Tetramorium mallenseana, Garcia & Fisher, 2012

Garcia, Francisco Hita & Fisher, Brian L., 2012, The ant genus Tetramorium Mayr (Hymenoptera: Formicidae) in the Malagasy region — taxonomy of the T. bessonii, T. bonibony, T. dysalum, T. marginatum, T. tsingy, and T. weitzeckeri species groups, Zootaxa 3365, pp. 1-123 : 70-73

Tetramorium mallenseana sp. n.

(figs 77, 104, 105, 106)

Holotype worker, MADAGASCAR, Fianarantsoa, Parc National de Ranomafana, Vatoharanana River , 4.1 km 231° SW Ranomafana, 21.29 S, 47.43333 E, 1100 m, montane rainforest, sifted litter (leaf mold, rotten wood), collection code BLF08400, 21.–31.III.2003 (B.L. Fisher, C. Griswold et al.) ( CASC: CASENT0039659 ) . Paratypes, one worker with same data as holotype ( CASC: CASENT039656 ) ; five workers from Fianarantsoa, 7 km W of Ranomafana, montane rainforest , pitfall trap 1000 m, 23.–28.II.1999 (W.E. Steiner) ( MCZ: CASENT0247148 ; CASENT0247157); and six workers from Fianarantsoa, 7 km W of Ranomafana , montane rainforest, pitfall trap 1000 m, 8.–13.III.1999 (W.E. Steiner) ( MCZ: CASENT0247153 ; CASENT0247154; CASENT0247155; CASENT0247156) .

Diagnosis

The following character combination distinguishes T. mallenseana from the other species of the group: short antennal scapes (SI 72–75); long and curved propodeal spines (PSLI 38–43); very short propodeal lobes; petiolar node rounded high nodiform, in dorsal view only slightly wider than long (DPel 110–123), petiolar dorsum only weakly tapering backwards posteriorly; postpetiole in dorsal view 1.7 to 2 times wider than petiolar node (PPI 168–200); dorsum of mesosoma with longitudinally rugose sculpture.

Description

HL 0.67–0.71 (0.70); HW 0.67–0.72 (0.70); SL 0.49–0.54 (0.51); EL 0.12–0.15 (0.14); PH 0.37–0.40 (0.38); PW 0.50–0.54 (0.52); WL 0.84–0.95 (0.88); PSL 0.27–0.29 (0.28); PTL 0.15–0.17 (0.16); PTH 0.30–0.33 (0.31); PTW 0.17–0.20 (0.19); PPL 0.20–0.23 (0.22); PPH 0.29–0.32 (0.30); PPW 0.29–0.38 (0.34); CI 99–101 (100); SI 72–75 (73); OI 18–21 (20); DMI 57–61 (59); LMI 42–44 (43); PSLI 38–43 (40); PeNI 33–38 (36); LPeI 48–53 (51); DPeI 110–123 (117); PpNI 58–76 (72); LPpI 66–79 (72); DPpI 145–165 (156); PPI 168–200 (182) (seven measured).

Head as long as wide (CI 99–101). Anterior clypeal margin with distinct median impression. Frontal carinae strongly developed, usually ending at posterior head margin. Antennal scrobes narrow and faint. Antennal scapes short, not reaching posterior head margin (SI 72–75). Eyes comparatively small (OI 18–21). Mesosomal outline in profile comparatively flat, moderately weakly marginate from lateral to dorsal mesosoma, promesonotal suture and metanotal groove absent; mesosoma comparatively stout and compact (LMI 42–44). Propodeal spines relatively thin, very long, and back-curved (PSLI 38–43). Propodeal lobes weakly developed, very short and triangular. Petiolar node in profile rounded high nodiform, approximately two times higher than long (LPeI 48–53), anterior and posterior faces almost parallel, anterodorsal margin situated higher than posterodorsal margin, dorsum weakly tapering backwards posteriorly; node shape in dorsal view only weakly elliptical, almost rounded, only between 1.1 to 1.2 times wider than long (DPeI 110–123). Postpetiole in profile rounded, approximately 1.3 to 1.5 times higher than long (LPpI 66–79), in dorsal view 1.4 to 1.7 times wider than long (DPpI 145–165). Postpetiole in profile a bit more voluminous than petiolar node, in dorsal view much wider than petiolar node, between 1.7 to 2 times wider (PPI 168–200). Mandibles distinctly longitudinally rugose, in some specimens unsculptured and smooth or weakly sculptured; clypeus with strong median longitudinal ruga and one often weaker ruga at each side; cephalic dorsum between frontal carinae with six to eight longitudinal rugae running to posterior head margin, some rugae broken or with cross-meshes; lateral and ventral head with weak reticulate-rugose sculpture; head with faint reticulatepunctate to punctate ground sculpture. Mesosoma laterally and dorsally strongly longitudinally rugose, rugae moderately meandering but distinctly longitudinally arranged with few cross-meshes. Petiole and postpetiole almost unsculptured, with few weak rugulae. Gaster unsculptured, smooth and shining. All dorsal surfaces of body with long, erect or suberect pilosity. Head, mesosoma, waist segments dark brown, appendages of lighter brown.

Notes

Tetramorium mallenseana is only known from the Parc National de Ranomafana and its vicinity, which is a montane rainforest situated at an altitude of 1000 to 1100 m.

Within the T. dysalum group, T. mallenseana has an interesting character combination that makes it unlikely to be misidentified with another group member. The propodeal spines are very long and strongly backcurved. This shape is only comparable with the shape of the spines seen in T. dysalum , although the species are unlikely to be confused since T. dysalum always has unsculptured, very smooth and shiny mandibles, whereas the mandibles of T. mallenseana are distinctly sculptured. The spines of T. steinheili are usually straight and only rarely backcurved, and if they are, then the propodeal lobes are very well-developed, whereas the lobes of T. mallenseana are very short and inconspicuous. The best character separating T. mallenseana from the other species, however, is the shape of the petiolar node, especially the relationship between petiolar node width and postpetiole width. The petiolar node in dorsal view is only weakly wider than long (DPeI 110–123), and its shape is only weakly elliptical and almost rounded, which is rare in the group. Also, the postpetiole is always between 1.6 to 2 times wider than the comparatively narrow petiolar node (PPI 168–200), while most other species have a postpetiole that is usually distinctly less than 1.5 times wider than the petiolar node (PPI 119–152).

Etymology

The species epithet is an arbitrary combination of letters, and the new species is dedicated to Sean Allen for his support to discover and identify life on earth.

Material examined

MADAGASCAR: Fianarantsoa, Parc National de Ranomafana, Vatoharanana River, 4.1 km 231° SW Ranomafana, 21.29 S, 47.43333 E, 1100 m, montane rainforest, 21.–31.III.2003 (B.L. Fisher, C. Griswold et al.); Fianarantsoa, 7 km W of Ranomafana, montane rainforest, 1000 m, 23.II.–13.III.1990 (W.E. Steiner) .