Lasius casevitzi Seifert & Galkowski 2016

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 : 60

4.4.19 Lasius casevitzi Seifert & Galkowski 2016

Lasius casevitzi Seifert & Galkowski 2016

[type investigation]

Type material: Holotype plus three paratype workers labelled ”FRA: 42.440°N, 8.868°E, 687 m Corse: Bonifatu, leg. Galkowski 2015.07.12 -1“ and deposited in MNHN Paris. Three paratype workers from the holotype nest and four paratype workers from another nest at the holotype locality labeled ”FRA: 42.440°N, 8.868°E, 687 m Corse: Bonifatu, leg. Galkowski 2015.07.12 -2“ in SMN Görlitz.

All material examined. A total of 15 samples with 36 workers were subject to NUMOBAT investigation. These originated from Corsica (6 samples) and NE Italy (9). For details see supplementary information S1.

Geographic range. So far only known from the Island of Corsica in altitudes between sea level and 800 m and from several localities in the urban region of Trieste /NE Italy.

Diagnosis ( Tab. 4 , Figs. 37 –38; key; images in www. antWeb.org with specimen identifier CASENT1038019):

Absolute size rather small (CS 845 µm). Scape and maxillary palp length indices high (SL/CS 900 0.999, MP6/ CS 900 0.212). Number of mandibular dents rather medium (MaDe 900 8.20). Clypeal pubescence dense (sqPDCL 900 3.39). Pronotal setae very long (PnHL/CS 900 0.159). Dorsum of scape with single and extensor profile of hind tibia with several semierect to erect setae (nSc 900 1.3, nHT 900 8.6). L. casevitzi is an unmistakable combination of very dense clypeal pubescence, long terminal segment of maxillary palps, rather long scape, and significant setae numbers on genae, extensor profile of hind tibia and metapleuron below propodeal spiracle. Coloration: whole body dark brown but scape, tibiae and tarsae a little lighter with a yellowish component and mandibles lighter with a reddish component.

Biology. Both the data from Corsica and NE Italy indicate that it is no species of open xerothermous grassland and prefers semi-arboreal habitats and dry open forest. Nests are in soil, under trees or under stones. In Corsica it is absent from the coastal environment and from elevations above 1100 m. The altitudinal extremes within 50 records were 23 m and 1100 m, with the majority of nests found between 300 m and 800 m. Within the municipality of Trieste it occurs preferentially in city parks with trees. Alates were not observed in the nests during collecting in July and August. The ants behave aggressively during disturbance of the nest by the collector.

Comments. L. casevitzi , L. bombycina and L. paralienus are perfectly separated by NC-clustering ( Fig. 112 ) for 84 nest samples with data on all 16 standard characters available. Furthermore, the classification error of the LDA is 0% in 192 individuals of the same sample after reducing the number of considered characters to 7 in order to avoid character overfitting.

Figures

Figs. 37 and 38: Lasius casevitzi; paratype

Figs. 112: NC-clustering of 49 nest samples of Lasius paralienus(light grey bars), 20 nest samples of L. bombycina (black bars) and 15 samples of L. casevitzi (dark grey bars).