Lasius casevitzi, Seifert, Bernhard & Galkowski, Christophe, 2016

Seifert, Bernhard & Galkowski, Christophe, 2016, The Westpalaearctic Lasius paralienus complex (Hymenoptera: Formicidae) contains three species, Zootaxa 4132 (1) : -

Description of Lasius casevitzi sp.nov.

Etymology. The species is dedicated to Janine Casevitz-Weulersse who investigated the Corsican ant fauna over many years.

Type material. See in section 2.2." Type Material".

Description of worker caste. Figs. 7–9 . Numeric data given in the following description are primary data (without removal of allometric variance) of 18 measured individuals.

Rather small-sized, CS 849 ± 41 [779,912] µm. Basic morphology not different from other members of the Lasius alienus group. Head moderately elongated, with convex sides and straight posterior margin of vertex, CL/ CW 1.078 ± 0.019 [1.039,1.123]. Scape rather long, SL/CS 1.006 ± 0.016 [0.981,1.036]. Eye medium-sized and moderately distant from posterior margin of head, EYE/CS 0.242 ± 0.004 [0.236,0.248], PoOc/CL 0.247 ± 0.005 [0.239,0.254]. Antennal socket situated rather close to posterior clypeal margin, dCLAn/CS 4.43 ± 0.26 [4.06,4.97]%. Masticatory border of mandibles with 8-9 teeth. Maxillary palps with six segments and much longer than in related species, MP6/CS 0.214 ± 0.009 [0.201,0.235]. Pubescence on whole body surfaces dense and whitish, sqPDCL 3.35 ±0.20 [3.00,3.72]. Mean length of pubescence hairs between frontal carinae 36.9 ± 2.23 [32.9,40.5] µm. Pilosity compared to next related species rather rich and long—in particular on genae and tibiae. Eyes with several microsetae of 11-16 µm length. Scape with no or very few standing setae: nSc 1.20 ± 0.89 [0.0,3.0]. Genae and extensor profile of hind tibia with more erect setae than in the next related species: nGen 3.86 ± 0.71 [2.5,5.0], nHT 7.85 ± 1.73 [5.5,12.5]. Underside of head and hind margin of vertex with rather numerous standing setae: nGu 3.69 ± 0.94 [2.0,6.0], nOcc 11.90 ± 1.83 [9.5,15.5]. Metapleuron below level of propodeal stigma with rather many erect to suberect setae: nSt 4.72 ± 0.87 [3.0,6.0]. Length of setae on pronotum rather large: PnHL/CS 0.157 ± 0.018 [0.107,0.175]. Whole body concolorous medium to dark brown; mandibles, scape and sometimes tibia lighter reddish or yellowish brown. Mesosoma in lateral view with an angulate-convex propodeal dome. Petiole scale low, in frontal view with slightly convex sides converging towards the dorsal crest which is straight or slightly convex.

Comments. It is an endemic of Corsica where it is a common species. It does not occur in xerothermous grassland unlike other members of the L. paralienus complex and prefers semi- arboreal habitats and dry open forest. Nests are in soil, under trees or under stones. 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. 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.

Figures

FIGURE 7. Head of a paratype of L. casevitzi sp. nov. from the holotype locality in dorsal view.

FIGURE 8. Mesosoma of a paratype of L. casevitzi sp. nov. from the holotype locality in lateral view.

FIGURE 9. Hind tibia of a paratype of L. casevitzi sp. nov. from the holotype locality seen in the plane of flexion.