Tetramorium ambanizana 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 : 59-61

Tetramorium ambanizana Hita Garcia & Fisher sp. n.

(Figs. 42, 43, 114, 115, 116, 142)

Holotype worker, MADAGASCAR, Toamasina, 5.3 km SSE Ambanizana, Andranobe, 15.66667 S, 49.96667 E, 425 m, rainforest, leaf litter (sifted mold, rotten wood), collection code BLF00926, 21.XI.2003 (B.L. Fisher) (CASC: CASENT0189238). Paratypes, four workers with same data as holotype (CASC: CASENT0189214, CASENT0218048, CASENT0218050, CASENT0270779).

Diagnosis

Within the T. noeli species complex T. ambanizana can be recognised by the following character combination: head weakly longer than wide (CI 97-98); propodeal spines extremely long (PSLI 60-65); petiolar node rectangular nodiform with the posterodorsal margin situated much higher than the anterodorsal margin, and the dorsum convex; postpetiole in profile around 1.2 to 1.3 times higher than long (LPpI 77-81), and in dorsal view approximately 1.1 times wider than long (DPpI 104-112).

Description

HL 0.85-0.95 (0.92); HW 0.82-0.93 (0.90); SL 0.68-0.76 (0.73); EL 0.20-0.21 (0.20); PH 0.43-0.48 (0.46); PW 0.61-0.69 (0.66); WL 1.08-1.23 (1.17); PSL 0.55-0.58 (0.57); PTL 0.31-0.35 (0.33); PTH 0.38-0.43 (0.40); PTW 0.26-0.30 (0.28); PPL 0.33-0.35 (0.34); PPH 0.41-0.46 (0.43); PPW 0.36-0.38 (0.37); CI 97-98 (98); SI 78-83 (81); OI 21-24 (22); DMI 56-58 (57); LMI 38-41 (39); PSLI 60-65 (62); PeNI 40-43 (42); LPeI 79-83 (81); DPeI 82-86 (84); PpNI 54-58 (56); LPpI 77-81 (79); DPpI 104-112 (108); PPI 127-138 (134) (five measured).

Head weakly longer than wide (CI 97-98); posterior head margin moderately concave. Anterior clypeal margin medially impressed. Frontal carinae strongly developed, diverging posteriorly, and ending at corners of posterior head margin. Antennal scrobes developed, moderately deep, but narrow and without defined posterior and ventral margins. Antennal scapes short to moderate, not reaching posterior head margin (SI 78-83). Eyes small to moderate (OI 21-24). Mesosomal outline in profile weakly convex, moderately marginate from lateral to dorsal mesosoma; promesonotal suture and metanotal groove absent; mesosoma comparatively stout and high (LMI 38-41). Propodeal spines extremely long, spinose, and acute (PSLI 60-65); propodeal lobes well-developed, triangular to elongate-triangular, and acute. Petiolar node in profile rectangular nodiform but comparatively high, approximately 1.2 to 1.3 times higher than long (LPeI 79-83), anterior and posterior faces approximately parallel, posterodorsal margin situated higher than anterodorsal, dorsum convex; node in dorsal view approximately 1.2 times longer than wide (DPeI 82-86). Postpetiole in profile subglobular and anteroposteriorly compressed, approximately 1.2 to 1.3 times higher than long (LPpI 77-81); in dorsal view around 1.1 times wider than long (DPpI 104-112). Postpetiole in profile higher and less voluminous than petiolar node, in dorsal view approximately 1.3 to 1.4 times wider than petiolar node (PPI 127-138). Mandibles distinctly longitudinally rugose; clypeus longitudinally rugulose, with one to six rugulae, median rugula always present, remaining rugulae variably developed; cephalic dorsum between frontal carinae with six to nine longitudinal rugae, most rugae running unbroken from posterior head margin to anterior clypeus, few rugae interrupted and none with cross-meshes; scrobal area mostly unsculptured; lateral and ventral head longitudinally rugose, very rarely with cross-meshes. Mesosoma laterally and dorsally distinctly longitudinally rugose. Forecoxae unsculptured, smooth, and shining, with weak, superficial ground sculpture. Waist segments strongly and very regularly longitudinally rugose, rugae absent from anterior face, but running unbroken from one side to other through posterior face. Base of first gastral tergite distinctly costulate, remainder of gaster unsculptured, smooth and shining. Ground sculpture generally faint to absent everywhere on body. 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 suberect to erect hairs. Body uniform dark brown to black in colour.

Notes

At present, T. ambanizana is only known from the type series from Ambanizana where it was collected from rainforest at an elevation of 425 m. The new species appears to inhabit leaf litter.

Within the species complex its petiolar node shape distinguishes it from T. aherni and T. singletonae since the latter two have a node with the anterodorsal and posterodorsal margins at about the same height. The node of T. ambanizana has a posterodorsal margin situated much higher than the anterodorsal margin. This node development is shared with the remaining species, T. noeli, which is generally fairly similar to T. ambanizana. Both are described as new and distinct species here, but it is possible that they are conspecific. Their general appearance is very much alike, and differentiating between the two requires measuring a few key characters. Tetramorium ambanizana is only known from the type locality, whereas T. noeli is found in several localities further north. This could mean that the first might be a geographic variation of the latter. However, we consider the following morphometric differences sufficient to consider them different species until more material, especially from T. ambanizana, becomes available. The head of T. noeli is always distinctly longer than wide (CI 92-95) while it is only weakly longer than wide in T. ambanizana (CI 97-98). In addition, both species have extremely long propodeal spines, but the spines of T. ambanizana are still much longer (PSLI 60-65) than the spines of T. noeli (PSLI 38-48). The third separating character is the shape of the postpetiole, which is relatively higher and broader in T. noeli (LPpI 68-72; DPpI 119-129) than in T. ambanizana (LPpI 77-81; DPpI 104-112).

Etymology

The new species is named after the type locality. The species epithet is a noun in apposition, and thus invariant.

Material examined

MADAGASCAR: Toamasina, 5.3 km SSE Ambanizana, 21.XI.2003 (B.L. Fisher).

Andranobe,

15.66667 S, 49.96667 E, 425 m, rainforest,