Lasius austriacus

A putative subterranean species. Specimens of the grass mealybug Euripersia europaea  Newstead 1897 (Homoptera: Pseudococcidae; P. J. Gullan, pers. comm.) have been found inside the nests of L. austriacus. This common root-feeding species is known to be associated with ants, especially Lasius spp. (Kosztarab & Kozar 1988). Sexuals were found to be present in the nests from early July to mid September. (Schlick-Steiner et al. 2003)

Identification
Seifert (2020) - Lasius austriacus is an unmistakable combination of, in terms of Lasius s.str., extremely small eye (EYE900 0.198), short terminal segment of maxillary palp (MP6900 0.144) and extremely small torulo-clypeal distance (dClAn900 2.61%). Low scape length is another rare character (SL/ CS900 0.892). Body size very small (CS 705 µm). Mean number of mandibular dents low (MaDe900 7.4). Petiole scale in lateral view thin and forming an acute tip. Clypeal pubescence dilute (sqPDCL900 5.51). Mean length of pubescence hairs on frons rather short (PLF900 30.5 µm). Dorsum of scape without or few, occasional setae. Coloration: Head, mesosoma and gaster dark brown; antennae, tibiae and tarsae yellowish.

The almost completely subterranean foraging lead to a significant reduction of eye size (EYE/ CS900 0.198 ± 0.009, n=40). This value is, however, larger than in the most large-eyed species of the entirely subterranean subgenus Cautolasius: Lasius alienoflavus with EYE/CS900 0.145 ± 0.006 (n=44) and Lasius flavus with EYE/CS900 0.147 ± 0.010 (n=200).

Schlick-Steiner et al. (2003) - Lasius austriacus is a species of the subgenus Lasius .str. It is classified within the Lasius brunneus group based on the character combination of a reduced number of mandibular dents (mean value < 8) and small body size. The only other Palaearctic species with reduced mandibular dentition, the Himalayan Lasius magnus (not belonging to the L. brunneus group), has an extremely large body size and a distinctly different pubescence pattern. Within the L. brunneus group, the workers of L. austriacus, Lasius neglectus and Lasius turcicus resemble each other and are clearly distinct from the other members of the group (Seifert 1992, for L. turcicus, at that time including L. neglectus; Seifert 2000, for L. neglectus and L. turcicus). The differential diagnosis of workers of L. neglectus and L. turcicus is mainly based on absolute size differences (Seifert 2000). Lasius austriacus is distinguished from L. neglectus and L. turcicus by the smaller eye and the larger postocular distance. An even clearer separation emerges from the discriminant function: D = 6 .2 * SL I CS (900) - 28 * Pooc I CL (900) + 6.1 * EYE (900) + 0.31 * dCLAN (900) + 0.5

Distribution
L. austriacus  is a rare species in Central Europe, restricted to undisturbed xerothermous grassland.

Seifert (2020) - In Europe known so far from only five sites in a 6500 km² area in the planar and colline region of east Austria and south Moravia (here north to 48.9°N). A single very remote site from outside this area was confirmed for Anatolia (38.9°N, 36.8°E, 1900 m). Due to hidden lifestyle and misidentification as “L. alienus” in the past it is certainly underrecorded throughout its range.

Distribution based on Regional Taxon Lists
Palaearctic Region: Austria, Czech Republic, Turkey.

Biology
Schlick-Steiner et al. (2003) - The L. austriacus population of Hnanice near Znoimo, Czech Republic, was referred to as L. neglectus by Seifert (2000). The identification as L. austriacus changes our picture of the distribution of the invasive L. neglectus, since no population of this pest species is known from a natural habitat in Central Europe so far.

Nomenclature

 *  austriacus. Lasius austriacus Schlick-Steiner, in Schlick-Steiner, Steiner, Schödl & Seifert, 2003: 726, figs. 1-6 (w.q.m.) AUSTRIA.

Worker
Very small overall body size, smallest known species of Palaearctic Lasius s.str. Head relatively long. Eye small, postocular distance relatively large. Clypeal keel very weak to nearly absent, in proximal and distal parts of clypeus completely absent. Lateral clypeal profile convex. Clypeal pubescence density very low. Distance from posterior clypeal suture to inner margin of antennal sockets very short. Scape very short, pubescence frequently 25° to 40°, single pubescence hairs nearly 90°. Number of dents on masticatory border of mandible 6 to 8, frequently 7. Pubescence on head between frontal carinae short and strongly depressed. 0 to 2 setae per gena. Mesosoma profile in lateral view with a straight posterior slope and a very flat dome equaling or nearly equaling mesonotum in height, mesopropodeal depression very shallow. Setae on whole body sparse, particularly from occipital margin to caudal end of eye, underside of the head; scape, hind tibia and on the area between lower margin of propodeal spiracle and upper margin of the bulla glandulate metapleuralis. Setae on underside of head and on pronotum relatively short.

