Camponotus roeseli

As an endemic and widespread species of Madagascar, C. roeseli generally occurs in the western portion of the island in areas ranging from littoral and rainforest habitats in the north to dry forest areas in the west-central region through spiny forest and thicket in the south (Fig. 71G). This species is also known to occupy savannah, Uapaca woodland, montane rainforests, and human-modified habitats of the south-central high plateau. Foraging behavior is mostly carried out on the ground surface and infrequently on low vegetation, while nests are located mainly in rotten logs, in the ground, and under stones, and rarely in rotting tree stumps and under root mat-litter on rocks.

Identification
In full-face view, lateral cephalic margins converging posteriorly towards eye level, posterior to eye level covered with erect hairs; two apical teeth of mandible closely spaced; head and gaster reddish black and mesosoma reddish orange or integument entirely reddish black.

Camponotus roeseli might be confused with Camponotus daraina because of the presence of erect hairs on the lateral margin of the head posterior to the eye level; however, the latter species can be distinguished by the reddish orange color of the entire body.

Distribution based on Regional Taxon Lists
Malagasy Region: Madagascar.

Nomenclature

 * . Camponotus roeseli Forel, 1910a: 20 (s.w.) MADAGASCAR.
 * Combination in C. (Myrmoturba): Forel, 1914a: 267;
 * combination in C. (Tanaemyrmex): Emery, 1925b: 89.
 * Status as species: Wheeler, W.M. 1922a: 1042; Emery, 1925b: 89; Bolton, 1995b: 120.
 * legionarius. Camponotus maculatus st. legionarium Santschi, 1911i: 283 (s.) MADAGASCAR.
 * Combination in C. (Tanaemyrmex): Emery, 1925b: 89.
 * Subspecies of maculatus: Emery, 1920c: 5; Wheeler, W.M. 1922a: 1041; Emery, 1925b: 89.
 * Status as species: Baroni Urbani, 1972: 132; Bolton, 1995b: 108.
 * Junior synonym of roeseli: Rakotonirina & Fisher, 2022: 151.

Type Material
Camponotus roeseli
 * Syntype major workers, Madagascar, Montagne d’Ambre (Rolle); 1 syntype major worker designated as lectotype, by Rakotonirina & Fisher (2022), AntWeb CASENT0101602 (MHNG) [Rakotonirina & Fisher, 2022].
 * Paralectotype major worker of same data as lectotype but with specimen code: CASENT0101788 (MHNG) [Rakotonirina & Fisher, 2022].

Camponotus maculatus legionarium
 * Holotype (by monotypy) major worker, Madagascar, Diego Suarez (Légion Étrangère 1903) AntWeb CASENT0101413 (MNHN) [Rakotonirina & Fisher, 2022].

Taxonomic Notes
The species name C. roeseli and the subspecies name C. maculatus legionarium were created and described by Forel (1910) and Santschi (1911b), respectively, based on major worker specimens. However, observations of the type specimens of the species and subspecies reveal no robust morphological characters to distinguish them. Samples of the minor workers for C. roeseli show striking morphological variation along the western dry forest of Madagascar, especially in body coloration that ranges from dark brown to black through the head; brown gaster; and mesosoma, petiolar node, and the basal portion of the legs yellowish orange. This indicates morphological variation of major workers within the species is likely. Therefore, C. maculatus legionarium was synonymized under C. roeseli by Rakotonirina & Fisher (2022).

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.
 * 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