Tetramorium elf

Tetramorium elf was collected from rainforests in Makirovana, Marojejy, Antalaha, and Ambalagoavy at elevations from 625 to 900 m. Despite being known from four localities, the available material consists of just 12 specimens, making T. elf a relatively rarely sampled species. The microhabitat of these ants is not clear since the specimens were collected from the ground, leaf litter, and malaise or pan traps.

Identification
A member of the Tetramorium andrei species complex of the Tetramorium tortuosum-species group.

Tetramorium elf is easily separable from the remainder of the species group due to the following combination of characters: propodeal spines extremely long (PSLI 59 - 64); petiolar node around 1.2 times higher than long (LPeI 80 - 83); posterodorsal corner of petiole not strongly protruding posteriorly; mandibles unsculptured, smooth, and shiny; body of yellowish colour. T. elf seems to be morphologically near to T. electrum and T. isoelectrum. All three share the small eyes (OI 16 - 19), the enormously developed propodeal spines (PSLI 46 - 64), usually higher than 50), and relatively small and blunted propodeal lobes. The conspicuous yellowish body colour, longer antennal scapes (SI 78 - 83), and a lower petiolar node (LPeI 80 - 83), however, separate T. elf from the very dark brown to black T. electrum (SI 67 - 74; LPeI 64 - 74). In addition, the likewise very darkly coloured T. isoelectrum has strongly sculptured mandibles, which contrasts with the unsculptured mandibles of T. elf. (Hita Garcia and Fisher 2012)

Distribution based on Regional Taxon Lists
Malagasy Region: Madagascar.

Nomenclature

 *  elf. Tetramorium elf Hita Garcia & Fisher, 2012: 34, figs. 12, 56, 58, 62, 63, 87-89, 141 (w.) MADAGASCAR.

Worker
HL 0.97 - 1.13 (1.07); HW 0.92 - 1.06 (1.02); SL 0.76 - 0.84 (0.81); EL 0.16 - 0.19 (0.18); PH 0.51 - 0.65 (0.55); PW 0.68 - 0.76 (0.73); WL 1.29 - 1.41 (1.36); PSL 0.59 - 0.70 (0.66); PTL 0.33 - 0.37 (0.35); PTH 0.40 - 0.45 (0.42); PTW 0.29 - 0.35 (0.32); PPL 0.33 - 0.38 (0.37); PPH 0.39 - 0.46 (0.42); PPW 0.35 - 0.41 (0.38); CI 92 - 96 (95); SI 78 - 83 (80); OI 17 - 18 (18); DMI 53 - 54 (54); LMI 38 - 46 (40); PSLI 59 - 64 (62); PeNI 43 - 45 (44); LPeI 80 - 83 (82); DPeI 88 - 96 (92); PpNI 51 - 54 (52); LPpI 84 - 93 (88); DPpI 100 - 108 (104); PPI 117 - 122 (119) (ten measured).

Head longer than wider (CI 95 - 96). Anterior clypeal margin medially impressed. Posterior head margin only weakly concave. Frontal carinae strongly developed, diverging posteriorly, and ending at corners of posterior head margin. Antennal scrobes weakly developed, shallow, narrow, and without defined posterior and ventral margins. Antennal scapes comparatively short, not reaching posterior head margin (SI 78 - 83). Eyes small (OI 17 - 18). Mesosomal outline in profile flat to weakly convex, moderately marginate from lateral to dorsal mesosoma; promesonotal suture and metanotal groove absent; mesosoma comparatively stout and high (LMI 38 - 46). Propodeal spines extremely long, spinose, and acute (PSLI 59 - 64); propodeal lobes short, triangular, and blunt. Petiolar node in profile rectangular nodiform with comparatively rounded angles, around 1.2 times higher than long (LPeI 80 - 83), anterior and posterior faces approximately parallel, anterodorsal and posterodorsal margins approximately at same height, dorsum straight to weakly convex; node in dorsal view around 1.1 times longer than wide (DPeI 88 - 96). Postpetiole in profile subglobular, approximately 1.1 to 1.2 times higher than long (LPpI 84 - 93); in dorsal view as wide as long to weakly wider than long (DPpI 100 - 108). Postpetiole in profile appearing less voluminous than petiolar node, in dorsal view approximately 1.2 times wider than petiolar node (PPI 117 - 122). Mandibles unsculptured, smooth, and shining; clypeus with longitudinally rugulose, usually with three rugulae, median rugula better developed than lateral rugulae; cephalic dorsum between frontal carinae with eight to ten longitudinal rugae, most rugae running unbroken from posterior head margin to posterior clypeus, rugae never with cross-meshes; scrobal area mostly unsculptured; lateral and ventral head longitudinally rugose without cross-meshes. Mesosoma laterally and dorsally distinctly longitudinally rugose. Forecoxae with weak, superficial punctate or rugulose sculpture only. Waist segments with weak to moderate rugulose sculpture, especially weakly developed laterally. Ground sculpture everywhere on body faint to absent. First gastral tergite unsculptured, smooth, and shining. All dorsal surfaces of head, mesosoma, waist segments, and gaster with abundant, long, and fine standing hairs. First gastral tergite without appressed pubescence. Anterior edges of antennal scapes with subdecumbent to erect standing hairs. Body of uniform yellowish colour.

Type Material
Holotype worker, MADAGASCAR, Antsiranana, Parc National de Marojejy, Manantenina River, 27.6 km 35° NE Andapa, 9.6 km 327° NNW Manantenina, 14.435 S, 49.76 E, 775 m, rainforest, sifted litter (leaf mold, rotten wood), collection code BLF08872, 15.-18.XI.2003 (B.L. Fisher et al.) (: CASENT0045788). Paratypes, one worker with same data as holotype (CASC: CASENT0045787); one worker with same data as holotype except sampled from yellow pan trap and collection code BLF08873 (CASC: CASENT0048893); and one worker from Antsiranana, Parc National de Marojejy, Manantenina River, 27.6 km 35° NE Andapa, 9.6 km 327° NNW Manantenina, 14.435 S, 49.76 E, 775 m, rainforest, ground foragers, collection code BLF09077, 17.XI.2003 (B.L. Fisher) (CASC: CASENT0487782).

Etymology
The new species is named after the "supernatural beings" from Old Norse and Old English myths. The species epithet is a noun in apposition, and thus invariant.

References based on Global Ant Biodiversity Informatics

 * Hita Garcia F., and B. L. Fisher. 2012. The ant genus Tetramorium Mayr (Hymenoptera: Formicidae) in the Malagasy regiontaxonomic revision of the T. kelleri and T. tortuosum species groups. Zootaxa 3592: 1-85.