Lasius illyricus

Information on the ecology and biology of this species is very scarce. Ecological segregation from Lasius emarginatus due to slightly different habitat preferences is witnessed in Greece (Borowiec & Salata, 2013), but no information is available from regions in which L. emarginatus is probably absent (Schifani & Massa, 2020).

Identification
Borowiec and Salata (2013) - L. illyricus is most similar to Lasius emarginatus, and both occur in similar habitat.

Near Agridi (N Peloponnese, Aroania Mts.) we found nests of both typical L. emarginatus and the L. illyricus form. This was the only locality where we observed sympatric occurrence of both taxa. In Ionian Islands and Central Peloponnese we observed only L. illyricus while in central and northern Greece only L. emarginatus. Halkidiki is an exception where in an extremely warm locality on the Sithona Peninsula near Parthenonas we found only L. lyrics and in Holomontas mountains only L. emarginatus.

Both species are very similar superficially although specimens of L. illyricus in comparison with southern populations of L. emarginatus are slightly larger (ML 1352 ± 115.9 vs. 1213.7 ± 94.7; HL 1020 ± 72 vs. 1002.3 ± 78.2, HW 981.1±99.5 vs. 952.8±97.6, and more contrasting coloured with thorax reddish, distinctly paler from head and abdomen thus they are more similar in coloration to the northern populations of L. emarginatus than to populations from Greece that are usually dark, with thorax reddish-brown to brown.

Lasius illyricus is easily distinguished from L. emarginatus by pubescence and setation of scapes and external margin of hind tibiae. In L. illyricus the scape in frontal view on dorsal apical 1/3 length has only erect hairs and 2-3erect setae while in the same area in L. emarginatus erect setae predominate. In the same view on the ventral side of the scape suberect hairs with some setae only slightly longer than hairs predominate in L. illyricus while in L. emarginatus setae distinctly longer than adjacent hairs predominate. The difference in chaetotaxy is more clearly visible on the anterior surface of the scape in dorsal view of antenna. In L. illyricus the surface has no to 3-4 erect setae, occasionally to 11 setae in large specimens while in L. emarginatus the setation is more clear with several long erect setae (usually 15-20, up to 34) and only occasionally in small specimens with only 9-10 setae. L. illyricus has sparser setation oh external edge of hind tibia with 6-18 erect setae (mean 13 ± 3), while in L. emarginatus there are 13-27 erect setae (mean 20.8 ± 3.9).

Distribution based on Regional Taxon Lists
Palaearctic Region: Armenia, Austria, Azerbaijan, Croatia, Greece, Montenegro, Republic of Macedonia, Russian Federation, Serbia, Turkey, Ukraine.

Biology
Borowiec and Salata (2013) - Prefers broadleaved forests, especially oak and platanus forests, but L. illyricus prefers more open and drier localities and on Korfu it is common in urban areas, gardens and olive plantations (on Korfu olive plantations are different than in other parts of Greece, more like natural-growth forests with extremely high unclipped trees overgrown by epiphytic mosses). On Peloponnese L. illyricus prefers forest margins.

Nomenclature

 * . Lasius alienus subsp. illyricus Zimmermann, 1935: 50 (w.q.m.) CROATIA.
 * Combination in L. (Lasius): Borowiec, L. & Salata, 2013: 353.
 * Junior synonym of alienus: Wilson, 1955a: 78; Smith, D.R. 1979: 1435.
 * Junior synonym of emarginatus: Seifert, 1992b: 34; Bolton, 1995b: 223; Radchenko, 2016: 367; Karaman, M.G. 2011: 89.
 * Senior synonym of pontica: Seifert, 2020: 71.
 * Status as species: Borowiec, L. & Salata, 2013: 353 (redescription); Borowiec, L. 2014: 86; Salata & Borowiec, 2018b: 157 (in key); Salata & Borowiec, 2018c: 46.
 * pontica. Lasius alienus var. pontica Stärcke, 1944a: 157 (w.) GEORGIA (Abkhazia).
 * Junior synonym of alienus: Wilson, 1955a: 78; Smith, D.R. 1979: 1435; Arakelian, 1994: 117 (error).
 * Junior synonym of emarginatus: Seifert, 1992b: 34; Bolton, 1995b: 225; Radchenko, 2016: 367.
 * Junior synonym of illyricus: Seifert, 2020: 71.

References based on Global Ant Biodiversity Informatics

 * Borowiec L. 2014. Catalogue of ants of Europe, the Mediterranean Basin and adjacent regions (Hymenoptera: Formicidae). Genus (Wroclaw) 25(1-2): 1-340.
 * Borowiec L., and S. Salata. 2013. Ants of Greece  additions and corrections (Hymenoptera: Formicidae). Genus (Wroclaw) 24(3-4): 335-401.
 * Borowiec L., and S. Salata. 2017. Ants of the Peloponnese, Greece (Hymenoptera: Formicidae). Polish Journal of Entomology 86: 193-236.
 * Bracko G., K. Kiran, C. Karaman, S. Salata, and L. Borowiec. 2016. Survey of the ants (Hymenoptera: Formicidae) of the Greek Thrace. Biodiversity Data Journal 4: e7945. doi: 10.3897/BDJ.4.e7945
 * Salata S., L. Borowiec, and A.Trichas. 2018. Taxonomic Revision of the Cretan Fauna of the Genus Temnothorax Mayr, 1861 (Hymenoptera: Formicidae), with Notes on the Endemism of Ant Fauna of Crete. Annales Zoologici (Warsaw) 68(4): 769-808.
 * Salata S., and L Borowiec. 2017. Species of Tetramorium semilaeve complex from Balkans and western Turkey, with description of two new species of (Hymenoptera: Formicidae: Myrmicinae). Annales Zoologici (Warsaw) 62:279–313.
 * Salata S., and L. Borowiec. 2018. Taxonomic and faunistic notes on Greek ants (Hymenoptera: Formicidae). Annals of the Upper Silesian Museum in Bytom Entomology 27: 1-51.
 * Salata S., and L. Borowiec. 2019. Preliminary division of not socially parasitic Greek Temnothorax Mayr, 1861 (Hymenoptera, Formicidae) with a description of three new species. ZooKeys 877: 81-131.