Camponotus imitator

Camponotus imitator has been collected by litter sifting, Malaise and pitfall traps, as well as beating low vegetation and from the ground in rotten logs. It nests underground. The minor worker of Camponotus imitator is thought to mimic the myrmicine ant Aphaenogaster swammerdami due to its color and the form of its constricted mesonotum and shape of propodeum, which could appear as a petiole in dorsal view. The distribution of C. imitator is sympatric with A. swammerdami through most of its range. (Rasoamanana et al., 2017)

Identification
Rasoamanana et al. (2017) - Camponotus imitator is easily recognizable within the group (Myrmopytia) on the basis of the following combination of characters: posterior region of head only slightly extended, not narrowed into a long neck in the minor worker, PoOC/CL 0.256 [0.224, 0.304] and trapezoidal in major worker, CWb/CL 0.951 [0.841, 1.031]; anterior clypeal margin with a rectangular projection ClyL/CL 0.289 [0.231, 0.316]; petiole nodiform PEW/CS 0.224 [0.203, 0.255]; both castes bicolored: head, mesosoma and appendages reddish brown to dark brown, gaster black (minor) to mainly black (major).

Rakotonirina & Fisher (2022) - With head in full-face view, posterior portion of head extending into a neck, and anteromedian clypeal margin continuously forming broad convexity; dorsal outline of mesosoma complex; body color black to dark brown.

Camponotus imitator can be easily separated from the other species of the Myrmosaga group in that it is the only species that is characterized by an elongate mesonotum that is constricted at midlength, and its propodeum is broadly convex when the mesosoma is viewed in proﬁle.

Distribution
Dry forest and woodland of western and southern Madagascar at elevations ranging from 25 m to 990 m.

Distribution based on Regional Taxon Lists
Malagasy Region: Madagascar.

Mimicry
Within Madagascar, there are four species of Camponotus, Camponotus imitator, Camponotus jodina, Camponotus karaha and Camponotus longicollis, that mimic the general form and behavior of the Aphaenogaster swammerdami group, specifically Aphaenogaster bressleri, Aphaenogaster gonacantha, Aphaenogaster makay, Aphaenogaster sahafina and Aphaenogaster swammerdami. These Camponotus mimics are often seen foraging with workers of Aphaenogaster, but potential benefits for Camponotus have not been studied (Csosz et al., 2021).

Nomenclature

 * . Camponotus imitator Forel, 1891b: 209, pl. 4, fig. 15; pl. 5, fig. 8 (w.) MADAGASCAR.
 * Combination in C. (Myrmosphincta): Forel, 1912i: 92;
 * combination in C. (Myrmopytia): Emery, 1920b: 257.
 * Status as species: Dalla Torre, 1893: 235; Emery, 1896d: 374 (in list); Forel, 1907g: 92; Wheeler, W.M. 1922a: 1048; Emery, 1925b: 115; Bolton, 1995b: 104; Rasoamanana, et al. 2017: 133 (redescription).
 * Senior synonym of resinicola: Rasoamanana, et al. 2017: 133.
 * resinicola. Camponotus imitator var. resinicola Santschi, 1911e: 133 (w.) MADAGASCAR.
 * Combination in C. (Myrmopytia): Wheeler, W.M. 1922a: 1049; Emery, 1925b: 115.
 * Status as species: Wheeler, W.M. 1922a: 1049.
 * Subspecies of imitator: Emery, 1925b: 115; Bolton, 1995b: 120.
 * Junior synonym of imitator: Rasoamanana, et al. 2017: 133.

Worker
Rasoamanana et al. (2007) - Minor Head suboval, posterior region of head only slightly and broadly extended with margins weakly convex. (CS) 1.68 mm [1.34, 2.18] (n=25). Standing setae present on posterolateral margin of head and vertex in full-face view. Eyes situated on posterior half of head, PoOC/CL 0.253 [0.224, 0.293]. Frontal carina convex, FR/CS 0.254 [0.209, 0.280], antennal scape surpassing posterior margin of head by more than half its length, SL/CS 1.517 [1.211, 1.731]. Anteromargin of clypeus with broad rectangular projection, posterior margin concave, ClyL/CL 0.271 [0.231, 0.293]; mandible with six teeth, palps long with respect to head size.

