Tetramorium aspina

Tetramorium aspina is known from a single collection from a nest that also contained Tetramorium immigrans workers. The nest was found in a subalpine area in the East Black Sea Region of Turkey. Tetramorium aspina is believed to be a parasite of T. immigrans.

Identification
Workers: The character combination of yellowish color and strong reduction of propodeal spines allows differentiation from all Tetramorium species in Europe, Mediterranean basin, and adjacent regions. Differentiation from Tetramorium nitidissimum workers (type locality: Firyuza, 25 km W Ashgabat, Turkmenistan) possible by three steps: (i) Tetramorium aspina exhibits a row of long hairs at posterior margin of head. Tetramorium nitidissimum does not show such long hairs. (ii) Frontal carinae and antennal fossae of Tetramorium nitidissimum type-workers are narrower (FL / CL = 0.332 - 0.337, dAN / CL = 0.246 - 0.247, n = 2) than in Tetramorium aspina (FL / CL = 0.451 ± 0.010 [0.435, 0.470], dAN / CL = 0.284 ± 0.007 [0.269, 0.296], n = 18). (iii) Distances from dorsocaudalmost point of propodeal lobe to most anteroventral point of metapleuron and to center of propodeal spiracle are smaller (MPPL / CL = 0.291 - 0.309, PLST / CL = 0.209 - 0.226) than in Tetramorium aspina (MPPL / CL = 0.369 ± 0.013 [0.351, 0.398], PLST / CL = 0.283 ± 0.013 [0.259, 0.309] n = 18).

Distribution based on Regional Taxon Lists
Palaearctic Region: Turkey.

Biology
Wagner et al. (2018) - The type locality is a subalpine, sparse, and almost 100-year-old spruce forest with large sun-exposed treeless areas. The type nest was located on a stony and rocky east slope with a 50 - 55° inclination, under a stone 30 × 20 cm in diameter and 5 - 10 cm high. Workers of T. aspina were distinguishable in the field from Tetramorium immigrans workers by their yellowish color and smaller size. The small eyes and yellowish color of T. aspina indicate subterranean activity.

The type nest was excavated thoroughly and it was believed most of the individuals of both species were collected. The colony comprised similar proportions of workers of each species, which were evenly distributed over all nest chambers. The brood chambers contained many larvae and one pupa. Based on the characteristic shape of the propodeum, the pupa could be assigned to T. aspina, but we could not assign the larvae to a species. If the larvae included individuals from T. immigrans, our observation could be interpreted as a case of a mixed colony. Alternatively, if the larvae only belonged to T. aspina, both species could be considered as co-inhabiting a compound nest. The only non-worker individual in the nest was a T. aspina queen found in a chamber 30 - 35 cm below ground. This species is believed to be a social parasite of Tetramorium immigrans.

At the type locality, the observed herb layer plants were Anthemisc sp., Daucus sp., Malva sp., Medicago sp., Myosotis sp., Poaceae species, Rosa sp., Rubus sp., Taraxacum sp., Trifolium sp., Verbascum sp., and Veronica sp. Camponotus aethiops, Formica cunicularia, Formica fusca, Lasius alienus, Lasius flavus, Manica rubida, Messor structor complex, Proformica pilosiscapa', Temnothorax artvinensis, Temnothorax unifasciatus, Tetramorium immigrans, Tetramorium'' cf. impurum, and a further non-identified Tetramorium sp. were also recorded from the same locality.

Nomenclature

 *  aspina. Tetramorium aspina Wagner et al., 2018: 29, figs. 3-4 (w.q.) TURKEY.

Worker
Morphometric data of holotype in μm: CL = 703, CW = 691, dAN = 201, EL = 122, EW = 97, FL = 319, HFL = 538, ML = 861, MPPL = 252, MPSP = 267, MPST = 185, MtpW = 353, MW = 468, PEH = 250, PEL = 137, PEW = 237, PLSP = 150, PLST = 194, PnHL = 188, PoOc = 256, PPH = 244, PPL = 96, Ppss = 29, PPW = 278, PreOc = 182, PSW = 287, RTI = 274, SLd = 516, SPST = 108. Meristic data of holotype: MC1TG = 7.8, unilateral number of ommatidia = 30, unilateral number of teeth = 10, POTCos = 7.5.

