Tetramorium ala Hita, 2012

Hita Garcia, F. & 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, pp. 1-85 : 21-23

Tetramorium ala Hita Garcia & Fisher sp. n.

(Figs. 51, 57, 66, 75, 76, 77, 141)

Holotype worker, MADAGASCAR, Toamasina, Montagne d'Anjanaharibe, 19.5 km 27° NNE Ambinanitelo, 15.17833 S, 49.635 E, 1100 m, montane rainforest, sifted litter (leaf mold, rotten wood), collection code BLF08150, 12.-16.III.2003 (B.L. Fisher, C. Griswold et al.) (CASC: CASENT0038473). Paratypes, 13 workers with same data as holotype (BMNH: CASENT0038387; CASC: CASENT0038371; CASENT0038374; CASENT0038389; CASENT0038410; CASENT0038414; CASENT0038453; CASENT0038459; CASENT0038464; CASENT0038467; MCZ: CASENT0038404; MHNG: CASENT0038423; NHMB: CASENT0038373); 1 worker with same data as holotype except sampled from ground and collection code BLF08230 (CASC: CASENT0497817); 9 workers with same data as holotype except sampled from root mat at ground layer and collection code BLF08185 (CASC: CASENT0498013; CASENT0498014; CASENT0498015).

Diagnosis

Tetramorium ala can be distinguished from the other T. andrei species complex members by the following combination of characters: eyes usually moderately sized (OI 20-21); propodeal spines long to very long (PSLI 38-42); petiolar node in dorsal view relatively slender and long, around 1.3 to 1.4 times longer than wide (DPeI 72-76); posterodorsal corner of petiolar node not strongly protruding posteriorly; body bright orange to light brown in colour.

Description

HL 0.88-1.01 (0.94); HW 0.83-0.96 (0.88); SL 0.69-0.76 (0.72); EL 0.17-0.19 (0.18); PH 0.43-0.49 (0.46); PW 0.63-0.74 (0.69); WL 1.16-1.29 (1.22); PSL 0.34-0.41 (0.37); PTL 0.29-0.34 (0.31); PTH 0.30-0.35 (0.32); PTW 0.21-0.26 (0.23); PPL 0.27-0.33 (0.30); PPH 0.30-0.36 (0.32); PPW 0.30-0.36 (0.32); CI 93-95 (94); SI 79-85 (81); OI 20-21 (20); DMI 54-58 (57); LMI 37-39 (38); PSLI 38-42 (40); PeNI 31-34 (33); LPeI 93-98 (95); DPeI 72-76 (75); PpNI 44-48 (46); LPpI 87-95 (92); DPpI 102-112 (107); PPI 135-143 (139) (12 measured).

Head distinctly longer than wide (CI 93-95). Posterior head margin concave. Anterior clypeal margin medially impressed. Frontal carinae strongly developed, strongly diverging posteriorly, and ending at corners of posterior head margin. Antennal scrobes developed, but shallow, narrow, and without defined posterior and ventral margins. Antennal scapes comparatively short to moderately long, not reaching posterior head margin (SI 79-85). Eyes short to moderately sized (OI 20-21). 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 37-39). Propodeal spines long to very long, spinose, and acute (PSLI 38-42); propodeal lobes well-developed and comparatively long, elongate-triangular, and acute. Petiolar node in profile rectangular nodiform with sharply defined angles, between 1.0 to 1.1 times higher than long (LPeI 93-98), anterior and posterior faces approximately parallel, anterodorsal and posterodorsal margins approximately at same height, dorsum straight; node in dorsal view around 1.3 to 1.4 times longer than wide (DPeI 72-76). Postpetiole in profile globular to subglobular, approximately 1.1 times higher than long (LPpI 87-95); in dorsal view 1.0 to 1.1 times wider than long (DPpI 102-112). Postpetiole in profile appearing less voluminous than petiolar node, in dorsal view approximately 1.3 to 1.4 times wider than petiolar node (PPI 135-143). Mandibles distinctly longitudinally rugose; clypeus always with a very well-developed and pronounced longitudinal median ruga and few much weaker, and often broken lateral rugae/rugulae; cephalic dorsum between frontal carinae with seven to ten longitudinal rugae, most rugae running unbroken from posterior head margin to posterior clypeus, rugae only very rarely with cross-meshes; lateral and ventral head usually longitudinally rugose, sometimes partly reticulate-rugose. Mesosoma laterally and dorsally distinctly longitudinally rugose. Forecoxae usually completely unsculptured, smooth, and shiny, sometimes with partial superficial sculpture. Waist segments longitudinally rugose. Ground sculpture generally faint to absent everywhere on body. First gastral tergite unsculptured, smooth, and shining. All dorsal surfaces of head, mesosoma, waist segments, and gaster with abundant, long, and fine standing hairs. Anterior edges of antennal scapes with suberect to erect standing hairs. Body colour uniformly bright orange to orange-brown.

Notes

The new species is currently only known to occur in the type locality Montagne d'Anjanaharibe where it was sampled in montane rainforest at 1100 m elevation. Most specimens were found in leaf litter.

Tetramorium ala has the longest petiolar node in dorsal view within the species complex, which is around 1.3 to 1.4 times longer than wide (DPeI 72-76), whereas all other species (except T. andohahela ) have much shorter and wider nodes (DPeI 82-114). Tetramorium andohahela also has a relatively long and slender node in dorsal view (DPeI 73-79), but the posterodorsal corner of the petiolar node distinctly protrudes posteriorly in this species, a character absent in T. ala. Not considering the node shape in dorsal view, T. ala is not easily confused with T. electrum, T. elf, or T. isoelectrum since the latter species have significantly smaller eyes (OI 16-19), much longer propodeal spines (PSLI 46-64), and much shorter propodeal lobes. The other two species with very small eyes, T. isectum (OI 15 -16) and T. nify (OI 16-17), are morphologically not very close to T. ala with its larger eyes (OI 20-21). Due to its fairly rounded anterodorsal and posterodorsal margins of the petiolar node, T. voasary can be easily separated from T. ala, which has very sharply defined margins. The last and most variable species of the complex, T. andrei, could be confused with T. ala since they share most morphological characters, especially in profile view. However, as mentioned above, the different node shape in dorsal view distinguishes them clearly (DPeI 72-76 in T. ala versus DPeI 82-98 in T. andrei).

Etymology

The species epithet is an arbitrary combination of letters.

Material examined

MADAGASCAR: Toamasina, Montagne d'Anjanaharibe, 19.5 km 27° NNE Ambinanitelo, 1100 m, montane rainforest, 12.-16.III.2003 (B.L. Fisher, C. Griswold et al.).

15.17833 S, 49.635 E,