Tetramorium nassonowii

Tetramorium nassonowii is distributed in the montane rainforests and rainforest belt of eastern Madagascar at altitudes ranging from 425 to 1700 m, although it is predominantly found in montane rainforests situated higher than 1000 m. Also, based on the available collection data, it seems that T. nassonowii inhabits leaf litter or the ground.

Identification
A member of the Tetramorium schaufussii species complex of the Tetramorium schaufussii species group. Hita Garcia and Fisher (2014) - Tetramorium nassonowii is clearly recognisable within the T. schaufussii complex on the basis of its petiolar node shape, which is relatively long and low, in profile around 1.2 to 1.4 times higher than long (LPeI 72–81) and in dorsal view between 1.0 to 1.2 times longer than wide (DPeI 87–98).

In the original description Forel (1892) compared T. nassonowii with Tetramorium schaufussii, and found them to be different in petiolar node shape and propodeal spine length. Tetramorium nassonowii is especially distinctive within the complex due to its large body size and characteristic petiolar node shape. As noted in the diagnosis, the lower and longer petiolar node shape of T. nassonowii, which in profile is around 1.2 to 1.4 times higher than long (LPeI 72–81) and in dorsal view between 1.0 to 1.2 times longer than wide (DPeI 87–98), clearly distinguishes it from the remainder of the T. schaufussii species complex. The other species all have a higher and broader petiolar node, in profile around 1.5 to 2.2 times higher than long (LPeI 45–67) and in dorsal view between 1.1 to 1.5 times wider than long (DPeI 109–154).

Despite the relatively wide distribution, we find T. nassonowii without much observable intraspecific variation.

Distribution based on Regional Taxon Lists
Malagasy Region: Madagascar.

Nomenclature

 *  nassonowii. Tetramorium (Xiphomyrmex) nassonowii Forel, 1892k: 521 (w.) MADAGASCAR. Combination in Xiphomyrmex: Wheeler, W.M. 1922a: 1031. Junior synonym of schaufussii: Bolton, 1979: 137. Revived from synonymy: Hita Garcia & Fisher, 2014: 121.

Worker
Hita Garcia and Fisher (2014) - (N=12). HL 0.82–0.96 (0.87); HW 0.74–0.86 (0.78); SL 0.52–0.64 (0.57); EL 0.18–0.21 (0.19); PH 0.38–0.45 (0.41); PW 0.54–0.62 (0.57); WL 1.02–1.16 (1.08); PSL 0.06–0.09 (0.08); PTL 0.21–0.26 (0.23); PTH 0.28–0.34 (0.30); PTW 0.20–0.25 (0.22); PPL 0.21–0.26 (0.23); PPH 0.28–0.34 (0.30); PPW 0.27–0.34 (0.30); CI 90–92 (91); SI 70–74 (72); OI 23–25 (24); DMI 51–54 (53); LMI 36–39 (38); PSLI 7–11 (9); PeNI 36–40 (38); LPeI 72–81 (77); DPeI 87–98 (95); PpNI 50–55 (52); LPpI 75–82 (78); DPpI 122–134 (128); PPI 130–145 (137).

