole (5 - 12), disc of gastral tergum I (14 - 18), premarginal row on gastral tergum I (11 - 14). Fine appressed pubescence absent, or nearly so, from most head and body surfaces (conspicuous only on scape shaft).

Body and appendages yellowish brown, head more brownish; gastral segments darker brownish, at least at base, sometimes largely brownish.

medium and small workers (n = 20). Measurements (mm): HL 1.65 - 2.00; HW 1.05 - 1.40; EL 0.40 - 0.55; SL 2.20 - 2.45; ML 2.60 - 3.15. Indices: CI 61 - 70; HFI 137 - 235; OI 25 - 28; SI 121 - 133.

Mandible shiny and weakly microreticulate and with scattered piligerous punctures; masticatory margin with six or seven teeth, proximal tooth robust and subtruncate, remaining teeth acute. Head distinctly longer than broad, lateral margins subparallel anterior to eyes, slightly convex and narrower behind eyes, preoccipital margin transverse (Note: The head shape of the minor worker is grossly distorted in the figure – no. 346 – by MACKAY & MACKAY 2002). Eye situated behind midlength of head; EL about 0.25 × HL; in frontal view outer margin extending slightly beyond margin of head; ICD 0.60 - 0.70 × HW. Clypeus and scape as in major worker, but anterior margin of clypeus consistently transverse. Frontal carinae separated anteriorly by about 0.40 × HW, widening posteriorly to about 0.30 × HW.

Mesosoma similar to major worker but propodeal profile more evenly rounded and metanotum not defined.

Head and body moderately shiny; head shinier than that of major worker and less conspicuously microreticulate, especially on malar and genal areas; malar area with scattered fine round punctures.

Pilosity about as in major; the following numbers of medium length to long brownish standing setae on the followng structures: scape shaft (0 - 2), profemur (8 - 13), pronotum (11 - 15), mesonotum (4 - 7), propodeum (5 - 7), petiole (4 - 8), disc of gastral tergum I (6 - 10), premarginal row on gastral tergum I (6 - 10).

Head, body and appendages yellowish brown, gastral terga with varying degrees of darker brownish at base.

Queen
Snelling (2006 - (n = 3), measurements: HL 2.56 - 2.72; HW 2.00 - 2.31; EL 0.72 - 0.77; SL 2.36 - 2.72; ML 4.51 - 4.92. Indices: CI 78 - 90; HFI 120 - 146; OI 28; SI 92 - 104.

Head about as in major worker but less strongly narrowed anteriorly and preoccipital margin slightly convex. Eye margin slightly exceeding head margin; ICD - 0.74 × HW. IOD about 4.5 times and OOD about 3.5 × OD.

Pilosity about as in media and minor workers.

Color about as described for major workers, but gaster more extensively infuscated.

Type Material
Snelling (2006): Because no type material of Camponotus festinatus, the pivotal species in the complex, is known to exist, its identity is here stabilized by the designation of a neotype worker: United States of America, Texas, Travis Co., Austin, 150 m (37.53° N, 097.74° W), 6.VIII.1954, leg. A.C. Cole, # T46, under stone. In case of destruction or loss of the neotype specimen, a replacement neotype can be designated from: a series of workers, same locality, 13. 14.IX.1942, leg. W. F. Buren; series of workers and queens, Ozona (17 mi S), Crockett Co., 24.VII.1955, leg. A.C. Cole, # T117, in soil under several large stones (, LACM,, , ).

Determination Clarifications
This species, and this species name, is a poster child for taxonomic confusion. Snelling (2006) best summarized the problem: "The prevailing concept of Camponotus festinatus (Buckley, 1866) beginning with Wheeler (1902) up to and including that of Mackay and Mackay (2002) has always been uncertain. In part, this has been due to the lack of a proper description of this taxon; the original description was hopelessly vague and subsequent descriptions have done little to improve matters. A further difficulty was that over its entire range, extending from central Texas to the Pacific Coast and south well into Mexico, C. "festinatus" displayed a bewildering array of variant forms."