Size: Smaller than in Tetramorium caespitum complex, CS = 646 ± 32 [590, 699] vs. 749 ± 64 [561, 988] μm. Dorsum of head light brown, ventralwards from level of frontal carinae continuously getting lighter and on eye level and ventral of eye yellowish. Appendices, mesosoma, petiole, and postpetiole yellowish. First 20 - 60% of first gastral tergite yellow, posteriorly continuously getting darker and last 10 - 50% light brown; remaining gaster yellowish with sometimes light brown caudal margins of tergites. Sculpture on dorsum of head highly variable from nearly completely smooth with only few rudiments of rugulae to pronounced longitudinally rugulose. Vertex completely smooth. Praeoculo-temporal area of head pronounced longitudinally rugulose, postoculo-temporal area of head smooth or moderately rugulose, POTCos = 5.8 ± 2.2 [1.0, 9.3]. Dorsum of mesosoma smooth with only small parts of longitudinal rugae or moderately rugulose, lateral side of mesosoma with strongly pronounced rugae and only parts of pronotum sometimes smooth; smooth and shiny area on lateral side of propodeum rather small, Ppss = 27 ± 17 [10, 79]. Dorsum of petiolar and postpetiolar nodes completely smooth. Small connected reticulate units scattered over 1st gastral tergite, MC1TG = 6.0 ± 1.2 [4.2, 8.2]. No sinuous hairs on ventral head. No erect hairs on lateral side of head. A row of hairs at posterior margin of head. Mesosoma hairs shorter than in Tetramorium caespitum complex, PnHL / CS = 0.208 ± 0.032 [0.153, 0.270]. Moderately long erect hairs on dorsum of mesosoma, petiole, postpetiole, and first gastral tergite. Erect gaster hairs on further gastral segments only at caudal margins of tergites and sternites. Head slightly elongated, CL / CW = 1.030 ± 0.020 [0.987, 1.059]. 8.3 ± 0.9 [6.5, 10] teeth. Palp formula as Tetramorium immigrans: Maxillary palp with 4 segments, labial palp with 3. Scape rather short, SLd / CS = 0.739 ± 0.018 [0.711, 0.770]. Twelve antennal segments. Distance between frontal lobes larger than in Tetramorium caespitum complex, between antennal fossae moderate, and between tops of ridges between antennal fossae smaller than in Tetramorium caespitum complex, FL / CS = 0.458 ± 0.010 [0.442, 0.484], dAN / CS = 0.288 ± 0.006 [0.273, 0.300], RTI / CS = 0.381 ± 0.013 [0.362, 0.399]. Eye small and number of ommatidia low, EL / CS = 0.165 ± 0.009 [0.147, 0.177], EW / CS = 0.133 ± 0.006 [0.121, 0.141], number of ommatidia 23.4 ± 3.7 [18.0, 30.0]. Preocular distance rather large, PreOc / CS = 0.268 ± 0.007 [0.258, 0.281], and postocular distance moderate, PoOc / CS = 0.403 ± 0.013 [0.375, 0.426]. Mesosoma longer and wider than in Tetramorium caespitum complex, ML / CS = 1.228 ± 0.021 [1.188, 1.274], MW / CS = 0.672 ± 0.015 [0.642, 0.698]. Promesonotal dorsum convex, metanotal groove moderately deep to deep. Propodeal syndrome common. Metapleuron and propodeum wider than in Tetramorium caespitum complex but (because of propodeal syndrome) highly variable, MtpW / CS = 0.508 ± 0.032 [0.446, 0.558], PSW / CS = 0.393 ± 0.050 [0.302, 0.471]. Hind femur short, HFL / CS = 0.751 ± 0.018 [0.718, 0.776]. Propodeal spine completely missing or rudimentary, MPSP / CS = 0.395 ± 0.018 [0.368, 0.430], SPST / CS = 0.166 ± 0.012 [0.155, 0.200], PLSP / CS = 0.206 ± 0.019 [0.177, 0.245]. Distance from anteroventralmost point of metapleuron to propodeal spiracle and propodeal lobe larger than in Tetramorium caespitum complex, MPST / CS = 0.269 ± 0.012 [0.252, 0.296], MPPL / CS = 0.374 ± 0.012 [0.358, 0.401]. Distance between propodeal lobe and propodeal spiracle larger than in Tetramorium caespitum complex, PLST / CS = 0.287 ± 0.013 [0.262, 0.312]. Postpetiole and petiole wider, higher, and shorter than in Tetramorium caespitum complex, PPW / CS = 0.421 ± 0.021 [0.392, 0.476], PEW / CS = 0.342 ± 0.025 [0.270, 0.380], PEH / CS = 0.373 ± 0.011 [0.358, 0.401], PPH / CS = 0.371 ± 0.014 [0.350, 0.407], PEL / CS = 0.211 ± 0.008 [0.196, 0.225], PPL / CS = 0.139 ± 0.008 [0.119, 0.154].

