Lasius psammophilus Seifert 1992

Seifert, Bernhard, 2020, A taxonomic revision of the Palaearctic members of the subgenus Lasius s. str. (Hymenoptera, Formicidae), Soil Organisms 92 (1), pp. 15-86 : 56

4.4.13 Lasius psammophilus Seifert 1992

Lasius psammophilus Seifert 1992 [type investigation]

Type material: Holotype plus 4 paratype workers labelled “GER: Kr. Weisswasser 4 km N Steinbach: N 135 30.7.1991, leg. Seifert“; 26 paratype workers from the same locality and date labelling but with nest 082, sample numbers N 005, N 023, N 027, N 029, N 048, N N 206, N 215; depository SMN Görlitz.

All material examined. A total of 150 nest samples with 528 workers were subject to NUMOBAT investigation. These originated from Belgium (1 sample), Georgia (1), Czechia (3), Denmark (5), England (3), Finland (2), France (10), Germany (86), Greece (7), Italy (14), Norway (2), Slovenia (1), Spain (1), Sweden (7), Switzerland (4), Turkey (3). For details see supplementary information S1.

Geographic range. European, temperate-submeridional. From British Isles and France across Central and East Europe. Rapid postglacial immigration into North Central Europe via sand dunes and the outwash plains of big ancient river valleys is highly probable. In Central Europe and S Fennoscandia most abundant in sandy regions of the planar and colline zone but penetrating also mountain areas along river valleys: in the S Schwarzwald ascending to 1000 m and in the Alps to 2030 m (in S Tyrol at 46.5°N). Competing with L. paralienus in the High Apennine grasslands. Absent from Iberia and probably also the S Balkans, in N Greece at 40°N between 1600 and 1900 m. Main border of northern distribution in Sweden and Finland at 63.5°N but ranging north to 65.8° along the shores of the Gulf of Bothnia. Sympatric occurrence with Lasius obscuratus in Asia Minor and Great Caucasus, here easternmost known site at 52.52°N, 44.94°E. Sympatric occurrence with L. piliferus occurs in the Pyrenees.

Diagnosis ( Tab. 3 , Figs. 25 –26; key; images in www. antWeb.org with specimen identifiers CASENT0172733, CASENT0179885, FOCOL0752):

Absolute size rather small (CS 826 µm). Scape and head length indices and number of mandibular dents medium (SL/CS 900 0.960, CL/CW 900 1.057, MaDe 900 8.3). Clypeal pubescence rather dilute (sqPDCL 900 4.56). Pronotal setae of medium length (PnHL/CS 900 0.146), significantly longer than gular setae (GuHL/CS 900 0.097). Dorsum of scape and extensor profile of hind tibia without or only few semierect setae. It differs from the eastern sister species L. obscuratus by the shorter terminal segment of maxillary palps(MP6/CS 900 0.145 vs. 0.173) and from the western sister species L. piliferus by longer scape (SL/ CS 900 0.960 vs. 0.929), larger eye (EYE/CS 900 0.238 vs. 0.220) and lower seta numbers. Coloration: head brown, mesosoma a little lighter brown with a yellowish tinge, gaster dark brown; petiole, coxae and femora yellowish brown; mandibles and anterior clypeal border yellowish-reddish, scape yellowish.

Biology. See Seifert (2018).

Comments. There is little morphological variation of L. psammophilus throughout its range except for significantly larger values of nSc 900, nGen 900, and PnHL/ CS 900 in the population from Olympos and Smolikas mountains in north Greece. The separation of L. psammophilus from L. obscuratus by NC-clustering was clear in the 120 samples with MP6 data available. Considering the standard characters CL/CW 900, SL/ CS 900, MP6/CS 900, PoOc/CL 900, EYE/CS 900, nGu 900, nSc 900, nHT 900, and nSt 900, the disagreement with the final species hypothesis was 1.7% in NC-part.kmeans, 3.3% in NC-Ward, and 1.7% in NC-NMDS-kmeans. NC-part.hclust showed an error of 2.5% and 6.7% of outliers. These data are a clear indication to accept heterospecificity according to the criteria of the GAGE species concept. The classification error of the controlling LDA was 2.7% in 331 worker individuals.

Figures

Figs. 25 and 26: Lasius psammophilus; CASENT0179885, photo E. Prado