Tetramorium yammer, 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 : 88-90

Tetramorium yammer sp. n.

(figs 88, 89, 125, 126, 127)

Holotype worker, MADAGASCAR, Antsiranana, Parc National de Marojejy, Antranohofa , 26.6 km 31° NNE Andapa, 10.7 km 318° NW Manantenina, 14.44333 S, 49.74333 E, 1325 m, montane rainforest, sifted litter (leaf mold, rotten wood), collection code BLF9080, 18.XI.2003 (B.L. Fisher) ( CASC: CASENT0042832 ) . Paratypes, one worker with same data as holotype ( BMNH: CASENT0042886 ) ; and 18 workers with same data as holotype except sampled ex rotten log and collection codes BLF9175 and BLF9189 ( CASC: CASENT0499759 , CASENT0499760 , CASENT0499761 , CASENT0499777 , CASENT0499781 ; MHNG: CASENT0499778 ) .

Diagnosis

Tetramorium yammer can be separated from all other group members by the following character set: short antennal scapes (SI 72–78); eyes small to moderate (OI 19–20); propodeal spines very long (PSLI 40–41); propodeal lobes very long and spinose; petiolar node squamiform with anterodorsal margin situated slightly higher than posterodorsal margin, dorsum tapering backwards posteriorly; dorsum of mesosoma with longitudinally arranged rugae; hairs on first gastral tergite erect or suberect.

Description

HL 0.88–0.94 (0.90); HW 0.89–0.95 (0.92); SL 0.67–0.74 (0.68); EL 0.17–0.19 (0.18); PH 0.46–0.52 (0.49); PW 0.66–0.72 (0.67); WL 1.16–1.30 (1.22); PSL 0.36–0.39 (0.37); PTL 0.16–0.18 (0.17); PTH 0.35–0.39 (0.37); PTW 0.27–0.31 (0.28); PPL 0.26–0.28 (0.27); PPH 0.34–0.39 (0.36); PPW 0.34–0.38 (0.35); CI 101–103 (102); SI 72– 78 (74); OI 19–20 (20); DMI 51–57 (55); LMI 39–41 (40); PSLI 40–41 (41); PeNI 40–46 (42); LPeI 42–48 (46); DPeI 162–172 (166); PpNI 51–57 (53); LPpI 71–79 (75); DPpI 124–134 (130); PPI 121–130 (125) (ten measured). Head wider than long (CI 101–103). Anterior clypeal margin with distinct median impression. Frontal carinae well-developed, usually ending at posterior head margin. Antennal scrobes narrow, shallow, and faint. Antennal scapes short, not reaching posterior head margin (SI 72–78). Eyes comparatively small (OI 19–20). Mesosomal outline in profile comparatively flat, moderately marginate from lateral to dorsal mesosoma, promesonotal suture and metanotal groove absent; mesosoma comparatively stout, high, and compact (LMI 39–41). Propodeal spines very long, spinose and acute (PSLI 40–41); propodeal lobes very long, spinose, and acute. Petiolar node in profile squamiform and anteroposteriorly compressed, approximately 2.2 to 2.3 times higher than long (LPeI 42–48), anterior and posterior faces almost parallel, anterodorsal margin situated slightly higher than posterodorsal margin, dorsum weakly tapering backwards posteriorly; node in dorsal view approximately 1.6 to 1.7 times wider than long (DPeI 162–172). Postpetiole in profile rounded, approximately 1.2 to 1.4 times higher than long (LPpI 71–79), in dorsal view 1.2 to 1.4 times wider than long (DPpI 124–134). Postpetiole in profile slightly more voluminous than petiolar node, in dorsal view approximately 1.2 to 1.3 times wider than petiolar node (PPI 121–130). Mandibles distinctly striate; clypeus with strong median longitudinal ruga and one or two weaker rugulae at each side; cephalic dorsum between frontal carinae with seven to nine longitudinal rugae, rugae running to posterior head margin, few rugae broken or with cross-meshes; lateral and ventral head with reticulate-rugose to longitudinally rugose sculpture; ground sculpture on head usually faint. Mesosoma laterally with irregular longitudinal rugae; mesosomal dorsum longitudinally rugose, rugae often meandering and with cross-meshes, still distinctly longitudinally arranged. Petiole and postpetiole almost unsculptured with few weak rugulae. Gaster unsculptured, smooth and shining. All dorsal surfaces of body with abundant, long, erect or suberect pilosity. Head, mesosoma, waist segments, and gaster very dark brown to black, appendages often of lighter colour.

Notes

Tetramorium yammer is only known from the type locality, the Parc National de Marojejy. It was collected from forest leaf litter in a montane rainforest habitat at 1325 m elevation.

Within the species group it is fairly easy to distinguish T. yammer from the remaining species. It differs from T. ambatovy in having very different sculpture on the mesosomal dorsum, and from T. dysalum (SI 64–69) in having distinctly longer antennal scapes (SI 72–78). The three species with short propodeal spines, T. macki (PSLI 21–24), T. orc (PSLI 19–23), and T. robitika (PSLI 20–22), cannot be confused with T. yammer with its very long and conspicuous propodeal spines (PSLI 40–41). In addition, due to its unsculptured mandibles, the moderately developed, triangular propodeal lobes, and light brown colouration, T. vohitra is not likely to be confused with T. yammer because the latter has strongly striate mandibles, very long and spinose propodeal lobes, and the colouration is of a very dark brown to black. Tetramorium yammer also has a more transverse petiolar node in dorsal view (DPel 162–172) compared to T. vohitra (DPel 120–138).

Tetramorium mallenseana is comparatively easy to discriminate from T. yammer . The propodeal lobes of T. mallenseana are very small and inconspicuous and the postpetiole is approximately 1.7 to two times wider than the petiolar node (PPI 168–200), whereas the lobes of T. yammer are very long and spinose and the postpetiole is only approximately 1.2 to 1.3 times wider than the petiolar node (PPI 121–130). Furthermore, T. sargina has decumbent to subdecumbent pilosity on the first gastral tergite, which differs significantly from the erect to suberect pilosity of T. yammer . Tetramorium steinheili , however, is very close to T. yammer , and, as mentioned in its description above, both could have been treated as one species. However, a weakly wider head (CI 101–103), distinctly smaller eyes (OI 19–20), very long propodeal spines (PSLI 40–41) together with the comparatively long and spinose propodeal lobes, and dark brown to black colour separate T. yammer from T. steinheili . The latter has a mostly longer head (CI 96–102), larger eyes (OI 21–23), and is usually of a much lighter colour. The propodeal spines (PSLI 27–44) and propodeal lobes are quite variable in this species, but the lobes are never spinose as in T. yammer . Some of these characters might appear weak, if considered individually, but in combination make us confident about treating them as discrete species.

Etymology

The new species is dedicated to George Zachary for his support to discover and identify life on earth, and we have named it after his company "Yammer".

Material examined

MADAGASCAR: Antsiranana, Parc National de Marojejy, Antranohofa, 26.6 km 31° NNE Andapa, 10.7 km 318° NW Manantenina, 14.44333 S, 49.74333 E, 1325 m, montane rainforest, 18.XI.2003 (B.L. Fisher).