Tetramorium freya 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 : 57-59

Tetramorium freya Hita Garcia & Fisher sp. n. Figs 21A, 33, 63

Type material.

Holotype, pinned worker, MADAGASCAR, Antsiranana, Diego-Suarez, 7 km N Joffreville [camp 2 of Fisher], 12.33333°S, 49.25°E, 360 m, in dry forest, Malaise trap, collection code MA-01-07-08, 6.-20.III.2001 (R. Harin’Hala) (CAS: CASENT0085551). Paratype, one pinned worker with same data as holotype except collected 20.III.-7.IV.2001 and collection code MA-01-07-09 (CASENT0083419).

Non-type material.

MADAGASCAR: Antsiranana, 4 km SW Ambositra (=Joffreville), 12.51667°S, 49.18333°E, 1000 m, rainforest,1.XII.1990 (P.S. Ward); Antsiranana, Nosy Be, Réserve Naturelle Intégrale de Lokobe, 6.3 km 112° ESE Hellville, 13.41933°S, 48.33117°E, 30 m, rainforest, 19.-24.III.2001 (B.L. Fisher et al.); Antsiranana, Sakalava Beach (vegetated beach dunes), 12.26278°S, 49.3975°E, 10 m, across sandy trail in dwarf littoral forest, 20.-28.VII.2001 (R. Harin’Hala).

Diagnosis.

The following character combination distinguishes Tetramorium freya from the other species of the Tetramorium cognatum species complex: frontal carinae weakly developed, merging with surrounding sculpture halfway between posterior eye margin and posterior head margin; petiolar node high nodiform with well rounded margins, in profile around 1.6 to 1.7 times higher than long (LPeI 58-62), in dorsal view 1.2 to 1.3 times wider than long (DPeI 124-131); lack of any long, standing pilosity on dorsal mesosoma.

Worker measurements

(N=5). HL 0.61-0.74 (0.68); HW 0.56-0.68 (0.62); SL 0.40-0.46 (0.44); EL 0.14-0.17 (0.16); PH 0.30-0.35 (0.33); PW 0.38-0.43 (0.40); WL 0.72-0.87 (0.81); PSL 0.12-0.15 (0.13); PTL 0.13-0.16 (0.15); PTH 0.21-0.27 (0.25); PTW 0.17-0.20 (0.19); PPL 0.16-0.21 (0.19); PPH 0.22-0.28 (0.25); PPW 0.23-0.28 (0.25); CI 90-92 (91); SI 68-71 (70); OI 25; DMI 44-54 (50); LMI 40-42 (41); PSLI 18-20 (19); PeNI 42-50 (46); LPeI 58-62 (59); DPeI 124-131 (127); PpNI 59-70 (63); LPpI 72-77 (75); DPpI 127-144 (134); PPI 133-140 (136).

Worker description.

Head much longer than wide (CI 90-92); in full-face view posterior head margin weakly concave. Anterior clypeal margin with distinct median impression. Frontal carinae weakly to moderately developed, merging with surrounding sculpture halfway between posterior eye margin and posterior head margin. Anten nal scrobes weak to absent, shallow and without clear and distinct posterior and ventral margins. Antennal scapes very short, not reaching posterior head margin (SI 68-71). Eyes relatively large (OI 25). Mesosomal outline in profile weakly to moderately convex, moderately high and stout (LMI 40-42), weakly to moderately marginate from lateral to dorsal mesosoma; promesonotal suture absent; metanotal groove present, but weakly developed. Propodeal spines short, triangular to elongate-triangular, and acute (PSLI 18-20), propodeal lobes triangular and short, always much shorter than propodeal spines. Petiolar node in profile high nodiform with well-rounded margins, around 1.6 to 1.7 times higher than long (LPeI 58-62), anterior and posterior faces approximately parallel and rounding smoothly onto dorsum, anterodorsal and posterodorsal margins situated at about same height, petiolar dorsum relatively noticeably convex; node in dorsal view 1.2 to 1.3 times wider than long (DPeI 124-131), in dorsal view pronotum between 2.0 to 2.4 times wider than petiolar node (PeNI 42-50). Postpetiole in profile globular to subglobular, between 1.3 to 1.4 times higher than long (LPpI 72-77); in dorsal view around 1.3 to 1.4 times wider than long (DPpI 127-144), pronotum between 1.4 to 1.8 times wider than postpetiole (PpNI 59-70). Postpetiole in profile appearing approximately as voluminous as petiolar node, postpetiole in dorsal view around 1.3 to 1.4 times wider than petiolar node (PPI 133-140). Mandibles completely unsculptured, smooth, and shiny; clypeus in parts irregularly longitudinally rugulose, median ruga never fully developed, usually reduced to a few traces, one or two irregular and broken lateral rugulae present on each side; cephalic dorsum between frontal carinae weakly irregularly longitudinally rugulose, rugulae weak, often interrupted or with cross-meshes and becoming much weaker posteriorly; scrobal area mostly irregularly longitudinally rugulose and merging with surrounding irregularly longitudinally rugose to reticulate-rugose sculpture present on lateral head. Head with very conspicuous punctate ground sculpture. Mesosoma laterally and dorsally with traces of irregular rugulae or reticulate-rugose sculpture overlaying a distinct punctate ground sculpture. Forecoxae in parts weakly longitudinally rugulose and partly unsculptured, smooth, and shining. Both waist segments and gaster fully unsculptured, smooth, and shining. Dorsum of head with several pairs of hairs. Mesosoma, waist segments, and first gastral tergite without any standing hairs at all; first gastral tergite with very short, moderately dense, and appressed pubescence. Anterior edges of antennal scapes and dorsal (outer) surfaces of hind tibiae with appressed hairs. Head, mesosoma, waist segments, and gaster uniform brown, appendages yellowish to light brown.

Etymology.

The name of the new species was inspired and derived from the name of the Old Norse goddess Freyja (which means “Lady” in Old Norse) who was considered the goddess of love, beauty, fertility, war, and death. As a name taken from Norse mythology, it is treated as an arbitrary combination of letters, thus invariant.

Distribution and biology.

Tetramorium freya is a rare species only known from a few localities at the northernmost tip of Madagascar and from the island of Nosy Be (Fig. 63). The species was collected in rainforests, dry forests, and coastal dunes at elevations from 10 to 1000 m. Also, Tetramorium freya was mostly sampled from Malaise traps or from vegetation and only once from leaf litter; considering there are only five known specimens, it seems likely that Tetramorium freya nests and forages in vegetation. Additional sampling in lower vegetation might yield more material of this otherwise very rare species.

Discussion.

The identification of Tetramorium freya is easy and straightforward since it is the only species of the species complex without any long, standing pilosity on the mesosomal dorsum. Beyond mesosomal pilosity, Tetramorium freya also has weakly developed frontal carinae and sculpture on the head and mesosoma, which separate it from Tetramorium gladius , Tetramorium myrmidon , Tetramorium proximum , and Tetramorium tenuinode . In addition, Tetramorium freya possesses a stouter and higher mesosoma (LMI 40-42) and a lower and thicker petiolar node (LPeI 58-62, around 1.6 to 1.7 times higher than long) compared to Tetramorium aspis , Tetramorium camelliae , Tetramorium cognatum , Tetramorium karthala , and Tetramorium rumo (LMI 35-40; LPeI 33-55, around 1.8 to 3.0 times higher than long).

Based on the limited number of specimens available for this study, there seems to be no significant intraspecific variation in Tetramorium freya .