Queen
Overall body size medium. Frontal groove fully developed from mid-ocellus to frontal triangle but weakly impressed. Mandibles with 8 to 9 dents, mandibular surface structure coarsely striate. Number of genal setae frequently 0, seldom 1, genal pubescence depressed. Pubescence of scape 30°, no setae projecting. Shortest distance from posterior clypeal suture to inner margin of antennal sockets very short. Mesosoma long, in lateral view high. Pubescence on scutellum dense. Petiolar scale broad, always emarginate with an angle of 100 to 140°. Upper corners rounded to angularly rounded, sides converging to the basis. Forewing with a big first discoidal cell, distance “a” always shorter than distance “b” by at least 10%. Microsculpture of median epiproct reticulate, meshes of homogeneous size in frontal direction from caudal end of epiproct.

Male
Very small overall body size, relatively short head. Details of male morphology are not the objective of this study.

Type Material
Holotype: worker labelled "Austria, Feldberg vic. Pulkau ( 15°51' E I 48°40' N), leg. B.C. Schlick-Steiner & F.M. Steiner(# 1 0982), 6.8.2002". Deposition: NM Wien.

Paratypes: 31 workers, 25 gynes and 63 males from the holotype nest series (Collection of B.C. Schlick-Steiner and F.M. Steiner,, ); 25 workers, 4 gynes and 47 males with same data but# 11055, (CBFS}; 24 workers, 6 gynes and 3 males, labelled "A. inf 10.vii.2002, Feldberg S Pulkau 48°4l'N 15°5l'E leg. Schodl; SS#l050" (NM Wien, SMN Goerlitz); 9 workers with same data but SS# 1052 (NM Wien}; 28 workers with same data but "5. vi.2002 Nest 2" ( NM Wien}; 37 workers with same data but "5.vi.2002 Nest 1" (NM Wien); 9 workers and 10 gynes labelled "Austria, Feldberg vic. Pulkau (15°51' E I 48°40' N), leg. B.C. Schlick-Steiner & F.M. Steiner (#10514), 10.7.2002" (CBFS); 45workersand 7 gynes from a nest series labelled "Austria, Braunsberg vic. Hainburg (16°57' E 1 48°09' N), leg. B.C. Schlick-Steiner & F.M. Steiner (# 10445), 2. 7.2002" (CBFS, SMN Goerlitz); 32 workers, 3 gynes and 7 males with same data but# 10449 (CBFS, SMN Goerlitz); 6 workers from the same locality but labeled "AUSTRIA inf. 18.v.1999 Hainburg I Braunsberg c. 300m; l6°57'E 48°09'N leg. Schodl; S.S.: 582" (NM Wien); 8 workers and 4 males from a nest series collected near Znoimo/Czech Republic, labelled "CZE: S Moravia: Hnanice 1.5 NNE, armer Steppenrasen mit Call una auf Fels, 1997.09.18-44" (SMN Goerlitz).

Type locality: Feldberg near Pulkau, Austria (15°51' E I 48°40' N). 360 m a.s.l., south exposed slope, inclination 0 - 5°, xerothermous grassland with interspersed vegetation-free silicate rocks that cover about 5 % of the total habitat area.

Etymology
The name is derived from Australia (lat.).

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.
 * Fiedler, K., F. Kuhlmann, B. C. Schlick-Steiner, F. M. Steiner and G. Gebauer. 2007. Stable N-isotope signatures of central European ants  assessing positions in a trophic gradient. Insectes Sociaux 54(4):393-402.
 * Kiran K., and C. Karaman. 2012. First annotated checklist of the ant fauna of Turkey (Hymenoptera: Formicidae). Zootaxa 3548: 1-38.
 * Steiner, F.M., B.C. Schlick-Steiner, S. Schödl, X. Espadaler, B. Seifert, E. Christian and C. Stauffer. 2004. Phylogeny and bionomics of Lasius austriacus (Hymenoptera, Formicidae). Insectes Sociaux 51(1): 24-29.
 * Talavera G., X. Espadaler, and R. Vila. Discovered just before extinction? The first endemic ant from the Balearic Islands (Lasius balearicus sp. nov.) is endangered by climate change. Journal of Biogeography doi:10.1111/jbi.12438