Queen
Size: Smaller than in Tetramorium caespitum complex, CS = 1073 μm. Dorsum of head medium brown, ventralwards from level of frontal carinae continuously getting lighter and on eye level and ventral of eye rather light brown. Appendices light brown. Mesosoma light brown, but with dark brown parts on mesonotum and scutellum, tegulae dark brown. Petiole and postpetiole medium to dark brown. First tergite of gaster medium brown, other tergites anteriorly light brown and posteriorly continuously getting darker and medium brown at caudal end. Head frontal longitudinally rugulose, only area between ocelli and caudalmost part of head smooth and shiny. Lateral side of head with pronounced rugulosity, POTCos = 11. Around half of mesonotum smooth and half longitudinally rugulose, smooth regions anteriorly and laterally. Scutellum longitudinally rugulose. Lateral side of mesosoma with longitudinal rugae, pronotum, anepisternite, and mesopleuron partly smooth. No erect hairs on lateral side of head, but long hairs at posterior margin of head and on dorsum of head. Moderately long mesosomal hairs, PnHL / CS = 0.242, short mesonotum hairs, long hairs on scutellum, metanotum, petiole (longest hair on petiole / CS = 0.305), and postpetiole (longest hair on postpetiole / CS = 0.287). Erect gaster hairs only at caudal margins of tergites and sternites. Head broader than in Tetramorium caespitum complex, CL / CW = 0.878. Scape longer than in Tetramorium caespitum complex, SLd / CS = 0.795. 8 teeth. 12 antennal segments. Distance between frontal lobes larger than in Tetramorium caespitum complex, between antennal fossae and between tops of antennal fossae ridges moderate, FL / CS = 0.443, dAN / CS = 0.279, RTI / CS = 0.370. Eye larger than in Tetramorium caespitum complex, EL / CS = 0.288, EW / CS = 0.244. Preocular distance moderate, PreOc / CS = 0.202, and postocular distance smaller than in Tetramorium caespitum complex, PoOc / CS = 0.336. Mesosoma shorter and narrower than in Tetramorium caespitum complex, ML / CS = 1.859, MW / CS = 1.067. Propodeal spiracle distance PSW / CS = 0.683. Hind femur moderately long, HFL / CS = 0.972. Propodeal spines shorter than in Tetramorium caespitum complex, MPSP / CS = 0.556, SPST / CS = 0.272, PLSP / CS = 0.269, SPWI / CS = 0.441. Distance from anteroventralmost point of metapleuron to propodeal spiracle and propodeal lobe smaller than in Tetramorium caespitum complex, MPST / CS = 0.344, MPPL / CS = 0.446. Distance between propodeal lobe and propodeal spiracle rather large, PLST / CS = 0.351. Petiole and postpetiole wider, lower, and shorter than in Tetramorium caespitum complex, PEW / CS = 0.505, PEH / CS = 0.458, PEL / CS = 0.224, PPW / CS = 0.715, PPH / CS = 0.448, PPL / CS = 0.155. Median petiole insection depth / CS = 0.027, median postpetiole insection depth / CS = 0.008.

Type Material
Giresun-Dereli-Çamlı Village (Turkey), 40.4767° N, 38.5108° E, 1953 meters above sea level, leg. K. Kiran, C. Karaman, and V. Aksoy, 12.VI.2012, 425 workers and 1 gyne. All type material from one nest, labeled “TUR: 40.4767° N, 38.5108° E, Giresun-Dereli-Çamlı Village, 1953 m, subalpine Picea orientalis forest, K. Kiran, C. Karaman & V. Aksoy, 12.VI.2012 [/] 12/0859b”. Holotype worker, 409 paratype workers, and 1 paratype gyne in entomological collection of Biological Department of Trakya University, Edirne (Turkey), five paratype workers in private collection of H.C. Wagner (Graz, Austria), three paratype workers in, three paratype workers in , three paratype workers in , and one paratype worker in Tiroler Landesmuseum (Hall, Austria).

Etymology
Named after its strongly reduced propodeal spines.