Tetramorium monticola

Tetramorium monticola lives in leaf litter.

Identification
A member of the Tetramorium schaufussii species complex of the Tetramorium schaufussii species group. Hita Garcia and Fisher (2014) - The following character combination distinguishes T. monticola from the other species of the T. schaufussii complex: head longer than wide (CI 92–94); eyes relatively large (OI 24–28); antennal scapes very short (SI 67–74); propodeal spines of moderate length, elongate-triangular to spinose, and usually acute (PSLI 8–11), propodeal lobes short, triangular, and usually blunt, always much smaller than propodeal spines, spines and lobes not strongly inclined towards each other; petiolar node high nodiform to high cuneiform, in profile around 1.7 to 2.0 times higher than long (LPeI 50–60), node in dorsal view around 1.2 to 1.3 times wider than long (DPeI 124–133); both waist segments with long, standing pilosity; body uniformly dark yellow to orange light brown.

Tetramorium monticola is well recognisable within the T. schaufussii complex. It differs from Tetramorium pseudogladius (OI 20) by its much larger eye size (OI 24–28), and from Tetramorium scutum by having propodeal spines and lobes not strongly inclined towards each other. Also, T. monticola (DPeI 124–133; LPeI 50–60) is very unlikely to be confused with Tetramorium nassonowii, which has a much longer and lower petiolar node (DPeI 87–98; LPeI 72–81). In addition, T. monticola is a relatively hairy species with long pilosity all over the body, which separates it from the few species with partly reduced pilosity, such as Tetramorium rala, Tetramorium sikorae, and Tetramorium obiwan, which all usually lack standing pilosity on the propodeum and waist segments, except in T. obiwan, where the petiole or postpetiole occasionally have a few long hairs. Nevertheless, T. monticola cannot be mistaken for T. obiwan. The latter is of larger body size (HW 0.71–0.84; WL 1.00–1.20), has longer antennal scapes (SI 77–82), and has a petiolar node with the antero- and posterodorsal margins situated at about the same height and well rounded. Tetramorium monticola is much smaller than that (HW 0.51–0.67; WL 0.67–0.88), has shorter antennal scapes (SI 67–74), and its petiolar node has the anterodorsal margin always higher and a little bit more angled than the posterodorsal margin with the petiolar dorsum tapering backwards.

The remaining three species, Tetramorium merina, Tetramorium schaufussii, and Tetramorium xanthogaster, are morphologically closer to T. monticola, and their separation requires more attention. Tetramorium schaufussii can be easily mistaken for T. monticola in northern Madagascar where both are sympatric, but T. schaufussii differs from T. monticola (and the other two) by having a much longer and thinner head in full-face view (CI 86–90). The other two species, T. merina and T. xanthogaster, usually have shorter, and in the case of T. merina much shorter, propodeal spines (PSLI 8–16) than T. monticola (PSLI 18–22). However, since the spine length is somewhat variable in the latter species, this character cannot be the sole distinguishing feature. In addition, T. monticola also differs from the other two by having relatively better developed frontal carinae and the cephalic dorsum between them with nine to thirteen relatively regularly shaped, mostly unbroken rugae. Tetramorium merina and T. xanthogaster have relatively weaker developed, and often shorter, frontal carinae and a cephalic dorsum with six to ten relatively irregularly shaped, often meandering or broken rugulae.

Key to Tetramorium schaufussii  species complex workers

Distribution
Tetramorium monticola is distributed in the northeast and north of Madagascar. The distribution range is outlined by Manongarivo in the west, the northernmost locality Makirovana, and the easternmost Ambanizana on the Masoala Peninsula. Most of the material available was collected in that triangle, but T. monticola is also known from Zahamena and Sandranantitra, which are located much further south. (Hita Garcia and Fisher 2014)

Distribution based on Regional Taxon Lists
Malagasy Region: Madagascar.

Habitat
All known collection localities are rainforests or montane rainforests situated at elevation ranging from 415 to 2000 m.

Nomenclature

 *  monticola. Tetramorium monticola Hita Garcia & Fisher, 2014: 116, figs. 42B, 44C, 45C, 47D, 48A, 48B, 51, 65 (w.) MADAGASCAR.

Worker
(N=12). HL 0.55–0.72 (0.62); HW 0.51–0.67 (0.58); SL 0.34–0.46 (0.40); EL 0.13–0.16 (0.15); PH 0.26–0.33 (0.29); PW 0.35–0.48 (0.41); WL 0.67–0.88 (0.77); PSL 0.10–0.15 (0.12); PTL 0.11–0.15 (0.12); PTH 0.20–0.26 (0.23); PTW 0.13–0.19 (0.16); PPL 0.14–0.18 (0.16); PPH 0.18–0.24 (0.21); PPW 0.19–0.26 (0.23); CI 92–94 (93); SI 67–74 (69); OI 24–28 (25); DMI 51–55 (54); LMI 35–39 (37); PSLI 18–22 (20); PeNI 37–42 (39); LPeI 50–60 (54); DPeI 124–133 (129); PpNI 54–60 (56); LPpI 71–78 (76); DPpI 131–153 (142); PPI 138–150 (143).

