Tetramorium sargina, 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 : 78-80

Tetramorium sargina sp. n.

(figs 84, 86, 113, 114, 115)

Holotype worker, MADAGASCAR, Antsiranana, Parc National de Marojejy , 25.7 km 32° NNE Andapa, 10.3 km 314° NW Manantenina, 14.445 S, 49.74167 E, 1575 m, montane rainforest, under moss, above ground, collection code BLF09320, 22.XI.2003 (B.L. Fisher) ( CASC: CASENT0487390 ) . Paratypes, seven workers with same data as holotype ( CASC: CASENT0247152 ; CASENT0487389; CASENT0487392) .

Diagnosis

Tetramorium sargina differs distinctly from the other members of the T. dysalum group due to the following character set: short antennal scapes SI 73–75; propodeal spines long (PSLI 30–32); mesosomal dorsum with longitudinally arranged rugae; first gastral tergite with decumbent to subdecumbent long hairs.

Description

HL 0.63–0.74 (0.70); HW 0.60–0.72 (0.68); SL 0.44–0.54 (0.50); EL 0.14–0.16 (0.15); PH 0.34–0.42 (0.39); PW 0.42–0.55 (0.51); WL 0.75–0.94 (0.87); PSL 0.19–0.24 (0.22); PTL 0.11–0.15 (0.14); PTH 0.27–0.31 (0.29); PTW 0.18–0.23 (0.21); PPL 0.19–0.22 (0.21); PPH 0.27–0.31 (0.29); PPW 0.27–0.33 (0.30); CI 96–99 (97); SI 73–75 (74); OI 21–23 (22); DMI 56–59 (58); LMI 43–46 (45); PSLI 30–32 (31); PeNI 39–43 (41); LPeI 41–50 (47); DPeI 148–164 (153); PpNI 56–64 (59); LPpI 72–78 (74); DPpI 129–148 (141); PPI 141–150 (144) (nine measured).

Head usually weakly longer than wide (CI 96–99). Anterior clypeal margin with distinct median impression. Frontal carinae well-developed, usually ending at or shortly before posterior head margin. Antennal scrobes shallow, narrow, and faint. Antennal scapes short, not reaching posterior head margin (SI 73–75). Eyes comparatively small to moderate (OI 21–23). Mesosomal outline in profile comparatively flat to weakly convex, weakly to moderately marginate from lateral to dorsal mesosoma, promesonotal suture absent, metanotal groove faint to absent; mesosoma comparatively stout, high, and compact (LMI 43–46). Propodeal spines long, spinose and acute (PSLI 30–32). Propodeal lobes well-developed, elongate-triangular, and usually acute. Petiolar node in profile rounded high nodiform, approximately 2 to 2.5 times higher than long (LPeI 41–50), anterior and posterior faces almost parallel, anterodorsal margin situated slightly higher than posterodorsal margin, dorsum weakly tapering backwards posteriorly; node in dorsal view between 1.4 to 1.7 times wider than long (DPeI 148–164). Postpetiole in profile approximately rounded, approximately 1.3 to 1.4 times higher than long (LPpI 72–78), in dorsal view 1.3 to 1.5 times wider than long (DPpI 129–148). Postpetiole in profile a bit more voluminous than petiolar node, in dorsal view much wider than petiolar node, between 1.4 to 1.5 times wider (PPI 141–150). Mandibles unsculptured, smooth, and shining; clypeus with three to six longitudinal rugulae, median rugula not more strongly developed than other ones, sometimes rugulae irregularly arranged; cephalic dorsum between frontal carinae with seven to ten longitudinal rugae, rugae running to posterior head margin, rugae often interrupted or with cross-meshes; lateral and ventral head with reticulate-rugose sculpture; ground sculpture on head generally faint. Mesosoma laterally and dorsally longitudinally rugose, rugae moderately meandering but distinctly longitudinally arranged with few cross-meshes. Petiole and postpetiole almost unsculptured with few weak rugulae laterally and posteriorly. Gaster unsculptured, smooth and shining. Head, mesosoma, and waist segments with long, erect or suberect pilosity; first gastral tergite with abundant long, decumbent to subdecumbent pilosity, and less abundant and shorter, but still comparatively long, appressed pubescence. Head, mesosoma, waist segments, and gaster dark brown, appendages of lighter brownish to yellowish colouration.

Notes

The new species is only known from two localities, which are widely separated from each other. The one is Marojejy in the northeast, and the other one is Kalambatritra in the southeast. Interestingly, there is not a single record from any locality in-between. Both localities are montane rainforests located at elevations of 1390 to 1575 m, and all specimens were sampled from leaf litter.

Tetramorium sargina is not likely to be misidentified with T. ambatovy due to the very different sculpture patterns on the mesosoma, and surely not with T. macki , T. orc , and T. robitika , which all possess very short propodeal spines (PSLI 19–24). Furthermore, T. dysalum with its very short antennal scapes (SI 64–69) should not be confused with T. sargina , which has much longer scapes (SI 73–75). The differentiation of T. sargina from the remaining species is less obvious, but still straightforward. Tetramorium mallenseana , T. steinheili , T. yammer , and T. vohitra are at first glance morphologically fairly close to T. sargina . However, T. mallenseana has minute propodeal lobes and the postpetiole is approximately 1.7 to 2 times wider than the petiolar node (PPI 168–200), whereas the propodeal lobes in T. sargina are well-developed and the postpetiole is approximately 1.4 to 1.5 times wider than the petiolar node (PPI 141–150). The remaining three species, T. vohitra , T. steinheili , and T. yammer , all have suberect to erect pilosity on the first gastral tergite, which distinguishes them from T. sargina with its decumbent to subdecumbent hairs.

Etymology

The new species is named in honor of Leonard M. and Sargina T. Silvani for their support to discover and identify life on earth.

Material examined

MADAGASCAR: Antsiranana, Parc National de Marojejy, 25.7 km 32° NNE Andapa, 10.3 km 314° NW Manantenina, 14.445 S, 49.74167 E, 1575 m, montane rainforest, 22.XI.2003 (B.L. Fisher); Toliara, Réserve Spéciale Kalambatritra, Befarara, 23.4178 S, 46.4478 E, 1390 m, montane rainforest, 7.–8.II.2009 (B.L. Fisher et al.); Toliara, Réserve Spéciale Kalambatritra, Ampanihy, 23.4635 S, 46.4631 E, 1270 m, montane rainforest, 9.II.2009 (B.L. Fisher et al.).