Tetramorium singletonae 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 : 64-66

Tetramorium singletonae Hita Garcia & Fisher sp. n.

(Figs. 30, 32, 38, 39, 120, 121, 122, 142)

Holotype worker, MADAGASCAR, Toamasina, 5.3 km SSE Ambanizana, Andranobe, 15.66667 S, 49.96667 E, 425 m, rainforest, pitfall trap, collection code BLF00906, 19.XI.1993 (B.L. Fisher) (CASC: CASENT0247161). Paratypes, five workers with same data as holotype (CASC: CASENT0188733; CASENT0247159; CASENT0270778).

Diagnosis

Tetramorium singletonae is easily recognisable within the T. noeli complex by the following combination of characters: eyes very small (OI 16-17); propodeal spines long, but very short for the species group (PSLI 27-29); petiolar node with anterodorsal and posterodorsal margins at about the same height, dorsum flat to weakly convex.

Description

HL 0.90-0.92 (0.91); HW 0.87-0.90 (0.89); SL 0.62-0.66 (0.64); EL 0.14-0.16 (0.15); PH 0.42-0.49 (0.47); PW 0.67-0.69 (0.68); WL 1.10-1.16 (1.13); PSL 0.25-0.27 (0.25); PTL 0.33-0.35 (0.34); PTH 0.33-0.36 (0.33); PTW 0.27-0.29 (0.28); PPL 0.30-0.31 (0.30); PPH 0.34-0.35 (0.34); PPW 0.35-0.37 (0.36); CI 97-98 (98); SI 70-74 (72); OI 16-17 (17); DMI 59-62 (60); LMI 38-44 (41); PSLI 27-29 (28); PeNI 40-42 (41); LPeI 94-106 (101); DPeI 81-85 (83); PpNI 51-54 (53); LPpI 86-91 (89); DPpI 115-122 (118); PPI 126-130 (128) (eight measured).

Head weakly longer than wider (CI 97-98). Anterior clypeal margin with median impression, sometimes weak, but always distinct. Frontal carinae well-developed, 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, not reaching posterior head margin (SI 70-74). Eyes very small (OI 16-17). Mesosomal outline in profile flat, moderately marginate from lateral to dorsal mesosoma; promesonotal suture and metanotal groove absent; mesosoma comparatively stout and high (LMI 38-44). Propodeal spines with very broad base, up-curved, elongate-triangular, and moderately long (PSLI 27-29); propodeal lobes well-developed, triangular and acute. Petiolar node in profile rectangular nodiform, ranging from weakly longer than high to weakly higher than long (LPeI 94-106), anterior and posterior faces approximately parallel, anterodorsal and posterodorsal margins approximately at same height, dorsum flat to weakly convex; node in dorsal view approximately 1.2 times longer than wide (DPeI 81-85). Postpetiole in profile globular, approximately 1.1 times higher than long (LPpI 86-91); in dorsal view around 1.2 times wider than long (DPpI 115-122). Postpetiole in profile appearing approximately as voluminous as petiolar node, in dorsal view approximately 1.2 to 1.3 times wider than petiolar node (PPI 126-130). Mandibles distinctly longitudinally rugose; clypeus longitudinally rugose, with three to five rugae; cephalic dorsum between frontal carinae with 8 to 11 longitudinal rugae, most rugae running unbroken from posterior head margin to posterior clypeus, few rugae interrupted or with cross-meshes; lateral and ventral head longitudinally rugose, rarely with cross-meshes. Mesosoma laterally and dorsally distinctly longitudinally rugose. Forecoxae unsculptured. Waist segments strongly irregularly longitudinally rugose. Base of first gastral tergite with costulate sculpture, remainder of gaster unsculptured, smooth, and shiny. 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 distinct, appressed pubescence. Anterior edges of antennal scapes with subdecumbent to erect, standing hairs. Body a uniform brown colour.

Notes

The available material from this new species was sampled from Ambanizana and Amparihibe. Both localities are rainforests located in the northeast of Madagascar at elevations of 425 to approximately 1000 m. Tetramorium singletonae appears to live and/or forage on the ground since most specimens were collected from pitfall traps.

Tetramorium singletonae is the species with the shortest antennal scapes (SI 70-74 vs. SI 78-86), smallest eyes (OI 16-17 vs. OI 21-24), and shortest propodeal spines (PSLI 27-29 vs. PSLI 38-65) encountered in the T. noeli species complex, and is thus easily recognisable. At first glance T. singletonae is also morphologically close to T. nify from the T. andrei species complex since both have shorter propodeal spines than most other T. tortuosum group species and similarly shaped waist segments, but the base of the first gastral tergite is unsculptured in T. nify.

Etymology

The new species is dedicated to Sarah Singleton for her support to promote the discovery and identification of life on earth.

Material examined

MADAGASCAR: Toamasina, 5.3 km SSE Ambanizana, Andranobe, 15.66667 S, 49.96667 E, 425 m, rainforest, 19.XI.1993 (B.L. Fisher); Toamasina, Amparihibe, 15° 2' S, 49° 34' E, II.-III.2003 (K.A. Jackson & D. Carpenter).