Head longer than wide (CI 92–94); posterior head margin weakly concave. Anterior clypeal margin with distinct median impression. Frontal carinae usually well developed, moderately raised on anterior half, strongly diverging posteriorly, and usually approaching or ending at posterior head margin. Antennal scrobes usually weakly developed, shallow and without clear and distinct posterior and ventral margins, sometimes scrobe better developed, slightly deeper and with weak posterior, and rarely even ventral margin. Antennal scapes very short, not reaching posterior head margin (SI 67–74). Eyes relatively large (OI 24–28). Mesosomal outline in profile flat to weakly convex, comparatively low and elongate (LMI 35–39), weakly marginate from lateral to dorsal mesosoma; promesonotal suture absent; metanotal groove weakly to moderately developed, sometimes slightly impressed, but mostly moderately deep. Propodeal spines of moderate length, elongate-triangular to spinose, and usually acute (PSLI 8–11), propodeal lobes short, triangular, and usually blunt, always much smaller than propodeal spines, spines and lobes not strongly inclined towards each other. Petiolar node in profile high nodiform to high cuneiform, around 1.7 to 2.0 times higher than long (LPeI 50–60), anterior and posterior faces approximately parallel, anterodorsal margin always higher and more angled than posterodorsal margin, petiolar dorsum usually weakly convex and tapering backwards posteriorly; petiolar node in dorsal view around 1.2 to 1.3 times wider than long (DPeI 124–133), in dorsal view pronotum between 2.4 to 2.7 times wider than petiolar node (PeNI 37–42). Postpetiole in profile globular, approximately 1.3 to 1.4 times higher than long (LPpI 71–78); in dorsal view around 1.3 to 1.5 times wider than long (DPpI 131–153), pronotum between 1.7 to 1.9 times wider than postpetiole (PpNI 54–60). Postpetiole in profile appearing always lower and having less volume than petiolar node, postpetiole in dorsal view around 1.4 to 1.5 times wider than petiolar node (PPI 138–150). Mandibles unsculptured, smooth, and shiny; clypeus usually longitudinally rugulose with two to six rugulae, median area usually either completely unsculptured without median rugula or only weakly sculptured with traces of median rugula, very rarely median rugula fully developed, lateral rugulae usually well developed and unbroken, sometimes irregularly shaped or broken; cephalic dorsum between frontal carinae longitudinally rugose with nine to thirteen rugae; rugae running from posterior clypeal margin to posterior head margin, generally very regularly shaped and only rarely broken or with cross-meshes; scrobal area partly unsculptured and laterally merging with surrounding longitudinally rugulose to reticulate-rugose sculpture present on lateral head; ground sculpture on head usually moderately punctate. Dorsum of mesosoma usually longitudinally rugose, sometimes irregularly so; lateral mesosoma irregularly longitudinally rugose to reticulate-rugose, sometimes lateral pronotum with less sculpture; ground sculpture on mesosoma weak to absent. Forecoxae always unsculptured, smooth and shining. Waist segments and gaster unsculptured, smooth, and shining. Dorsum of head with numerous pairs of long, fine, standing hairs; dorsum of promesonotum with at least ten pairs of long, standing hairs ranging from anterior pronotum to posterior mesonotum, propodeum usually without long, standing pilosity, sometimes with one or two shorter pairs of hairs; petiole usually with at least two pairs and postpetiole with at least three to four pairs; first gastral tergite with short, scarce to abundant, decumbent to appressed pubescence in combination with abundant, long, standing hairs. Anterior edges of antennal scapes and dorsal (outer) surfaces of hind tibiae usually with decumbent to suberect hairs. Body uniformly dark yellow to orange light brown, gaster sometimes of darker brown, appendages usually slightly lighter.

Type Material
Holotype, pinned worker, MADAGASCAR, Antsiranana, Betaolana Forest, along Bekona River, 14.52996°S, 49.44039°E, 880 m, rainforest, ex rotten log, collection code BLF22473, 4.III.2009 (B.L. Fisher et al.) (: CASENT0152401). Paratypes, 1 pinned worker with same data as holotype (CAS: CASENT0152402); three pinned workers with same data as holotype except collection codes BLF22465, BLF22486, and BLF22504 (CAS: CASENT0151864; CASENT0151868; CASENT0152427); and four pinned workers with same data as holotype except collection date 5.III.2009 and collection codes BLF22612, BLF22644, and BLF22667 (: CASENT0151589; CAS: CASENT0151590; CASENT0151949; : CASENT0152285).

Etymology
The name of the new species is a Latin noun and means “inhabitant of the mountains” referring to the fact that T. monticola is predominantly found in higher elevation montane forests. The species epithet is a nominative noun, and thus invariant.