Tetramorium impurum

This species is parasitized by three species: Tetramorium atratulum, Strongylognathus testaceus, and Strongylognathus alpinus

Identification
A member of the Tetramorium caespitum complex. The species can be determined with a discriminant analysis of a set of morphological measurements. See Wagner et al. (2017) and https://webapp.uibk.ac.at/ecology/tetramorium/

Distribution
Wagner et al. (2017) - Eastern clade: Anatolia, Balkans, Italy, Central Europe, Benelux northward to 52° N. Western clade: Iberia, western France.

Distribution based on Regional Taxon Lists
Palaearctic Region: Andorra, Austria, Belgium, Croatia, Czech Republic, Germany , Hungary, Iberian Peninsula, Italy, Montenegro, Netherlands, Poland, Portugal, Romania, Russian Federation, Slovenia, Spain, Switzerland.

Biology
Wagner et al. (2017) - Less thermophilic than most other species of complex, different from all species except Tetramorium caucasicum. Temperature difference (t-test, p = 0.000) between eastern (TAS of 124 sites 13.7 ± 2.7 °C) and western clade (TAS of 31 sites 15.7 ± 2.3 °C). Eastern clade in Central Europe in mountain areas but also lowlands, in southern Europe on high evaluation. Typical habitats are meadows, semi-dry grasslands, rocky pastures, subalpine dwarf-shrub heathland, heaths, gravel pits, rock heaps, road embankments, avalanche trenches, rocky bright forests (pine, spruce, larch). In Central Europe often on loamy soil. Eastern clade of T. impurum shows strong affinity to stony habitats, while T. caespitum is more frequently collected from meadows. Western clade of T. impurum in sandy areas near coast, riverbanks, and oak forests. Nests typically under stones, but small soil mounds exist.

Monogynous (Seifert 2007).

Adult sexuals in nests on 23 August ± 27 [29 June, 14 October] (n = 36).

Tetramorium atratulum, Strongylognathus testaceus, and Strongylognathus alpinus were found in nests of T. impurum.

Nomenclature

 *  impurum. Myrmica impura Foerster, 1850a: 48 (w.) GERMANY.
 * Emery, 1925c: 184 (q.); Kutter, 1977c: 151 (m.).
 * Combination in Tetramorium: Mayr, 1855: 426.
 * Junior synonym of caespitum: Curtis, 1854: 215; Mayr, 1855: 427; Nylander, 1856b: 87; Smith, F. 1858b: 117; Roger, 1863b: 26; Mayr, 1863: 456; Mayr, 1865: 89; Smith, F. 1871b: 3; André, 1874: 203 (in list); Forel, 1874: 100 (in list); Emery & Forel, 1879: 458; Dalla Torre, 1893: 132; Emery, 1924d: 276.
 * Subspecies of caespitum: Emery, 1925c: 178.
 * Status as species: Kutter, 1977c: 159; Pasteels, et al. 1981: 675; Cammaerts, et al. 1985: 109; Agosti & Collingwood, 1987b: 277 (in key); López, 1991a: 31; Bolton, 1995b: 409; Radchenko, et al. 1998: 109; Sanetra, et al. 1999: 321; Czechowski, et al. 2002: 65; Seifert, 2007: 248; Casevitz-Weulersse & Galkowski, 2009: 497; Boer, 2010: 68; Czechowski, et al. 2012: 178; Borowiec, L. 2014: 199 (see note in bibliography); Radchenko, 2016: 246; Wagner, et al. 2017: 120 (redescription).
 * Senior synonym of gregori: Wagner, et al. 2017: 120.
 * Senior synonym of penninum: Sanetra, et al. 1999: 321; Radchenko, 2016: 246; Wagner, et al. 2017: 120.
 * gregori. Tetramorium staerckei var. gregori Kratochvíl, in Kratochvíl, et al. 1944: 66, fig. 7 (w.q.m.) CZECHOSLOVAKIA.
 * Subspecies of impurum: Bolton, 1995b: 408.
 * Junior synonym of impurum: Wagner, et al. 2017: 120.
 * penninum. Tetramorium caespitum var. penninum Santschi, 1927a: 54 (w.) SWITZERLAND.
 * Subspecies of caespitum: Novák & Sadil, 1941: 87 (in key); Bolton, 1995b: 412.
 * Junior synonym of impurum: Sanetra, et al. 1999: 321.

Worker
Wagner et al. (2017) - Medium size, CS = 741 ± 48 [624, 891] μm. Light brown to blackish, eastern clade often with lighter mesosoma.

Head moderately elongate, CL / CW = 1.017 ± 0.017 [0.951, 1.049]. Smallest eye of complex, EYE / CS = 0.168 ± 0.005 [0.155, 0.181]. Scape moderately long, SLd / CS = 0.779 ± 0.015 [0.741, 0.820]. Mesosoma short and moderately wide, ML / CS = 1.146 ± 0.025 [1.082, 1.200], MW / CS = 0.632 ± 0.011 [0.606, 0.654].

Promesonotal dorsum convex, metanotal groove shallow. – Head dorsum and occiput with longitudinal costae and costulae. Postoculo-temporal area of head with rather many costae and costulae, POTCos = 8.80 ± 1.78 [5.00, 14.75]. Mesosoma dorsum longitudinally rugulose, lateral side of propodeum with pronounced sculpture, Ppss = 29.4 ± 14.2 [3.4, 79.5]. – Dorsum of petiolar node usually with stronger costae and often fine transverse or reticulate microsculpture, exceptionally smooth. General surface appearance rather dull compared with other species. – Connected stickman-like or reticulate microsculpture: small units scattered over 1st gastral tergite, MC1TG = 15.25 ± 2.93 [6.70, 24.92]. – Some workers with long c-shaped, crinkly, or sinuous hairs on ventral head posterior to buccal cavity.

Male
Wagner et al. (2017) - Paramere structure belongs to impurum-like form: rounded ventral paramere lobe without any sharp corner in dorsal or ventral view but with clear division of ventral and dorsal paramere lobes, visible by deep emargination between lobes in posterior view. No sharp corner at end of ventral lobe visible in posterior view. Relatively short dorsal paramere lobe, visible in posterior and dorsal view. Paramere structure length in lateral view > 1014 μm. No corner on ventral paramere lobe between lobe top and emargination with dorsal lobe in dorsal and posterior view.

Type Material
Wagner et al. (2017) - Neotype designation: Schlicksteiner & al. 2006: 267. Mirwart vic. Saint-Hubert (Belgium), (50.03° N 05.27° E), 360 m a.s.l., leg. Y. Roisin, 4.VIII.2000.