Tapinoma subboreale

Part of a cryptic species complex, a recent morphometric taxonomic study made no mention of any natural history details of this species.

Distribution based on Regional Taxon Lists
Palaearctic Region: Belgium, Germany, Greece, Russian Federation, Turkey.

Nomenclature

 *  subboreale. Tapinoma subboreale Seifert, 2012: 143, figs. 1, 2, 4 (w.q.m.) GERMANY.

Worker
Worker (Table 1): All data primary ratios (without RAV correction). Rather small, mean CS 699 μm. Depth of anteromedian clypeal excision 5.2% of cephalic size, much lower than in Tapinoma erraticum or Tapinoma nigerrimum but equal to Tapinoma madeirense. In general most similar to T. madeirense but the following three characters show statistically significant differences: With maximum cephalic length in visual plane, excavation of hind vertex just notable, being ± 0.43% of CS (in T. madeirense almost zero). Head and mesosoma more elongated than in T. madeirense, CL / CW 1.153, ML / CS 1.362. Using the seven characters, presented in Table 1, there was no clear clustering of workers in a PCA while a DA and LOOCV-DA resulted in error rates of 12.5 and 18.7% in 62 workers (data not shown). The univariate analysis of variance (ANOVA) confirmed as highly significant difference to T. madeirense a smaller CL / CW0.75, ExOcc / CS0.75 and ML / CS0.75 (Tab. 1). For differences to T. erraticum and T. nigerrimum see Table 1.

Queen
Gyne (Tab. 2): Rather small, CS 836-930 μm. Depth of anteromedian clypeal excision much lower than in Tapinoma erraticum or T. nigerrimum but equal to T. madeirense. In all studied characters most similar to T. madeirense but statistically significant differences are the more elongated head, the larger distance of the inner margins of antennal fossae and the larger eye length (Tab. 2). Using the seven characters presented in Table 2, there was no clear clustering of gynes of T. subboreale sp.n. and T. madeirense in a PCA while a DA and LOOCV-DA resulted in error rates 5.1 and 15.4% in 38 gynes (data not shown). For differences to T. erraticum and T. nigerrimum see below and Table 2.

Male
Absolute body size equal to Tapinoma madeirense, ML 1310-1630 μm. Anteromedian clypeal incision shallow, clearly wider than deep. With the genital in ventral view and the subgenital plate positioned in visual plane, stipal tips much less surpassing the caudal tips of the subgenital plate than in T. madeirense (dSPST 122-172 vs. 252-268 μm), the divergence of the caudal tips of the subgenital plate is much larger (SPdT 472-563 vs. 370-435 μm, compare also Figs. 3 and 4). As a result, the ratio SPdT / dSPST is much larger than in T. madeirense – 3.04-4.12 vs. 1.46-1.88. Due to extreme elongation and strong divergence of the tips of subgenital plate these are clearly visible also in dorsal aspect of the genital – there is no other Tapinoma species in Europe with a comparable morphology of the subgenital plate.

Type Material
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 in Senckenberg Museum für Naturkunde Görlitz.

Etymology
The species epithet is an adjective derived from Latin, meaning "below northern" – referring to the fact that the most northern Scandinavian populations are found south of the boreal zone.