Pronotum weakly undulant. Suberect pronotal setae numerous (more than 12). Mesonotum straight, MPD/CS 1.181 [0.954, 1.403]. Erect mesonotal setae varying from absent to numerous (two or three pairs anterior to mesothoracic spiracle). Mesothoracic spiracles prominent; propodeal dorsum protuberant. Erect propodeal setae moderate in number (4–6). ML/CS 1.957 [1.670, 2.149]. Petiole nodiform, dorsum of node convex, petiole higher than broad, PEW/CS 0.242 [0.164, 0.264]. Erect setae present on petiolar apex.

Color: head and mesosoma red to reddish brown, gaster dark brown to black. Erect setae light brown. Sparse appressed pubescence present.

Major In full-face view, head truncated posteriorly, evenly tapering to base of mandibles, posterior margin of head weakly concave. Absolute cephalic size (CS) 3.26 mm [2.32, 3.94] (n=22). Cephalic margin with scattered short hairs; cephalic dorsum coarsely reticulate-foveolate. Eye situated on posterior half of the head, PoOC/CL 0.284 [0.242, 0.323]. Frontal carinae sinuate, FR/CS 0.260 [0.209, 0.280], coronal line distinct, antennal scape just surpassing the posterior margin of head by length of one funiculus segment, SL/CS 0.853 [0.711, 1.155]. Anterior margin of clypeus with a rectangular projection, medially straight to slightly convex, ClyL/CL 0.294 [0.269, 0.326]; masticatory margin of mandible with 7–10 teeth, microreticulate at base, becoming finely striolate apically, with scattered piligerous punctures, rarely with a few weak longitudinal rugae near base.

Dorsal outline of mesosoma complex. Promesonotum forms a regular convexity with a shallow impression at the promesonotal suture and is stepped to the propodeal dorsum. Suberect promesonotal setae inclined anteriorly, ML/CS 1.337 [1.168, 1.655]; metanotum distinct; propodeal dorsum almost straight to evenly convex, posterodorsal margin forms rounded angle with declivity.

Petiole higher than broad, node summit flat; brown standing setae present on entire dorsum. PEW/CS 0.221 [0.199, 0.247].

Color: head, mesosoma, petiole, and base of first gastral segment reddish brown, remainder of gaster dark brown to black. Scattered appressed pubescence generally present. Setae light brown.

Taxonomic Notes
Rasoamanana et al. (2017) - We propose that Camponotus imitator resinicola (Santschi, 1911) is synonymized with Camponotus imitator Forel. In the original descriptions, the former differs from the latter by the presence of reddish patches on the first gastral segment near the petiolar insertion. Examination of material from 10 collection events of C. imitator colonies indicates that this trait is highly variable within colonies, and no other reliable characters were found to separate the subspecies from imitator. Moreover, no other qualitative trait or biogeographic evidence exists that would underpin the subspecies status of resinicola.

References based on Global Ant Biodiversity Informatics

 * Fisher B. L. 1997. Biogeography and ecology of the ant fauna of Madagascar (Hymenoptera: Formicidae). Journal of Natural History 31: 269-302.
 * Fisher B. L. 2003. Formicidae, ants. Pp. 811-819 in: Goodman, S. M.; Benstead, J. P. (eds.) 2003. The natural history of Madagascar. Chicago: University of Chicago Press, xxi + 1709 pp.
 * Ravelomanana A., and B. L. Fisher. 2013. Diversity of ants in burned and unburned grassland, and dry deciduous forest in the Beanka Reserve, Melaky Region, western Madagascar. Malagasy Nature 7: 171-183.
 * Wheeler W. M. 1922. Ants of the American Museum Congo expedition. A contribution to the myrmecology of Africa. IX. A synonymic list of the ants of the Malagasy region. Bulletin of the American Museum of Natural History 45: 1005-1055