Tetramorium olana Hita 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 : 41-43

Tetramorium olana Hita Garcia & Fisher sp. n.

(figs 43, 54, 55, 56)

Holotype worker, MADAGASCAR, Antsiranana, Forêt d' Andavakoera, 21.4 km 75° ENE Ambilobe, 4.6 km 356° N Betsiaka, 13.1183 S, 49.23 E, 425 m, rainforest, sifted litter (leaf mold, rotten wood), collection code BLF10260, 15.XII.2003 (B.L. Fisher) ( CASC: CASENT0044485 ) . Paratypes, 12 workers with same data as holotype ( BMNH: CASENT0044353 ; CASC: CASENT0044342 ; CASENT0044359; CASENT0044381; CASENT0044399; CASENT0044402; CASENT0044407; CASENT0044477; CASENT0044484; CASENT0044503; MHNG: CASENT0044458 ) .

Diagnosis

Tetramorium olana is distinguishable from the remainder of the species group by the following character combination: mesosoma with well-developed anterior face of pronotum, but without distinct anterodorsal median protuberance; petiolar node cuneiform and not strongly anteroposteriorly compressed dorsally (LPeI 45–50; DPeI 183–200); body of uniformly yellow to light brown colour.

Description

HL 0.56–0.65 (0.62); HW 0.54–0.63 (0.61); SL 0.39–0.45 (0.43); EL 0.12–0.15 (0.14); PH 0.33–0.36 (0.34); PW 0.38–0.46 (0.43); WL 0.71–0.82 (0.77); PSL 0.21–0.23 (0.22); PTL 0.10–0.13 (0.11); PTH 0.22–0.26 (0.24); PTW 0.19–0.24 (0.22); PPL 0.17–0.23 (0.21); PPH 0.22–0.27 (0.25); PPW 0.21–0.26 (0.24); CI 96–100 (98); SI 69–73 (70); OI 22–24 (23); DMI 54–58 (56); LMI 43–46 (44); PSLI 33–37 (35); PeNI 49–52 (51); LPeI 45–50 (47); DPeI 183–200 (192); PpNI 54–56 (56); LPpI 77–88 (83); DPpI 111–124 (115); PPI 106–115 (109) (11 measured).

Head weakly longer than wide to as long as wide (CI 96–100). Anterior clypeal margin with median impression. Frontal carinae weakly to moderately developed, fading out between posterior eye margin and posterior head margin. Antennal scrobes absent. Antennal scapes short, not reaching posterior head margin (SI 69– 73). Eyes of moderate size (OI 22–24). Mesosoma with well-developed anterior face but without distinct anterodorsal median protuberance on pronotum, margination from lateral to dorsal mesosoma weak to moderate; promesonotal suture and metanotal groove absent; mesosoma comparatively high, compact, and stout (LMI 43– 46). Propodeal spines long to very long, spinose, and acute (PSLI 33–37); propodeal lobes small and triangular. Petiolar node in profile cuneiform, weakly anteroposteriorly compressed dorsally, approximately 2 to 2.2 times higher than long (LPeI 45–50), anterior and posterior faces not parallel, anterodorsal margin situated higher than posterodorsal, dorsum moderately tapering backwards posteriorly; node in dorsal view between 1.8 to 2 times wider than long (DPeI 183–200). Postpetiole in profile approximately rounded, approximately 1.1 to 1.3 times higher than long (LPpI 77–88), in dorsal view approximately 1.1 to 1.3 times wider than long (DPpI 111–124). Postpetiole in profile appearing somewhat more voluminous than petiolar node, in dorsal view weakly wider than petiolar node (PPI 106–115). Mandibles striate; clypeus with distinct median longitudinal ruga and one or two weaker and often shorter rugae laterally; cephalic dorsum between frontal carinae with five to nine longitudinal rugae, rugae ending at posterior head margin but often broken or with cross-meshes, close to posterior head margin reticulate-rugose, always with one well-developed longitudinal median ruga, median ruga running from posterior head margin to posterior clypeal margin, approximately at eye level diverging into two rugae leading to posterior clypeal margin; lateral and ventral head mainly reticulate-rugose to longitudinally rugose. Ground sculpture on head weakly to moderately developed. Mesosoma anterodorsally strongly reticulate-rugose, posteriorly and laterally reticulate-rugose to irregularly longitudinally rugose. Waist segments and gaster unsculptured, smooth, and shiny. All dorsal surfaces of body with abundant, long, fine, and erect pilosity. Body of uniform yellow to light brown colour.

Notes

The new species is only known to occur in three localities in the north and northwest of Madagascar: Manongarivo, Ampasindava, and Andavakoera. All three are rainforests situated at elevations between 400 to 600 m. The available collection data suggests that T. olana lives or forages in leaf litter or lower vegetation.

Within the species group, T. olana differs strikingly from T. bonibony , T. popell , and T. trafo since they possess a distinct anterodorsal median protuberance on the pronotum which is absent in T. olana . It can also not be easily confused with T. kali , although the general appearance and the similar petiolar node shape might be misleading. Tetramorium olana has a well-developed anterior pronotal face and shorter antennal scapes (SI 69–73) versus an almost absent anterior pronotal face and longer antennal scapes (SI 76–83). The remaining three species, T. vony , T. sada , and T. nosybe , all display a dorsally much more anteroposteriorly compressed petiolar node (LPeI 25–43; DPeI 232–462) while the node of T. olana is much less anteroposteriorly compressed (LPeI 45–50; DPeI 183–200). Due to its uniformly yellowish colour it is also unlikely to be confused with T. sada , which is dark brown and yellow, or T. nosybe , which is uniformly dark brown. However, T. olana and T. vony are both yellowish in colour, and are morphologically relatively similar. They differ mainly in the shape of the petiolar node and the habitats they live in (for further details see the description of T. vony ).

Etymology

The name of the new species is Malagasy and means "problem". It refers to the initially difficult species delimitation of T. olana . The species epithet is a noun in apposition and thus invariant.

Material examined

MADAGASCAR: Antsiranana, Ampasindava, Forêt d'Ambilanivy, 3.9 km 181° S Ambaliha, 13.79861 S, 48.16167 E, 600 m, rainforest, 4.–9.III.2001 (B.L. Fisher, C. Griswold et al.); Antsiranana, Forêt d' Andavakoera, 21.4 km 75° ENE Ambilobe, 4.6km 356° N Betsiaka, 13.11833 S, 49.23 E, 425 m, rainforest, 15.–16.XII.2003 (B.L. Fisher); Antsiranana, R.S. Manongarivo, 10.8 km 229° SW Antanambao, 13.96167 S, 48.43333 E, 400 m, rainforest, 8.XI.1998 (B.L. Fisher).