Tapinoma subboreale Seifert 2011

Seifert, Bernhard, Kaufmann, Bernard & Fraysse, Lorenzo, 2024, A taxonomic revision of the Palaearctic species of the ant genus Tapinoma Mayr 1861 (Hymenoptera: Formicidae), Zootaxa 5435 (1), pp. 1-74 : 61

Tapinoma subboreale Seifert 2011 [type investigation]

The species was described from Germany. Investigated were the holotype male labelled “GER: 51.2294 °N, 11.7329°E, Weischütz-Kirche 1.7 km NE, limestone grassland, 215 m, Seifert 2002.06.14 -542”, “ Holotype Tapinoma subboreale Seifert ”; five paratype males and five paratype workers with the same locality label and “ Paratype Tapinoma subboreale Seifert ” on a separate pin (1 male, 2 workers) and in ethanol (4 males, 3 workers); all material from the same nest sample; five paratype gynes labelled “GER: 50.879°N, 10.840°E, 300 m, Wanderlebener Gleiche, B. Seifert 1984.09.03 ” and “ Paratype Tapinoma subboreale Seifert ”; all material deposited in SMN Görlitz. A wild card run in a LDA using the characters ML, SPExc, SPdT, SPWPR, dSPST allocated the holotype with p= 0.9996 to the T. subboreale cluster (see above). The paratype workers from the holotype nest were allocated with p=0.947 to the T. subboreale cluster .

Material examined. Considering also samples with weak separation from the sibling species T. madeirense , numeric phenotypical data were taken in workers in 45 samples with 110 individuals. They originated from Bosnia (1 sample), Bulgaria (1), Croatia (2), Czechia (1), France (6), England (2), Germany (18) Hungary (1), Italy (8), Slovakia (1), Sweden (3) and Ukraine (1). For details see supplementary information SI1, SI2. Males were investigated in 23 samples with 77 individuals. They originated from France (15 samples), Germany (5), Italy (1) and Sweden (2). For details see supplementary information SI3.

Geographic range. Considering the available vouchers with sufficiently safe morphological and/or genetic indication, the natural range should include South England (50.65°N, 1.97°W), France, South Sweden (Öland and Gotland, 57.5°N), Central Europe, Italy (here south to 40°N), the Balkans and the Ukraine (49.42°N, 32.06°E). The glacial refuge centers of T. subboreale were most probably situated in the Balkans and the Apennine Peninsula. During postglacial spreading it moved west to south France from where it went north to West Germany, South England and South Sweden. East Austria, East Germany and Poland were certainly colonized from the Balkans via the route over the Hungarian plain. Recent findings of T. subboreale within the range of T. madeirense in several gardening centers and public parks in the Montpellier region should represent introductions from Italy which is suggested by habitat, microsatellite data and mtDNA haplotype sharing with Italian samples. Near the southern distributional border (41.9°N) T. subboreale goes up to 1600 m.

Diagnosis:—Worker ( Tab. 2): All shape ratios given below are, in contrast to those in Tab. 2, primary ratios without RAV and all data are given as arithmetic mean ± standard deviation. Extremely similar to T. madeirense . Slightly larger than the latter, CS 720 ± 71 µm. Head moderately elongated CL/CW 1.145 ± 0.037. Postocular distance medium-sized, PoOc/CL 0.415 ± 0.009. Anteromedian clypeal excision slightly deeper and wider than in T. madeirense, ExCly /CS 5.19 ± 0.60 %, ExClyW 7.34 ± 0.82 %. The margin of clypeal excision forms a sharp cuticular edge and is at same level as the adjacent clypeal surface. Sum of pubescence hairs and smaller setae protruding at a few micron across margin of clypeal excision low, nExCly 1.81 ± 0.75. Posterior margin of head in full face view usually not excavated, ExOcc/CS 0.34 ± 0.37 %. Scape moderately elongated, SL/CS 1.019 ± 0.022. Minimum distance of the inner margins of antennal socket rings medium-sized, dAN/CS 0.294 ± 0.007. Eye rather large, EL/CS 0.280 ± 0.007. Metanotal groove slightly deeper than in T. madeirense , MGr/CS 3.35 ± 1.02 %. Mesosoma relatively wide and long, MW/CS 0.660 ± 0.021, ML/CS 1.365 ± 0.028. Second funiculus segment slightly longer than in T. madeirense, Fu 2L/CS 13.12 ± 0.37 %, IFu2 1.472 ± 0.071. Pubescence, seta characters and pigmentation as in T. madeirense .

—Male genital ( Tab. 6, Fig. 34 ): Tips of subgenital plate more distant and depth of excision of subgenital plate much larger than in T. madeirense , SPdT/ML 0.350 ±0.023, SPExc/ML 0.204 ±0.014. Longitudinal distance of the tips of subgenital plate and of the tips of the harpago much smaller than in T. madeirense , dSPST/ML 0.100 ±0.014.

Taxonomic comments. The taxonomic relations to the cryptic sister species T. madeirense were discussed above. Despite hybridization in a contact zone in southern France, we maintained the specific status of T. subboreale because there is, on a larger geographic scale, a sufficient separation by genetics and male genital characters.

Biology. For a condensed description see Seifert (2018). Recent field sampling in the French Rhône valley showed that T. subboreale is more easily found than T. madeirense , as it builds larger solaria and exhibits higher densities in all dry to moist meadows, where it co-occurs with T. erraticum . In the transition zone between T. subboreale and T. madeirense , both species are difficult to find and their favored habitat remains unclear. In a large ecological study in Central Europe, Seifert (2017) could demonstrate a strong competive exclusion between T. subboreale and T. erraticum based on the contrast between high overlap of fundamental niche spaces and avoidance of syntopic occurrence in the sympatric range.

Figures

FIGURE 34. Tapinoma subboreale, male genital in ventral view, Percile / Italy, 2013.06.23.