Head clearly longer than wide (CI 90–92); posterior head margin weakly concave. Anterior clypeal margin with distinct median impression. Frontal carinae weakly to moderately developed, moderately raised, diverging posteriorly, and usually fading out halfway between posterior eye margin and posterior head margin or approaching posterior head margin. Antennal scrobes present but weak, shallow and without clear and distinct posterior and ventral margins. Antennal scapes short, not reaching posterior head margin (SI 70–74). Eyes moderate to large (OI 23–25). Mesosomal outline in profile flat to weakly convex, comparatively low and long (LMI 36–39), weakly to moderately marginate from lateral to dorsal mesosoma; promesonotal suture absent; metanotal groove weakly developed or absent. Propodeal spines reduced to very short teeth (PSLI 7–11), propodeal lobes short, triangular, and blunt or acute, usually longer than propodeal spines, rarely as long as propodeal spines, spines and lobes not strongly inclined towards each other. Petiolar node rounded nodiform, in profile around 1.2 to 1.4 times higher than long (LPeI 72–81), anterior and posterior faces not parallel, anterodorsal and posterodorsal margins situated at about same height, petiolar dorsum distinctly convex; node in dorsal view weakly longer than wide (DPeI 92–96), in dorsal view pronotum between 2.5 to 2.8 times wider than petiolar node (PeNI 36–40). Postpetiole in profile globular, approximately 1.2 to 1.3 times higher than long (LPpI 75–82); in dorsal view around 1.2 to 1.3 times wider than long (DPpI 122–134), pronotum between 1.8 to 2.0 times wider than postpetiole (PpNI 50–55). Postpetiole in profile appearing more or less of same volume as petiolar node, postpetiole in dorsal view around 1.3 to 1.5 times wider than petiolar node (PPI 130–145). Mandibles unsculptured, smooth, and shiny; clypeus weakly longitudinally rugulose with three to seven rugulae, rugulae often interrupted or irregularly shaped, median area often weakly sculptured, median ruga usually absent or mostly reduced, very rarely fully developed; cephalic dorsum between frontal carinae irregularly longitudinally rugose/rugulose with six to nine rugae/rugulae; rugae/rugulae running from posterior clypeal margin to posterior head margin, often meandering, broken or with cross-meshes; scrobal area mostly unsculptured and laterally merging with surrounding reticulate-rugose to longitudinally rugose sculpture present on lateral head; ground sculpture on head weak to absent. Dorsum of mesosoma irregularly longitudinally rugose to reticulate-rugose, lateral mesosoma mostly irregularly longitudinally rugose; ground sculpture on mesosoma weak to absent. Forecoxae mainly unsculptured, smooth and shining. Waist segments and gaster unsculptured, smooth, and shining. Dorsum of head with several pairs of long, fine, standing hairs; dorsum of mesosoma with at least six or seven pairs of long, standing hairs ranging from anterior pronotum to posterior mesonotum, propodeum without long, standing pilosity; petiole with one pair and postpetiole with one or two pairs; first gastral tergite with short, scarce, appressed pubescence in combination with scattered, long, standing hairs. Anterior edges of antennal scapes and dorsal (outer) surfaces of hind tibiae with appressed to decumbent hairs. Body uniformly light brown to dark brown colour, appendages often lighter.

Type Material
Hita Garcia and Fisher (2014) - Lectotype [designated here], pinned worker, MADAGASCAR, Antananarivo (Province central de Madagascar), Andrangoloaca, 47.27729°E, 18.22198 S (Sikora) (: CASENT0101289) [examined]. Paralectotype [designated here], pinned worker with same data as lectotype (MHNG: CASENT0101290). [Note 1: the GPS data of the type locality was not provided by the locality label or the original description. The data presented above is based on our own geo-referencing of the Foret d’ Andrangoloaca and should be considered as an approximation and not the exact position of the type locality.] [Note 2: one specimen from the MHNG collection (CASENT0101556) with the label data “Tetramorium nassonowii Forel var., no. 14, Moramanga (Sikora)” also has a red type label. However, we do not consider this as a real name-bearing type specimen since the original description of Forel (1892) only mentioned the type material from Andrangoloaca and nothing from Moramanga. This specimen from Moramanga (which is also partly broken) is actually not conspecific with T. nassonowii, but belongs to the newly described species T. obiwan.]

References based on Global Ant Biodiversity Informatics

 * Hita Garcia F, and B. L. Fisher. 2014. The hyper-diverse ant genus Tetramorium Mayr (Hymenoptera, Formicidae) in the Malagasy region - taxonomic revision of the T. naganum, T. plesiarum, T. schaufussii, and T. severini species groups. ZooKeys 413: 1-170.