Lasius obscuratus

A soil nesting species often found under stones.

Identification
Seifert (2020) - Palaearctic Lasius s. str. species belonging to the Lasius obscuratus species complex. The morphology of Lasius obscuratus shows a significant structuring in dependence from geography. Sixty-nine specimens from the Baikal region, Mongolia and northeast Tibet (Lasius gebaueri in my conception of 1992) differ from 63 specimens of the remaining western population (L. obscuratus in my former conception) by shorter pronotal setae (PnHL/CS900 0.134 vs. 0.152), larger eyes (EYE/ CS900 0.248 vs. 0.240) and smaller postocular distance (PoOc/CL900 0.229 vs. 0.239).

Distribution
Seifert (2020) - Huge range in Asia between 27°E to 115°E and 34.5°N to 53.2°N. Known from entire Asia Minor, Great Caucasus, Armenia, N Iran (Elburs Mountains), Tadzhikistan, Mongolia and NE Tibet. The altitudinal distribution ranges from 900 to 2600 m in Asia Minor and Great Caucasus, from 1900 to 3160 in Elburs Mountains and W Pamirs, from 1300 to 3400 m in NE Tibet and Gansu, from 700 to 2100 m in Mongolia, and from 536 to 620 m near Lake Baikal.

Distribution based on Regional Taxon Lists
Oriental Region: Tibet. Palaearctic Region: China, Georgia, Mongolia, Russian Federation.

Biology
Seifert (2020) - Lasius obscuratus prefers habitats with xerothermous conditions such as open steppe habitats with diverse phytoassociations, short-grassy pastures, and light steppe forest. It was also found in less dry habitats such as cut meadows, floodplain pastures, sunny willow stands, and montane stunted-growth forest at the tree line. Nest were found in soil, preferentially under stones.

Nomenclature

 * . Lasius brunneus var. obscuratus Stitz, 1930: 239 (w.q.) TAJIKISTAN.
 * Junior synonym of alienus: Wilson, 1955a: 78; Smith, D.R. 1979: 1435.
 * Status as species: Seifert, 1992b: 21 (redescription); Bolton, 1995b: 225; Collingwood & Heatwole, 2000: 12; Gratiashvili & Barjadze, 2008: 136; Guénard & Dunn, 2012: 33; Borowiec, L. 2014: 89.
 * Senior synonym of gebaueri: Seifert, 2020: 55.
 * gebaueri. Lasius (Lasius) gebaueri Seifert, 1992b: 22, fig. 15 (w.) CHINA (Tibet).
 * Status as species: Bolton, 1995b: 223; Guénard & Dunn, 2012: 33.
 * Junior synonym of obscuratus: Seifert, 2020: 55.

Worker
Seifert (2020) - Absolute size rather small (CS 840 µm). Scape and head length indices and number of mandibular dents medium (SL/CS900 0.956, CL/CW900 1.065, MaDe900 8.4). Clypeal pubescence moderately dense (sqPDCL900 4.35). Pronotal setae of medium length (PnHL/CS900 0.140), significantly longer than gular setae (GuHL/CS900 0.091). Dorsum of scape and extensor profile of hind tibia without or only very few semierect setae. It differs from the sister species Lasius psammophilus by longer terminal segment of maxillary palps (MP6/CS900 0.173 vs. 0.145). Coloration: head, mesosoma and gaster dark brown, mandibles, antennae, and legs light yellowish-brown.

See table 3 in Seifert 2020 for additional morphometrics. The abbreviated names of various quantitative data shown above are defined here: Seifert 2020 Lasius characters.

Type Material
Seifert (2020) - Lectotype worker labelled “West- Pamir VII.X. 28 leg.Reinig”, ”Dschailgan 7 x. 1800m“. ”LECTOTYPE designated by E.O.Wilson 1954“, “Lasius brunneus obscurata Stitz lectotype”, “Type”, “GBIF -D/FoCol 2739 specimen and label data documented”; 3 paralectotype workers labelled “West-Pamir VII.X. 28 leg.Reinig”, ”Dschailgan 7 x. 1800 m“ “Lasius brunneus Latr. obscurata St.”; depository.

References based on Global Ant Biodiversity Informatics

 * Antonov I. A. 2013. An addition to the myrmecofauna (Hymenoptera, Formicidae) of Baikalian Siberia. Journal of Zoology (in Russian) 92(8): 991-993.
 * Borowiec L. 2014. Catalogue of ants of Europe, the Mediterranean Basin and adjacent regions (Hymenoptera: Formicidae). Genus (Wroclaw) 25(1-2): 1-340.
 * Collingwood C., and H. Heatwole. 2000. Ants from Northwestern China (Hymenoptera, Formicidae). Psyche 103 (1-2): 1-24.
 * Dubovikoff D. A., and Z. M. Yusupov. 2018. Family Formicidae - Ants. In Belokobylskij S. A. and A. S. Lelej: Annotated catalogue of the Hymenoptera of Russia. Proceedingss of the Zoological Institute of the Russian Academy of Sciences 6: 197-210.
 * Gratiashvili N., Barjadze S. 2008. Checklist of the ants (Formicidae Latreille, 1809) of Georgia. Proceedings of the Institute of Zoology (Tbilisi) 23: 130-146.
 * Guénard B., and R. R. Dunn. 2012. A checklist of the ants of China. Zootaxa 3558: 1-77.
 * Pfeiffer M., R. Schultz, A. Radchenko, S. Yamane, M. Woyciechowski, U. Aibek, and B. Seifert. 2007. A critical checklist of the ants of Mongolia (Hymenoptera: Formicidae). Bonner Zoologische Beiträge 55: 1-8.
 * Ran H., and S. Y. Zhou. 2012. Checklist of chinese ants: formicomorph subfamilies (Hymenoptera: Formicidae) II. Journal of Guangxi Normal University: Natural Science Edition 30(4): 81-91.
 * Seifert B. 1992. A taxonomic revision of the Palaearctic members of the ant subgenus Lasius s.str. (Hymenoptera: Formicidae). Abhandlungen und Berichte des Naturkundemuseums Görlitz 66(5): 1-67.