Camponotus alamaina

Camponotus alamaina is a widespread species occurring mainly in the dry forest habitats in western Madagascar. Members of the species are known also from the spiny forest and thickets of the south and southwest, the montane rainforest of the central plateau and the southeast, and the littoral forest of the north of the island. Although this species is both arboreal and terrestrial, its members commonly are found foraging on low vegetation and nesting in dead branches, twigs, or rot pockets above the ground. Nests sites also may be built in rotten logs or sticks, and rotting tree stumps. (Rakotonirina et al. 2016)

Identification
Rakotonirina et al. (2016) - Anterior margin of petiolar node convex and posterior margin more or less straight; propodeal spiracle anterior to posterolateral margin of propodeum; head and mesosoma black to dark brown, gaster and appendages dark brown to yellow or light yellow; anterior margin of pronotum broadly rounding to the dorsum; dorsolateral and posterolateral margins of propodeum strongly carinate.

Camponotus alamaina is one of the common species in the edmondi group and displays remarkable morphological variation in the shape of the propodeum, form of the petiolar node, and color of the legs. Three different variants are recognized based on this morphological diversity, but gradually merge into one another across the geographic distribution of the species.

Variant 1. Workers are typical Camponotus alamaina and can be recognized by having dorsolateral and posterolateral margins of the propodeum that extend into sharp carinae, but the junction of the dorsum to the posterolateral portion is rounded or bluntly angulate and does not form a pair of teeth or tubercles laterally; in oblique profile view, the dorsal border of petiolar node is straight or slightly excised medially; and the legs are yellow.

Variant 2. This variant is known from Parc National Baie de Baly, Réserve de Bemarivo and Kirindy Forest near Marofandilia, and is characterized by the lateral projection into tubercles of the posterodorsal corner of the propodeum, the presence of numerous erect hairs on the dorsum of the propodeum, a much thicker petiolar node with a dorsal margin extending medially into a blunt tooth in frontal view, and a much darker-colored foreleg.

Variant 3. This variant expresses intermediate characters of the previous two variants, in that the posterodorsal corners of the propodeum are bidentate, the dorsal margin of petiolar node is slightly excised medially in frontal view, and the legs are yellow. Specimens of this variant have been collected from sites in the north of Madagascar, including Ankarana, Orangea, Montagne des Français, Binara, and Analabe.

Distribution based on Regional Taxon Lists
Malagasy Region: Madagascar.

Nomenclature

 *  alamaina. Camponotus alamaina Rakotonirina, Csősz & Fisher, 2016: 105, figs. 5A, 6B, 8A, 19, 34 (w.) MADAGASCAR.

Worker
Minor. In full-face view head longer than broad (CWb/CL: 0.79–0.91); lateral margin more or less straight, feebly converging toward base of mandibles and broadly rounding to the convex posterior margin. Anterior clypeal margin generally convex, posteromedian margin notched. Level of posterior ocular borders generally located from posterior third to posterior fifth of head (PoOc/CL: 0.2–0.271); antennal scape somewhat long (SL/CS: 1.02–1.18), roughly its distal portion extending beyond rear border of head. Mandible subtriangular, apical margin armed with six teeth. In profile, anterior margin of pronotum broadly rounding to the dorsum; anterodorsal angle weakly marginate; junction of dorsum and sides of premesonotum rounded, without margination; dorsolateral margins of propodeum extending into sharp carina. In dorsal view, junction of mesonotum and propodeum laterally compressed; metanotal groove impressed. In profile, propodeal dorsum raised into a very short edge, descending feebly posteriorly and joining declivity by distinct angle; propodeal spiracle located anterior to posterolateral margin of propo-deum. Maximum width of procoxa larger than width of meso-metapleuron. In profile, petiolar node anteroposteriorly flattened and tapered dorsally; anterior margin slightly convex and posterior margin more or less straight; dorsal margin straight or weakly excised medially. Constriction between abdominal segments III and IV lacking.

Dorsum of head, mesosoma, and petiole with imbricate sculpture; gaster with finer imbrication; mandible coriarious-puncticulate. Pairs of erect hairs arranged as follows: three on clypeus, one near margin of frontal carina, at level of eyes, posterior portion of head, dorsum of mesonotum and propodeum. Two rows of sparse, erect hairs arranged on anterior and posterior portions of each of first three gastral tergites. Pubescence short and scattered on dorsum of body. Head, mesosoma and petiole black to dark brown; gaster, mandible, antenna, coxa and tarsus brown; rest of legs yellow.

Major. With characteristics of minor worker except the following divergent features: head subquadrate (CWb/CL: 0.87–1) in full-face view, posterior margin approximately straight; level of posterior ocular borders at about posterior fourth of head (PoOc/CL: 0.24–0.28); anterior clypeal margin straight and medially excised; antennal scape barely extending beyond rear cephalic border (SL/CS: 0.69–0.89); metanotum distinct between mesonotum and propodeum; dorsum of propodeum strongly inclined posteriorly and rounding into declivity; dorsal margin of petiolar node medially excised; few erect hairs present on dorsum of pronotum and more than one pair on mesonotum and propodeum.

Type Material
Holotype worker. Madagascar, Province Mahajanga, Mahavavy River, 6.2 km 145° SE Mitsinjo, –16.05167, 45.90833, 20 m, gallery forest, ex dead branch above ground, 1–5 Dec 2002 (Fisher, Griswold et al.) collection code: BLF06982, specimen code: CASENT0481799. Paratype. 8 workers with same data as holotype.