Camponotus orombe Rakotonirina, Csosz & Fisher

Rakotonirina, Jean Claude, Csosz, Sandor & Fisher, Brian L., 2016, Revision of the Malagasy Camponotusedmondi species group (Hymenoptera, Formicidae, Formicinae): integrating qualitative morphology and multivariate morphometric analysis, ZooKeys 572, pp. 81-154 : 124-127

Taxon classification Animalia Hymenoptera Formicidae

Camponotus orombe Rakotonirina, Csosz & Fisher sp. n. Figures 15A, 28, 43

Holotype worker.

Madagascar, Province Toliara, Forêt Ivohibe 55.0 km N Tolagnaro, -24.569, 47.204, 200 m, rainforest, ex dead twig above ground, 12 Mar 2006 (B.L. Fisher et al.) collection code: BLF15534, specimen code: CASENT0178923 (CASC).

Paratypes.

3 workers, 1 worker same data as holotype but with specimen code CASENT0122867; 2 workers with the following data: Forêt Ivohibe 55.6 km N Tolagnaro, -24.56167, 47.20017, 650 m, rainforest, beating low vegetation, 12 Apr 2006, BLF15587 and CASENT0122787, BLF15628 and CASENT0121500 (BMNH, CASC).

Additional material examined.

MADAGASCAR: Province Toliara: Forêt Ivohibe 55.0 km N Tolagnaro, -24.569, 47.204, 200 m, rainforest, (B.L. Fisher et al.) (CASC); Forêt Ivohibe 55.6 km N Tolagnaro, -24.56167, 47.20017, 650 m, rainforest, (B.L. Fisher et al.) (CASC).

Diagnosis.

In profile, anterior and posterior margins of petiolar node convex; in profile, propodeal dorsum and declivitous surface separated by blunt angle; in dorsal view, mesonotum less than twice as broad as long; mesopleuron with propodeal surface together distinctly wider than lateral portion of pronotum; in profile, propodeal dorsum roughly as long as declivitous margin; dorsum of head and mesosoma densely and finely reticulate punctate; erect hairs lacking on dorsum of pronotum; distance between meso-metapleural suture and dorsolateral margin of propodeum not changing along the dorsolateral carina of propodeum.

Description.

Minor worker (Figs 15A, 28). In full-face view head slightly longer than broad (CWb/CL: 0.88); lateral margins weakly convex and converging slightly towards base of mandibles; posterior border broadly convex. Level of posterior ocular margins at about posterior fourth portion of head (PoOc/CL: 0.23-0.24). Anteromedian margin of clypeus with slightly blunt angle; posterior margin weakly notched. Mandible triangular, masticatory margin with six teeth. Antennal scape relatively long, distal portion almost extending beyond posterior border of head. In lateral view, pronotum dorsally flat, anterior margin projecting into narrow ridge; dorsolateral portion of promesonotum longitudinally marginate. In dorsal view, mesonotum less than twice as broad as long, posterodorsal corner without visible posterior lobe; lateral margin convex and gradually converging to metanotal groove. In lateral view, propodeum strongly compressed anteroposteriorly, junction between dorsal margin and declivity not distinctly visible; ridge on posterolateral portion distinct; distance between meso-metapleural suture and posterolateral ridge of propodeum remaining the same along dorsolateral carina of propodeum. Propodeal spiracle on lower third of posterior face of propodeum. Maximum width of procoxa as large as width of meso-metapleuron and propodeal surface together. In lateral view, anterior margin of petiolar node convex; posterior margin sloping posteriorly to about mid-height and descending almost vertically to posteroventral angle. No constriction between abdominal segments III and IV.

Dorsum of head, mesosoma, and petiolar node with fine and dense reticulate punctures. Mandible with sparse piligerous punctures between smooth surfaces. Numerous pairs of whitish erect hairs on dorsum of head; one pair on mesonotum; numerous erect hairs arranged along junction of propodeal dorsum and declivity. No erect hair on declivitous surface above propodeal spiracle level. Posterior face of petiole with a row of four erect hairs near lateral margin and posterodorsal angle. Shorter and slender erect hairs organized transversely on anterior and posterior portions of each gastral tergite. Pubescence present on dorsum of head, mesosoma, petiole and gaster. Head, mesosoma, and petiole black in color; antennal scape and first five flagellar segments, mandible, trochanter, and tarsus yellow to light brown; gaster, apical portion of antennal segments, femur, and tibia dark brown.

Major worker. Similar to minor worker, but with the following divergent characters: in full-face view, head subquadrate (CWb/CL: 0.98), lateral borders almost parallel and converging strongly near base of mandibles; level of posterior margins of eyes located at about posterior third portion of head (PoOc/CL: 0.3). Anterior margin of clypeus medially excised; mandible robustly built; antennal scape barely surpassing posterior cephalic border. Anterior portion of pronotum not strongly marginate; in dorsal view, metanotum visible between metanotal groove and propodeum. Junction of dorsum and sides of propodeum more or less rounded; petiolar node more flattened anteroposteriorly.

Distribution and biology.

Camponotus orombe is known only from a few individual workers collected from Ivohibe Forest between 200 m and 650 m of altitude in the southeast of Madagascar (Fig. 43). They were found foraging on low vegetation and nesting in dead twigs above the ground.

Discussion.

Camponotus orombe can be confused to Camponotus mifaka , but the latter has numerous erect hairs on the dorsum of its mesosoma. Camponotus orombe can be differentiated from Camponotus tafo and Camponotus edmondi by the fact that the propodeum of these two latter species is not strongly compressed anteroposteriorly and the distance between the meso-metapleural suture and the dorsolateral margin of the propodeum is largest near the junction of the dorsolateral carina and the declivitous surface.

In the morphometric dendrogram, Camponotus orombe is represented by a successfully classified small cluster of three individual specimens that falls close to the cluster of Camponotus varatra , Camponotus tafo , Camponotus mifaka , Camponotus zavo , and Camponotus tratra . Based on qualitative morphology, Camponotus varatra , Camponotus zavo , and Camponotus tratra differ from Camponotus orombe by the sculpture on the dorsum of their head and mesosoma, which is imbricate or smooth and shiny with sparse piligerous punctures. This information supports the separation of Camponotus orombe from the other three species.