Tetramorium pseudogladius Hita Garcia & Fisher

Hita Garcia, Francisco & Fisher, Brian L., 2014, The hyper-diverse ant genus Tetramorium Mayr (Hymenoptera, Formicidae) in the Malagasy region taxonomic revision of the T. naganum, T. plesiarum, T. schaufussii, and T. severini species groups, ZooKeys 413, pp. 1-170 : 95-97

Tetramorium pseudogladius Hita Garcia & Fisher sp. n. Figs 41A, 54, 65

Type material.

Holotype, pinned worker, MADAGASCAR, Toamasina, Parc National de Zahamena, Tetezambatana forest, near junction of Nosivola and Manakambahiny Rivers, 17.74298°S, 48.72936°E, 860 m, rainforest, sifted litter (leaf mold, rotten wood), collection code BLF21974, 18.-19.II.2009 (B.L. Fisher et al.) (CAS: CASENT0153605).

Diagnosis.

Tetramorium pseudogladius can be easily separated from the remainder of the species complex by its relatively small eyes (OI 20).

Worker measurements

(N=1). HL 0.74; HW 0.68; SL 0.55; EL 0.14; PH 0.36; PW 0.53; WL 0.96; PSL 0.16; PTL 0.14; PTH 0.27; PTW 0.19; PPL 0.21; PPH 0.28; PPW 0.27; CI 91; SI 80; OI 20; DMI 55; LMI 38; PSLI 22; PeNI 35; LPeI 52; DPeI 132; PpNI 51; LPpI 75; DPpI 129; PPI 146.

Worker description.

Head longer than wide (CI 91); in full-face view posterior head margin weakly to moderately concave. Anterior clypeal margin with distinct median im pression. Frontal carinae well developed, diverging posteriorly, approaching posterolateral corners of head. Antennal scrobes very weak, shallow and without clear and distinct posterior and ventral margins. Antennal scapes of moderate length, not reaching posterior head margin (SI 80). Eyes relatively small (OI 20). Mesosomal outline in profile relatively flat, moderately low and long (LMI 38), moderately marginate from lateral to dorsal mesosoma; promesonotal suture absent; metanotal groove mostly reduced. Propodeal spines moderately long, elongate-triangular to spinose, acute (PSLI 22), propodeal lobes short and triangular, much shorter than propodeal spines, spines and lobes not strongly inclined towards each other. Petiolar node in profile high rounded nodiform, around 1.9 times higher than long (LPeI 52), anterior and posterior faces approximately parallel, anterodorsal and posterodorsal margins situated at about same height and weakly rounded, petiolar dorsum weakly convex; node in dorsal view around 1.3 times wider than long (DPeI 132); in dorsal view pronotum around 2.8 to 2.9 times wider than petiolar node (PeNI 35). Postpetiole in profile globular, around 1.3 times higher than long (LPpI 75); in dorsal view around 1.3 times wider than long (DPpI 129); in dorsal view pronotum around 1.9 to 2.0 times wider than postpetiole (PpNI 51). Postpetiole in profile appearing more or less of same volume as petiolar node, postpetiole in dorsal view around 1.4 to 1.5 times wider than petiolar node (PPI 146). Mandibles completely unsculptured, smooth, and shiny; clypeus longitudinally rugulose with three similarly weak but unbroken rugulae; cephalic dorsum between frontal carinae longitudinally rugose with six or seven rugae, rugae running mostly unbroken from posterior clypeal margin to posterior head margin, a few rugae interrupted or with cross-meshes; scrobal area partly unsculptured, but mostly merging with surrounding reticulate-rugose to longitudinally rugose sculpture present on lateral head; ground sculpture on head weakly to moderately punctate. Dorsum and sides of mesosoma mostly irregularly longitudinally rugose; forecoxae mostly unsculptured, smooth, and shining; ground sculpture on mesosoma very weak to absent. Both waist segments and gaster completely unsculptured, smooth, and shining. Dorsum of head with several pairs of long, fine, standing hairs; dorsum of mesosoma with six pairs restricted to pronotum and mesonotum, propodeum without standing pilosity; waist segments and first gastral tergite without any standing hairs; first gastral tergite with very short, scarce, appressed pubescence in combination with a few scarce, long, standing hairs. Anterior edges of antennal scapes and dorsal (outer) surfaces of hind tibiae with appressed to decumbent hairs. Head, mesosoma, waist segments and gaster uniformly reddish, orange-brown contrasting with lighter yellowish to light brown mandibles, antennae, and legs.

Etymology.

The name of the new species is a combination of the ancient Greek word “pseudes”, which means “false” or “lying”, and the species name of Tetramorium gladius from the Tetramorium cognatum complex. This combined name takes account for the fact that both species are almost identical in morphology. The species epithet is treated as a nominative noun, and is thus invariant.

Distribution and biology.

At present, Tetramorium pseudogladius is known only from the type locality, Parc National de Zahamena (Fig. 65) where it was collected in lowland rainforest at an altitude of 860 m. In addition, the new species was sampled from leaf litter.

Discussion.

Like Tetramorium gladius in the Tetramorium cognatum complex, Tetramorium pseudogladius is also immediately recognisable on the basis of its much smaller eyes (OI 20). The other species of the Tetramorium schaufussii complex all have much larger eyes (OI 22-28). In addition, Tetramorium pseudogladius lacks the long, standing pilosity on the waist segments present in most other members of the species complex, and has relatively long antennal scapes (SI 80).

Generally, Tetramorium pseudogladius looks very similar to Tetramorium gladius in the Tetramorium cognatum species complex and they also share most of their morphometric range. Indeed, if not for the few long, standing hairs on its first gastral tergite, the holotype of Tetramorium pseudogladius could be easily confused with Tetramorium gladius . They also differ in antennal scape length, however, which is longer in Tetramorium pseudogladius (SI 80) than in Tetramorium gladius (SI 71-74). Until more material from the type locality becomes available, we consider these differences as diagnostic to delimit the species boundary between these two species.